Scientia Agricultura Sinica

Genetic Analysis of Flag Leaf Traits in Wheat Under High and Low Nitrogen

WU YaRui,LIU XiJian,YANG GuoMin,LIU HongWei,KONG WenChao,WU YongZhen,SUN Han,QIN Ran,CUI Fa,ZHAO ChunHua

Scientia Agricultura Sinica. 2022, 55(1): 1-11. doi:10.3864/j.issn.0578-1752.2022.01.001

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【Objective】 Flag leaf is an important place for wheat photosynthetic carbon fixation, which plays an important role in wheat yield. The genetic characteristics and the genetic mechanism were analyzed under high and low nitrogen for flag leaf traits of wheat, which will provide a reference for excellent plant-type breeding and high-yield breeding. 【Method】 188 recombinant inbred line (RIL) populations derived from a cross between Kenong9204 and Jing411 was used in this study, which were planted in low nitrogen (LN) and high nitrogen (HN), respectively. The flag leaf traits of 188 RILs were investigated in 6 different environments, then the genetic analysis was conducted to determine the number of genes controlling each trait, and to estimate the genetic effect value and the heritability. In addition, the relationship between flag leaf characters and yield related traits of wheat was also studied.【Result】 Under LN environment: The optimal genetic model of flag leaf length was 2MG-CE (two pairs of interaction major genes) in E3. The additive × additive epistatic interaction value was 1.098, and the heritability of major genes was 31.35%. The flag leaf length was polygenic in another LN environment. The width of flag leaf was polygenic in all the LN environment. The optimal genetic model for flag leaf area (except E5) was 2MG-CE. The additive × additive epistatic interaction value was 1.884 and the heritability of major genes was 36.7%, while it was polygenic inheritance in E5. Under HN environment: The optimal genetic model for flag leaf length (except E4) was 2MG-CE, the additive × additive epistatic interaction value was 1.133, and the heritability of major genes was 32.6%. The optimal genetic model was 2MG-ER (two pairs of recessive epistatic major genes) in E4, which the additive effect value was 1.431 and 1.108 for the first and the second major genes respectively, and the heritability of the major gene was 51.77%. The optimal genetic model for flag leaf width (except E2) was 2MG-CE, the additive × additive epistatic interaction value was 0.119, and the heritability of major genes was 37.29%, while it showed polygenic inheritance in E2. The optimal genetic model for flag leaf area was 2MG-CE, which the additive × additive epistatic interaction value was 3.067 and the heritability of the main gene was 44.42%. The genetic models of flag leaf traits were different in different environments, which the genetic model was more stable under HN than that in LN. The correlation analysis of flag leaf and yield traits showed that flag leaf traits were significantly positively correlated with grain number per spike, grain weight per spike and yield per plant, and the influence degree was different in the 6 environments. 【Conclusion】 Flag leaf traits are easily affected by environment, and the performance of flag leaf traits is different in HN and LN. Flag leaf traits exhibited different major gene inheritance and polygene inheritance in LN, while they showed major gene inheritance which controlled by two pairs of interactions genes in most of HN environment, which might be major QTLs. Yield per plant and grain weight per spike could be increased by improving flag leaf traits.

Candidate Gene Association Analysis of Maize Transcription Factors in Flowering Time

MA ShuanHong, WAN Jiong, LIANG RuiQing, ZHANG XueHai, QIU XiaoQian, MENG ShuJun, XU NingKun, LIN Yuan, DANG KunTai, WANG QiYue, ZHAO JiaWen, DING Dong, TANG JiHua

Scientia Agricultura Sinica. 2022, 55(1): 12-25. doi:10.3864/j.issn.0578-1752.2022.01.002

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【Objective】 Maize growth period traits, including flowering time, are the ones of most important in maize breeding. The advancement of heading date, silking time, and the pollen shed can ensure maize kernels fully dehydrated and thus suited to machinery harvesting. Moreover, the saved time can also leave for wheat sowing under the Maize-Wheat farming mode in Huang-Huai-Hai area. Transcription factors are important up-stream trans-action factors of gene expression regulation, which play roles in transcriptional activation or inhibition on target genes by binding to and driving their promoters. It is of great significance to analyze the regulatory effects of transcription factors on maize flowering time at the whole genome scale, it is also emergence to obtain the maize transcription factor haplotypes which associated with earlier flowering and higher yield. The haplotypes, or the haplotype combinations, will be served as excellent germplasm resources for maize breeding. 【Method】 In this study, candidate gene association analysis was performed to analyze maize flowering time related transcription factors and significant SNPs. DAP-seq was carried out to obtain the binding sites and down-stream genes of the key transcription factors. Followed by GO analysis on the down-stream genes to explore the transcription factor dependent gene expression regulatory network. 【Result】 There are 75, 75, and 128 significant SNPs detected in combinations of the traits Silking time and Heading date, the traits Silking time and Pollen shed, and the traits Heading date and Pollen shed, respectively. Altogether, there are 58 significant SNPs associated with all three flowering time traits. These results suggest that the three traits of flowering time may be regulated by the same transcription factors. Flowering time associated transcription factor genes that containing 3 or more significant SNPs were selected for DAP-seq to capture the key motifs and down-stream genes. Down-stream genes bound by flowering time associated transcription factors are significantly enriched in transcription factor activity, DNA binding, RNA binding, organonitrogen compound metabolic process, reproduction-related developmental processes, etc. Different transcription factors have co-regulated downstream genes related to flowering time. The key regulatory transcription factors for flowering time traits are ARF, MYB and NAC. Through haplotype analysis, the optimal TF haplotype combination that shows earlier flowering and no negative impact on yield was selected. 【Conclusion】 In this research, through candidate gene association and DAP-seq, the regulatory network of transcription factors on the flowering time related agronomic traits were established at the whole genome scale. The optimal haplotype combination of transcription factors that not only advances the flowering time, but also has no negative impact on yield was selected for further use in maize breeding.

