Scientia Agricultura Sinica

Genetic Inheritance and Breeding of Stripe Rust and Powdery Mildew Resistance in Wheat

LI ShunDa, LAN CaiXia

Scientia Agricultura Sinica. 2024, 57(1): 1-3. doi:10.3864/j.issn.0578-1752.2024.01.001

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Current Situation and Strategy of Stripe Rust Resistance Genes Untilization in Winter Wheat Cultivars of Northwestern Oversummering Region for Puccinia striiformis f. sp. tritici in China

BAI Bin, ZHANG HuaiZhi, DU JiuYuan, ZHANG XiaoYang, HE Rui, WU Ling, ZHANG Zhe, ZHANG YaoHui, CAO ShiQin, LIU ZhiYong

Scientia Agricultura Sinica. 2024, 57(1): 4-17. doi:10.3864/j.issn.0578-1752.2024.01.002

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【Objective】Eestern and Southern Gansu is one of the epidemic centers of stripe rust and over-summering region for Puccinia striiformis f. sp. tritici (Pst) with continuous emergening of new Pst races in Northwestern China. The objective of this study is to analyze the genetic architecture of stripe rust resistance in winter wheat cultivars grown in those regions since 1990s for a better genetic diversity control of the disease, breeding of durable resistant cultivars, sustainable green and healthy ecological agriculture in Southern Gansu. 【Method】The seedling and adult plant stage resistance to the prevailing Pst races CYR33, CYR34, etc. of 117 wheat cultivars (lines) were evaluated at greenhouse in 2021 and field trials in Qingshui of Gansu and Pixian of Sichuan, respectively, during 2019-2020 and 2020-2021 cropping seasons. Molecualr markers for 15 Yr genes were also applied to detect the presence of known stripe rust resistant genes. 【Result】Of the 117 varieties and lines tested, thirty-four (29.1%) were found to perform adult plant stage resistance (APR) in the field, among these, 25.6% and 3.4% of cultivars were released in Southern Gansu, and Eastern Gansu, respectively. Another 25.6% susceptible cultivars from Southern Gansu exhibited slow rusting with disease severity (DS) less than 20%. Eighty-two cultivars (70.1%) were resistant to the race CYR33 of Pst at the seedling stage. Among them, 67 (57.3%) and 15 (12.8%) were planted in Southern and Eastern Gansu, respectively. However, only seven (6.0%) of the total entries were resistant to the dominant race CYR34 at the seedling stage, and all of these were cultivars from Southern Gansu, such as Lantian 131 etc. The stripe rusts resistant cultivars named as Lantian, Zhongliang, and Tianxuan series at both seedling and adult plant stages were mainly released after 2010. Molecular markers screening identified the presence of Yr9 (49.6%), Yr10 (1.7%), Yr17 (12.8%), Yr18 (7.7%), Yr26 (12.8%), Yr28 (20.5%), Yr29 (10.3%), Yr30 (34.2%), Yr41 (2.6%), Yr46 (16.2%), YrZH22 (15.4%) and YrZH84 (27.4%) in some cultivars, preferly as 2-5 genes combinations in 73 (62.4%) cultivars. Pyramiding of YrZH84, YrZH22, and Yr17 with other stripe rust resistance genes could provide better disease resistance than other gene combinations. In addition, high frequency of Yr10, Yr17, Yr18, Yr28, Yr29, Yr30, Yr41, and Yr46 was detected in wheat cultivars grown in the dry highland Pst oversummering region. However, Yr26, Yr30, YrZH22, and YrZH84 were mainly identified in wheat cultivars of the valley Pst overwintering region, indicating significant genetic architecture difference for the stripe rust resistance genes between the cultivars of the oversummering and overwintering regions. Higher genetic diversity of stripe rust resistance genes was found in the cultivars of the oversummering region, compared with that released in the overwintering region. 【Conclusion】Our results revealed the current status of stripe rust resistance genes and their utilization in winter wheat cultivars of Gansu, the northwest oversummering region for Pst of China, in the past 20 years. Diversification of stripe rust resistance genes have been successfully applied in the winter wheat breeding program to develop commercial wheat cultivars and lines for sustainable control of the stripe rust disease. The development of wheat cultivars with stacked stripe rust resistance genes has solved the historical problem of wheat cultivars with narrow genetic background and mono-resistance gene, domonstrating the successful control of wheat stripe rust epidemics using genetic diversity of wheat resistance gene in this region. The present study provides theoretical basis for genetic diversity control of stripe rust disease and set an example for the sustainable green ecological agriculture by breeding wheat cultivars with durable disease resistance.

Identification and Evaluation of Stripe Rust Resistance in 153 Wheat Collections

ZHOU JingWei, YE BoWei, ZHANG PengFei, ZHANG YuQing, HAO Min, YIN YuRuo, YUAN Chan, LI ZhiKang, LI ShunDa, XIA XianChun, HE ZhongHu, ZHANG HongJun, LAN CaiXia

Scientia Agricultura Sinica. 2024, 57(1): 18-33. doi:10.3864/j.issn.0578-1752.2024.01.003

