Table of Content

01 December 2023, Volume 56 Issue 23

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SPECIAL FOCUS: FIBER DEVELOPMENT IN COTTON

Fiber Development in Cotton

LI FuGuang

Scientia Agricultura Sinica. 2023, 56(23):  4561-4564.  doi:10.3864/j.issn.0578-1752.2023.23.001

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Identification and Expression Analysis of Fuzz Fiber Development Related Long Noncoding RNAs in Gossypium arboreum

WANG XiaoYang, PENG Zhen, XING AiShuang, ZHAO YingRui, MA XinLi, LIU Fang, DU XiongMing, HE ShouPu

Scientia Agricultura Sinica. 2023, 56(23):  4565-4584.  doi:10.3864/j.issn.0578-1752.2023.23.002

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【Objective】Long non-coding RNAs(lncRNAs) are a group of RNA molecules longer than 200 bp with no protein coding capacity, which are involved in various biological regulatory processes. In this study, we aim to analyze the RNA-sequencing data of two Gossypium arboreum isogenic lines, a fuzzless mutant (GA0149) and its wildtype (GA0146), to identify the lncRNA involved in early fuzz fiber development, providing a foundation for investigation the mechanism of fiber development. 【Method】We collected 0 DPA, 3 DPA and 5 DPA ovule and 8 DPA ovule and fiber from the G. arboreum fuzzless mutant GA0149 and its isogenic line GA0146 with normal fuzz and lint fibers, were used for RNA-seq to identify lncRNA and predict their target genes. Differentially expressed mRNA (DE-mRNA) and lncRNA(DE-lncRNAs) between the samples were identified. The KOBAS software was used to predict the KEGG enrichment pathways which DE-lncRNAs targets were involved in. To ensure the quality of high-through sequencing, 25 DE-lncRNAs were selected for RT-qPCR detection. 【Result】We identified 15 339 lncRNA-encoding transcripts that 11 595 lncRNAs were located to intergenic regions, 2 428 lncRNAs were classified as antisense lncRNAs, 350 were categorized as intronic lncRNAs and 966 belonged to sense lncRNAs. Compared to mRNAs, lncRNAs in Asian cotton showed shorter exons and lower GC content. Most of lncRNAs had cis-regulatory effects on their neighboring mRNAs. We identified 1 932 differentially expressed (DE) lncRNAs, with 8 134 predicted DE-lncRNA target genes. Further analysis showed that 788 genes (mRNA) were differentially expressed (DE-genes) during four fiber development stages. KEGG enrichment pathways analysis showed that DE-target-mRNAs were mainly enriched in plant hormone signal transduction and protein processing in endoplasmic reticulum. Co-expression network analysis revealed that lncRNA (MSTRG.454250.3) and its associated target genes showed identical expression trends during four fuzz fiber development stages, while lncRNAs (MSTRG.454261.4) and its associated target genes showed contrary expression tendency, exhibiting dramatic higher expression in fuzzless GA0149 compared to wildtype GA0146. The results of RT-qPCR analysis confirmed the authenticity of our RNA-seq data.【Conclusion】A total of 26 specifically expressed lncRNAs were identified which related to cotton fuzz fiber development process. We further confirmed that these lncRNAs affected the fuzz fiber development by regulating the expression of indole-3-acetic acid-amido synthetase (Ga03G2421) and Auxin-responsive protein (Ga05G1344) in the plant hormone signal transduction pathway.

Genome-Wide Identification and Expression Analysis of β-tubulin Family in Cotton Fiber Development

DANG YuanYue, MA JianJiang, YANG ShuXian, SONG JiKun, JIA Bing, FENG Pan, CHEN QuanJia, YU JiWen

Scientia Agricultura Sinica. 2023, 56(23):  4585-4601.  doi:10.3864/j.issn.0578-1752.2023.23.003

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【Objective】β-tubulin is the basic structural unit of cotton fiber, regulates fiber cell morphogenesis, and plays a vital role in fiber development. But there is less understood how β-tubulin gene influenced the distinct characteristic of fiber quality traits in cotton. In this study, members of the β-tubulin gene family were identified in cotton, their expression profiles were analyzed, and role of β-tubulin genes were explored for fiber quality. 【Method】BLAST method was used to identify members of the β-tubulin gene family in the genomes of four cotton species. ProtParam tool was utilized to analyze physicochemical properties, MEGA7.0 to construct phylogenetic tree, Mapchart2.2 to draw chromosomal localization map, MEME to analyze conserved motif, and PlantCARE to analyze promoter cis-acting elements. Expression levels of β-tubulin genes were characterized by using transcriptome data from 39 studies on fiber development. Spearman correlation analysis was used to identify candidate genes for fiber quality traits. 【Result】Importantly, 36, 37, 19 and 18 β-tubulin genes were identified in the genomes of Gossypium hirsutum (AD₁), Gossypium barbadense (AD₂), Gossypium arboretum (A₂) and Gossypium raimondii (D₅), respectively. The number of β-tubulin genes in tetraploid cotton species is almost double than that of diploid cotton species. Phylogenetic analysis classified these genes into 5 main clusters. Phylogenetic and collinearity analysis revealed that β-tubulin genes in Gossypium barbadense is closely related to Gossypium arboretum and Gossypium raimondii as compared to Gossypium hirsutum. Furthermore, all genes have typical conservative domains with Tubulin and Tubulin-C. The genes physicochemical properties showed amino acids range from 421 to 508 with isoelectric point of 4.68 to 5.09. The analysis of promoter cis-acting elements identified growth responsive, hormone responsive, and stress responsive elements which showed β-tubulin mediates various mechanisms of cell growth regulation. Interestingly, cluster analysis on 36 β-tubulin gene expression profiles showed 42% genes in cluster П had dominant expression in fiber. In particular, 1, 6, and 11 β-tubulin genes exhibited significant correlation with fiber micronaire value, fiber strength, and fiber length, respectively. Four genes were found to influence fiber length and fiber strength traits simultaneously. 【Conclusion】A total of 110 β-tubulin gene family members were identified in the four cotton species. Their physicochemical properties and sequences of amino acids were highly conserved and the promoter sequence had diverse regulatory elements. This study characterized the expression profiles as well as molecular function of β-tubulin gene family in cotton fiber. Further discovered the potential candidate genes that probably regulate fiber quality traits in cotton. Our results may have great potential for cotton fiber quality improvement by genetic engineering.

