月季切花SNACs转录因子调节花朵失水胁迫耐性的机理解析

Cut roses (Rosa hybrida) account for more than 30% of all cut flowers traded in worldwide market. Water deficit stress inhibits petal expansion resulting in abnormal flower opening and results in quality loss during the marketing of cut flowers. It is theoretically and practically meaningful for the development of preservation technologies to explore the molecular mechanism of dehydration tolerance in cut roses. Stress-responsive NAC transcriptional factors (SNACs) are the key regulatory factors responsive to water deficit stress in cut roses. In our previous study, we screened out SNAC genes from suppression subtractive hybridization library and 454 sequencing transciptomic data in rose flower. In this study, we aim to further investigate and compare the expression patterns under abiotic stresses, biochemical characteristics and transcriptional activation of these SNACs. We will also analyze the functions through silencing SNACs in rose petals or overexpressing them in Arabidopsis respectively. The transciptomic data regulated by key SNAC will be obtained and analyzed by illumina 100bp and 50 bp sequencing technology and the key SNAC-regulated genes are expected to be functionally identified in rose flower. Taken together, our study aims to explore the regulatory mechanism of SNACs in cut roses to confer dehydration tolerance and improve flower opening at transcriptional levels. These results would contribute to the development of preservation technologies and genetic modification of tolerance improvement in cut roses.

月季切花在全球鲜切花贸易中占所有切花贸易额30%以上。失水胁迫是引起切花流通运输损耗的主要原因，导致花朵不能正常开放。探明月季切花失水胁迫耐性机理，解析其关键基因作用机制，对开发切花采后保鲜技术具有理论和实践意义。逆境响应NAC转录因子基因（SNACs）是月季花朵失水胁迫响应的关键调控因子。本研究在月季花朵失水胁迫SSH文库和转录组454测序的基础上，获得月季切花SNACs基因。进一步拟比较失水胁迫响应的SNACs基因表达、蛋白生化特性和转录激活能力等；利用病毒诱导的基因沉默和转化模式植物进行功能研究；通过RNA-seq技术分析SNACs基因的转录调控，筛选验证下游关键功能基因。重点从转录调节的层面探讨不同SNACs基因在响应失水胁迫调节月季花瓣细胞扩展中的分子机制，获得月季切花失水胁迫耐性关键SNACs基因，进而为开发针对月季切花的高效保鲜技术提供依据，为切花采后基因工程提供基因储备。

月季切花在全球鲜切花贸易中的贸易额达30%以上。失水胁迫是引起切花流通运输损耗的主要原因。探明月季切花失水胁迫耐性机理，解析其关键基因作用机制，对开发切花采后保鲜技术具有理论和实践意义。逆境响应NAC转录因子基因（SNACs）是月季花朵失水胁迫响应的关键调控因子，但是其响应失水胁迫的机制上不明确。本研究取得以下主要进展：.1）初步解析了月季SNACs类转录因子启动子表达特性解析.a）明确了SNACs类转录因子RhNAC3，主要通过启动子上的ABRE元件，参与对失水胁迫的响应。RhNAC3通过直接或间接调控ABA相关基因的表达，影响月季花瓣的失水胁迫耐性。.b）发明专利“一种具有串联ABRE顺式作用元件的RhNAC3启动子及其应用”。.c）明确了RhNAC4的启动子中关键的顺式作用元件，以及其对不同激素和非生物胁迫响应的调节机制，同时明确了RhNAC4时空表达的特异性。.2）SNACs类转录因子通过介导激素互作参与失水胁迫过的程。.发现在月季花瓣失水胁迫和衰老过程中， RhNAP和RhCKX6被诱导表达，而且RhNAP通过直接靶定到RhCKX6的启动子上，促进RhCKX6的表达，从而促进细胞分裂素的降解。此外RhNAP也可以通过抑制PP2C基因的表达来调节ABA信号转导途径。综上所述，RhNAP/RhCKX6起着重要的作用在提高月季花瓣的失水胁迫耐性和促进月季花瓣的衰老过程中。.3）SNACs类转录因子的转录调节机制及下游基因的功能鉴定。.在月季花瓣遭受可恢复的失水胁迫时，就会形成一种忍受胁迫的能力。在这个过程中是通过RhABF2/RhFer1模块，而不是Fe运输基因储存过多的游离Fe2+，从而调节月季花瓣细胞铁平衡，减少氧化胁迫。而在月季花瓣衰老过程中，RhABF2/RhFer1和Fe运输基因协同调节Fe的回收利用，来影响衰老进程。.本研究重点从转录调节的层面探讨不同SNACs基因在响应失水胁迫调节月季花瓣细胞扩展中的分子机制，获得了月季切花失水胁迫耐性关键SNACs基因，进而为开发针对月季切花的高效保鲜技术提供依据，为切花采后基因工程提供基因储备。