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【Objective】Stripe rust, caused by Puccinia striiformis f. sp. tritici (Pst), significantly reduced wheat production worldwide. Breeding resistant wheat varieties is currently considered to be one of the most economical and effective ways to control this disease. Understanding the resistance level of Chinese and International Maize and Wheat Improvement Center (CIMMYT) wheat breeding materials and the distribution of known disease resistance genes will greatly helpful for discovering the new resistance resources and improving the utilization efficiency of disease resistance genes. 【Method】In the present study, we phenotyped 153 wheat breeding lines derived from China and CIMMYT at both seedling against prevalent Chinese Pst races CYR33 and CYR34. In 2018-2019, 2019-2020 and 2020-2021, using the Pst races CYR33 and CYR34 to identify the materials at the adult plant stages in Ezhou, Hubei. In addition, we used the gene-based or closely linked molecular markers of known stripe rust resistance genes Yr5, Yr9, Yr10, Yr15, Yr17, Yr18, Yr26, Yr29 and YrSP to genotype the whole set of wheat collections. 【Result】We found 10 lines immune against CYR33 at the seedling stage (IT: 0), including seven Chinese cultivars (Shannong 28, Luomai 163, Shimai 13, Zhongyi 6, Tanmai 98-2, Zhongmai 175, Taishan 21) and three CIMMYT lines (CIM-53, CIM-60 and CIM-71). However, only two cultivars, Tanmai 98-1 and Shannong 102, showed immune to CYR34 at the seedling stage. Based on the three years field tests, we found 64 lines showed highly resistance to stripe rust (final disease severity, FDS≤5%), including seven Chinese cultivars and 57 CIMMYT lines. The molecular marker analysis of known stripe rust resistance genes showed that there were 31, 23, 73, 2, 4, 50 and 2 lines carrying resistance genes Yr9, Yr10, Yr17, Yr18, Yr26, Yr29 and YrSP, respectively. None of any lines had Yr5 and Yr15. Based on the phenotype, only CIM-53 showed immune against two races at both seedling and adult plant stages (IT=0, FDS=0) and it might carry the known stripe rust resistance gene combination of Yr17+Yr29 based on the genotype. 【Conclusion】A total of 153 wheat collections from China and CIMMYT were showed adult plant resistance to the prevalent Pst races. Among these, Chinese wheat varieties mainly carry Yr9, Yr10 and Yr26, while CIMMYT wheat line mainly carry Yr17, Yr18 and Yr29, indicating that near-immunity resistance of CIMMYT wheat lines due to combinations of 1-2 moderate seedling resistance gene and 2-3 adult plant resistance genes resulting in durable resistance. Therefore, it is very urgent to expand the resistance sources and identify new resistance genes for pyramiding more genes biotechnology methods to develop new wheat varieties with durable rusts resistance and good agronomic traits. This plays an important role for controlling stripe rust in China by improving the resistance level of wheat variety overall.

Current Status and Strategies for Utilization of Stripe Rust Resistance Genes in Wheat Breeding Program of China

LIU ZhiYong, ZHANG HuaiZhi, BAI Bin, LI Jun, HUANG Lin, XU ZhiBin, CHEN YongXing, LIU Xu, CAO TingJie, LI MiaoMiao, LU Ping, WU QiuHong, DONG LingLi, HAN YuLin, YIN GuiHong, HU WeiGuo, WANG XiCheng, ZHAO Hong, YAN SuHong, YANG ZhaoSheng, CHANG ZhiJian, WANG Tao, YANG WuYun, LIU DengCai, LI HongJie, DU JiuYuan

Scientia Agricultura Sinica. 2024, 57(1): 34-51. doi:10.3864/j.issn.0578-1752.2024.01.004

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Wheat stripe rust caused by Puccinia striiformis f. sp. tritici (Pst) is a devastating disease threaten food security in China and worldwide. Epidemics of wheat stripe rust have been under control through applying resistant cultivars and crop protection approaches. However, due to climate change, innovation of cropping system, improvement of breeding technology, yield level enhancement of wheat cultivars, variation in structure and frequency of virulence genes in Pst populations in the new era, the current status of stripe rust resistance genes in wheat breeding programs need to be evaluated. The results could provide useful information for applying stripe rust resistance genes to develop new wheat cultivars with broad-spectrum and durable rust resistance. After multiple year’s stripe rust resistance survey, genetic analysis, molecular tagging and mining of stripe rust resistance genes in wheat cultivars and advanced breeding lines, the current status of major stripe rust resistance genes utilization was reviewed. We summarized the present situations of major stripe rust resistance gene discovery and germplasm innovation, the most frequently used stripe rust resistance genes, new strategy for pyramiding adult plant partial resistance and all stage resistance, and molecular marker assisted selection for developing wheat cultivars with broad spectrum and durable resistance in China. This review also proposes the major research areas in wheat stripe rust resistance breeding in the new era.

Genetic Analysis of Adult Plant Resistance to Powdery Mildew in Common Wheat Arableu#1

LI ZiMeng, YUAN Chan, ZHANG YuQing, REN Yan, LIU PengPeng, YAN ShanShan, XI MengHan, MU PeiYuan, LAN CaiXia

Scientia Agricultura Sinica. 2024, 57(1): 52-64. doi:10.3864/j.issn.0578-1752.2024.01.005