Construction and Application of Detection Model for Amylose and Amylopectin Content in Sorghum Grains Based on Near Infrared Spectroscopy

ZHANG BeiJu,CHEN SongShu,LI KuiYin,LI LuHua,XU RuHong,AN Chang,XIONG FuMin,ZHANG Yan,DONG LiLi,REN MingJian

Scientia Agricultura Sinica. 2022, 55(1): 26-35. doi:10.3864/j.issn.0578-1752.2022.01.003

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【Objective】 Sorghum is one of the main raw materials for wine making and feed. The ratio of amylose content to amylopectin content in its grains is closely related to liquor quality and feed quality. Traditional chemical detection methods of sorghum components are no longer suitable for high-throughput testing. Modified PLS is used to perform spectral preprocessing, score processing and result monitoring on the near-infrared spectra of sorghum samples to establish sorghum grain amylose and amylopectin. The prediction model of amylose content aims to obtain a fast, efficient and low-cost detection method, laying the foundation for genetic improvement and quality analysis of sorghum. 【Method】 From 450 sorghum resources, 112 representative varieties were selected as calibration set and verification set. The chemical values of amylose and amylopectin content in 112 sorghum varieties were measured, and near-infrared spectra with wavelengths of 850-1 048 nm were collected, and the spectrum was scanned data matrix and chemical data calculated score (PL1) processing and interpreting the differences between the spectra, and eliminating abnormal species with Global H (GH) greater than 3 to reduce modeling errors. Modified PLS regression technology is used for modeling, and different calibration models are established through different scattering processing and derivative processing methods. Determine the best model according to the cross-validation standard deviation (SECV) and cross-validation correlation coefficient (1-VR), and perform result monitoring and non-parametric testing to evaluate the predictive performance of the model.【Result】 The near-infrared prediction model SECV of amylose is 2.7732, 1-VR is 0.9503, and the correlation coefficient (RSQ) is 0.9688. Bias=0.229<2.7732(SECV)×0.6, that is, the deviation (Bias) is less than 0.6 times of the calibration model SECV; the predicted standard deviation (SEP)=1.266<2.7732(SECV)×1.3=3.60516, that is, the SEP is less than the calibration. The model SECV is 1.3 times, 11.01(SD)-10.81(SD)=0.2<11.02(SD)×0.2=2.204, that is, the difference between the standard deviation (SD) of the chemical data and the near-infrared prediction data is less than 20% of the chemical data SD. The near-infrared prediction model SECV of amylopectin is 1.7516, 1-VR is 0.8818, and RSQ is 0.9127. Bias=-0.014<1.7516(SECV)×0.6 means that Bias is less than 0.6 times of SECV of calibration model, SEP=1.316<1.7516(SECV)×1.3=2.2708 means SEP is less than 1.3 times of SECV of calibration model, 5.30-5.29=0.01<5.30×0.2=1.06, that is, the difference between the chemical data and the near-infrared prediction data SD is less than 20% of the chemical data SD. Using 30 sorghum grains outside the model to conduct a two-pair sample non-parametric test on the validity of the model, the results showed that the difference between the measured and predicted values of amylose content and amylopectin content was not significant (P=0.262>0.05; P=0.992>0.05).【Conclusion】 The established near-infrared model has high accuracy and good stability, can accurately and quickly detect the content of amylose and amylopectin in sorghum, and can be used for the genetic improvement of sorghum and the detection of sorghum quality.

Effects of Sowing Dates on Eating Quality of Different Indica Hybrid Rice in the Sub-Suitable Region of Ratoon Rice

LI Bo,YANG Fan,QIN Qin,ZHONG XiaoYuan,LI QiuPing,ZENG YuLing,LU Hui,CHEN Yong,WANG Li,TAO YouFeng,LI Juan,FENG BingLiang,REN WanJun,DENG Fei

Scientia Agricultura Sinica. 2022, 55(1): 36-50. doi:10.3864/j.issn.0578-1752.2022.01.004

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【Objective】 The aim of this study was to clarify the effects of sowing dates on the eating quality of indica hybrid rice in sub-suitable area of ratoon rice, so as to provide the theoretical and practical basis for the adjustment of planting structure and high quality cultivation in sub-suitable area of ratoon rice.【Method】 Field sowing dates experiments were conducted in the two sub-suitable area of ratoon rice in Sichuan (Longchang and Qianwei) with three indica hybrid rice varieties, namely Chuanyou 6203, Yixiangyou 2115, and Fyou 498. The effects of sowing dates on eating quality of indica hybrid rice in sub-suitable area of ratoon rice were studied by the determination of amylose and protein content, and the analysis of rice aroma, appearance, palatability, flavor, cold rice texture, as well as comprehensive score following the national standard sensory evaluation method.【Result】 (1) The eating quality of indica hybrid rice was affected by location, sowing date, variety, and their interactions. (2) The effects of sowing dates on the eating quality of different rice varieties were different to the study locations in the sub-suitable area of ratoon rice. The amylose content, protein content, palatability, taste, and flavor in the two study years, as well as the palatability and comprehensive score in 2018 in Longchang were significantly lower than that in Qianwei. Compared wtih the conventional sowing date, suitably delayed sowing date could improve the amylose content, palatability, and taste of rice by decreasing the temperature stress during grain filling stage, which resulted in the increase in comprehensive score of rice. This made the taste quality of rice closer to that of the ratoon rice. (3) Correlation analysis showed that amylose content, palatability, and flavor had significantly or extremely significantly negative correlation with the average daily maximum, minimum, and average temperatures, and sunshine hours from the 20 days after heading to mature stage, while comprehensive score was significantly and negatively related to the average daily minimum temperature from the 20 days after heading to mature stage. (4) The GGE-bioplot double plot analysis showed that the third sowing date in Longchang and second and third sowing dates in Qianwei had higher score and better stability of comprehensive score. 【Conclusion】 On the basis of ensuring the yield of rice, Longchang ecological point was sowed at the third sowing date (early May), and Qianwei ecological point was sowed at the second sowing date (March 20-March 25), which could avoid high temperature stress during the grain filling period of rice and improve the eating quality of hybrid indica rice. Furthermore, the selection of high-quality eating varieties as Yixiangyou 2115 and Chuanyou 6203 with suitable delaying of sowing date possessed higher taste quality in the sub-suitable area of ratoon rice.

Effects of 1.5℃ Field Warming on Rice Yield and Quality in High Latitude Planting Area

DENG AiXing,LIU YouHong,MENG Ying,CHEN ChangQing,DONG WenJun,LI GeXing,ZHANG Jun,ZHANG WeiJian

Scientia Agricultura Sinica. 2022, 55(1): 51-60. doi:10.3864/j.issn.0578-1752.2022.01.005

