| High temperature and humidity (HTH) stress during soybean seed development and maturity in the field easily leads seed to pre-harvest deterioration. It often causes reduced vigor and germination rate, et al.This phenomenon has become a major obstacle of spring soybean production.At present, Related with seed deterioration research mainly focuses on the reasons that caused seed deterioration, cytology and genetics in the process of deterioration. The researches on cytological, physiological and molecular basis about seed deterioration and deterioration resistance are lack.1.92of Spring soybean landraces and cultivars from South China were used to evaluate seed deterioration resistance by incubating weathering treatment. One germplasm (Xiangdou NO.3) identified to resist to pre-harvest seed deterioration and one (Ningzhen NO.1) identified not to resist pre-harvest seed deteriorations were screened out.2. Transmission electron micrograph analysis indicated that HTH stress resulted in some ultrastructure changes in the cells of the developing seed of cv. Ningzhen No.1and the change was not significant in the cells of the developing seed of cv. Xiangdou No.3.In the cells of the developing seed of cv. Ningzhen No.1, the cells of the developing seed tended to exhibit thinner cell wall, smaller chloroplasts and protein bodies, more irregular cell nucleus and nuclear core, and bigger vacuoles and lipid bodies under HTH stress. Additionally, under HTH stress it was found that the decrease of starch grains in number and the increase of mitochondria and smooth endoplasmic reticula in number in the cell of the seed.3. It was found that the HTH stress caused heavy accumulated ROS in the cells of the developing seed and breaked the original redox balance system;In the seed of cv. Ningzhen No.1showed higher electrolyte leakage and the content of MDA than cv. Xiangdou No.3.It showed the lower activity of CAT and the content of ASA than cv. Xiangdou No. 3,HTH stress was also caused change of chemical composition of the seed.The content of protein and oil were more decrease of cv. Ningzhen No.1than cv. Xiangdou No.3;the content of Endogenous ethylene of cv. Ningzhen No.1higher than cv. Xiangdou No.3; The chlorophyll content in the leaves and seeds and Fv/Fm were all significantly decreased.; Compared to the control, the content of NO3-and NH4+in HTH-stressed developing seed of cv. Ningzhen No.1were significantly increased while the NO2-content was significantly decreased, the content ofNO3-,NO2-,NH4+in HTH-stressed developing seed of cv. Xiangdou No.3were all decrease.4. Metabolic profiling based on GC-MS showed46differentially expressed metabolites. These metabolites were classified into6categories.There were8kinds of sugar,4of sugar alcohol and1kinds of sugar acids,28.3%of the total that related to calvin cycle,With the Calvin cycle related substances significantly upregulated expression in cv. Xiangdou No.3and significantly downregulated expression.in cv. Ningzhen No.1;To detect the5kinds of PPP pathway of sugar phosphate material from cv. Ningzhen No.l, in HTH-stressed,they were upregulated expression;Detection of Phosphoglycolate, Ser and Gly3that they were related to photorespiratory patyway and were upregulated; There were6kinds material of TCA pathway,these material were upregulated in cv. Ningzhen No.1and were downregulated.in cv. Xiangdou No.3;14kinds of amino acids were detected, accounting for30.4%of the total number of detected objects in the two species were significantly or very significantly up-regulated expression; Detected7kinds of substances associated with secondary metabolite biosynthesis pathway, significantly up-regulated expression in the two species.5. Compared the proteome composition of developing seed of cv. Xiangdou NO.3and cv. Ningzhen No.1at different HTH stress time points with their corresponding controls by2-DE.87protein spots were found to be differentially expressed and successfully identified by MALDI-TOF MS:45protein spots were found to be differentially expressed and successfully identified in cv. Xiangdou NO.3. there were21spots upregulated and24spots downregulated,These proteins were involved in13of cellular responses and metabolic processes including carbohydrate metabolism, signal transduction, proteinbiosynthesis, photosynthesis, protein folding and assembly, energy pathway, cell rescue and defense, cell cycle, nitrogen metabolism, lipid metabolism,amino acid metabolism, transcription regulation, and secondary metabolite biosynthesis;42protein spots were found to be differentially expressed and successfully identified in cv. Ningzhen No.1. There were22spots upregulated an20spots downregulated.These proteins were involved in13cellular responses and metabolic processes including carbohydrate metabolism, signal transduction, proteinbiosynthesis, photosynthesis, protein folding and assembly, energy pathway, cell rescue and defense, cell cycle, nitrogen metabolism, lipid metabolism,amino acid metabolism, transcription regulation, and secondary metabolite biosynthesis.6. According to discussed, the seed deterioration resistant mechanism were found in cv. Ningzhen No.1including:①. Increased synthesis of Arg;②. Glutamine synthesis pathway enhancement;③. CO2absorption enhancement;④. Enhanced photorespiration;⑤. The enhancement of secondary metabolite synthesis;⑥. Enhanced PPP pathy; Ⅶ. Enhanced ROS scavenging and DNA repair. The seed deterioration mechanism in cv. Ningzhen No.1including:①. cell cycle reduced;②. photosynthetic rate down;③. TCA cycle enhanced;④.protein synthesis reduction;⑤. oil synthetic pathy decrease;⑥. protein folding and assembly downregulated;⑦.Nitrogen assimilation.The seed deterioration resistant mechanism in cv. Xiangdou NO.3including:①. photosynthetic rate upregulated;②. protein folding and assembly upregulated;③. Protein degradation decline;④. Energy consumption reduction;⑤. The enhancement of secondary metabolite synthesis;⑥. The increase of ASA synthesis. The seed deterioration mechanism in cv Xiangdou NO.3including:①. CO2absorption reduction;②. Cell wall synthesis reduction;③. protein synthesis;④. oil synthetic pathy decrease;⑤. Scavenging of reactive oxygen species antioxidase activity weakened. |
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