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【Objective】China is a significant wheat producer and consumer in the world. It is very important for our food security to making sure the stable wheat production. Wheat powdery mildew is an important leaf disease to affect the global wheat yield. Breeding resistant wheat varieties is one of the most economically and environmentally effective way to manage this disease. Identification of new adult plant resistant loci is very important for breeders to develop durable powdery mildew-resistant wheat varieties. 【Method】The CIMMYT-derived common wheat (Triticum aestivum L.) Arableu#1, showed susceptibility to powdery mildew at the seedling stage, but exhibited a high level of resistance to this disease at the adult plant stage in the field. In order to understand the genetic basis of powdery mildew resistance in this line, we made an F₅ recombinant inbred line (RIL) population between Arableu#1 and the susceptible line Apav#1 and genotyped by genotyping-by-sequencing (GBS) platform. We obtained 4 298 polymorphic molecular markers between the parents and analyze the 142 RILs. Joinmap 4.1 and IciMapping 4.1 were respectively used to construct the linage maps and identify the powdery mildew resistance QTL in this study. 【Result】Four adult plant resistance loci from Arableu#1 were identified on wheat chromosome arms 1BL, 5BL, 6BS and 7BL, while two loci from Apav#1 on chromosomes 2DS and 4BL, which can explain the powdery mildew disease severity variation from 3.1% to 28.5%. The MFDS of RIL reached the lowest level when it carried all six detected resistance loci, while RILs combing QPm.hzau-1BL, QPm.hzau-4BL, QPm.hzau-5BL, and QPm.hzau-7BL also showed lower disease severity over multiple environments. 【Conclusion】KASP markers KASP-5B-1 and KASP-7B-2 for QPm.hzau-5BL and QPm.hzau-7BL, respectively, were developed in the present study. The two loci showed varying degrees of resistance to powdery mildew when present individually or in combination based on the genotype and phenotype of 570 wheat germplasm collections. Additionally, the frequency of these two loci in Chinese wheat materials is lower compared to CIMMYT's wheat germplasm. A line combining 6 QTLs was found and it showed near-immune resistance to powdery mildew in the field. This material will be an important germplasm resource for breeders to develop powdery mildew-resistant wheat varieties.

Effects of Planting Density and Row Spacing Configuration on Sugar Accumulation and Lodging Performance of Wheat Stem Under Rainfall Harvesting Planting Mode

QIN Feng, WANG XiaoFei, WU Zhen, HU YiBo, WANG XiaoQin, ZHANG JiaWei, CAI Tie

Scientia Agricultura Sinica. 2024, 57(1): 65-79. doi:10.3864/j.issn.0578-1752.2024.01.006

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【Objective】The aim of this study was to analyze the effects of different planting densities and row spacing configurations on stem carbohydrate accumulation and lodging resistance of wheat under ridge-furrow rainfall harvesting planting mode, and to clarify the reasonable density and row spacing of wheat under ridge-furrow rainfall harvesting planting mode, so as to provide a theoretical basis for further stabilizing and increasing wheat yield. 【Method】Xinong 979 was the main wheat cultivar in the arid area of north China, which was used as the experimental material. In 2019-2021, two planting densities (low density: 1.8 million plants per hm²; high density: 2.25 million plants per hm²) and two row spacing (equal row spacing: 20 cm; non-equal spacing: 12.5 cm:35 cm:12.5 cm) treatments were set in the rainfall harvesting planting mode. The effects of different densities and row spacing on photosynthetic rate of middle and lower leaves in wheat plants, content of stem non-structural carbohydrates and structural carbohydrates, stem breaking moment and lodging index, and grain yield were analyzed. 【Result】The net photosynthetic rate (Pn) of the middle and lower leaves (the third leaf, the fourth leaf and the fifth leaf) in wheat plants, the content of non-structural carbohydrates (glucose, fructose, sucrose) and structural carbohydrates (hemicellulose, cellulose) in the second internode at the base of stem, and the stem breaking moment were significantly decreased with the increase of planting density in the rainfall harvesting planting mode, but the stem lodging index increased significantly. However, under high-density planting condition, non-equal row spacing treatment could significantly change all plant indexes. Compared with high planting density + equal spacing treatment, the Pn of the third leaf, the fourth leaf and the fifth leaf in plants increased significantly, with increases of 7.7%-16.5%, 5.3%-37.7% and 11.9%-24.9%, respectively; the content of glucose, fructose and sucrose in stems increased by 9.8%-15.0%, 8.8%-27.4% and 8.2%-41.1%, respectively; the content of hemicellulose and cellulose increased by 4.5%-19.8%, 5.9%-31.2%, respectively; the stem breaking moment increased by 4.8%-17.3%, the stem lodging index decreased by 10.9%-25.9%, while wheat yield was significantly increased by 13.5%-15.2%. Correlation analysis showed that, the content of glucose, fructose and sucrose in the basal internode of wheat stem were positively correlated with the content of hemicellulose and cellulose. Non-structural carbohydrates and structural carbohydrates in wheat stem were positively correlated with Pn of middle and lower leaves as well as stem breaking moment, however, they were negatively correlated with lodging index. 【Conclusion】Under the rainfall harvesting planting mode, adjusting population spatial distribution by non-equal row spacing could effectively increase photosynthetic rate of middle and lower leaves of wheat plants, promote the synthesis and accumulation of sugar substances in stems, and enhance the lodging resistance of wheat stem, furthermore, reduce the lodging incidence of wheat and improve grain yield.

Leaf Area Index Inversion of Cotton Based on Drone Multi-Spectral and Multiple Growth Stages

SHI HaoLei, CAO HongXia, ZHANG WeiJie, ZHU Shan, HE ZiJian, ZHANG Ze

Scientia Agricultura Sinica. 2024, 57(1): 80-95. doi:10.3864/j.issn.0578-1752.2024.01.007