Genome-Wide Identification of Cotton FLA Gene Family and Functional Analysis of GhFLA05 in Cotton Fiber Development

TANG LiYuan, CAI Xiao, WANG HaiTao, LI XingHe, ZHANG SuJun, LIU CunJing, ZHANG JianHong

Scientia Agricultura Sinica. 2023, 56(23):  4602-4620.  doi:10.3864/j.issn.0578-1752.2023.23.004

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【Background】It is of great importance to improve the quality of cotton fiber to meet the improvement of cotton textile production and the pursue of people for high quality cotton. Fasciclin-like arabinogalactan proteins (FLAs) play an important role in the initial development of cotton fibers and secondary wall synthesis. 【Objective】Comprehensive identification and analysis of cotton FLA gene family members to reveal their common characteristics and specific expression patterns, provided a reference for the function study of FLAs in cotton fiber development.【Method】According to the whole genome data of cotton, members of FLA gene family were identified by HMMER3.0 and further verified by online softwares of Pfam and Smart. Physical and chemical properties and transmembrane domains of these proteins were analyzed by ExPASy and TMHMM. Phylogenetic tree construction, chromosome localization, collinearity analysis and protein conserved domain sequence alignment were conducted and displayed using GSDS, MCScanX, MEGA, MEME, TBtools and Jalview. Expression of FLA genes in different tissues were analyzed by cotton transcriptome data. Expression differences of GhFLAs in different developmental stages of ovules and fibers between different fiber quality materials was analyzed by quantitative real-time polymerase chain reaction (qRT-PCR). Function of GhFLA05 was verified by virus induced gene silencing (VIGS). 【Result】A total of 41, 40, 20 and 21 FLA family members were identified in G.hirsutum, G. barbadense, G. arboreum and G. raimondii, respectively. The phylogenetic tree showed that cotton FLA proteins could be divided into four groups. Gene structure and motif composition were relatively conserved in each group. Further analysis of FLA proteins in Gossypium hirsutum showed that all 41 FLA members had 1-2 AGP-like glycosylation regions and 1-2 fasciclin-like domains (FAS), 37 of which contained signal peptide (SP) and 25 contained glycosylphosphatidylinositol anchored protein (GPI) anchoring signals. Subcellular localization showed that GhFLA05_D showing aggregated granules in the cytoplasm was probably localized in endoplasmic reticulum, and GhFLA18_A and GhFLA22 were expressed in cell membrane/wall, cytoplasm and nucleus. Transcriptome sequencing results showed that FLA proteins in Group A and B were mainly highly expressed in fibers, which may be involved in the process of cotton fiber elongation development and secondary wall thickening. In general, group A and B members had a similar expression pattern in two materials with significant differences in fiber quality and expressed mainly in the secondary wall development stage, especially in 20-25 DPA period. GhFLA05 exhibited specific expression at the secondary wall thickening stage with significant differences between two materials, which expressed with a high maximum value in earlier stage of secondary wall thickening stage in high specific strength material RIL229, suggesting GhFLA05 may take a part in the regulation of cotton fiber strength difference formation. The fiber strength and micronaire value decreased in GhFLA05 gene-silenced cotton plants by VIGS.【Conclusion】A sum of 122 FLA family members were identified in Gossypium hirsutum, Gossypium barbadense, Gossypium arboreum and Gossypium raimondii, which could be divided into four groups. Members of different groups had high structural and functional similarities, and the genes related to cotton fiber development were identified. It was clarified that GhFLA05 specifically expressed in the secondary wall synthesis stage, and closely related to the difference in fiber strength of different upland cotton materials.

Genome-Wide Identification and Interspecific Comparative Analysis of the EXO70 Gene Family in Cotton

DONG YanYu, XU BiYu, DONG ZeYu, WANG LuYao, CHEN JinWen, FANG Lei

Scientia Agricultura Sinica. 2023, 56(23):  4621-4634.  doi:10.3864/j.issn.0578-1752.2023.23.005

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【Objective】The two main types of allotetraploid cotton that are currently cultivated are upland cotton, known for its high yield and good adaptability, and island cotton, which boasts excellent fiber quality but lower yield. EXO70, a vital subunit of the exocyst complex, plays a significant role in plant growth, development, and stress response. By identifying and analyzing members of the EXO70 gene family in upland and island cotton at the whole-genome level, and studying their functions in fiber development and environmental adaptation, we can shed light on the molecular basis for the differences in traits between these two varieties. 【Method】The reference sequences of EXO70 protein in Arabidopsis were obtained from the TAIR database. HMMER, ExPASy, MEME, TBtools, and other analysis tools were used to identify and analyze the members of EXO70 gene family in the genomes of upland cotton TM-1 and island cotton Hai7124. The similarities and differences in gene expression patterns, correlations with crucial agronomic traits, and stress responses of this family were systematically compared. 【Result】Through genome-level analysis of upland cotton and sea-island cotton, 54 EXO70 family members were identified in both upland and sea-island cotton, which could be divided into eight subgroups based on phylogenetic analysis. Orthologous genes between upland cotton and sea-island cotton can be paired one-to-one and are distributed across the 20 chromosomes of both species. The majority of the members have single exons, while 12 pairs of homologous genes displayed significant differences in the reading frame sequences. Most orthologous genes in Gossypium hirsutum and Gossypium barbadense display similar expression patterns, but differences in expression levels are observed during the same fiber development stage, such as GH_A04G1208 and its orthologous gene GB_A04G1253 in subgroup A. Single gene association analysis revealed that more genes were associated with fiber quality traits in sea-island cotton, while more genes were associated with yield traits and environmental adversity sensitivity in upland cotton. Some trait association differences resulted from genetic structural differences between Gossypium hirsutum and Gossypium barbadense. Under different stresses, upland cotton showed a significantly higher number of induced genes compared to sea-island cotton. 【Conclusion】The sequence structure and gene expression patterns of the EXO70 family were found to be relatively conserved in both upland and island cotton during the formation, differentiation, and domestication of tetraploid cotton. However, in terms of EXO70 family members, island cotton had more genes related to fiber quality traits, while upland cotton had more genes related to yield traits and exhibited greater sensitivity to environmental stress.

Research Advances of Map-Based Cloning Genes in Cotton

ZANG XinShan, WANG KangWen, ZHANG XianLiang, WANG XuePing, WANG Jun, LIANG Yu, PEI XiaoYu, REN Xiang, LÜ YuLong, GAO Yu, WANG XingXing, PENG YunLing, MA XiongFeng

Scientia Agricultura Sinica. 2023, 56(23):  4635-4647.  doi:10.3864/j.issn.0578-1752.2023.23.006

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Map-based cloning is a classical and effective method to identify candidate genes for specific phenotypic variants. Map-based cloning of functional genes plays important roles in the innovative utilization of germplasm resources, molecular design breeding and improving breeding efficiency. In recent years, the whole-genome sequencing of Gossypium raimondii, Gossypium arboreum, Gossypium hirsutum, and Gossypium barbadense has been completed and improved. Map-based cloning has entered into a crucial period. In 2016, the dominant glandless gene Gl₂^e (GoPGF) was the first map-based cloning gene in cotton. So far, 20 qualitative traits genes and 5 quantitative traits genes have been identified by map-based cloning technology. In this paper, research progress was systematically reviewed in fiber, gland, nectary, leaf type, plant architecture, plant color, and fertility in terms of gene symbols, names, chromosomal positioning, and candidate genes. Moreover, map-based cloning strategies were systematically reviewed in mapping populations and bulked segregate analysis-sequencing (BSA-seq). With the reduction of sequencing cost and utilization of BSA-seq, it is believed that more and more genes will be cloned by map-based cloning technology. In addition, transformation and genome editing have been successfully used to evaluate the function of the candidate gene in the target interval. It is believed that map-based cloning could provide a theoretical basis and genetic resources for molecular design breeding in cotton.

