Submitted to: Soybean Biotechnology Meeting
Publication Type: Abstract Only
Publication Acceptance Date: 4/2/2006
Publication Date: N/A
Technical Abstract: Long-term high temperature stress can occur during soybean seed development through maturity and negatively impact seed quality. The effects of high temperature stress were investigated using seeds harvested from soybean plants grown in environment-controlled chambers. After being treated with high day and night temperatures (37/30 degrees C) from stages R5 through R8, the total fatty acid in mature dry seeds increased; ratios of palmitic, stearic and oleic acid increased; while linoleic and linolenic acid decreased. Sucrose and stachyose levels also decreased, but total protein and phytic acid concentration changes were not significant. High temperature stress decreased seed quality associated with smaller seed size, a greater proportion of abnormal seeds, and reduced seed germination. High temperature stress damaged the integrity of cellular membranes as indicated by increased electrolyte leakage. Proteomic analysis of mature dry seeds identified 20 protein spots as exhibiting changes in accumulation by high temperature stress. Among them, fourteen spots were identified as seven subunits of seed storage proteins glycine or beta-conglycine. The remaining six proteins were identified as those responding to abiotic stresses (sucrose binding protecin [SBP], Class III acidic endochitinase, heat shock protein [HSP22], late embryo abundant protein [EM], Bowman-Birk proteinase inhibitor) or having a function during respiration (formate dehydrogenase [FDH]). SBP is associatd with sucrose transportation through the plasma membrane and decreased accumulation of SBP by high temperature stress might explain the lower sucrose levels and smaller size of seeds. Decreased FDH and damage of the integrity of the cellular membrane might be related to reduced seed vigor by high temperature stress. Our continuing research is to identify genes whose expressions are associated with the changes in seed composition or with reduced seed vigor by high temperature stress.