干旱胁迫下多胺对小麦籽粒灌浆的调控及其生理机制

Grain filling determines grain weight of wheat, and drought notably inhibited the grain filling of wheat. Polyamine significantly affected the drought resistance and the grain filling of wheat. However, the effect of polyamine on grain filling of wheat under drought was still unclear. In the present study, two experiments were conducted: (1) the cultivars with different drought resistance were selected and different soil moisture treatments were used, (2) the polyamine, spermine (Spm), spermidine (Spd) and putrescine (Put), was external applied respectively, under drought conditions. The endogenesis polyamine levels, the activity of the enzymes regulate the polyamine synthesis and the express levels of the genes regulate these enzymes were measured. Besides these, the hormonal changes, the starch and protein contents and the activity of the enzymes regulate the starch and protein synthesis also be measured. The objective of the present study was to investigate the effect of polyamine on grain filling of wheat under drought condition and the relationship of polyamine, hormone, and synthesis of starch and protein in regulate the grain filling of wheat under drought condition.

籽粒灌浆是小麦的重要农艺性状之一，决定了小麦粒重进而影响其产量。干旱胁迫显著抑制小麦籽粒灌浆，降低小麦粒重及产量。多胺参与了小麦等植物对干旱胁迫的响应，与植物的抗旱性密切相关，同时，多胺显著影响小麦等禾谷类作物籽粒灌浆，但是，关于干旱胁迫下多胺对小麦籽粒灌浆的调控及其机理，还未见相关研究。本项目拟选用抗旱性不同的小麦品种，采用人工控水控制土壤水分，同时结合外源施用多胺处理，塑造灌浆特性不同的小麦群体，测定不同处理小麦籽粒灌浆特性以及不同部位內源多胺含量、多胺合成相关酶活性及基因表达，阐明內源多胺对灌浆期干旱的响应及其对小麦籽粒灌浆的影响，同时测定激素含量变化、淀粉及蛋白含量、淀粉及蛋白合成相关酶活性等，分析多胺和激素、碳氮代谢在小麦籽粒灌浆响应干旱中的相互作用，从多胺、激素、碳氮代谢等角度探讨干旱胁迫下多胺调控小麦籽粒灌浆的生理机制，为明确干旱胁迫对小麦籽粒灌浆的影响机理提供理论依据。

干旱胁迫显著抑制小麦籽粒灌浆。前人研究表明多胺与籽粒灌浆、植株衰老、植物对干旱胁迫的响应等密切相关。但是，关于干旱胁迫下多胺对小麦籽粒灌浆的影响及其机理，还缺乏相关研究。本项目选取对干旱胁迫敏感性不同的小麦品种，设置不同的水分处理，测定籽粒灌浆期不同类型内源多胺含量的变化。同时，在干旱胁迫下外源喷施不同类型多胺，观测其对小麦籽粒灌浆的影响，同时测定其灌浆期内源激素含量变化。该研究的目的是探讨干旱胁迫下多胺对小麦籽粒灌浆的影响及其机理。研究结果表明亚精胺和精胺能显著缓解干旱胁迫对小麦籽粒灌浆的抑制作用，而腐胺则加剧了干旱胁迫对小麦籽粒灌浆的抑制作用。研究表明，较高的SAMDC和SPD合成酶有利于由Put向Spd的转变，这有利于提高内源亚精胺和精胺含量、降低腐胺含量，从而提高了小麦籽粒灌浆期的抗旱性，缓解了干旱胁迫对小麦籽粒灌浆的抑制作用。干旱胁迫下多胺对小麦籽粒灌浆的影响与内源ETH、Z+ZR、ABA密切相关。外源Spd和Spm显著提高了内源ABA和Z+ZR含量、显著降低了内源ETH释放速率，这促进了干旱胁迫下小麦籽粒灌浆。外源Put显著提高了内源ETH释放速率、促进了ABA在籽粒中的过度积累，这加剧了干旱胁迫对小麦籽粒灌浆的抑制作用。这表明，多胺和激素的相互作用，而不是单个激素的作用，在调控小麦籽粒灌浆响应干旱胁迫过程中起着关键作用。