TILLAGE & CULTIVATION·PHYSIOLOGY & BIOCHEMISTRY·AGRICULTURE INFORMATION TECHNOLOGY

Effect of Different Strip Distances on Light Energy Utilization in Strip Intercropping Maize

WU Jing, CHEN Meng, WANG ZhiHua, YANG JiZhi, LI YanLi, WU YuShan, YANG WenYu

Scientia Agricultura Sinica. 2023, 56(23):  4648-4659.  doi:10.3864/j.issn.0578-1752.2023.23.007

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【Objective】The objective of this study is to investigate the effect of different strip distances on light energy utilization of maize in maize-soybean strip intercropping, when the single maize plant was grown in the same environment.【Method】This experiment was conducted in 2021-2022 with traditional intercropping (1M1S, 2M1S) and maize-soybean strip intercropping (2M2S, 2M3S, 2M4S) as research objects, five maize strip distance treatments at 1 m (1M1S, 1 row maize﹕1 row soybean), 1.2 m (2M1S, 2 rows maize﹕1 row soybean), 1.6 m (2M2S, 2 rows maize﹕2 rows soybean), 2 m (2M3S, 2 rows maize﹕3 rows soybean), 2.4 m (2M4S, 2 rows maize﹕4 rows soybean) were set, and two monocropping maize treatments were conducted as controls with a row spacing of 80 cm (M80) and 40 cm (M40), respectively. The effect of the difference of light environment on light energy interception and radiation use efficiency (RUE) of maize was analyzed.【Result】Compared to monocropping maize, strip intercropping improved the light transmission at the lower and middle part of the maize canopy, which significantly increased the leaf area and light energy utilization of maize, increased the accumulation of maize dry matter, maintained a higher net photosynthetic rate of maize leaves, and promoted the increase of yield. With the increasing distance between maize strip, the light transmittance in the lower and middle part of maize increased by 30.67%, 20.62%, 10.10% and 112.70%, 96.35% and 79.23% for the 2M2S, 2M3S and 2M4S treatments, respectively. Compared to the monocropping M80 and M40 treatments, 2M4S treatment showed the 44.72% and 53.54% lower light energy interception of maize per unit land area due to the least occupied planting area, respectively, while the RUE of 2M4S treatment was 1.14 times higher than that of M80 and 2.16 times higher than that of M40. The yield of strip intercropping 2M2S, 2M3S and 2M4S treatments increased by 4.97%, 10.47%, 13.43% and 50.05%, 57.08% and 61.31% compared to that of M80 and M40 treatments, respectively.【Conclusion】When the growth environment of each single maize is consistent, the increase of the distance between maize strip improved the light transmission in the lower and middle part of the maize canopy, increased the leaf area of maize, and maintained a higher net photosynthetic rate and photosynthetic product accumulation in the leaves, which leads to the increase of maize RUE. The 2M4S treatment showed the highest light transmission in the lower and middle part of the maize, and the highest net photosynthetic rate and dry matter accumulation in maize, resulting in the highest light energy utilization and yield.

Regulation of Single-Seed Sowing and Phosphorus Application on Interspecific Competition and Growth of Intercropping Peanut

JIANG WenYang, CHEN JunNan, ZAN ZhiMan, WANG JiangTao, ZHENG Bin, LIU Ling, LIU Juan, JIAO NianYuan

Scientia Agricultura Sinica. 2023, 56(23):  4660-4670.  doi:10.3864/j.issn.0578-1752.2023.23.008

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【Background】Maize (Zea mays) intercropping with peanut (Arachis hypogaea) (maize||peanut) has outstanding interspecific effects between aboveground and underground, and the intercropping advantage in yield is prominent, which plays an important role in alleviating the conflict between oil and grain in our country. However, peanut is at the disadvantage of interspecific competition, which becomes the bottleneck restricting the further improvement of intercropping advantage.【Objective】The objective of this study is to explore the regulation measures and mechanism of enhancing peanut interspecific competition in maize||peanut system, and to provide theoretical basis and technical support for maize||peanut high-yield cultivation.【Method】Maize ‘Zhengdan 958’ and peanut ‘Huayu 16’ were used as test materials in the experimental farm of Henan University of Science and Technology from 2021 to 2022. A completely randomized block experiment with three factors: planting pattern, peanut sowing method and phosphorus application rate was set up. In other words, planting patterns were peanut monoculture and maize||peanut, peanut seeding methods were single-seed sowing and double-seed sowing, and phosphorus application rates were 0 (P₀) and 180 kg P₂O₅·hm^-2 (P₁₈₀). Peanut double-seed sowing of maize||peanut was used as control, effects of peanut single-seed sowing on interspecific competitiveness of intercropping peanut over maize, net photosynthetic rate, maximum growth rate, dry matter accumulation and distribution, and yield advantage of intercropping were studied.【Result】Compared to the strong and weak plants with double-seed sowing peanut, single-seed sowing significantly increased the aggressivity and crowding coefficient of intercropping peanut over maize, the aggressivity increased by 29.72%-80.85% and 38.91%-87.07%, respectively, and the crowding coefficient increased by 76.59%-172.02% and 244.43%-308.70%, respectively. The net photosynthetic rate of intercropping peanut with single-seed sowing was significantly higher than that with double-seed sowing, and the maximum growth rate was significantly higher than that of strong and weak plants with double-seed sowing, respectively. The dry matter in the later growth period was significantly increased, dry matter distribution ratio to pod was increased, the contribution rate of stem and leaf dry matter to pod was improved, compared to the strong and weak plants with double-seed sowing peanut. The yield and advantage of intercropping with single seeding were higher than those with double seeding, and the yield was 18.84%-33.32% higher, the difference was significant. Compared with no phosphorus fertilizer, phosphorus application significantly increased the net photosynthetic rate and maximum growth rate of intercropping peanut, and promoted the dry matter accumulation and increased yield of intercropping peanut.【Conclusion】Peanut single-seed sowing can improve intercropping peanut yield and intercropping advantage, the key lies in the fact that single-seed sowing can enhance interspecific competitiveness of intercropping peanut compare with double-seed sowing, significantly increase the net photosynthetic rate, and promote the accumulation of dry matter and distribution to the pod. Phosphorus application promotes the growth and development of intercropping peanut under single-seed sowing.