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【Objective】The leaf area index (LAI) is a vital indicator for evaluating crop growth, photosynthesis, and transpiration. The objective of this study is to explore the cotton LAI estimation models based on multi-spectral data from drones at different growth stages and multiple growth stages, clarify the variation patterns of cotton LAI estimation models during different growth stages, and to provide a basis for real-time understanding of cotton growth and scientific field management tailored to local conditions. 【Method】The DJI Elf 4 multi-spectral UAV was used to acquire multi-spectral images and RGB images of cotton at budding stage, initial flowering stage, boll setting and open-boll stages. Five multi-spectral indices, namely normalized difference vegetation index (NDVI), normalized green difference vegetation index (GNDVI), normalized difference red-edge index (NDRE), leaf chlorophyll index (LCI), optimized soil adjusted vegetation index (OSAVI), and five color indices, namely modified green-red vegetation index (MGRVI), green-red vegetation index (GRVI), green leaf algorithm (GLA), excess red index (EXR), and visible atmospherically resistant vegetation index (VARI), were selected to build a data set for each growth stage of cotton and multiple growth stages of cotton growth, respectively. Combined with the punching method to obtain actual ground LAI data, the machine learning algorithms of partial least squares regression (PLSR), ridge regression (RR), random forest (RF), support vector machine (SVM) and back propagation (BP) were used to construct a cotton LAI prediction model. 【Result】The LAI of cotton exhibited an increasing and then decreasing pattern during the growth stage. Notably, the mean LAI values of cotton at the inner side of the budding stage, initial flowering stage, and boll setting stage were significantly greater than those at the lateral side (P<0.05). The selected indices exhibited significant correlations with each other across the periods (P<0.05). In general, the correlation between multi-spectral index and color index showed a decreasing trend as the growth stage progressed, and the selected indices were significantly correlated with cotton LAI in all stages (P<0.05), the correlation coefficients of multi-spectral index ranged from 0.35 to 0.85, and the correlation coefficients of color index ranged from 0.49 to 0.71, and those with a larger absolute value of the correlation coefficients were mostly multi-spectral indices, while those of the correlation coefficients of color index and cotton LAI were smaller. The estimated model performance results showed that the multi-spectral index was better than the color index in the cotton growth models, the predictive performance of the index models showed certain regularity with the change of growth, and NDVI was the optimal index for predicting cotton LAI. From the model results, the RF model and BP model obtained higher estimation accuracy under each growth stage. The LAI inversion model at the initial flowering stage had the highest accuracy, with the optimal model validation set R² of 0.809, MAE of 0.288, and NRMSE of 0.120. The optimal model validation set for the multiple growth stages had the R² of 0.386, MAE of 0.700, and NRMSE of 0.198. 【Conclusion】There are significant differences in LAI between the inner and lateral sides of cotton during the budding stage, initial flowering stage, and boll setting stage. NDVI emerged as the optimal index for predicting cotton LAI at all growth stages, with the RF and BP models demonstrating superior performance. The effectiveness of the multiple growth stages model was notably lower compared to that of the single-growth model, with the optimal index identified as GNDVI and the optimal model as BP. The initial flowering stage appeared to be the optimal window for predicting cotton LAI. These findings can provide theoretical basis and technical support for utilizing UAV remote sensing to monitor cotton LAI.

Rational Design and Innovative Application Strategy for the Insecticidal Protein Based on Bt Toxin

XU ChongXin, JIN JiaFeng, SUN XiaoMing, SHEN Cheng, ZHANG Xiao, CHEN ChengYu, LIU XianJin, LIU Yuan

Scientia Agricultura Sinica. 2024, 57(1): 96-125. doi:10.3864/j.issn.0578-1752.2024.01.008

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Bt toxin is a macromolecular protein derived from Bacillus thuringiensis with special insecticidal function. Its preparation and transgenic crops have been widely used in pest control, and have produced huge economic and social ecological benefits. Exploiting and improving the application value of Bt toxin is a hot spot of continuous research. In particular, as the structure and function of Bt toxin and its mechanism of action appear clearer, it has created conditions for its functional modification and innovative application. As a result, the related research has flourished and achieved remarkable results. A large number of studies have shown that strategies such as site directed mutagenesis, domain replacement or fusion, and anti-idiotype antibody simulation are effective means to rationally design novel insecticidal proteins with higher activity, greater stability, wider insecticidal spectrum and higher non-target biosecurity. Those novel insecticidal proteins are different from parent Bt toxins, of which are mutants, structural heterozygotes and even functional effector antibodies. In addition, it is also an important approach to promote the application value of Bt toxin by use of innovative synergistic strategies such as catalytic toxin activation, driving toxin-targeted receptor binding, promoting toxin expression and the synergistic effect of combination or co-expression of homologous or heterologous insecticidal materials. This paper summarizes the structure and function of Bt toxin and its mechanism of action. It also reviews the research progress in rational design of novel insecticidal proteins such as mutants, structural heterozygotes and functional effector antibodies based on Bt toxin function modification, and innovative application strategies based on Bt toxin function enhancement. The future development trend and potential shortcut of rational design and innovative application strategy for insecticidal protein based on Bt toxin were discussed. Furthermore, the author’s team combined it with the latest achievements in targeting design and development of the insecticidal function effector antibodies simulating Bt toxin. This paper is expected to provide more comprehensive and valuable literature information and enlighten ideas for the related research based on Bt toxin.

Effects of Soil Application of Passivating Agent and Compound Microbial Fertilizer on Cadmium Accumulation in Winter Wheat

WANG Yu, SONG YiFan, ZHANG Rong, MU HaiMeng, SUN LiFang, FU KaiXia, WU ZiJun, HUANG QingQing, XU YingMing, LI GeZi, WANG YongHua, GUO TianCai

Scientia Agricultura Sinica. 2024, 57(1): 126-141. doi:10.3864/j.issn.0578-1752.2024.01.009