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【Background】 Rice (Oryza sativa L.) is the most important cereal crop in China. An importance rice cultivation location in high latitude in China is Northeast region due to its superior production area. This region accounts for over 50% high quality japonica rice production in China. However, for nearly half a century, the annual average temperature of this region has increased by 1.1℃, making it the most obvious region of climate warming in China. 【Objective】 To ensure the continuous production of high-yielding and good quality japonica rice, it is of great significance to assess the impact of climate warming on rice yield and grain quality in the Northeast region of China. 【Method】 A 2-year field warming experiment (1.5℃) with two japonica rice cultivars (Longdao 5 and Longdao 18) employed under a free air temperature increase (FATI) facility was conducted in Harbin city, Heilongjiang province. The aim of this study was to evaluate the effects of elevated temperature (ET) on rice growth period, grain yield, milled quality, appearance quality, nutrient and cooking quality. 【Result】 The results of the study showed that the growth duration of rice under ET was reduced by 6-7 days and 4-5 days when compared with CK in 2017 and 2018, respectively. This was as a result of the shortened duration from the transplanting stage to heading stage. The average yield of Longdao 5 and Longdao 18 for the two-year increased by 5.8% and 14.4%, respectively, mainly due to the increase in effective panicle number per unit area. The ET significantly decreased amylose content in the rice grain, but varied slightly in-terms of brown rice rate, milled rice rate, head rice rate and protein content. The peak viscosity, hot paste viscosity and cool paste viscosity increased under ET, while consistence viscosity decreased. There was no significant influence of elevated temperature on setback viscosity in both Longdao 5 and Longdao 18. 【Conclusion】 Based on the lower background air temperature, increasing temperature by 1.5℃ in the high latitude region of Northeast promoted japonica rice yield and cooking quality, however, the continued warming would increase the uncertainties of rice quality variation in the future.

Effects of Different Configurations on Nitrogen Uptake and Utilization Characteristics of Maize-Peanut Intercropping System in West Liaoning

FENG Chen,HUANG Bo,FENG LiangShan,ZHENG JiaMing,BAI Wei,DU GuiJuan,XIANG WuYan,CAI Qian,ZHANG Zhe,SUN ZhanXiang

Scientia Agricultura Sinica. 2022, 55(1): 61-73. doi:10.3864/j.issn.0578-1752.2022.01.006

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【Objective】 This study clarified the nitrogen absorption and utilization characteristics in maize-peanut intercropping by studying the nitrogen concentration, nitrogen uptake, nodulation of peanut and nitrogen distribution under different configurations, which provided a basis for regional screening and application of nitrogen efficient model of maize-peanut intercropping system. 【Method】 A field study with 10 treatments was conducted in National Agricultural Experimental Station for Agricultural Environment in Fuxin in 2015 and 2016, including four cropping systems, such as sole maize (M), sole peanut (P), intercropping system of 2 rows maize and 4 rows peanut (M2P4), and intercropping system of 4 rows maize and 4 rows peanut (M4P4). Each maize treatment included three maize planting densities (6, 9 and 12 plants/m²). The characteristics and advantages of nitrogen uptake and utilization in maize-peanut intercropping system with different configurations (row proportion and maize density) were analyzed. 【Result】 Compared with monocropping, the change of nitrogen concentration in maize and peanut plants was not significant, the yield and nitrogen yield of maize and peanut in intercropping was lower than that in monocropping due to the different proportion of land occupy, and was consistent with intercropping biomass performance. Maize-peanut intercropping significantly increased the system nitrogen uptake, nitrogen uptake equivalent ratio (NER)>1, which was mainly due to the nutrient absorption advantage of maize (pNER_m was 0.63-0.80). The NER was increased with the row and density of maize increasing. The nitrogen uptake under M4P4 pattern (NER 1.06-1.22) was significantly higher than that under M2P4 pattern (NER 1.0-1.06). In maize-peanut intercropping system, maize was more competitive than peanut (A_mp>0), and the competitive ability to absorb nitrogen was also stronger (CR_mp>1), and M4P4 pattern and maize densification could enhance maize competition for nitrogen and increase the advantage of nitrogen uptake (△NU>0) and the contribution of intercropping nutrients to yield. Intercropping with maize could promote nodule formation of peanut. The number of nodule, weight of nodule per plant and weight per nodule of peanut under M4P4 pattern were higher than those under M2P4 pattern, and medium and low planting density treatments were better for nodulation. The soil available nitrogen content (N_min) in the intercropping system was higher in the peanut strip than in the maize strip, and the N_min in the sole peanut strip was higher than that in the intercropped peanut strip, while the N_min in the sole maize strip was lower than that in the intercropped maize strip. 【Conclusion】 Maize-peanut intercropping could significantly improve the nitrogen uptake and utilization in the system, and maize contributed more to the system nitrogen uptake. Moderate increase of maize row ratio and density was beneficial to increase the nitrogen uptake equivalent ratio, enhance maize competition for nitrogen nutrition, and the contribution of intercropping nutrients to yield. In this study, M4P4-6 and M4P4-8 were the better pattern for maize-peanut intercropping. The promotion of maize-peanut intercropping on dry matter and peanut biological nitrogen fixation, as well as the competitive ability of maize to absorb nitrogen, were the important reasons for the advantages of maize-peanut intercropping in nitrogen utilization.

Detection of ‘Candidatus Liberibacter asiaticus’ by Membrane Adsorption Method Combined with Visual Loop-Mediated Isothermal Amplification

LI ZhenXi,LI WenTing,HUANG JiaQuan,ZHENG Zheng,XU MeiRong,DENG XiaoLing

Scientia Agricultura Sinica. 2022, 55(1): 74-84. doi:10.3864/j.issn.0578-1752.2022.01.007

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【Background】 Citrus Huanglongbing (HLB) is a citrus disease caused by ‘Candidatus Liberibacter asiaticus’ (CLas). The main approaches to control HLB include plant quarantine, establishing disease-free nurseries, removing disease trees, and concentrating on large area joint control of citrus psyllids (Diaphorina citri). The first three methods all rely on accurate HLB diagnosis techniques.【Objective】 The objective of this study is to establishment of a rapid and handy field/laboratory nucleic acid detection method of CLas using loop-mediated isothermal amplification (LAMP) combined with membrane adsorption rapid DNA extraction and Gelgreen fluorescence dye visualization.【Method】 The LAMP primers were designed using the β-operon and the prophage DNA polymerase gene of CLas as templates, including outer primer F3/B3, inner primer FIP/BIP, loop primer LoopF/LoopB and stem primer StemF/StemB. The LAMP primer set was optimized by setting different dosage combinations for loop primers and stem primers to determine the appropriate primer concentration. A total of 188 field citrus leaves were detected using the optimized LAMP primer set, and the receiver operating characteristic (ROC) curves were constructed to analyze the accuracy of real-time fluorescent LAMP (qLAMP) for CLas detection. The qLAMP premixed reaction solution was dried in two steps at room temperature, storage temperature (4, 25 and 35℃) and storage time (1, 2 and 4 weeks) were also set to assess the enzyme activity stability of the dry LAMP reagent. Using dry LAMP reagent, combined with membrane adsorption rapid DNA extraction technique in this study, 71 citrus leaf samples and 35 citrus fruit samples collected in the field were detected, while the detection results of real-time fluorescent quantitative (qPCR) were used as controls to compare the coincidence rates of the two detection methods.【Result】 The addition of loop primer, stem primer or increasing their concentrations in LAMP reaction could promote the increase of reaction rate, and the addition of both loop primer and stem primer at a final concentration of 1.6 μmol·L^-1 could further improve the reaction rate. The reaction activity of LAMP premix could be maintained unchanged by two-step drying at different temperatures for 1-4 weeks, indicating that the two-step drying LAMP reagent prepared in this experiment had good detection performance and fair stability at low and room temperatures, and only at 35℃ storage would slightly increase the reaction time of LAMP reagent. Using 0.1 μm pore size nylon membrane instead of cellulose filter paper as nucleic acid adsorption material could improve the sensitivity of rapid diagnostic techniques. The overall accuracy of rapid DNA diagnosis for HLB established by combining rapid DNA extraction and visual LAMP was high, and the lowest detectable plasmid concentration was 10² copies/μL. The diagnostic results of this method were not significantly different from those of qPCR by paired Chi-square test. The visual LAMP rapid detection was less cost and time-consuming than routine detection, and visual LAMP rapid detection required no expensive instruments such as centrifuges and PCR instruments, requiring only a 65℃ thermostatic device.【Conclusion】 The rapid DNA detection method for CLas established in this study has low cost and can observe detection results in 30 min, easy to operate and high accuracy, which can replace qPCR for rapid identification of HLB in the field.

