月季细胞壁相关类受体激酶RhWAKLs介导失水胁迫诱导花朵早衰的机制解析

Cut rose flowers (Rosa hybrida), which are generally harvested at bud stage 2, are susceptible to dehydration stress resulting in failure of opening or abnormal flowering during postharvest handlings, and these phenotypes of precocious senescence lead more than 30% marketing loss in rose flower industry. However, it is remained unclear for the molecular mechanisms underlining the stress-induced senescence in cut rose. In this study, we compared the transcriptomes of dehydrated and naturally senescing rose flowers and obtained both dehydration- and natural senescence-responsive Wall-Associated Kinase (WAK)-like kinase (RhWAKL) genes. We screened and confirmed the roles in the dehydration tolerance and petal senescence of induced-RhWAKLs gene by virus induced gene silencing (VIGS) in petal discs or cuttings. We will further elucidate the molecular mechanisms of key RhWAKLs mediating the dehydration-induced precocious senescence in rose flower. The expression profiles, transcription regulations and interaction proteins of RhWAKLs will be investigated and functionally identified as well as RhWAKLs downstream regulatory networks during dehydration and senescing processes. After the fulfillment of this project, the mechanisms of key RhWAKLs mediating the dehydration-induced precocious senescence in rose flower are expected to be clearer. On the other side, we try to elucidate the transcriptional regulation of postharvest losses caused by dehydration in rose flower, which would guide the research and development of postharvest marketing technologies.

月季切花蕾期采收，采后长途运输易遭受失水胁迫导致不能充分开放等早衰表型，造成30%以上的流通损耗。但是，月季花朵胁迫诱导早衰的生理分子机制仍不清晰。本研究在比较切花失水胁迫和花朵自然开放衰老转录组的基础上，对失水和自然衰老同时响应的细胞壁类受体激酶RhWAKLs基因进行功能解析。项目通过离体花瓣圆片和月季组培苗VIGS体系验证关键RhWAKLs的功能，研究基因的时序表达特性、转录调节、互作蛋白、下游信号转导等，解析RhWAKLs基因介导月季切花失水胁迫诱导早衰的调节机制。本项目的实施，一方面有望明确月季花朵RhWAKLs基因参与失水胁迫导致早衰的分子机制；另一方面，项目从转录和转录调节层面分析失水胁迫导致切花采后损耗的机理，有望为月季切花采后保鲜技术研发提供理论依据。

月季切花是世界范围内非常重要的切花种类。月季切花在采后长距离贮运过程中，容易遭受失水胁迫造成的花朵早衰，导致高达40%的经济损失。然后，月季花朵失水胁迫诱导早衰的分子机制仍不清晰。本研究在月季切花自然开放衰老和失水胁迫转录组数据库中，获得了5个重叠响应的细胞壁类受体激酶RhWAKLs家族基因。通过表达模式分析和生物学功能筛选，锁定了RhWAKL14基因。通过Y2H、BiFC、pull down实验筛选并验证了RhWAKL14的互作蛋白。并且RhWAKL14通过体外磷酸化稳定互作蛋白。进一步通过病毒诱导的基因沉默和RNA-seq等实验解析了RhWAKL14参与的月季失水胁迫诱导花朵早衰的分子机制。本实验的实施，为月季切花采后胁迫损耗机理及采后保鲜措施提供新的基因储备。