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【Objective】The passivation effect of passivator and compound microbial fertilizer on cadmium (Cd) activity in slightly Cd-polluted weak alkaline farmland soil in northern Henan Province was studied, and their effects on Cd accumulation and translocation in different organs and yield of winter wheat were investigated too. The purpose of this study was to explore soil remediation materials for efficient remediation of Cd-contaminated soil, to reduce Cd content in winter wheat grains, and to screen wheat varieties with low Cd accumulation, so as to provide the technical support for the safe and efficient production of wheat in lightly polluted weak alkaline farmland in northern Henan Province. 【Method】In two consecutive winter wheat growing seasons of 2020-2022, two-factor split field comparison experiments of four different soil remediation materials (CK, no soil remediation treatment; CMF, single application of compound microbial fertilizer; GP, single application of soil passivator; CMF+GP, combination of compound microbial fertilizer and soil passivator) and six winter wheat varieties (Xinhuamai818, Luomai 163, Zhengmai 9023, Xinmai 296, Zhengmai 136, and Zhengmai 7698) in northern Henan Province were set up and used in the weakly Cd-polluted alkaline farmland. The changes of available Cd in soil, Cd contents in aboveground organs of wheat plants, enrichment coefficient (BCF), transport coefficient (TF), their correlations, and winter wheat yields and its components were analyzed. 【Result】(1) In two winter wheat growing seasons (2020-2021 and 2021-2022), compared with CK, single application and equal combination application of passivation agent and compound microbial fertilizer could remarkably reduce the content of available Cd in soil. CMF+GP treatment had the best effect, which significantly and effectively reduced the available Cd content by 17.6%-22.4% in the surface soil of the roots among the six varieties. The decreased available Cd in soil was related to the changes of Cd content in the aboveground organs of winter wheat plants, and there were also some differences between the same organs of different varieties. (2) Single application of soil passivator and compound microbial fertilizer, as well as equal combined application of soil passivator and compound microbial fertilizer, could make Xinhuamai 818, Luomai 163 and Zhengmai 9023 decrease TF_{Stem sheath-leaf}, TF_{Stem sheath-grain}, increase TF_{Stem sheath-(Spike shaft+chaff)}, TF_{Leaf-(Spike shaft+chaff)}, reduce BCF_{Stem sheath} and BCF_Leaf, and make wheat body in order to reduce BCF _Grain, the content of Cd in it shifted to panicle axis + glume. In contrast, they did not reduce TF_{Stem sheath-Leaf} and BCF_{Stem sheath} of Xinmai 296, whereas increased BCF _{Stem sheath} of Zhengmai 136 and Zhengmai 7698. (3) Application of passivating agents and compound microbial fertilizers in soil could comprehensively regulate the number of ears, grains per ear and 1000-kernel weight of winter wheat plants, and improve the grain yields of winter wheat. However, variance analysis on soil remediation treatment and varieties showed that the increased grain yields in their interactions was mainly due to the increased ear numbers. Under CMF+GP treatment, the grain yield of Zhengmai 136 variety was the highest among all treatments, which was 7 317.17 kg·hm^-2 and 10 485.32 kg·hm^-2 in two consecutive 2020-2021 and 2021-2022 winter wheat growing seasons, respectively. 【Conclusion】The application of compound microbial fertilizer and soil passivator could effectively reduce the available Cd content in the rhizosphere soil with weak alkaline and mild Cd pollution in northern Henan Province, and regulate the enrichment coefficient and transport coefficient of soil Cd in various organs of winter wheat plants. The combination treatment of compound microbial fertilizer and soil passivator with the same applied amounts was better than single treatment, which could also reduce the Cd content of winter wheat grains to the maximum extent, and significantly improve the yield of winter wheat varieties. In addition, the combination of planting modes combined with the low Cd accumulation and high yield variety Zhengmai 136 screened out, could achieve the high grain yields and safe production of winter wheat in the farmland with weak alkaline Cd pollution in northern Henan Province.

Environmental Residues of Organosiloxane-Based Adjuvants and Its Environmental Risks for Use as Agrochemical Adjuvants

WANG XiaoBin, YAN Xiang, LI XiuYing, TU Cheng

Scientia Agricultura Sinica. 2024, 57(1): 142-158. doi:10.3864/j.issn.0578-1752.2024.01.010

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Organosiloxane-based adjuvant (or organosilicon adjuvant), one of the silicone-fluide products, is polysiloxane, predominantly composed of covalently bonded silicon and oxygen atoms. Organosiloxane-based adjuvants are widely used as additives for daily chemicals and textile products, but also as agrochemical adjuvants in agriculture due to their super spreading and penetrating abilities. At present, China’s production and sales of silicone products have reached above 2 million tons, accounting for more than 50% of the world’s total amount. China has become the world’s largest producer, consumer and net exporter of raw materials of silicone, and the production capacity of polysiloxane has reached more than 60% of the world’s total. As organosiloxane residues detected in environment (especially in water, sludge/soil and other environmental samples, aquatic food chain, as well as human tissues), their impacts on agricultural ecological environment are increasingly exposed due to the widely application of organosiloxane-based adjuvants, while the environmental risks from silicone-based agrochemical adjuvants, including ecotoxicity and environmental safety risks, have also attracted great concern. In recent years, volatile cyclomethylcyclosiloxanes (such as D4 (octamethylcyclotetrasiloxane), D5 (decamethylcyclopentasiloxane) and D6 (dodecylcyclohexasiloxane)) have been recognized as emerging organic pollutants, or listed as priority controlled chemicals by EU and other countries, because of their environmental persistence, bioaccumulation and potential toxicity. Based on the relevant scientific research literatures published since 1991 on the environmental residues of organosiloxane-based adjuvants and the ecological environmental safety risks in the use of organosiloxane-based adjuvant (including organosiloxane-based agrochemical adjuvants), this paper reviewed and analyzed the environmental residues of organosiloxane-based adjuvants, and their impacts directly or indirectly on agricultural ecological environmental safety. This review mainly focused on the following two aspects: (1) the organosiloxane residues in environment and their impacts on the agricultural ecological environment safety, including organosiloxane residues and fates in the process of wastewater treatment, aquatic food chain pollution risks from organosiloxane residues in water, soil ecological pollution risks from organosiloxane residues in sludge, and human health risks from organosiloxane residues in food; (2) the current situation and environmental safety risks for the use of organosiloxane-based agrochemical adjuvants, including organosiloxane residues and ecotoxicity risks from siloxane-based agrochemical adjuvants, and the management for the use of organosiloxane-based agrochemical adjuvants. This paper also discussed the management status and problems associated with siloxane-based products. For organosiloxane as agrochemical adjuvants, organosiloxane-based adjuvants were largely assumed to be “biologically inert”, and usually no risk assessment (such as ecotoxicity test and environmental monitoring) was required. Also, the adjuvant inert ingredients were generally protected as “trade-secrets” or confidential business information, and the inert ingredients were rarely identified on product labels. At present, there are no regulatory requirements for the use of organosilicone-based adjuvants in fertilizer products as agrochemical adjuvants (such as foliar fertilizer additives) in China, posing potential environmental safety risks. This paper discussed that over-addition with organosiloxane-based agrochemical adjuvants might increase their residues in soil-crop-water systems, and their ecotoxicity risks, as well as potential threats to food safety and human health. It is suggested that relevant management and research units need to pay more attention to environmental monitoring for organosiloxane residues and fates in the application process of organosiloxane-based adjuvants, and especially strengthen the research on the impacts of organosiloxane residues from organosiloxane-based agrochemical adjuvants on water, soil, animal and plant growth, as well as human health.

