ABA参与嫁接黄瓜砧穗互作应答低温胁迫的生理机制研究

Grafting is an effective way to improve the stress tolerance of vegetable. ABA plays an important role in regulating plant to response to abiotic stress. However, no information has been provided on the mechanism of ABA involved in grafting-induced low temperature intensity tolerance of plants. This work focuses on the problems, such as the retardation of metabolism, limitation of growth, decrease in yield and quality of cucumber caused by low temperature stress in solar-greenhouse. In the study, the ‘Jinmama5(M5)’ pumpkin and ‘jinyou 35’ cucumber are used as the experimental materials and grafted with each other. Combining with the use of donor and inhibitor or scavenger of ABA and ROS, we will carry out the following researches by the means of physiological and molecular biology: 1) to analyze the dynamic change of ABA in rootstocks and scions as well as the relationship between ABA and chilling tolerance of plant under low temperature intensity;2) to explore the ways of ABA in rootstock and scion and the interaction response to low temperature;3) to reveal the cross and interaction of ABA and ROS, and the signal pathway of ABA in the chilling tolerance of cucumber enhanced by grafting. Our results can provide guidance for the further study of stock-scion communications and the signal transduction pathway of ABA and also are significant in selecting stock-scion combination with high stress tolerance and alleviating the low temperature adversity of cucumber in solar-greenhouse.

嫁接是提高蔬菜抗逆性的有效途径，ABA在调控植物对非生物胁迫的响应中发挥重要作用，然而ABA在嫁接诱导植物耐冷性中的作用机理尚不清楚。本项目针对日光温室低温逆境导致黄瓜代谢受阻，生长受抑，产量和品质降低等问题，拟以‘金妈妈5号（M5）’南瓜和‘津优35号’黄瓜为试材，互为砧穗嫁接，并用ABA和ROS及其抑制剂或清除剂进行处理，通过生理和分子生物学手段开展研究：1）分析低温下砧木和接穗ABA的动态变化及其与耐冷性的关系；2）探讨砧-穗中的ABA对低温的交互应答方式；3）揭示ABA与ROS的相互作用及其在嫁接提高黄瓜耐冷性中的信号途径。该研究可为深入开展ABA参与植物砧-穗互作及其信号转导途径研究提供借鉴，对筛选抗逆性强的砧穗组合，缓解日光温室黄瓜低温逆境障碍具有重要意义。

嫁接是提高蔬菜抗逆性的有效途径，ABA在调控植物对非生物胁迫的响应中发挥重要作用。本项目首先以本实验室收集的不同南瓜砧木材料为试材，以‘黑籽南瓜（H）’和‘津优35 黄瓜（JY35）’为对照，研究发现不同南瓜砧木材料对低温弱光胁迫的响应不同，但以M5 砧木的综合表现最优，且其高耐冷性与低温弱光胁迫下叶片和根系中的高ABA 增加量有关；分析整株、地上部和地下部低温下Cs/Cs（黄瓜接穗/黄瓜砧木）和Cs/Cm（黄瓜接穗/南瓜砧木）ABA含量变化发现，与对照相比，5℃/5℃、5℃/25℃、25℃/5℃处理下，Cs/Cs幼苗叶片中ABA含量分别增加了14.39%、14.38%和43.37%，而根中ABA含量仅在25℃/5℃条件下增加了15.39%，茎中ABA含量变化趋势与根一致，而三种不同低温处理条件下Cs/Cm幼苗的叶片、根和茎中的ABA含量均显著增加，增幅在5.49%-102.16%，且Cs/Cs幼苗的ABA含量低于同处理下的Cs/Cm幼苗，结合不同低温处理下ZEP mRNA表达量的变化，初步确定幼苗叶片中ABA含量的增加主要是由根部运输而来，且Cs/Cm幼苗根部输出的ABA要显著高于Cs/Cs；为进一步探明ABA与嫁接幼苗耐冷性的关系，以Cs/Cs、Cs/Cm、Cm/Cs和Cm/Cm幼苗为试材，结合ABA合成抑制剂处理发现，抑制内源ABA合成会加剧低温对幼苗的伤害，而抑制内源H202合成，同样会导致嫁接黄瓜的光合作用下降，耐冷性显著降低。综上说明砧穗间存在互作，而地下部砧木对嫁接植株的耐冷性贡献较大，且低温诱导根部ABA合成，进而通过H202信号参与调控嫁接诱导的低温耐性。