葡萄糖苷酶基因在柿果实成熟衰老过程中的作用及功能解析

Ripening and senescent regulation is the basis of de-astringent of persimmon and quality control, and it not only is essential question in persimmon research, but also the problem of development of persimmon industry limited. Previous research shows that phytohormone abscisic acid (ABA) plays an important role in development, ripening and senescent regulation of fruits, however, mechanism on physiological and molecular by ABA regulating in these process still is unclear. β-glucosidase gene (BG) controlling release of free ABA from ABA-GE form, plays a key role in modulating ABA accumulation, mean that this enzyme may plays an important role in ripening and senescent regulation of persimmon. Therefore, we clone major BG gene from persimmon fruit, and research the spatio-temporal expression, response character and relationship between BG and a series of physiological and biochemical changes and to analyze the function of BG. In consideration of difficult of persimmon tree genetic transformation, and two kinds of fruits in persimmon and tomato fruit, has similar mechanism in development and ripening. Therefore, in the study of BG, plan that by means of tomato transformation system, namely transform SlBG-OE and SlBG-RNAi driven by E8 into tomato, on that basis, analyze expression of BG in transgenic fruit, change of ABA-GE, ABA content and ABA metabolic products, in especial to analyze the role of BG in fruit development and quality control. The above results, preliminary clarify the role and molecular mechanism of BG during ripening and senescent of persimmon.

柿果成熟衰老调控是柿果脱涩和品质调控的基础，这既是柿子研究中一个核心问题，也是限制柿产业化发展的难题。以往的研究表明，脱落酸在柿果成熟衰老调控中起着重要的作用，但ABA调控这些过程的生理和分子机理尚不清楚。葡萄糖苷酶基因（BG）调控ABA由结合态向游离态的释放，在ABA的累积中起着关键作用，这意味着该酶可能在柿果成熟衰老过程中起着重要作用。为此，本文拟从磨盘柿果实克隆BG基因，研究所得基因的时空表达、ABA应答特性及其和一系列生理生化变化值间的关系，以确定主效基因。在此基础上，以与柿果发育和成熟调控机理相似、已建立转基因体系的番茄为试材，进一步分析和验证该基因的功能，即将SlBG-超表达及SlBG-RNAi转化番茄，分析转基因果实中BG基因的表达特性及其对脱落酸水平的调控，特别是分析SlBG在果实发育和品质调控中的作用等。综上，初步阐明BG在柿果成熟衰老过程中的作用和分子机理。

柿果成熟衰老调控是柿果脱涩和品质调控的基础，这既是柿子研究中的一个核心问题，也是限制柿产业化发展的难题。以往的研究表明，脱落酸在柿果成熟衰老调控中起着重要的作用，但ABA调控这些过程的生理和分子机理尚不清楚。葡萄糖苷酶基因（BG）调控ABA由结合态向游离态的释放，在ABA的累积中起着关键作用，这意味着该酶可能在柿果成熟衰老过程中起着重要作用。为此，本研究将磨盘柿转色期的果实进行转录组分析，分离了10个全长的葡萄糖苷酶基因DkBGs，发现它们全部都表达，尤其是DkBG1在柿果实中表达量最高，并且在花后95天的果实中出现峰值。接着我们通过原核表达DkBG1蛋白，发现它可以在体外将ABA-GE水解为游离的ABA。在此基础上，以与柿果发育和成熟调控机理相似、已建立转基因体系的番茄为试材，进一步分析和验证该基因的功能，即将DkBG1-OE转化番茄。我们发现DkBG1-OE株系通过增加的ABA加快了果实成熟的起始，这也导致了乙烯释放的提前。并且改变了ABA相关成熟基因的表达，从而改变了果实相关性状。我们的结果表明DkBG1在果实发育和品质调控中起作用。综上，初步阐明葡萄糖苷酶在柿果成熟衰老过程中的作用和分子机理。