Effects of Inoculation with Indigenous and Exogenous Arbuscular Mycorrhizal Fungi on Drought Resistance of Pyrus betulaefolia and Its Adaptation Mechanism

LI Han, JIANG ShangTao, PENG HaiYing, LI PeiGen, GU ChangYi, ZHANG JinLian, CHEN TingSu, XU YangChun, SHEN QiRong, DONG CaiXia

Scientia Agricultura Sinica. 2024, 57(1): 159-172. doi:10.3864/j.issn.0578-1752.2024.01.011

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【Objective】Arbuscular mycorrhizal (AM) fungi play a significant role in enhancing plant growth and improving resistance to environmental stress. The aim of this study was to screen AM fungi that can withstand drought stress in pear seedlings, so as to establish a theoretical foundation and technical approach for pear mycorrhizal cultivation. 【Method】In this study, a pot experiment and high-throughput sequencing technology were employed to investigate the effects of single and mixed inoculation with indigenous AM fungi, including Claroideoglomus lamellosum (Cl), the exogenous fungus Funneliformis mosseae (Fm), Rhizophagus intraradices (Ri), and Acaulospora mellea (Am), on the growth of Pyrus betulaefolia seedlings under normal and drought conditions. The changes in the AM fungal community in the roots and rhizosphere soil of P. betulaefolia seedlings were analyzed under mixed inoculation (Mix) after 0, 3, and 6 weeks of drought treatment. 【Result】 Under normal and drought conditions, the single inoculation with Cl, Ri, and Mix significantly increased the plant height, stem diameter, leaf area, and relative water content of the leaves of pear seedlings, resulting in a dry weight increase of 35.26% to 52.20%. Additionally, the uptake of phosphorus, potassium, calcium, and magnesium in the aboveground part of the seedlings was enhanced, especially phosphorus uptake, with a mycorrhizal phosphorus uptake effect of up to 1.0. The exogenous fungus Am showed less effectiveness, while Fm inhibited the growth of P. betulaefolia seedlings under normal water supply conditions. Regression analysis indicated that the growth and element absorption effects of mycorrhizal fungi increased with the degree of infection. Under drought stress, AM fungal inoculation significantly reduced the MDA (malondialdehyde) content in the leaves of P. betulaefolia seedlings and increased the activity of antioxidant enzymes and the content of proline to varying degrees. Sequencing results demonstrated that the structure of the AM fungal community in the roots and rhizosphere soil of P. betulaefolia seedlings changed significantly under drought stress compared with normal water conditions. The exogenous fungus Ri dominated the community, followed by Cl and Am, while Fm was the least abundant. The abundance of Ri in the roots significantly increased with the degree of drought stress. 【Conclusion】In conclusion, the different AM fungi had varying effects on the growth of P. betulaefolia seedlings, with the indigenous strain Cl and the exogenous strain Ri showing strong growth-promoting effect and drought resistance. The increase in Ri abundance in the AM fungal community was an important adaptation mechanism for P. betulaefolia seedlings to withstand drought stress.

Comprehensive Evaluation and Selection of Hybrid Offsprings of Early Flowering Spray Outdoor Chrysanthemum

SONG Xiang, WANG ZhongMan, ZHANG QiuLing, WEI YuanYuan, ZHAO XiaoGang, LIU Bo, DAI SiLan

Scientia Agricultura Sinica. 2024, 57(1): 173-189. doi:10.3864/j.issn.0578-1752.2024.01.012