PLANT PROTECTION

Effect of Temperature on the Occurrence of Cotton Verticillium Wilt and Host Defense Response

ZHANG YaLin, JIANG Yan, ZHAO LiHong, FENG ZiLi, FENG HongJie, WEI Feng, ZHOU JingLong, ZHU HeQin, MA ZhiYing

Scientia Agricultura Sinica. 2023, 56(23):  4671-4683.  doi:10.3864/j.issn.0578-1752.2023.23.009

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【Objective】The objective of this study is to analyze the effect of different temperatures on the occurrence of cotton Verticillium wilt and the mechanism of regulating host defense response, reveal the dual effects of temperature on pathogen and host, and to provide a theoretical basis for the green control and temperature regulation of this disease.【Method】Cotton Verticillium wilt resistant variety Zhongzhimian 2 (ZZM2) and susceptible variety Jimian 11 (JM11) were employed as experimental materials, indoor experiments and disease nursery experiments were jointly used to set constant temperatures (22, 25, 28, and 32 ℃) and natural temperature variation to determine the effect of temperature on the growth, infection and colonization of Verticillium dahliae, and the occurrence of cotton Verticillium wilt. The mechanism of temperature regulation of cotton host defense response was analyzed by utilizing indicators such as reactive oxygen species (ROS) outbreak, H₂O₂ content, callose accumulation, and the expression of defense-related genes.【Result】On the culture media, 25 ℃ was the optimal temperature for the mycelial growth of V. dahliae, and the range of 22-28 ℃ was suitable for spore yield. Compared with the culture media, the leaf extracts of resistant variety ZZM2 and susceptible variety JM11 had a promoting effect on the growth of V. dahliae, and JM11 promoted stronger. When the temperatures were between 25 and 28 ℃, both ZZM2 and JM11 suffered from severe Verticillium wilt, and low temperature 22 ℃ and high temperature 32 ℃ were not conducive to the occurrence of Verticillium wilt. Meanwhile, under 25 ℃ treatment, the colonization ability of V. dahliae in cotton was strong, JM11 was more susceptible to V. dahliae infection than ZZM2, which was basically consistent with the results of the cotton Verticillium wilt disease index. Furthermore, temperature significantly affected the host defense response of cotton: compared with 22-28 ℃, whether inoculated with V. dahliae or not, the ROS outbreak produced by ZZM2 and JM11 under 32 ℃ treatment was stronger; under 25 ℃ treatment, the H₂O₂ content in ZZM2 and JM11 leaves was the lowest; under 32 ℃ treatment, the accumulation of callose in ZZM2 and JM11 leaves was higher, which was 2.04 and 1.80 times higher than that of the untreated control, respectively; the expression level of PAL, POD, and PPO defense-related genes in cotton leaves decreased under treatments at 25-28 ℃, which was lower than that under treatments at 22 and 32 ℃.【Conclusion】Temperature has a dual effect on the growth of V. dahliae and host defense response, which in turn affects the occurrence of cotton Verticillium wilt. Regardless of constant temperature or natural temperature variation, 25-28 ℃ are beneficial for the colonization of V. dahliae in cotton, significantly reduce the host defense response, and lead to severe cotton Verticillium wilt.

Identification of Viruses Infecting Bottle Gourd in Guangdong Province and Establishment of Multiplex RT-PCR Detection Method

SU Qi, TANG YaFei, SHE XiaoMan, LAN GuoBing, YU Lin, WU ZhengWei, LI ZhengGang, HE ZiFu

Scientia Agricultura Sinica. 2023, 56(23):  4684-4695.  doi:10.3864/j.issn.0578-1752.2023.23.010

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【Objective】The objective of this research is to determine the various viruses that infect bottle gourd, establish a multiplex RT-PCR detection method that can simultaneously detect multiple bottle gourd viruses, so as to enhance the efficiency of identifying bottle gourd virus species, and provide a foundation for accurate prevention and control of bottle gourd viral diseases.【Method】From 2018 to 2022, 78 bottle gourd samples of suspected virus infection were collected from the main planting areas of bottle gourd in Guangdong Province, including Guangzhou, Huizhou, Qingyuan, Shantou, and Zhanjiang. The collected samples were sorted by region and symptom, and the total RNA of each sample was extracted. The RNA samples with similar symptoms from each region were mixed for small RNA deep sequencing analysis. According to the results of small RNA deep sequencing analysis, specific primers were designed for RT-PCR verification to identify the specific virus species infecting bottle gourd in Guangdong Province. Six viruses with higher incidence and more losses were selected, and multiplex PCR detection primers based on the GenBank database were designed. After optimizing the reaction system and conditions, a method for simultaneous detection of all six viruses via multiplex RT-PCR was established.【Result】A total of 12 viruses were detected in 78 bottle gourd samples of suspected virus infection. These viruses were ranked in order of infection rate, from highest to lowest: Lagenaria siceraria alphaendornavirus (LSEV) (64.1%), cucumber green mottle mosaic virus (CGMMV) (62.8%), zucchini tigre mosaic virus (ZTMV) (51.3%), watermelon green mottle mosaic virus (WGMMV) (43.6%), watermelon virus A (WVA) (32.1%), papaya ringspot virus (PRSV) (19.2%), zucchini yellow mosaic virus (ZYMV) (9.0%), cucurbit aphid-borne yellows virus (CABYV) (7.7%), squash leaf curl China virus (SLCCNV) (7.7%), cucurbit chlorotic yellows virus (CCYV) (5.1%), cucurbit yellow stunting disorder virus (CYSDV) (3.8%), melon yellow spot virus (MYSV) (1.3%). It was found that 80.8% of the 78 samples were infected with multiple viruses. The types of mixed infection included 2 viruses (14.1%), 3 viruses (16.7%), 4 viruses (23.1%), 5 viruses (17.9%), 6 viruses (7.7%) and 7 viruses (1.3%), respectively. The WVA+CCYV+ZTMV+PRSV primers were added firstly in the multiplex RT-PCR system, followed by the WGMMV+ CGMMV primers after 12 reaction cycles. The volumes of primers were used: WVA 0.5 μL, CCYV 0.5 μL, CGMMV 0.4 μL, WGMMV 0.4 μL, ZTMV 0.6 μL, and PRSV 0.6 μL. Thus, a multiplex RT-PCR assay capable of simultaneously amplifying six viruses was established.【Conclusion】There are 12 primary viruses that infect bottle gourd in Guangdong Province. Among them, CGMMV, ZTMV, WGMMV, and WVA are the most predominant viruses. Mixed infection is a commonly observed phenomenon, with three, four, and five viruses’ co-infection being the most prevalent types. A multiplex RT-PCR detection method has been developed to simultaneously identify six viruses in bottle gourd, which improves the detection efficiency of virus species in bottle gourd.

