百合LbNAP转录因子调控干旱胁迫下花瓣衰老的分子机制

Lily (Lilium spp.) is one of the most important fresh cut flowers. One of the momentous goals of lily breeding is to prolong the flowering time. Previous studies have shown that Arabidopsis with inserting inactivation of AtNAP can significantly delay the senescence of leaves, fruits and petals. In the screening transcriptome analysis of the early senescence stage of lily petals induced by drought stress, we obtained a transcription factor LbNAP which was highly homologous with AtNAP. The expression of LbNAP increased during lily petal senescence, while drought can also improve its expression level. All these works suggested that LbNAP might be associated with the petals aging of lily under drought stress. On this basis, we plan to: clarify the binding properties, subcellular localization and protein interaction of LbNAP and drought responsive elements; through building the over-expression vectors and transforming them into Arabidopsis, detect the petal aging process , physiological and biochemical changes, the downstream genes’ expression, analysis its effects on Arabidopsis petal senescence under normal and drought conditions; employing VIGS to silence LbNAP of Lily, test the petal aging process, physiological and biochemical changes, downstream genes’ expression, analysis its effects on lily petal senescence under normal and drought environments. The research results will theoretically elucidate the molecular mechanism of Lily petal senescence.

百合是一种十分重要的鲜切花，延长花期是百合育种的重要目标之一。已有研究表明插入失活拟南芥AtNAP转录因子能够显著延缓叶片、果实和花瓣的衰老。申请人在前期对干旱诱导百合花瓣衰老过程进行转录组分析筛选到一个与AtNAP高度同源的转录因子LbNAP，在百合花瓣衰老过程中，该转录因子表达量不断升高，同时干旱可以诱导其表达量的增加，推测其可能与干旱诱导下百合花瓣衰老相关。本研究在此基础上，研究LbNAP与干旱响应元件结合特性、亚细胞定位和互作蛋白等方面，阐明其基本特性；通过构建过表达载体转化拟南芥，检测正常和干旱诱导下花瓣衰老进程、生理生化和下游相关基因表达的变化，解析其对干旱诱导下拟南芥花瓣衰老的影响；利用VIGS沉默百合LbNAP转录因子，监测正常和干旱诱导下百合花瓣衰老进程、生理生化和下游相关基因表达的差异，探索其对干旱胁迫下百合花瓣衰老的调控。为阐明百合花瓣衰老的分子机理提供理论依据。

云南昆明是我国鲜切花生产销售中心，百合是排名前五的鲜切花之一。延长切花花期（延缓花朵衰老）是百合等观花植物育种的重要方向之一，因此研究百合花衰老的调控机理对培育长观赏期的百合新品种有重要意义。在本项目支持下，项目组在四年的时间中，进行了如下研究：（1）获得了干旱胁迫下鲜切花百合花瓣转录组的变化情况；（2）克隆了LbNAP转录因子，并研究了该转录因子在不同器官时空表达，LbNAP蛋白的亚细胞定位，和转录激活特性。（3）用VIGS将LbNAP在花瓣中沉默，并研究了干旱胁迫下的各项生理生化指标的变化，LbNAP和衰老相关基因的表达变化，结果表明沉默LbNAP可以延长切花的瓶插期。（4）将转LbNAP到拟南芥，获得过表达阳性植株，研究了转基因植株和野生型在干旱胁迫下与衰老和抗逆相关的生理生化指标的变化，LbNAP和衰老相关基因的表达，结果显示过表达的植株其衰老比野生型的加快，抗干旱能力下降。（5）克隆了一批与抗逆相关的基因以及这些基因的转录水平的变化；研究了GABA对提高百合抗旱能力的机制；研究了SLs通过调控 LbCu/ZnSOD and LbMnSOD的表达，提高切花百合抗干旱胁迫的能力。（6）项目发表论文4篇，授权1项发明专利，2项实用新型专利；培养5名硕士研究生，毕业2名。通过项目组的研究初步揭示百合中LbNAP基本特性,解析对衰老调控以及在干旱胁迫下对衰老的调控机制。本项目的研究成果为探索LbNAP调控百合花衰老和抗旱机理奠定一定基础，为延长瓶插期的新切花百合育种工作提供理论支持。