Effects of Agricultural Landscape on the Population Dynamic of Grapholitha molesta Adults in Apple Orchards in Southern Xinjiang

SONG BoWen,YANG Long,PAN YunFei,LI HaiQiang,LI Hao,FENG HongZu,LU YanHui

Scientia Agricultura Sinica. 2022, 55(1): 85-95. doi:10.3864/j.issn.0578-1752.2022.01.008

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【Objective】 Grapholitha molesta is an important fruit pest in apple orchards in southern Xinjiang, which seriously affects the yield and quality of apple. The influence of agricultural landscape configuration and composition on the population number of G. molesta in apple orchards was clarified to provide a theoretical basis for the rational design of agricultural landscape that reduces the harm of G. molesta under the adjustment of cropping structure in southern Xinjiang.【Method】 A total of 50 apple orchards were selected as experimental sites in Aksu area from 2017 to 2020. The landscape composition within a radius of 2.0 km of each site was investigated. The insect sex pheromone traps were used to investigate the population dynamics of G. molesta adult. Regression models of Shannon diversity index (SHDI), perimeter area ratio (PARA), edge density (ED), and the area proportion of non-crop habitats, host crops and other (non-host) crops in landscapes at four scales (0.5, 1.0, 1.5 and 2.0 km) were fitted with the number of adults of the first, second and third generations in apple orchards.【Result】 In the study area, the proportion of host crops was highest (45.7%-55.0%), followed by other crops (18.2%-21.0%) and non-crop habitats (13.5%-19.7%). There was a negative correlation between the abundance of the first generation adult and the proportion of other crops at 2.0 km scale (P=0.062). The abundance of the second generation was negatively correlated with other crops at four scales (0.5 km, P<0.001; 1.0 km, P<0.001; 1.5 km, P=0.028; 2.0 km, P=0.043), negatively correlated with the proportion of host crops at 1.0 and 1.5 km scales (1.0 km, P=0.026; 1.5 km, P=0.048), negatively correlated with the proportion of non-crop habitats at 0.5 and 1.0 km scales (0.5 km, P=0.023; 1.0 km, P=0.019), but positively correlated with Shannon diversity index (SHDI) (0.5 km, P<0.001; 1.0 km, P=0.005). The abundance of the third generation was negatively correlated with the proportion of non-crop habitats at 0.5 km scale (P<0.001).【Conclusion】 Increasing the proportion of host crops, other crops, and non-crop habitats within agricultural landscape decreased the occurrence of G. molesta in apple orchards. However, landscape diversity (Shannon diversity index) promoted the population number of G. molesta. Therefore, increasing the area of the other crops and non-crop habitats coupled with no mixed planting of host crops in landscapes could be beneficial to the management of G. molesta.

Influence of Typical Rotation Systems on Soil Phosphorus Availability Under Different Fertilization Strategies

LI ShuaiShuai, GUO JunJie, LIU WenBo, HAN ChunLong, JIA HaiFei, LING Ning, GUO ShiWei

Scientia Agricultura Sinica. 2022, 55(1): 96-110. doi:10.3864/j.issn.0578-1752.2022.01.009

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【Objective】 In order to provide a scientific basis for the efficient utilization of phosphorus in farmland, the effects of different rotation systems on the availability of soil phosphorus were explored to evaluate the potential of soil phosphorus activation in different crop rotation systems. 【Method】 The experiment was conducted at Rugao Institute of Agricultural Sciences, Jiangsu Province from 2018 to 2020. Four paddy-upland rotation systems in the experiment included rice-wheat (R-W), rice-oilseed rape (R-O), rice-cabbage (R-C), and rice-fallow (R-F) rotation. Three fertilization treatments under each rotation system were applied, including no fertilization treatment (CK), no phosphate treatment (NK), and NPK fertilization treatment (NPK). The variation patterns and main influencing factors of soil phosphorus balance and availability under different paddy and upland rotation systems were clarified by analyzing the phosphorus uptake by aboveground crops, soil phosphorus fraction contents, soil microbial biomass and soil alkaline phosphatase activity under different phosphorus application conditions in dry season and rice season maturity. 【Result】 The severe imbalance of soil phosphorus under NK treatment resulted in differences in the supplement of soil available phosphorus in different rotation systems. Under NK treatment, R-O rotation could maintain a higher phosphorus output and promote the replenishment of soil available phosphorus. Specifically, the relative content of soil labile phosphorus in R-O rotation in dry season under NK treatment was 5.7%-7.3% lower than that in other rotations, and the relative content of soil moderately labile phosphorus and stable phosphorus were 4.2%-6.4% and 0.9%-1.9% higher than that in other rotations, respectively. However, the relative content of soil moderately labile phosphorus in R-O rotations under NK treatment in rice season was 0.5%-3.0% higher than that under other rotations, and the soil labile phosphorus and stable phosphorus were 0-1.5% and 0.2%-2.3% lower than that under other rotations, respectively. Under NK treatment, the soil microbial biomass C/P ratios of R-O rotation was relatively small in both dry season and rice season, and it was significantly lower than that under R-W rotation in rice season. The soil microbial biomass N/P ratios also had a similar trend. But the soil alkaline phosphatase activity of R-O rotation maintained a high level in both dry season and rice season. The path analysis model showed that the phosphorus accumulation (-0.53) and the soil alkaline phosphatase (-0.51) had the most contribution to the soil available phosphorus in dry season and rice season, respectively. 【Conclusion】 When the soil phosphorus was relatively imbalance, the rice-oilseed rape rotation released more alkaline phosphatase in dry season and regulated the soil microbial biomass C/P ratio in rice season, which was conducive to promoting the activation of the non-labile phosphorus by microorganisms to supplement the labile phosphorus, so as to ensure the relative stable of soil available phosphorus content without affecting phosphorus output.