SOIL & FERTILIZER·WATER-SAVING IRRIGATION·AGROECOLOGY & ENVIRONMENT

40 Years’ Change Characteristics of Soil Basic Properties in the Main Planting Area of Winter Oilseed Rape

HUO RunXia, ZHANG Zhe, LI WenPing, ZHANG YangYang, LIAO ShiPeng, REN Tao, LI XiaoKun, LU ZhiFeng, CONG RiHuan, LU JianWei

Scientia Agricultura Sinica. 2023, 56(23):  4696-4705.  doi:10.3864/j.issn.0578-1752.2023.23.011

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【Objective】The objective of this study was to investigate the changes in basic physical and chemical properties of soils in the main winter oilseed rape producing areas in the Yangtze River Basin over the past 40 years, and to clarify the characteristics of changes in comprehensive soil fertility of arable land in winter rape growing areas, in order to provide a scientific basis for conservation and soil fertility improvement in low and middle yielding fields in the Yangtze River Basin.【Method】By collecting and organizing the data from published literatures, master’s and doctoral dissertations at home and abroad in the past 40 years, the temporal variation characteristics of basic soil properties in winter oilseed rape growing areas in the Yangtze River Basin were analyzed. Then the variation characteristics of integrated soil fertility (IFI) and its correlation with basic soil physical and chemical properties were evaluated. 【Result】The average values of soil organic matter, total nitrogen, available phosphorus and potassium, and pH in the main winter oilseed rape producing areas of the Yangtze River Basin were 18.54 g·kg^-1, 1.16 mg·kg^-1, 8.60 mg·kg^-1, 42.90 mg·kg^-1, and 6.26 during the period of 1981-1990, respectively, but enhanced to 25.60 g·kg^-1, 1.41 mg·kg^-1, 18.66 mg·kg^-1, 108.98 mg·kg^-1, and 6.31 by 2016-2020, respectively. Clearly, the soil basic physical and chemical properties have been improved extensively in planting area of winter oilseed rape in the Yangtze River Basin. The average annual increase rate was 1.2% in soil organic matter and 0.7% in soil total nitrogen. Soil available phosphorus and available potassium were enhanced by 3.0% and 4.0% per year, respectively. Soil pH remained stable in the past 40 years, with the mean range of 6.21-6.45 among different periods. Based on the improved Nemerow index method, soil IFI value was also found enhanced in the past four decades. Compared with the mean IFI in the period of 1981-2000, the value was significantly increased by 14.8%-30.4% during the period of 2001-2020. The IFI was positively correlated with soil organic matter, pH, total nitrogen, available phosphorus and available potassium. Path analysis showed that soil available potassium was the most important index affecting IFI, followed by soil total nitrogen and available phosphorus. 【Conclusion】The basic physical and chemical properties and comprehensive fertility of the soil was significantly improved in the past 40 years in the planting area of winter oilseed rape. Developing the planting area of oilseed rape would be benefit for soil fertility and productivity improvement in the Yangtze River Basin, especially for the farmland with low yield productivity.

Interaction Between Transverse Ridge Tillage and Topography on Soil Erodibility Along the Long Gentle Slope in a Typical Black Soil Region of Northeast China

YU BoWei, ZHANG QingWen, HAO Zhuo, SHI YuLong, LI XueLiang, LI MengNi, JING XueKai

Scientia Agricultura Sinica. 2023, 56(23):  4706-4716.  doi:10.3864/j.issn.0578-1752.2023.23.012

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【Objective】The soil erosion of slope farmland in Chinese black soil region is becoming more and more serious. This study mainly focused on the interaction between transverse ridge tillage and topography on soil erodibility, which could provide a scientific theoretical basis for precise prevention of soil erosion of slope farmland in black soil region. 【Method】A typical slope farmland in the Hongxing farm in Beian city of Heilongjiang Province was selected as research object. A total of 25 sampling points were designed along both the transverse ridge tillage direction and longitudinal waterline direction. The soil erodibility K values of the corresponding sample points were calculated and tested by One-way ANOVA method. The influence factors of soil erodibility K value were analyzed by using the geographic detector model. 【Result】In the transverse ridge tillage direction, the ridge soil erodibility decreased gradually from the top to the foot of slope, and the K value decreased by 6.2%. The furrow soil erodibility decreased gradually from the shoulder to the foot of slope, and the K value decreased by 5.8%. In the waterline direction, due to the blocking effect of ridge terrace on surface runoff, soil erodibility K value of ridge and furrow did not change significantly along the slope. Geodetector analysis showed that the influence of the transverse ridge tillage on soil erodibility K value was the greatest, and its interpretation rate was more than 51% and 18% in the ridge and furrow, respectively. The transverse ridge tillage and other factors had a significant interaction enhancement effect on K value, particularly the interaction between the transverse ridge tillage and topography. 【Conclusion】 The soil erodibility K value of slope farmland in the black soil region had obvious spatial variability. There was significant interaction between the transverse ridge tillage and topography on soil erodibility. The transverse ridge tillage could significantly intercept runoff and reduce soil erosion. Due to the long slope in the transverse ridge tillage, it was easy to collect runoff at the foot of the slope, and increase the potential risk of ridge failure.

Research Progress on the Carbon and Nitrogen Sink of Duckweed Growing in Paddy and Its Effects on Rice Yield

JING LiQuan, LI Fan, ZHAO YiHan, WANG XunKang, ZHAO FuCheng, LAI ShangKun, SUN XiaoLin, WANG YunXia, YANG LianXin

Scientia Agricultura Sinica. 2023, 56(23):  4717-4728.  doi:10.3864/j.issn.0578-1752.2023.23.013

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Duckweed (Lemna minor L.) is a floating microscopic plant that is usually found in standing water. Climate change is characterized by rising temperature, which is mainly due to increasing atmospheric CO₂ concentration, and it poses potential risks to food production. Owing to factors such as climate warming and/or the eutrophication of water, duckweed growth in paddy fields has shown an increasing trend year by year in China. This paper focused on the impacts of duckweed on paddy fields and highlighted some vital trends. Duckweed reduced the water temperature of paddy by 0.86-2.76 ℃ and the pH value by 0.10-0.45, changed the structure of microbial community, reduced the NH₃ volatilization by 18.2%-59.0%, and increased the nitrogen utilization rate by 17.2%-78.0%. As a result, the nitrogen sink of paddy increased and the rice yield rose by 9.0%-34.6% upon duckweed growing in paddy. Duckweed grew and reproduced rapidly, and its annual biomass could reach 8×10³-13×10³ kg·hm^-2, making its carbon sink almost equal to that of rice in the same season. The mutualism between duckweed and rice was greater than its competition, and the coexistence of duckweed and rice in paddy showed an adaptation of the rice field ecosystem to environmental changes. Future research in this field should focus on the effect and its mechanism of duckweed on the paddy environment changes, rice growth, yield, and quality, and the risks which might bring to the paddy fields, especially the interaction with environmental factors (elevated temperature and CO₂ concentration, etc.). Such research would provide theoretical support for the sustainable agricultural development of rice farming technology based on biological collaboration, such as rice-duckweed, which can adapt to future changes in climate and environment.

