小麦胚中不同形态多胺含量的变化及其与耐旱性的关系

摘要

This study aimed at understanding the functions of different kinds of polyamine in developing embryos of wheat under drought stress. The drought resistant variety “Luomai 22” and the drought-sensitive variety “Yumai 48” were treated for 10 days with drought stress (DS) and DS plus exogenous polyamines (Spd and Spm) and inhibitors (MGBG and O-Phen) on the 10th day after anthesis. In both varieties, the levels of free Put, Spd, and Spm and the content of acid soluble covalently conjugated poly-amines (ASCC-PA) increased under DS treatment, particularly, the free Put content in Yumai 48 increased rapidly and continu-ously during 10 days after treatment. The increased magnitude of free Spd and Spm contents in Luomai 22 embryos was similar to that in Yumai 48 embryos at the early stage of DS, but significantly larger than that in Yumai 48 embryos at later stage of DS. The content of acid insoluble covalently conjugated Put (AISCC-Put) was low in both varieties at early stage of DS, however, in-creased obviously in Luomai 22 at later stage of DS, with a significantly higher level in Luomai 22 than in Yumai 48. Application of exogenous Spd or Spm resulted in significantly increased free Spd and Spm contents in Yumai 48 at later DS stage; simultane-ously, the relative water content of flag leaf and the relative dry matter increase rate of grain increased and the relative plasma membrane permeability of flag leaf decreased, indicating improved drought resistance in Yumai 48. Polyamine inhibitors showed negative effects on drought resistance, in which MGBG had a strong inhibition on the conversion from free Put to free Spd or Spm in embryos of Luomai 22 and O-Phen depressed AISCC-Put induction by drought stress. These results suggest that drought toler-ance of wheat might be improved by the easy conversion from free Put to free Spd, Spm, or AISCC-Put after flowering.%为解析发育籽粒胚中不同种类和不同形态多胺在小麦耐旱机制中的作用,以强抗旱性的洛麦22和弱抗旱性的豫麦48为材料,于小麦花后第10天施以根际自然干旱、喷施外源多胺及其合成抑制剂处理,研究不同类型多胺含量变化及其与品种耐旱相关生理指标和产量相关性状的关系。干旱胁迫处理10天内,2个品种籽粒胚中游离态腐胺(Put)、亚精胺(Spd)和精胺(Spm)以及酸可溶性共价结合态多胺(ASCC-PA)含量均上升,尤其是豫麦48的游离态 Put一直表现为急剧升高趋势。干旱处理前期两品种籽粒中游离态Spd和Spm的上升幅度没有明显差异,处理后期洛麦22中Spd和Spm的上升幅度明显大于豫麦48；两品种胚中的酸不溶性共价结合态腐胺(AISCC-Put)含量前期均较低,到后期洛麦22的AISCC-Put含量上升明显。外源Spd和Spm处理后,不仅显著提升了干旱胁迫后期豫麦48胚的游离态 Spd 和 Spm 的含量,并且提高了旗叶相对含水量和籽粒相对干物质增长速率,降低了旗叶相对质膜透性,抗旱性得到改善。MGBG处理强烈抑制了洛麦22胚中游离态 Put向 Spd和 Spm转化,也明显降低小麦的抗旱性。外施菲咯啉显著抑制了干旱胁迫所诱导的 AISCC-Put 增加,同时也降低了小麦对干旱胁迫的抗性。上述结果暗示花后胚中游离态Put向游离态Spd、Spm和AISCC-Put的顺利转化可以提高小麦抗干旱能力。