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【Objective】The aim of this study was to establish a comprehensive evaluation system for early flowering garden chrysanthemums, and to select plant lines with flowering periods from mid-September to mid-October, of which flower colors were close to pure red or yellow with novel flower type, round plant shape and excellent comprehensive performance to enrich ornamentals for early autumn festivals in Northen China, so as to provide breeding materials and selection methods for further breeding of early flowering garden chrysanthemum. 【Method】Using 3 early-flowering parents and 1 high double-flowering parent with bright color of small flowered chrysanthemum and 25 asexual hybrid progenies as test materials, 30 original traits were observed from 5 aspects, including flower color, flowering period, flower type, plant type, and leaf type. The selected 18 key traits were used as evaluation factors, and then a comprehensive evaluation system was established using Analytic Hierarchy Process and K-Means clustering analysis to conduct the comprehensive screening of hybrid lines. 【Result】The weight values of each trait of analytic hierarchy process were determined with the breeding objectives of early flowering, round flower type, and stable red and yellow flower color. Among them, the weight value of the initial flowering time (0.1817) was the largest, followed by the flower color stability (0.1695), the number of flowers per plant in the full flowering period (0.1383), the flowering duration (0.1301), the flower color suitability (0.0565), the flower uniformity in the full flowering period (0.0565 ), the inflorescence diameter (0.0539), and the number of ligulate flowers (0.0574). The 29 materials were divided into 3 grades by K-Means clustering analysis: 10 in grade I, 11 in grade II, and 8 in grade III, accounting for 34.38%, 37.93% and 27.59%, respectively. The traits of the hybrid progeny were widely separated, and the flower color, flower type, and plant type all showed transgressive traits, but the flowering period was still the earliest in the two early flowering parents, which was in line with the previous studies that the flowering period was a quantitative trait controlled by multiple genes. Therefore, the early flowering breeding still needs to screen parents and increase the resources of open-field small chrysanthemums that can be used in early autumn. 【Conclusion】 This evaluation method integrated the advantages of various evaluation systems, characterized the traits observed in the field with quantitative results, and conducted hierarchical analysis and evaluation guided by breeding objectives, which provided a quantitative method for comprehensive evaluation and screening of excellent varieties of early flowering garden chrysanthemum. The data analysis results indicated that the evaluation system established in this study could effectively evaluate and screen early flowering garden chrysanthemums, providing a reliable method for the breeding of new varieties of early flowering garden chrysanthemums, and helping to improve the efficiency of selecting excellent germplasm for future breeding project. Finally, 10 early flowering garden chrysanthemum strains with excellent ornamental traits were selected, which could be used as new varieties or strains and also as further breeding materials.

Effects of Mannitol on Production Characteristics and ROS Scavenging Ability of Volvariella volvacea Subcultured Strains

ZHAO FengYun, CHENG ZhiHong, TAN QiangFei, ZHU JiaNing, SUN WanHe, ZHANG WenWei, YUN JianMin

Scientia Agricultura Sinica. 2024, 57(1): 190-203. doi:10.3864/j.issn.0578-1752.2024.01.013

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【Objective】The aim of this study was to investigate the effects of mannitol on production characteristics and reactive oxygen species (ROS) scavenging ability of Volvariella volvacea subcultured strains, and to explore a simple and effective method for the rejuvenation of V. volvacea degenerated strains. 【Method】The tissue isolation subcultured strains T6, T12 and T19 were obtained by previous study of our research group, and T6 was obtained after 6 successive subculture, while T12 and T19 was obtained after 12 and 19 successive subculture, respectively. The original strain (T0), referred to as V844, was a strain used in commercial agricultural cultivation. The glucose in the traditional potato dextrose agar (PDA) was replaced by mannitol of the same mass, then physiological traits were determined in mycelia. The agronomic characters of fruiting body were measured by adding mannitol to the culture medium. ROS accumulation was reflected using nitrotetrazolium blue chloride (NBT) staining of V. volvacea mycelia, superoxide anion ($\mathrm{O}_{2}^{\bar{.}}$) and hydrogen peroxide (H₂O₂) content. The expression levels of antioxidant enzyme genes were detected by real-time quantitative PCR (RT-qPCR). The activity of antioxidant enzymes was measured by the kit. The number of nuclei and mitochondrial membrane potential were determined by mycelium staining. The energy indexes were determined by high performance liquid chromatography (HPLC). 【Result】Mannitol treatment had no significant effect on non-degraded strains T0 and T6, but could effectively restore the production characteristics and ROS scavenging ability of degraded strains T12 and T19. After mannitol treatment, the mycelial growth rate of T12 and T19 was increased by 31.46% and 20.99%, respectively, and the mycelial biomass was increased by 97.33% and 76.36%, respectively. The mannitol treatment shortened the production cycle of T12 by 12.24% and increased the biological efficiency by 17.97%, thus restoring it to T0 level. In addition, the mannitol treatment caused T19 to regrow its fruiting body, which had been severely degraded and lost its ability to produce fruiting bodies. Meanwhile, mannitol treatment increased the relative expression of Cu/Zn superoxide dismutase (Cu/Zn-sod) gene in T12 and T19 by 24.64% and 61.54%, respectively, and the relative expression of Mn-sod2 gene by 19.76% and 267.09%, respectively. Similarly, the relative expression of glutathione peroxidase (gpx) gene was up-regulated by 25.67% and 55.82%, respectively. More importantly, the activity of SOD in T12 and T19 increased by 10.79% and 72.32%, and the activity of GPX increased by 16.98% and 103.85%, respectively. The accumulation of ROS in T12 and T19 was significantly reduced by mannitol treatment, in which the $\mathrm{O}_{2}^{\bar{.}}$ content in T12 and T19 decreased by 35.96% and 41.62%, while the H₂O₂ content decreased by 14.44% and 18.26%, respectively. Furthermore, the mannitol treatment significantly increased the number of nuclei and mitochondrial membrane potential in T12 and T19. Mannitol treatment could increase ATP content in T12 and T19 by 17.08% and 14.55%, and EC value by 4.52% and 0.92%, respectively. 【Conclusion】Mannitol treatment could significantly improve the antioxidant capacity and mitochondrial function of the degenerated strains T12 and T19, and effectively restore their production traits.

