MdARF19调控重力介导苹果自根砧不定根GSA形成的分子机制

苹果是我国重要的农业产业之一，目前建园的首选为自根砧。但苹果自根砧不定根向重力性定点角（GSA）较大，导致其抗性差。而关于苹果自根砧不定根GSA形成的分子层面研究甚少。申请人前期研究发现MdARF19参与调控苹果自根砧不定根的GSA，且MdARF19与MdIAA3、MdIAA6在酵母中互作。本项目拟利用BiFC、CoIP等实验，明确MdARF19与MdIAA3、MdIAA6蛋白互作方式；利用酵母单杂交、GUS瞬时表达、EMSA等实验明确MdARF19对MdPIN7的调控模式，并利用遗传转化验证MdARF19、MdPIN7等基因的功能；利用回转器模拟微重力，明确重力信号在苹果自根砧不定根GSA形成中的作用，从而解析MdARF19与MdIAA3、MdIAA6蛋白互作在重力介导苹果自根砧不定根GSA形成过程中的分子调控机制。本项目的研究结果可为苹果砧木抗性分子设计育种提供参考。

Apple is one of the important agricultural industries in China. At present, the apple self-rooted stock is the preferred stock for garden construction. The resistance of apple self-rooted stock was poor due to the bigger gravitropic set-point angle (GSA) of the adventitious root. However, the regulatory mechanisms underlying the formation of GSA in apple self-rooted stock adventitious root are largely unknown, currently. Our previous results found that the auxin response factor MdARF19 was involved in regulating the formation of GSA in the apple self-rooted stock adventitious root, and proved that MdARF19 interacted with MdIAA3 and MdIAA6 in yeast. In this project, BiFC and CoIP assay will be performed to clarify the interaction between MdARF19 and MdIAA3, MdIAA6 proteins. The molecular regulatory patterns of MdPIN7 by MdARF19 was determined through the yeast one-hybrid, GUS transient expression system and EMSA, and then their biological functions will be verified with genetic transformation of apple. The microgravity was simulated with a rotator to clarify the role of gravity signal in the formation of GSA in apple self-rooted stock adventitious root. So, this project will elucidate the molecular mechanism of the interaction between MdARF19 and MdIAA3, MdIAA6 proteins in the process of gravity-mediated GSA formation of the apple self-rooted stock adventitious root. We hope the results presented of this project can provide a basis for molecular design and breeding of resistance in apple rootstocks.