玉米弱势粒库活性与籽粒内源激素及多胺含量的关系

摘要

玉米籽粒形成期的库活性是弱势粒败育或灌浆受限的核心限制因子,明确弱势粒中内源激素及多胺水平对其库活性的调控机制,对探索密植条件下玉米弱势粒调控途径具有重要意义.本研究以典型玉米杂交种郑单958和先玉335为材料,在控制授粉条件下(不完全授粉IcP、完全授粉CP),比较分析了成功发育弱势粒(IcP处理)和发育不良弱势粒(CP处理)的内源激素及多胺水平差异及其与库活性的关系.结果表明,品种和年度对籽粒库活性、内源激素和多胺水平整体无显著影响.IcP处理下弱势粒的可溶性酸性蔗糖转化酶(SAI)活性显著高于CP处理,平均差异和最大差异分别达13.5%和21.8%.在玉米籽粒形成期,弱势粒中玉米素和玉米素核苷(Z+ZR)、生长素(IAA)、赤霉素(GA3)和脱落酸(ABA)含量在两种控制授粉处理间无显著差异.弱势粒中多胺含量表现为IcP处理显著高于CP处理,而乙烯释放速率则恰恰相反.弱势粒中SAI活性与多胺含量显著正相关,而与乙烯释放速率显著负相关,且多胺含量与乙烯释放速率显著负相关.可见,在玉米籽粒形成期,其弱势粒中Z+ZR、IAA、GA3和ABA与其库活性即SAI活性无关;弱势粒库活性主要受多胺和乙烯含量影响,多胺促进SAI活性而乙烯则抑制其活性,二者的平衡关系决定了弱势粒成功发育与否;多胺和乙烯平衡关系受同化物质供应水平的调控.%Sink activity at blister stage of maize is the primary limiting factor of the abortion and/or filling stagnation of inferior kernels. Clarifying the effect of endogenous hormone and polyamine contents on sink activity of inferior kernels in maize is of great importance for regulating inferior kernels in crowding maize colony. In this present study, two typical commercial maize hybrids Zhengdan 958 and Xianyu 335 were planted in 2014 and 2015. At silking stage, two pollination treatments, incomplete pollination (IcP) and complete pollination (CP), were imposed to each cultivar. The objective of incomplete pollination, in which the pollinated filaments within the basal region of ear was decreased by hand-cutting, was to stimulate the inferior kernel setting in the apical region of ear, where the inferior kernels should be aborted or filling-stagnated in complete pollination. The endoge-nous hormone and polyamine contents were compared between IcP and CP treatments during blister stage, and the relationship of sink activity with endogenous hormone and/or polyamine contents was analyzed. There was no remarkable effect of hybrids and years on sink activity, endogenous hormone and polyamine of kernels. The soluble acid invertase activity of IcP was significantly higher than that of CP, by 13.5% on an average and 21.8% at the maximum. There was no significant difference in contents of Z+ZR, IAA, GA3, and ABA of the inferior kernels between IcP and CP treatments during blister stage. The polyamine content of IcP was significantly higher than that of CP, but the ethylene producing rate was just the opposite. SAI activity correlated with polyamine content positively, but with ethylene release rate negatively, moreover, ethylene release rate showed negative correla-tion with polyamine content. The results suggested that, during the blister stage of maize, the contents of Z+ZR, IAA, GA3, and ABA of inferior kernels have nothing to do with SAI activity. SAI activity of inferior kernels is mainly affected by polyamine and ethylene, which is promoted by polyamine content and inhibited by ethylene release rate. The balance between polyamine and ethylene determines the result of inferior kernel development, which is radically regulated by assimilate supply of maize plant.