Phosphorus Availability and Transformation of Inorganic Phosphorus Forms Under Different Organic Carbon Levels in a Tier Soil

LU Peng,LI WenHai,NIU JinCan,BATBAYAR Javkhlan,ZHANG ShuLan,YANG XueYun

Scientia Agricultura Sinica. 2022, 55(1): 111-122. doi:10.3864/j.issn.0578-1752.2022.01.010

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【Objective】 The influence of organic carbon on the contents and transformation of soil in organic phosphorus fractions were investigated, which can help to formulate soil managemental strategies whereby to improve phosphorus use efficiency in tier soil.【Method】 The soil samples were collected and selected with a gradient of organic carbon levels but similar in Olsen-P (ranges from 17.41 mg·kg^-1to 18.72 mg·kg^-1) under winter wheat summer maize cropping in the Guanzhong Plain of Shaanxi Province. The organic carbon contents of the selected soil samples were 6.38, 8.34, 10.17, 11.95, 13.64 and 15.74 g·kg^-1, respectively. Then the soil inorganic phosphorus fractions (dicalcium phosphate (Ca₂-P), octa-calcium phosphate (Ca₈-P), apatite (Ca₁₀-P), aluminum bounded phosphate (Al-P), iron bounded phosphate (Fe-P) and occluded phosphate (O-P)) were analyzed with the phosphorus fractionation procedure proposed by Chang & Jackson and modified by Jiang and Gu.【Result】 The results showed that organic carbon played an important role in transformation of soil inorganic phosphorus in the winter wheat-summer maize cropping in Guanzhong Plain of Shaanxi Province. The soil Ca₂-P, Ca₈-P, Al-P, Fe-P, O-P fractions, moderately labile P (Ca₈-P, Al-P and Fe-P), and stable P (O-P and Ca₁₀-P) pools were increased significantly and linearly with increasing soil organic carbon, whereas Ca₁₀-P remained unchanged. The relative contents of labile-P (Ca₂-P), moderately labile P (mainly Al-P) were significantly and positively correlated with SOC content, but stable P (mainly Ca₁₀-P) showed significant negative correlation with SOC. Soil Olsen-P increased significantly and linearly with increasing stable P.【Conclusion】 Under the similar soil Olsen-P and total phosphorus conditions, soil organic carbon improved the availability of soil phosphorus mainly through promoting the conversion of stable P to moderately labile P and labile P in the soil, increasing the ratio of available phosphorus to inorganic phosphorus, and improving the availability of soil phosphorus. The results implied that improvement of soil fertility (SOC) could promote the activation and utilization of legacy phosphorus in soil.

Effects of Fertilization Methods on Ammonia Volatilization from Vegetable Field Under Greenhouse Cultivation

WANG Cong,SUN HuiFeng,XU ChunHua,WANG ZhanFu,ZHANG JiNing,ZHANG XianXian,CHEN ChunHong,ZHOU Sheng

Scientia Agricultura Sinica. 2022, 55(1): 123-133. doi:10.3864/j.issn.0578-1752.2022.01.011

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【Objective】 The massive ammonia (NH₃) volatilization from excessive nitrogen (N) fertilization is a common issue in greenhouse cultivated vegetable production in China. To alleviate this problem, a field experiment was conducted to study the effects of different fertilization methods on NH₃ volatilization of greenhouse vegetable fields.【Method】 The study was carried out with 6 fertilization treatments via one-time basal fertilization and two-time topdressings, including N fertilizer-blank treatment (Control), conventional fertilization treatment (CF), 20% N-reduced slow-release fertilizer treatment (SF), 20% N-reduced organic fertilizer treatment (OF), 20% N-reduced microbial fertilizer treatment (MF) and integrated management of water and fertilizer treatment (IM). Except for the Control treatment, an identical application ratio of N, P and K fertilizers was employed to each treatment throughout the whole vegetable growing season. The NH₃ volatilization fluxes under different fertilization methods were observed by using venting absorption method. The potential influencing factors of NH₃ volatilization were also investigated synchronously.【Result】 The dynamics of NH₃ volatilization under different fertilization treatments were similar, and the occurrence of the peaks of NH₃ flux was highly associated with fertilization time. During basal fertilization period, for the most of treatments, the NH₃ fluxes peaks appeared 3-days after the application of basal fertilizer, while it was only 1-day under IM treatment. The maximum fluxes of NH₃ ranged from 0.12 to 0.26 kg NH₃·hm^-2·h^-1 during basal fertilization period. The occurrence of the peaks of NH₃ fluxes were ahead by 1-2 days during topdressing periods. The maximum fluxes of NH₃ volatilization were 0.08-0.19 kg NH₃·hm^-2·h^-1 during the first topdressing period, and 0.13-0.18 kg NH₃·hm^-2·h^-1 during second topdressing period. Significant differences were found among different fertilization treatments in the seasonal cumulative NH₃ volatilizations. The seasonal cumulative NH₃ volatilizations in the decreasing order of different treatments were CF, MF, OF, SF, IM, Control. Compare with CF treatment, the treatments of SF and IM markedly reduced NH₃ volatilization from greenhouse vegetable field by 24.2% and 42.4% (P<0.05), and reduced by 10.1% and 8.3% (P>0.05) under MF and OF treatments, respectively. The NH₃ volatilization-induced N losses in the decreasing order of different treatments were MF, OF, CF, SF, IM. Compare with the rest of the applied treatments, the IM treatment consistently showed lower NH₃-N loss rate during the whole season. However, the NH₃-N loss rates under MF and OF treatments were different during basal fertilization and topdressing periods. In the basal fertilization period, the MF and OF treatments showed lower NH₃-N loss rates compare with CF treatment, however, during topdressing period, the NH₃-N loss rates under MF and OF treatments were higher than that under CF treatment. 【Conclusion】 Compare with CF treatment, both of the SF and IM treatments could significantly reduce the NH₃ volatilization that derived from applied N fertilizer. The IM treatment reduced NH₃-N-induced N fertilizer loss in both basal fertilization and topdressing periods, while the SF treatment mainly reduced the NH₃ volatilization during basal fertilization period. On balance, both the application of slow-release fertilizer and the technique of integrated management of water and fertilizer were the effective ways in the reduction of NH₃ volatilization from greenhouse vegetable field, and were worthy for recommendation.