Study of Key Genes and Signaling Pathways Regulating Dry Feather Traits in Yellow-Feathered Broiler Chickens Based on Transcriptome Analysis

JI GaiGe, CHEN ZhiWu, SHAN YanJu, LIU YiFan, TU YunJie, ZOU JianMin, ZHANG Ming, JU XiaoJun, SHU JingTing, ZHANG HaiTao, TANG YanFei, JIANG HuaLian

Scientia Agricultura Sinica. 2024, 57(1): 204-215. doi:10.3864/j.issn.0578-1752.2024.01.014

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【Objective】 The study aimed to identify important candidate genes and signaling pathways associated with dry feather traits by comparing the morphological and gene expression differences between the feather follicles of dry and undried feathers. 【Method】 Three samples of skin tissue were selected from each of the undried and dried feathers. The histological examinations were used to compare the morphological differences between the feather follicles of dried and undried feathers. RNA-seq technology was employed to compare the differentially expressed genes (DEGs) between the two groups of skin samples. The accuracy of transcriptome results was validated by using the fluorescent quantitative PCR technique (RT-qPCR). 【Result】 By histological H.E staining, it was confirmed that the feather follicles of the undried feathers were in the growth phase, while the feather follicles of the dried feathers were in the resting phase. The feather follicle skin samples at the growth stage were used as controls, 942 DEGs were identified in resting feather follicle samples (|fold-change|>2 and P<0.05), including 384 significantly down-regulated DEGs and 558 upregulated DEGs. Gene ontology (Go) analysis suggested that the DEGs were significantly enriched in cell division, cycle regulation, and other related biological processes. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway results showed that the DEGs were related to MAPK, TGF-β, p53, and cell cycle-related signaling pathways. Protein-protein interaction (PPI) network was constructed and six hub genes were obtained by CytoHubba analysis, including CDK1, MAD2L1, BUB1, CCNB2, PLK1, and BUB1B. Gene Set Enrichment Analysis (GSEA) results indicated that the signaling pathways related to the tight junction, insulin, MAPK, TGF-β, and cell cycle-related pathways were significantly associated with the growth cycle of chicken feather follicles. The expression patterns of 8 DEGs detected by RT-qPCR were consistent with the RNA-seq results. 【Conclusion】 In summary, the dry feather traits of chickens were related to the development of feather follicle cycles. Signaling pathways such as MAPK and TGF-β might play important roles in feather growth and development by regulating the expression of cell cycle-related genes. The study provided clues for understanding the molecular regulatory mechanisms for dry feather traits in yellow-feathered broiler chickens.

Mycoplasma Hyopneumoniae Destroyed the Inflammatory Balance of Respiratory Tract Through Suppressing the Function of SPLUNC1

WANG HaiYan, ZHANG ZhenZhen, NI Bo, LIU BeiBei, FENG ZhiXin

Scientia Agricultura Sinica. 2024, 57(1): 216-226. doi:10.3864/j.issn.0578-1752.2024.01.015

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【Background】Mycoplasma hyopneumoniae (Mhp) invades the body through respiratory mucosa, then it destroys the inflammatory balance and causes inflammatory damage. Short palate lung and nasal epithelial clone1 (SPLUNC1) is a protein secreted by respiratory mucosa with important antibacterial and anti-inflammatory functions, it is considered to be a “signal sensor” for respiratory mucosa in the face of danger signals. 【Objective】This study focused on the interaction between Mhp and SPLUNC1, and analyzed the influence of Mhp on the expression of SPLUNC1 and the regulatory effect of SPLUNC1 on the inflammatory response caused by Mhp. This study also revealed a new mechanism of inflammatory damage caused by Mhp, and it was of great significance to resolve the problem of persistent infection of Mhp. 【Method】Quantitative PCR, indirect immunofluorescence and Western-blotting methods were used to detect the effects of Mhp on SPLUNC1 transcription and expression in PBECs and piglets. Porcine SPLUNC1 gene was cloned and amplified from the PBECs, and the eukaryotic and prokaryotic expression recombinant plasmids pCDNA3.1- SPLUNC1 and pET28a-SPLUNC1 were constructed successfully. Meanwhile, siRNA interference sequence targeting SPLUNC1 were also designed. The effect of SPLUNC1 on the growth of Mhp was clarified by in vitro incubation experiment and SPLUNC1 blocking experiment in mice. After over-expressing or siRNA interfering of SPLUNC1, Western-blotting, IFA and ELISA were used to detect the effects of SPLUNC1 on the Mhp adhesion, CXCL8 expression and the activation of MAPK pathway. 【Result】Mhp infection induced inflammatory damage, accompanied by CXCL8, TNFα and IL-1β expression in the lung. Meanwhile, the transcription and protein expression of SPLUNC1 was also inhibited in vivo and PBECs after Mhp infection. The above studies indicated that Mhp induced pulmonary inflammatory response and inhibited the expression of SPLUNC1. Over-expression of SPLUNC1 in PBECs significantly decreased CXCL8 expression, on the contrary, the knockdown of SPLUNC1 by siRNA interference significantly increased CXCL8 expression. The result showed that SPLUNC1 negatively regulated CXCL8 expression caused by Mhp infection. The growth of Mhp in vivo and vitro was not significantly inhibited by SPLUNC1. Over-expression or siRNA interference of SPLUNC1 also had no significant effect on the adhesion of Mhp. The over-expression of SPLUNC1 inhibited the activation of pERK and IκBα, whereas siRNA interference of SPLUNC1 upregulated the activation of pERK and IκBα. SPLUNC1 inhibited CXCL8 expression by inhibiting the activation of MAPK-ERK pathway. 【Conclusion】The respiratory mucosa regulated the expression of CXCL8 through SPLUNC1 to maintain the inflammatory balance of the host. However, in the process of infection, Mhp destroyed the inflammatory balance by inhibiting SPLUNC1 expression, thus causing inflammatory damage. Finally, this study provided an important basis for understanding the mechanism of infection and injury of Mhp.

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