南瓜砧木lncRNA调控嫁接西瓜果实发育基因表达的分子机制

Grafting technique is the most efficient technique to overcome problems of continuous cropping, to increase yield, and to improve fruit quality. The Cucurbita maxima x Cucurbita moschata interspecific hybrid is one of the most widely used rootstocks in watermelon grafting. However, such rootstocks may alter the gene expression network during scion fruit development, resulting negative fruit quality issues. The molecular mechanism behind rootstock-scion interactions is unclear. It has been proved that rootstocks can regulate scions’ gene expression through long-distance trafficking of RNA signals, and then regulate their growth and development. Long non-coding RNA (lncRNA) functions a key role in the precise control of many plant physiology activities, including fruit development. But there is no study published on whether the lncRNA is long-distance transmissible, or on how the rootstock lncRNA regulates scions’ gene expression network. In this project, we intend to focus on the regulatory role of rootstock lncRNA in the fruit development of the watermelon scion, and then identify the key rootstock lncRNAs and their target genes, which involve in the control of the scion fruit development. This will shed light on the molecular mechanisms on how the rootstock lncRNAs are transmitted to long-distant organs, and how they control the scion fruit development through controlling target genes’ expression. The research findings will broad our understanding of the theoretical basis in grafting mechanisms and provide guidance to the genetic improvement and the grafting production of high quality fruits.

嫁接栽培是解决西瓜连作障碍、达到丰产优质最有效的生产技术。南瓜杂交种(印度南瓜x中国南瓜)是西瓜嫁接最常用的砧木物种之一，但易导致西瓜果实品质劣变，此砧穗互作的分子机制尚不明确。砧木RNA能移动到接穗调控其基因表达，影响其生长发育。长链非编码RNA(lncRNA)在植物生长发育的精细调节中有关键作用，但其是否存在长距离运输机制，以及砧木lncRNA如何影响接穗基因表达，目前未见研究报道。本项目计划从砧木南瓜lncRNA调控接穗西瓜果实发育的角度入手，利用砧木南瓜-接穗西瓜嫁接体系，鉴别出西瓜果实中调控果实发育的，来自于砧木南瓜的关键lncRNA及其靶基因，解析砧木lncRNA长距离运输、调节接穗基因表达，从而影响接穗果实发育的分子机制，为全面了解砧木南瓜影响接穗西瓜果实品质发育的分子机制奠定基础。本项目的研究成果将丰富嫁接分子机制的理论基础，为南瓜砧木育种改良与嫁接优质生产提供技术指导。

建立了利用全转录组测序检测长距离运输lncRNA的分析方法，鉴定了西瓜果实lncRNA的种类和数量，构建了嫁接西瓜果实在关键发育时期的基因共表达调控网络，探究了砧木嫁接中，基因表达、植物激素以及果实品质表型之间的关联与分子机制，分析了共表达网络中的核心基因对果实品质表型的潜在影响。以上结果将丰富嫁接分子机制的理论基础，为南瓜砧木选育与嫁接优质生产提供理论参考。