Transcriptome Analysis of Genes Involved in ABA-Induced Anthocyanin Accumulation in Grape

XU XianBin,GENG XiaoYue,LI Hui,SUN LiJuan,ZHENG Huan,TAO JianMin

Scientia Agricultura Sinica. 2022, 55(1): 134-151. doi:10.3864/j.issn.0578-1752.2022.01.012

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【Objective】 The aim of this study was to analyze the genes involved in the regulation of ABA induced grape coloring, and to explore the molecular mechanism of ABA induced anthocyanin accumulation in grape. 【Method】 In present study, Benibalado was used as the experimental material. In the early stage of veraison, the grape clusters were treated with 300 mg·L^-1ABA, water treated as control. The grape phenotypes were observed and anthocyanins were determined by UPLC-MS. The mechanism of ABA promoting anthocyanin accumulation was analyzed by transcriptome sequencing. 【Result】 After 3 days of exogenous ABA treatment, the grape berries were obviously colored, and the variety and content of anthocyanins were also increased. Among them, Peonidin 3-O-glucoside and Malvidin 3-O-glucoside increased most significantly. By KEGG enrichment analysis, 11 DEGs related to ABA signaling and 52 DEGs that related to anthocyanin biosynthesis, and transportation were identified, all of which were up-regulated. After exogenous ABA treatment, the DEGs from RNA-seq were searched by using BLAST against the grape TF database, and 297 transcription factors were identified. Through the further analyzing of the expression patterns of identified TFs, 15 members of MYB, bHLH, bZIP, NAC, Dof, and HD-ZIP families were observed to regulate anthocyanin biosynthesis. The analyzing of cis-acting elements in promoters showed that ABREs were identified in most of the promoters. The accuracy of RNA-seq was validated by qRT-PCR analysis of some candidate genes. 【Conclusion】 Overall, ABA promoting anthocyanin accumulation in grape was a complex process, including 11 DEGs related to ABA signal transduction, 52 DEGs that related to anthocyanin biosynthesis, modification and transportation, 15 transcription factors. This study provided a basis for revealing the molecular mechanism of ABA promoting anthocyanin accumulation in grape fruits.

Identification of Co-Expression Gene Related to Tea Plant Response to Glyphosate Based on WGCNA

GUO YongChun, WANG PengJie, JIN Shan, HOU Binghao, WANG ShuYan, ZHAO Feng, YE NaiXing

Scientia Agricultura Sinica. 2022, 55(1): 152-166. doi:10.3864/j.issn.0578-1752.2022.01.013

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【Objective】 This study aimed at analyzing both expression patterns and regulatory pathways of tea plants in response to glyphosate stressing, which could revealed the effect of glyphosate herbicides on tea plants at transcriptional level and identify key genes of tea plants. 【Method】 C. sinensis cv Jin-guanyin was applied as material plant. A recommended concentration of glyphosate was irrigated to test plants. The leave samples were collected at different time intervals (0, 0.25, 1, 3 and 7 d). The samples were sequenced by transcriptome, the content of shikimic acid was also quantified. The WGCNA method was used to jointly analyze transcriptome and shikimic acid content data, to identify co-expressed gene modules related to glyphosate response, and to screen out key regulatory genes. 【Result】 The content of shikimic acid in tea leaves reduced gradually during first 3 days. However, it suddenly reached a peak on the 7th day (6.99 times compared with no glyphosate treated sample). A total of 12 568 differential expression genes (DEGs) were also identified, which mainly enriched in phenylpropane, flavonoid biosynthesis and plant hormone signal transduction pathways. In addition, the glyphosate treatment induced 24, 52, 31 and 69 genes respectively which related to shikimic acid metabolism, phenylpropane, flavonoid biosynthesis and hormone signal transduction pathways. A total of 19 modules were screened out by WGCNA method. The correlation analysis of transcriptome and shikimic acid content indicated two key modules, including 2 024 and 2 305 genes, respectively. The top 50 genes with the highest connectivity in the key modules were selected for co-expression analysis, and 6 key response genes were obtained, including 2 resistance genes (SHMT and RPM), 1 drug resistance gene (PDR), 1 ion transport gene (At), 1 membrane transport gene (GPT), and 1 transcription factor gene (ERF).【Conclusion】 Glyphosate could affect downstream genes transcription of phenylpropane, flavonoid biosynthesis and hormone signal transduction pathways by interfering shikimic acid metabolism of tea plants. In addition, this study also identified two co-expression modules closely related to glyphosate response, and found that multiple potential candidate genes and transcription factors could resist glyphosate stress, such as SHMT, RPM, At, PDR, ERF and GPT.

Optimization and Mechanism of Ultrasonic-Assisted Two-Phase Extraction of Tea Saponin

DU JinTing,ZHANG Yan,LI Yan,WANG JiaJia,LIAO Na,ZHONG LiHuang,LUO BiQun,LIN Jiang

Scientia Agricultura Sinica. 2022, 55(1): 167-183. doi:10.3864/j.issn.0578-1752.2022.01.014

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【Objective】 Tea saponin is a naturally active substance with wide application prospective, and its purity is the key factor limiting its application and value. In this study, the optimal conditions for ultrasonic-assisted two-phase extraction (UAATPE) of tea saponin from camellia meal were explored, and the possible extraction mechanism was discussed in order to develop an efficient, high-purity extraction technology, so as to provide a technical guidance for high-value utilization of camellia meal. 【Method】 On the basis of the single factor experimental results, the key factors affecting the yield of tea saponin were screened by Plackett Burman design, and the extraction process was optimized by Box-Behnken design. The extraction efficiency of tea saponin using the UAATPE method was evaluated by comparing the extraction yield and purity to the traditional ethanol extraction method and water extraction method. Scanning electron microscopy (SEM) was employed to analyze the microstructure of camellia meal, and the possible mechanism of extraction by the UAATPE method was discussed. 【Result】 The key factors affecting the yield of tea saponin were mass fraction of ethanol, mass fraction of ammonium sulfate, and ultrasonic time. The process parameters optimized by Box-Behnken design were as follows: an ethanol content of 27.50% (W/W), an ammonium sulfate content of 19.60% (W/W), a liquid-solid ratio of 50﹕1, an ultrasonic time of 32 min, an ultrasonic power of 300 W and an extraction temperature of 60℃, and the yield of tea saponin at (26.21±0.54)% was achieved under the optimized conditions. Compared with the traditional method of ethanol extraction, the purity of tea saponin extracted by the UAATPE method increased by 6.57% (P<0.05), although the difference of the yield of tea saponin extracted by these two methods was not significant. Compared with the traditional method of water extraction, the yield and purity of tea saponin extracted using the UAATPE method were increased by 17.74% and 40.23%, respectively (P<0.01). The microstructure showed that owing to the effect of the camellia meal treated by the UAATPE method, the ultrasonic cavitation accelerated the tissue damage of the camellia meal, producing a large number of voids and strong surface shrinkage, which effectively promoted the release of tea saponin in the camellia meal. In the process of the UAATPE extraction, the tea saponin first entered the bottom phase with high electrical conductivity through solid-liquid extraction in the two-phase water system, and then moved to the top phase with high polarity through liquid-liquid extraction, achieving primary purification and improving the purity of tea saponin. 【Conclusion】 The UAATPE method could significantly improve the yield and purity of tea saponin, thus providing a new novel method for the efficient utilization of camellia meal.