HORTICULTURE

Analysis of Genetic Effect of Fruit Color Controlled by Epistatic Genes in Eggplant

CHEN JinRong, LÜ ZiJian, FAN LiSha, YOU Qian, LI Tao, GONG Chao, SUN GuangWen, LI ZhiLiang, SUN BaoJuan

Scientia Agricultura Sinica. 2023, 56(23):  4729-4741.  doi:10.3864/j.issn.0578-1752.2023.23.014

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【Objective】Fruit color is an important trait that affects the commercial value of eggplant fruit. By analyzing the causes for the special segregation ratio of individual plants with purple red peel and with white peel in the F₂ population constructed by crossing between two white-fruit parents, this paper could lay the foundation for elucidating the mechanism of epistatic gene interaction on regulating eggplant fruit coloration.【Method】The white-flower and white-peel female parent 19141 with mutation at the structural gene ANS involving in the anthocyanin biosynthesis pathway, white-flower and white-peel male parent 19142 with unknown mutation genes involving in the anthocyanin biosynthesis pathway, and their F₁ population with purple red peel and F₂ population with separate peel colors were used to explore the epistatic inheritance of eggplant fruit coloration. Genes and their mutation patterns were studied by cloning the known genes, D (SmMYB1) and Y (SmDFR) related to peel color in male parent 19142. Molecular basis of peel color-controlling epigenetic genes was analyzed by developing molecular markers based on genetic variations of peel color genes, analyzing the relationship between genotype and phenotype in E4450F₂ population, and crossing with other eggplant parents without anthocyanin pigmentation in peel.【Result】The segregation ratio of plants with purple red fruit and white fruit in E4450 F₂ progeny was consistent with the segregation ratio of 27:37 controlled by three pairs of epistatic genes, that is, mutations occurred at the P gene locus in 19141, with genotype DDppYY, and mutations occurred at both D and Y gene loci in 19142, with genotype ddPPyy. The results of cloning and sequencing showed that alternative splicing occurred in SmMYB1 of 19142, which led to the second exon skipping. In 19142, SNP (C→G) in the promoter region’s -326 bp upstream of the start codon resulted in the absence of a CAAT-box cis-acting element in SmDFR gene. An SNP, G to C, at the last base of the second exon, was annotated as splicing mutation, which might cause abnormal function of SmDFR gene in 19142, resulting in the eggplant peel’s inability to synthesize anthocyanin. Based on the genetic variation of SmMYB1, SmANS and SmDFR, the functional molecular markers were developed, and the progenies of E4450F₂ were genotyped. The results showed that genotype and phenotype were completely consistent. D_P_Y_ corresponded to phenotypes of purple flower and purple red peel, ddP_Y_ corresponded to phenotype of purple flower and white peel, D_ppY_, D_P_yy, D_ppyy, ddppY_, ddP_yy and ddppyy genotypes corresponded to white flower and white peel phenotypes. When 19142 was crossed with white-peel inbred line 19147 (d^td^tPPYY), and green-peel inbred line 19144 (DDPPyy), it was found that the fruit color of the two F₁ progenies were white and green, respectively, and there was no anthocyanin pigmentation in the peel, which further proved that 19142 was a double mutant in SmMYB1 and SmDFR.【Conclusion】When two eggplant parents without anthocyanin pigmentation in the peel were crossed, the peel of the F₁ generation had anthocyanidin pigmentation, and the segregation ratio of plants with anthocyanin pigmentation and non-anthocyanin pigmentation in F₂ population was 27:37, it was because one of the parents had a mutation at a gene locus in the anthocyanin biosynthesis pathway, and the other parent had mutations at two other loci in the anthocyanin biosynthesis pathway. When two parents without anthocyanin pigmentation were crossed, the peel of F₁ was able to synthesize anthocyanin and present purple red color, which was due to the simultaneous dominance of three epistatic gene loci D, P and Y, and anthocyanin biosynthesis was restored. Mutation of the structural gene of SmANS or SmDFR inhibited anthocyanin biosynthesis in all parts of the plant. The regulation of transcription factor mutation SmMYB1 was tissue specific, and its mutation inhibited anthocyanin biosynthesis in the peel, but did not inhabit anthocyanin biosynthesis in the flower.

Evaluation of Heat Tolerance of Herbaceous Peony and Screening of Its Identification Indices

HOU ZhaoYu, GONG YiZhao, QIAN Yi, CHENG ZhuoYa, TAO Jun, ZHAO DaQiu

Scientia Agricultura Sinica. 2023, 56(23):  4742-4756.  doi:10.3864/j.issn.0578-1752.2023.23.015

