小麦花后干旱胁迫下不同施磷方式延缓胚乳细胞程序性死亡的机理研究

The living endosperm cells developed dead nutrient stores in wheat. Essentially, there were two process of endosperm programmed cell death (PCD) and nutrient substance accumulation simultaneously existing during the grain filling. Our earlier work has shown that the process of endosperm PCD is accelerated during post-anthesis drought stress. Different phosphorus application has an important role that regulated grain development and starch synthesis under post-anthesis drought in wheat. The drought condition is accelerated the progression of endosperm PCD, which shorten the period of grain filling and lead to low quality and yield of wheat grains in most of Xinjiang. In this study, two wheat varieties are employed to explore the progression of endosperm PCD by different phosphorus application under the drought condition. The progression of endosperm PCD is studied by histochemical staining, transmission electron microscopy, enzyme chemical localization and endosperm PCD genes transcription. Based on these results the mechanism of endosperm PCD is delayed by different phosphorus application is elucidated upon the view of morphological structure, physiological biochemistry, and gene transcription of endosperm cells under the drought condition. The objective of this study is to provide more information for using cultivation practice to delay the occurrence of endosperm PCD and further improve the yield and quality.

小麦胚乳细胞经历了由活细胞到死的营养贮存库转变，籽粒灌浆过程是胚乳PCD与营养物质充实并进过程。前期研究表明花后干旱胁迫下胚乳细胞程序性死亡（PCD）进程加快，不同施磷方式对花后干旱下小麦籽粒发育和淀粉合成具有重要调控作用。新疆麦区籽粒灌浆期干旱，加速胚乳PCD进程，缩短灌浆期，粒重减轻，造成减产和品质降低。本研究以新疆两个冬小麦主栽品种为材料，从胚乳细胞形态结构、生理生化、基因表达等层面应用组织化学染色、透射电镜观察、酶化学定位、PCD相关基因表达等技术探明不同磷肥施用方式对花后干旱胁迫下小麦籽粒发育过程中胚乳PCD变化特征，揭示不同磷肥施用方式下磷素通过吸收转运，增强胚乳细胞间物质运输从而延缓花后干旱胁迫下胚乳PCD进程机理，验证不同磷肥施用方式调控胚乳PCD减缓干旱胁迫危害。结果可为通过栽培措施调控植株营养状况，延缓胚乳PCD进程，延长小麦籽粒灌浆期，增加粒重，减少损失提供理论基础。

小麦籽粒灌浆期干旱是造成新疆小麦减产和品质下降的重要原因之一。花后干旱胁迫下胚乳细胞程序性死亡（PCD）进程加快，不同施磷方式对花后干旱下小麦籽粒发育和淀粉合成具有重要的调控作用。本研究从PCD变化特征入手，揭示不同施磷方式下磷素吸收转运，增强胚乳胞间物质运输延缓干旱下PCD进程机理，取得了以下重要结果：.（1）小麦花后干旱胁迫不同施磷方式下胚乳PCD变化特征，表现为外界干旱胁迫使得胚乳PCD进程加快，从胚乳PCD发生方式、胚乳细胞核变化及超显微结构变化、胚乳基因组DNA片段化等PCD变化特征上P3施磷方式在这些方面较P1、P2能够延缓胚乳PCD发生进程。.（2）外界干旱胁迫下胚乳细胞ACPase在P3施磷方式上的沉淀较P1、P2多，表明有更多的ACPase参与了胚乳细胞磷素的吸收运转，从而增强了胚乳间物质运输，因而在胚乳细胞核数目变化、胚乳核酸酶活性、胚乳DNA含量以及PCD相关基因的转录上表现出P3施磷方式相较于其它施磷方式在延缓胚乳PCD进程的明显优势。.（3）外界干旱胁迫加速胚乳PCD进程，造成籽粒减产和品质下降，P3施磷方式相较其它施磷方式在干旱胁迫下增加粒重，提高籽粒蛋白含量，提高胚乳淀粉平均粒径，P1施磷方式相对于其他施磷方式可显著提高胚乳淀粉粒结晶度。正常灌溉时，P1施磷方式可显著提高胚乳淀粉粒的直支比。籽粒中磷含量与糊化特性存在显著相关性，因此在生产上可通过调节水分和选择在不同生育期按不同比例施磷来生产不同加工品质的小麦。这些验证结果有利于通过磷素运筹调控PCD进程减缓干旱胁迫危害。. 综上所述小麦花后干旱胁迫下胚乳PCD进程加快，胚乳细胞经历活细胞到死营养贮存库转变。小麦籽粒灌浆期P3施磷方式下磷素通过吸收转运，增强胚乳细胞间物质运输从而延缓外界干旱胁迫加速胚乳细胞程序性死亡进程，提高了小麦籽粒灌浆后期抗旱能力，增加粒重，减缓了外界干旱胁迫。.这些结果有助于创制新种质，并通过栽培措施调控小麦植株营养状况，延缓胚乳PCD进程，延长籽粒灌浆期增加粒重，减少损失提供理论基础。