Knockdown Goat KLF12 to Promote Subcutaneous Adipocytes Differentiation

DU Yu,WANG Yong,MENG QingYong,ZHU JiangJiang,LIN YaQiu

Scientia Agricultura Sinica. 2022, 55(1): 184-196. doi:10.3864/j.issn.0578-1752.2022.01.015

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【Background】Subcutaneous adipose tissue (SAT) under the skin is an important factor affecting the taste of meat. Exploring the molecular regulation mechanisms of SAT deposition is very important for breeding improvement and the development of animal husbandry. Krüppel-like factors 12 (KLF12) is a conserved transcription factor that evolutionarily conserved, and it was found that it could be expressed in a variety of cell types and control a wide range of cellular processes. 【Objective】 This study aimed to obtain the coding sequence (CDS) of goat KLF12 and to explore its molecular characteristics. Moreover, the study also intended to clarify the expression pattern of KLF12 in goat tissues and subcutaneous adipocytes, and to explore the role of KLF12 in goat subcutaneous preadipocytes differentiation via interference KLF12, so as to provide a theoretical basis for further research on the potential role of KLF12 in the process of fat deposition. 【Method】 In this study, the goat KLF12 CDS sequence was cloned by Reverse Transcription PCR ( RT-PCR) method, and the nucleotide sequence and amino acid sequence of goat KLF12 were analyzed on online bioinformatics analysis software. The Quantitative Real-time PCR (qRT-PCR) technology was used to detect the expression levels of KLF12 in goat heart, liver, abdominal fat, subcutaneous fat, triceps brachii, longissimus dorsi and other 14 tissues. Furthermore, the expression level of KLF12 in subcutaneous preadipocytes in different differentiation periods was investigated. Then, the goat KLF12 small interfering RNA (si-KLF12) was chemically synthesized and transfected into goat subcutaneous preadipocyte in vitro by using Lipofectamine RNAiMAX transfection reagent. Subsequently, 100 µmol·L^-1 oleic acid induced adipocyte differentiation. Oil red O and Bodipy staining methods and qRT-PCR techniques were used to clarify the effects of interference KLF12 on the accumulation of lipid droplets in subcutaneous preadipocytes and the mRNA expression levels of adipose differentiation marker genes from the perspectives of morphology and molecular biology. 【Result】 The goat KLF12 (1 315 bp) were successfully obtained, which contained an Open Reading Frame (ORF) (1 209 bp) and encoded 402 amino acids. The subcellular localization results showed that KLF12 was mainly located in the nucleus. In addition, KLF12 had no transmembrane domain and signal peptide but 3 typical zinc finger domains (ZnF_C2H2) at amino acids 317-341, 347-371 and 377-399. Tissue expression profile showed that the expression level of KLF12 in goats’ heart and spleen were significantly higher than that in other tissues (P<0.01). Moreover, during subcutaneous preadipocytes differentiation, the expression level of KLF12 was peaked at 60 h. After transfection of si-KLF12 into goat subcutaneous preadipocytes, the results of oil red O and Bodipy saining showed that accumulation of lipid droplets in adipocytes were significantly increased. At the same time, the results of qRT-PCR showed that the expression levels of key adipogenic regulatory genes like lipoprotein lipase (LPL) and peroxisome proliferator-activated receptor γ (PPARγ) were significantly increased (P<0.05), while the expression level of preadipocyte growth factor (Pref-1) was extremely significantly reduced (P<0.01). Combined with the morphological observation results and the changes in the expression levels of key adipogenic regulatory genes, it was speculated that KLF12 played a negative regulatory role in the differentiation of subcutaneous adipocytes. 【Conclusion】 By investigating the basic molecular biological characteristics and its expression pattern between tissues and cells of goat KLF12 and analyzing the potential regulatory effects of KLF12 on differentiation process of goat subcutaneous adipocytes, the results suggested that KLF12 played a negative role in goats subcutaneous preadipocytes differentiation, and this effect achieved by regulating LPL, PPARγ and Pref-1, which laid a foundation for further exploring the molecular mechanism of KLF12 in regulating the differentiation of adipocytes.

Development and Application of a Real-Time Fluorescent RPA Diagnostic Assay for African Swine Fever

ZHANG JingYuan,MIAO FaMing,CHEN Teng,LI Min,HU RongLiang

Scientia Agricultura Sinica. 2022, 55(1): 197-207. doi:10.3864/j.issn.0578-1752.2022.01.016

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【Objective】 After the first outbreak of African Swine Fever (ASF) in Shenyang, China in 2018, it has rapidly spread to the whole country, severely hitting the pig industry. This study aimed to establish an optimized nucleic acid testing technique for African Swine Fever Virus (ASFV), so as to provide a fast and accurate method for early diagnosis and accurate treatment of ASF outbreaks. 【Method】 Appropriate primers and probes were designed and screened for the conserved gene B646L (p72) of ASFV, and a real-time fluorescent RPA assay based on recombinase polymerase amplification (RPA) was established. The reaction system, reaction conditions and sample treatment steps were optimized. Specificity and sensitivity of the optimized detection method were evaluated by using quality controls. In addition, 1 009 clinical samples were tested by the optimized real-time RPA, after which the results were further confirmed by the real time PCR recommended by OIE and through virus isolation. 【Result】 A pair of primers-probe combinations was successfully screened, and a real-time fluorescence RPA for detection of ASFV p72 gene was developed. The total volume of optimized reaction system was 25 μL. The reaction conditions were set as 39℃ 10 s, 39℃ 20 s, 40 cycles on the fluorescence quantitative PCR instrument, and the whole amplification reaction needs about 20 min. The analysis method at room temperature could replace the traditional nucleic acid extraction method, thus the whole process of sample treatment, nucleic acid amplification and result reading could be completed in 30 min. Specific evaluation showed that the real-time RPA was negative for porcine parvovirus (PPV), pseudorabies virus (PRV), circovirus type1/2 (PCV1/2), classical swine fever virus (CSFV) and porcine reproductive and respiratory syndrome virus (PRRSV); the sensitivity evaluation showed that the assay could detect type I/II/IX ASFV samples, and could detect 10 copies/μL of ASFV positive simulated blood samples and 1﹕10^3.0 dilution of positive clinical samples, which was as sensitive as the OIE-recommended qPCR method. Seventeen out of 1 009 clinical samples were tested positive using the real-time RPA, with the same results as by qPCR, 17 positive cultures were obtained from virus isolation. 【Conclusion】 A real-time RPA diagnostic method for ASF was developed, which was proved to be simple, less time consuming with high sensitivity and specificity, providing a new, simple, specific and rapid diagnostic method for ASF.