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【Objective】 The multivariate statistical analysis method was used to evaluate the heat-tolerance of different herbaceous peony (Paeonia lactiflora Pall.) varieties, to screen the heat-tolerance identification indexes of peony, and finally to establish a more comprehensive and reliable heat-tolerance evaluation system of peony. 【Method】 In this study, 140 peony varieties were used as materials, and field experiments were used to measure 8 morphological and structural indexes, including heat damage index, plant height, crown width, and SPAD value; at the same time, 13 physiological indexes, such as malondialdehyde and relative electrical conductivity, were measured in August after high-temperature stress in summer. Correlation analysis, subordination function method, principal component analysis, cluster analysis and stepwise regression analysis were used to comprehensively evaluate the peony heat-tolerance and to screen the identification indexes of heat-tolerance. 【Result】 There were different degrees of variation among the 21 indicators, and the variation coefficient ranged from 6.66% to 78.02%. The variation coefficient was shown as follows: Catalase (CAT)>POD>Pn>qN>SOD>stomatal density>barrier tissue thickness/sponge tissue thickness>SSC>SPC>heat damage index>SPAD>Y(Ⅱ)>b>MDA>Y(NO)>crown width>leaf thickness>plant height>REC>Fv/Fm>Hue angle (H), among which, CATwas the largest coefficient of variation, and H was the smallest coefficient of variation; through the correlation analysis of each index, it was found that X₁ (heat damage index) and X₂ (plant height), X₃ (crown width), X₄ (SPAD), X₇ (Fv/Fm), X₁₂ (leaf thickness), X₁₇ (SSC ) were extremely significantly negatively correlated, which were significantly negatively correlated with X₆ (Pn), X₈ [Y(Ⅱ)], X₁₃ (stomatal density), X₂₀ (CAT), while they were extremely significantly positively correlated with X₅ (REC), X₉ [Y(NO)], X₁₆ (MDA) and X₁₈ (SPC). There were different degrees of correlation among the indicators, which was relatively complicated; 21 indicators were extracted into 7 principal component factors through the principal component analysis method, and the contribution rates were 20.50%, 11.66%, 8.24%, 7.24%, 7.06%, 5.31%, and 4.85%, respectively, while the cumulative contribution rate reached 64.87%; the comprehensive score (W) of 140 peony varieties were calculated by the membership function analysis method. On this basis, cluster analysis was used to classify the peony cultivars into four types of heat resistance: “excellent” “good” “medium” and “poor”. The “excellent” type accounted for 14.3%, “good” type accounted for 26.4%, “medium” type accounted for 46.4%, and “poor” type accounted for 12.9%; the stepwise regression analysis was further used to establish the optimal linear regression equation: W=0.228-0.166X₁+0.002X₄+0.325X₇-0.257X₉+0.112X₁₀+0.00028X₁₃+0.002X₁₇+0.00015X₁₉+0.001X₂₀, and 9 indicators were selected from 21 indicators (heat damage index), including X₁(heat damage index), X₄ (SPAD), X₇ (Fv/Fm), X₉ [Y(NO)], X₁₀ (qN), X₁₃ (pore density), X₁₇ (SSC), X₁₉ (SOD), and X₂₀ (CAT), which were used as identification peony indicators of heat-resistance. 【Conclusion】 By using multivariate statistical analysis method to evaluate the heat resistance of peony, 140 peony varieties were divided into 4 categories (excellent, good, medium, and poor). 9 indexes including heat damage index and SPAD value were screened as identification indexes of heat-resistance of peony, to quickly evaluate the heat-resistant ability of peony, thereby significantly improving the efficiency of heat-resistant identification of peony.

ANIMAL SCIENCE·VETERINARY SCIENCE

miR-535 Targets the GAB2 Gene to Promote Goat Granulosa Cell Proliferation Through Activation of the PI3K/AKT Signaling Pathway

WANG Peng, LIU ZiYi, LIU YuFang, CHU MingXing

Scientia Agricultura Sinica. 2023, 56(23):  4757-4771.  doi:10.3864/j.issn.0578-1752.2023.23.016

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【Background】MicroRNAs (miRNAs) are short RNA molecules of 18-25 nt in length that play an important role in the regulation of follicle development in mammalian ovary granulosa cells (GCs). The previous sequencing of the transcriptome of the ovaries of high and low kidding individuals in Yunshang black goats showed that miR-535 was able to influence the kidding number of goats, but the specific regulatory mechanism was not yet clear. 【Objective】 The aim of this study was to investigate the molecular mechanisms of miR-535 targeting the GRB2 associated binding protein 2 (GAB2) and its associated signaling pathway PI3K/AKT affected the proliferation of goat GCs, so as to further investigate the molecular biological regulation mechanism. 【Method】In this study, three high- and low-fertility Yunshang black goats with the kidding number record of more than two litters were selected, and their follicular ovarian tissues were collected after synchronous estrus treatment for collecting primary GCs. The expression of miR-535 and GAB2 in high- and low-yield ovary tissues of Yunshang black goats was detected by reverse transcription-quantitative PCR (RT-qPCR). The overexpression/inhibitor of GAB2 vector was constructed and the effect of candidate GAB2 on the proliferation of goat GCs was detected using RT-qPCR, Western blot, immunofluorescence, CCK8, EdU and Apoptosis, respectively. The prediction of the targeted relationship between miR-535 and GAB2 was performed with miRDB and miRanda software. The Wild-type and Mutant vectors of GAB2 were constructed and the targeting relationship between miR-535 and GAB2 was detected by the dual luciferase activity assay. The overexpression/inhibitor miR-535 vector was constructed to explore the effect of its GCs proliferation and downstream gene function. 【Result】 The RT-qPCR results showed that the expression of GAB2 was significantly lower in ovarian tissues of Yunshang black goats with high-fertility than that in low-fertility groups, and the expression of miR-535 was the opposite (P<0.05). The results of RT-qPCR and Western blot showed that the expression of CCND2, CDK4 and BCL2 was significantly increased (P<0.05), while the expression of BAX was significantly decreased (P<0.05) after overexpression of GAB2 in GCs, and the inhibition of their expression was the opposite. Both EdU and CCK8 assays showed that GAB2 overexpression significantly promoted the proliferation of granulosa cell, while inhibition of its expression was the opposite (P<0.05). Dual luciferase reporter assays showed that miR-535 inhibited dual luciferase activity in the 3'UTR region of the GAB2 gene. The results of RT-qPCR and Western blot showed that the expression of GAB2, CCND2, CDK4 and BCL2 in goat GCs was significantly decreased and the expression of BAX was significantly increased after miR-535 overexpression, while the opposite was true after miR-535 inhibition (P<0.05). Both EdU and CCK8 assays showed that miR-535 overexpression significantly inhibited the proliferation of GCs, while the opposite was true after miR-535 inhibition (P<0.05). Apoptosis assays showed that miR-535 overexpression promoted GCs proliferation and the opposite was true after inhibition of its expression. The expression levels of the PI3K/AKT signaling pathway marker AKT in goat GCs were significantly increased after inhibition of miR-535, respectively (P<0.05). 【Conclusion】 In conclusion, the results of this study suggested that miR-535 inhibited the proliferation of goat granulosa cells by suppressing the expression of GAB2. These results provided a theoretical basis for further investigation of the biological functions of miR-535 regulating goat GCs.

