贮藏期菊芋果聚糖降解动态及其外水解酶分子调控机制

Jerusalem artichoke(Helianthus tuberosus L.) is a new cash crop that has received extensive attention in recent years. Fructan, as main material in processing andutilization of Jerusalem artichoke, the change of content and chain length in thestorage period are related to quality of processing. The researches indicate thatfructan content and chain length gradual reduced in storage. Therefore, how toenhance the storability and reduce the fructans degradation in storage is becominga key of development of fructan industry of Jerusalem artichoke. This researchproject aims to fructan degradation dynamic characteristics in storage, fructanexohydrolase gene cloning and sequence analysis, promoter cloning and functionanalysis, the characteristics of gene expression in storage, validation of fructanexohydrolase gene function by RNAi. It is expected to explaining Jerusalemartichoke fructan degradation in storage, understanding molecular mechanism of fructan degradation regulation by fructan exohydrolase gene in storage,constructing RNAi vector and genetic transformation system, also providing an.important theoretical basis through molecular breeding to improve the storabilityof Jerusalem artichoke, and further enrich and deepen the study of fructanmetabolism pathway of higher plants.artichoke fructan degradation in storage, understanding molecular mechanism of.fructan degradation regulation by fructan exohydrolase gene in storage,constructing RNAi vector and genetic transformation system, also providing animportant theoretical basis through molecular breeding to improve the storabilityof Jerusalem artichoke, and further enrich and deepen the study of fructanmetabolism pathway of higher plants.

菊芋是近年来受到广泛关注的新兴经济作物，果聚糖作为菊芋加工利用的主要物质，在贮藏期的含量和组成变化与加工品质直接相关。研究发现，在贮藏过程中，果聚糖含量和链长会发生不同程度的减小，如何增强菊芋耐贮性、减少贮藏期果聚糖的降解损失，成为菊芋果聚糖产业发展的关键。本项目拟通过贮藏期果聚糖降解动态特征与影响因素、果聚糖外水解酶基因克隆与序列分析、启动子克隆与功能分析、贮藏期不同条件下的基因表达特性以及RNAi介导的基因沉默技术验证基因功能等方面的研究，阐释贮藏期菊芋果聚糖降解规律，明晰果聚糖外水解酶基因调控贮藏期果聚糖降解的分子机制，同时，构建基因的RNAi载体和转化体系，为通过分子育种以提高菊芋耐贮性提供重要的理论依据，进一步丰富和深化高等植物果聚糖代谢途径研究。

菊芋是近年来受到广泛关注的新兴经济作物，果聚糖作为菊芋加工利用的主要物质，在贮藏期的含量和组成变化与加工品质直接相关。如何增强菊芋耐贮性、减少贮藏期果聚糖的降解损失，成为菊芋果聚糖产业发展的关键。本研究以相对耐贮藏青芋1号菊芋和不耐贮藏的青芋3号菊芋为实验材料，研究了不同贮藏方式和不同贮藏温度对其果聚糖含量和聚合度的影响，结果表明，菊芋块茎更适合贮藏在库房环境中，最适宜贮藏的温度在-5℃~5℃。利用同源克隆的方法，分离得到了菊芋的FEHs基因的CDS和gDNA序列，其中，FEHI的gDNA大小为2657bp，CDS大小为1683bp；FEHII的gDNA大小为3509bp，CDS大小为1746bp，它们分别都由5个内含子和6个外显子组成。利用双酶切的方法将FEHⅠ和FEHII基因的靶序列克隆到pTRV2载体上，构建了pTRV2-FEHgs载体，和pTRV1一起注射菊芋苗期叶片，结果显示，注射过的叶片果聚糖含量明显高于未注射的植株，我们推测，pTRV2-FEHⅠ和pTRV2-FEHⅡ的注入，导致菊芋本身的FEH基因沉默，使之失去了果聚糖的降解功能。