Identification and Analysis of MicroRNAs in the Larval Gut of Apis cerana cerana

FENG RuiRong,FU ZhongMin,DU Yu,ZHANG WenDe,FAN XiaoXue,WANG HaiPeng,WAN JieQi,ZHOU ZiYu,KANG YuXin,CHEN DaFu,GUO Rui,SHI PeiYing

Scientia Agricultura Sinica. 2022, 55(1): 208-218. doi:10.3864/j.issn.0578-1752.2022.01.017

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【Objective】 In this study, transcriptome-wide identification and analysis of miRNAs in the larval guts of Apis cerana cerana was conducted using a combination of small RNA-seq (sRNA-seq) technology and bioinformatic method, aiming to enrich the information of A. c. cerana miRNAs and offer a basis for further investigation of miRNA-regulated molecular mechanism underlying A. c. cerana larval gut development.【Method】 Gut samples of A. c. cerana 4-, 5-, and 6-day-old larvae (Ac1, Ac2, and Ac3 ) were sequenced using sRNA-seq technology, and clean tags were obtained after quality control. By using Blast tool, clean tags were continuously mapped to Apis cerana genome and miRBase database to identify known miRNAs and novel miRNAs. TPM method was used to perform normalization of miRNAs’ expression. The ratio of sRNAs, length distribution of miRNAs and first base bias were calculated with GraphPad Prism 7 software. Using related software, target mRNAs of above-mentioned miRNAs were predicted followed by GO and KEGG database annotation. Further, regulatory networks between genes associated with development and immune-related pathways and corresponding target miRNAs were constructed and analyzed, followed by visualization of regulatory networks with Cytoscape software. The authenticity of miRNA expression and sequence was verified by using Stem-loop RT-PCR, molecular cloning and Sanger sequencing.【Result】 In total, 371 known miRNAs and 64 novel ones of A. c. cerana were identified; their length was distributed among 18-25 nt, and the first base had an U bias. The aforementioned miRNAs could target 14 750 mRNAs, involving 2 270 GO terms such as ion binding, metal ion binding, membrane, membrane part and single-organism process, as well as 332 KEGG pathways including endocytosis, apoptosis, mTOR signaling pathway, RNA transport and insect hormone biosynthesis. Further investigation suggested that 156 miRNAs could target 67 genes relative to development-associated pathways such as Wnt, Hippo, Notch and mTOR signaling pathways, while 145 miRNAs could target 21 genes relevant to immune-associated pathways such as Toll, Imd/JNK, Jak-STAT signaling pathways and antimicrobial effectors. Stem-loop RT-PCR result indicated that specific fragments with expected sizes could be amplified from miR-8-y, miR-9-z, miR-14-y, miR-281-y, miR-283-x and miR-306-x; Sanger sequencing result demonstrated that sequences of above-mentioned six miRNAs were in accordance with those in deep sequencing result.【Conclusion】 Our findings provide number, structural characteristics and expression profile of A. c. cerana miRNAs, and unraveled that miRNAs in A. c. cerana larval gut potentially regulate a lot of life processes and cellular activities, part of miRNAs can participate in regulation of development-related and immune-related pathways by targeting corresponding mRNAs.

Multi-Locus Genome-Wide Association Analysis of Yield-Related Traits and Candidate Gene Prediction in Sesame (Sesamum indicum L.)

CUI ChengQi, LIU YanYang, JIANG XiaoLin, SUN ZhiYu, DU ZhenWei, WU Ke, MEI HongXian, ZHENG YongZhan

Scientia Agricultura Sinica. 2022, 55(1): 219-232. doi:10.3864/j.issn.0578-1752.2022.01.018

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【Objective】 Genome-wide association studies (GWAS) were performed using multi-locus random-SNP-effect mixed linear (mrMLM) model to identify the significantly associated SNPs and candidate genes with yield traits, and lay a foundation for molecular marker-assisted selection breeding for sesame high yield.【Method】 In this study, 363 diverse sesame lines were assembled into an association-mapping panel. Eight yield-related traits, including seed yield per plant, capsule number per plant, seed number per capsule, 1000-seed weight, plant height, capsule axis length, first capsule height and apparent harvest index, were investigated. Genome-wide association studies were performed using mrMLM to detect significantly associated SNPs and predict important candidate genes related to yield traits.【Result】 Eight yield-related traits measured in four environments exhibited extensive phenotypic variation with 1.63%-17.29% of phenotypic variation coefficients. The seed yield per plant was positively correlated with capsule number per plant, plant height, capsule axis length, and apparent harvest index respectively. Analysis of variance indicated that significant variations were observed across environment, genotype, and the genotype × environment interaction. GWAS were performed and a total of 210 SNPs were detected for yield traits. Among these SNPs, 47, 35, 35, 53, and 75 SNPs were detected in 2018NY, 2019NY, 2018PY, 2019PY and BLUP, explaining 1.63%-17.29%, 1.94%-11.90%, 2.15%-15.90%, 1.25%-11.13% and 1.44%-13.58% of phenotypic variation, respectively. These 210 SNPs corresponded to 175 loci, and 10 loci were detected in more than 3 environments. A total of 214 candidate genes were identified, including 156 genes involved in metabolism, biological regulation, and developmental and growth process. Among these genes, 4 genes were selected as important candidate genes. SIN_1006338, encoding 1-aminocyclopropane-1-carboxylate synthase 3-like protein, was involved in ethylene biosynthesis. SIN_1024330, encoding transcription factor IBH1-like 1, was involved in regulating cell and organ elongation. SIN_1014512, encoding indole-3-acetic acid-amido synthetase GH3.6, was involved in shoot and hypocotyl cell elongation. SIN_1011473, encoding protein DA1-like, was involved in restricting the period of cell proliferation.【Conclusion】 One hundred and seventy-five loci were identified by mrMLM, and 4 important genes related to yield traits were selected.

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