Influences of Phosphorus Level in Diet of Parent Pigeons on Biochemical Index, Untargeted Metabolomics Profile of Serum, and Gene Expression of Phosphate Transporters in Squabs

AN Yong, QIN ShiZhen, SHI ZhaoGuo, GONG LiYuan, ZHANG Shuai, JI Feng

Scientia Agricultura Sinica. 2023, 56(23):  4772-4788.  doi:10.3864/j.issn.0578-1752.2023.23.017

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【Objective】The aim of this study was to investigate the effects of different levels of inorganic phosphorus (P) on serum biochemical parameters, non-targeted metabolites, and expression of phosphate transporter genes in the small intestine and kidney of pigeon, so as to provide a theoretical basis for the regulation of phosphorus nutrition in pigeon during the period of rapid growth.【Method】A total of 192 pairs of parental Silver King pigeons (40 weeks of age) were randomly allocated to four treatment groups, each consisting of eight replicates of 6 pairs per replicate. The study lasted for 46 days including the phases of egg-hatching and squab-rearing. Dietary treatments included the basal diet (containing 0.3% of P), the basal diet supplemented with 0.2%, 0.4%, or 0.8% inorganic P. The calcium (Ca) content in diets of parent birds were kept at 1.40% in every group. The levels of Ca, P, PTH and ALP activity in serum of 7, 14 and 21 d old squabs were determined, and the content of Ca and P in crop milk were analyzed. The gene expression of Pi transporters (NaPi-Ⅱb, PiT-1, and PiT-2) in small intestine (duodenum and jejunum), and Pi transporters (NaPi-Ⅱa, PiT-1, and PiT-2) in kidney of squabs were determined. Serum metabolome profiles of 14 and 21 d old squabs in the groups of control, 0.4% and 0.8% P-supplemented were analyzed. 【Result】(1) The P contents in crop milk sampled from squabs were very significantly (P<0.01) increased by P supplementation in diets of parent pigeons. (2) No significant effect of P supplementation in diet of parent birds on serum P level, ALP activity and PTH level of squabs were observed in this study. However, the serum Ca content in birds of 0.8% P supplemental group decreased very significantly (P<0.01). The serum ALP and PTH level of squabs significantly decreased with increased age (P<0.05). (3) There was a tendency of increased gene expression of NaPi-IIb in small intestine of squabs with dietary P levels of breeding birds, however, the difference was not significant (P>0.05). The expression profile of PiT-1 and PiT-2 in kidney of squabs at the age of 7 and 14 d were very significantly higher (P<0.01) than those in duodenum and jejunum. However, the difference of the mRNA expression level of PiT-1 and PiT-2 between kidney and intestine was not observed at the age of 21 d, and the PiT-1 value of kidney samples was even lower than that of jejunum. The mRNA expression levels of PiT-1 of 7 and 14 d old squabs were significantly increased by dietary P levels of breeding birds. The mRNA expression of PiT-2 in the group of dietary 0.4% P supplementation was significantly higher (P<0.05) than that of 0.8% group when the squabs were 7 and 21 d old. The interaction of tissue and dietary P levels was significant (P<0.05) on PiT-1 mRNA level of 7 and 14 d, and PiT-2 mRNA level of 21 d old birds. The mRNA expression level of NaPi-IIa in kidney of 14 d squabs significantly decreased in the group of 0.8% P supplementation, compared with the control and 0.4% group. (4) At the age of 14 and 21 d, about half of the significantly different metabolites among the control and P-added groups were included in the category of lipids and lipid-like molecules, organic acids and derivatives was the second, and benzenoids next. The biological pathways involved in the metabolism of differentially expressed metabolites were mainly carbohydrate metabolism, metabolism of protein and amino acids, translation and lipid metabolism etc. 【Conclusion】(1) There was a significant effect of P supplementation in the diet of parent pigeons on P content in crop milk fed to squabs. The values of serum P of young birds were stable. However, the serum Ca of squabs in the group of highest dietary P treatment decreased, which might indicate that pigeons were intolerant to high dietary P level. (2) The expression levels of P transporters (PiT-1 and PiT-2) mRNA in the kidney mostly increased with dietary P supplementation. The regulation mechanisms of P reabsorption in pigeons need to be studied further. (3)The serum metabolome profiles of squabs indicated that P was involved in many important metabolic processes, such as lipid metabolism and bone mineralization etc.

RESEARCH NOTES

Changes of Endogenous Hormones and Polyamines During Ovule Development of Stenospermocarpic Seedless Grape

ZHU PeiPei, QIN HaoXiang, ZHANG JianXia

Scientia Agricultura Sinica. 2023, 56(23):  4789-4800.  doi:10.3864/j.issn.0578-1752.2023.23.018

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【Objective】By exploring the effects of endogenous hormones and polyamines on embryo development during the ovule development of seedless grape, this study provided a theoretical basis for promoting embryo development by spraying exogenous hormones before anthesis and adding exogenous hormones into the medium in vitro culture of ovule.【Method】In this study, the European grape (Vitis vinifera L.) variety Jingxiu and its F₁ generation stenospermocarpic seedless variety Qinxiu were used as test materials. The content of endogenous hormones and polyamines in ovule of fruit at different developmental stages were compared by high performance liquid chromatography mass spectrometry (HPLCMS) and ultra performance liquid chromatography (UPLC).【Result】The content of IAA, ZT, ZR, and iPAS reached their highest values at 39 DAF (days after flowering) for Jingxiu and 42 DAF for Qinxiu, and the highest values of the former were higher than those of the latter (more than 1.5 times). For the content of JA and SA, Jingxiu started to rise sharply at 36 DAF (2 000 ng∙g^-1 and 6 500 ng∙g^-1, respectively), and reached the highest values at 39 DAF (6 500 ng∙g^-1 and 10 000 ng∙g^-1, respectively), and then, which were declining and remaining at a high level at 42-45 DAF, while Qinxiu was declining and remaining at a low level from 36 DAF (3 500 ng∙g^-1 and 3 000 ng∙g^-1, respectively). The ACC content of Jingxiu was almost 0 ng∙g^-1 at 39 DAF, then increased rapidly and reached its highest value (1 200 ng∙g^-1) at 45 DAF, while Qinxiu reached its highest value (900 ng∙g^-1) at 39 DAF, then declined to 0 ng∙g^-1 at 42 DAF, and remained at a very low level. The ABA content of Jingxiu was almost 0 ng∙g^-1 from 36 to 45 DAF, while that of Qinxiu rose sharply from 0 ng∙g^-1 at 39 DAF to the highest value (900 ng∙g^-1) at 42 DAF. The trends of Put (putrescine), Spm (spermine), and Spd (spermidine) were similar for the two varieties, but Jingxiu was consistently higher than Qinxiu. The highest values of Put and Spd were 42 DAF for Jingxiu and 39 DAF for Qinxiu, except for the highest values of Spm, which were all found at 42 DAF. 【Conclusion】 The lower content of growth promoting substances (IAA, CTK, GA₃, ACC, JA, SA, Put, Spd, and Spm) and the higher content of growth inhibiting substances (ABA), and lower ratios of (IAA+GA₃)/ABA, (IAA+ZT+GA₃)/ABA, Spm/PAs, (Spd+Spm)/PAs, and (Spd+Spm)/Put in the ovules of the seedless variety Qinxiu compared with the seeded variety Jingxiu might be one of the main reasons for seedless grape embryo abortion. Therefore, in the process of seedless grape embryo rescue, the embryo abortion could be inhibited by spraying before flowering or adding to media a certain concentration of growth promoting substances.