基于水孔蛋白研究月季切花采后失水的发生机制与调控

Cut roses, as the first of the world's four mainstream cut flowers, are very prone to water loss and wilting of petals and leaves during their postharvest period, which directly disrupts their ornamental quanlity and commodity value. Aquaporins (AQPs) are channel proteins of biological membranes including plasma membrane and tonoplast, which highly facilitate the transportation of water across these membranes. But so far, there is little research in the mechanism of water loss of cut flowers and the postharvest regulation based on aquaporins in cut flowers, especially for cut roses. Hence, the present project, using cut rose flowers as the experimental materials, via in vitro (namely detached petals, leaves and isolated guard cells obtained precisely by Laser Microdissection technology) and in vivo (namely the cut flowers during vase period and simulated transportation), based on the investigations of the effects of various physical and chemical postharvest treatments (including AQPs regulator, abscissic acid, light/dark, environment temperature and humidity, etc) on the AQP gene expression and activity, the regulation of stomatal movement and water loss, and their ornamental appearance, aims at exploiting and understanding the physiological and molecular mechanism of postharvest water loss in cut roses, and the inherent relationships among AQPs, stomatal movement and water loss. The research results from this project will help to reveal the roles in water loss and its postharvest regulation mechanism of cut roses, and to address new approaches and technologies, by means of regulating the activity of AQPs, to decrease postharvest water loss and wilting of cut roses and even other cut flowers.

月季为世界“四大切花”之首，采后易发生花瓣和叶片的失水凋萎，并导致观赏品质降低。水孔蛋白（Aquaporins，AQPs）作为质膜和液泡膜等生物膜上高效转运水分子的通道蛋白，在植物水分代谢中起关键作用。但迄今有关AQPs在切花采后失水中的作用及其调控研究极少。本项目以月季切花为试材，着重围绕离体研究（花瓣、叶片及保卫细胞）和活体研究（瓶插和贮运期间切花）两条主线，分别研究相关理化处理（AQPs调控剂、脱落酸及光、温和湿度等环境因子）对该切花AQPs基因表达与活性、（叶片）气孔运动和水分散失的调控作用及对观赏品质的影响，藉此探究该切花采后水分散失的生理与分子机制及AQPs、气孔运动和水分散失之间的内在关系。本项目研究，有助于揭示和阐明AQPs在月季切花采后失水中的作用与调控机制，并可为探寻一条通过调控AQPs活性来减轻月季及其他切花采后失水凋萎的新思路以及提出相应的采后处理技术提供理论依据。

月季切花为世界“四大切花”之首，但其采后易发生叶片和花瓣的失水凋萎，并严重影响其观赏品质和经济价值。水孔蛋白（aquaporins，AQPs）作为质膜和液泡膜等生物膜上快速转运水分子的通道蛋白，可参与植物气孔运动。叶片气孔被认为是植物水分散失的主要途径，并受到一些重要理化因子的调控。本项目以月季‘影星’切花等为试材，首先就其气孔分布特征进行研究，并观察到该切花气孔主要分布在叶片下表皮，同时发现在叶柄、萼片下表皮、花茎表皮和花萼上表皮也有少量气孔分布；接着观察和研究了不同月季切花品种气孔的形态特征及精细结构；其次，探究光/暗交替、光质（白光、红光、绿光和蓝光）、水孔蛋白抑制剂（乙酰唑胺、四乙胺、纳米银、硝酸银等）处理对月季‘影星’切花离体叶片气孔开放和水分散失的影响及二者之间的密切关系，并发现月季切花离体叶片的气孔开放（开放率和开放度等指标）和水分散失之间具有明显的相关性；再者，着重研究外源脱落酸（abscisic acid，ABA）和表油菜素内酯（epi-brassinolide，EBR）处理对月季‘影星’切花叶片气孔开放、水分散失以及4个质膜AQPs基因（RhPIP1;1、RhPIP1;2、RhPIP2;1和RhPIP2;2）和4个液泡膜AQPs基因（RhTIP1;1、RhTIP1;2、RhTIP2;1和RhTIP4;1）共8个AQPs基因表达的调控作用，并揭示ABA和EBR处理可能通过调控月季切花叶片AQPs基因表达来调节气孔运动和水分散失。项目研究成果有助于丰富AQPs在月季及其他切花采后失水中作用与调控的生理和分子机制的认识，并为研发减轻切花采后失水、降低采后损耗的新技术提供坚实的理论基础。依托本项目，项目组已在《Postharvest Biology and Technology》（共4篇）、《Scientia Horticultraue》（1篇）、《The Journal of Horticultural Science and Biotechnology》（1篇）、《HortScience》（1篇）以及中文核心刊物《北方园艺》（1篇）等国际和国内期刊发表论文9篇、会议论文21篇、著作1本。另外，培养硕士生10名，其中5名已经取得硕士学位，5名在读。