木薯活性氧清除调控储藏根采后生理性变质机制的研究

The post-harvest physiological deterioration (PPD) of cassava storage roots is a unique biological phenomenon to cassava and occurs rapidly which causes the decay of its storage roots. After harvest, cassava storage roots must be processed within 72 hours. Therefore, it is currently one of the major bottlenecks for cassava industrialization. The occurrence of PPD is triggered by oxidative damage of parenchyma cells at the wound sites and has a close relationship with reactive oxygen species (ROS). The project is to explore the biological functions of key genes related to ROS generation and scavenging, including superoxide dismutase (MeCu/ZnSOD), catalase (MeCAT1) and ascorbic acid peroxidase (MeAPX2). Our approach is to coupling increase the capacity of ROS scavenging to free radicals and H2O2, which can lead to the development of an effective way for interfere PPD process. Transgenic cassava expressing genes of MeCu/ZnSOD and MeCAT1 or MeCu/ZnSOD and MeAPX2, alone or together, will be analyzed for their effects on the physiological and biochemical changes of PPD. By the combination of Solexa throughput expression profiling analysis, our understanding of PPD mechanism will be increased, and the feasibility for delayed PPD occurrence will be explored, both will provide theoretical basis and application support for engineering prolonged storage of cassava storage roots.

储藏根采后生理性变质(PPD)是木薯特有的生物学现象，发生迅速并导致储藏根变质，收获后72小时内必须加工，因此是当前木薯产业化面临的主要瓶颈之一。PPD是由氧化激发的储藏根薄壁细胞生理生化衰变的过程，其发生与活性氧（ROS）有着密切的关系。本课题旨在通过解析ROS转换与清除密切相关的超氧化物歧化酶（MeCu/ZnSOD）、过氧化氢酶（MeCAT1）及抗坏血酸过氧化物酶(MeAPX2)在PPD发生中的功能，并采用偶联提高清除超氧根离子和H2O2能力的思路，探索通过强化ROS清除机制来延缓PPD进程的有效途径。构建单价和双价表达MeCu/ZnSOD与MeCAT1及MeCu/ZnSOD与MeAPX2的表达载体，转化木薯，研究上调这些基因的表达对PPD进程的生理生化影响，结合Solexa高通量表达谱分析，了解发生机制和探索延缓PPD发生的可行性，为基因工程培育耐储藏木薯建立理论基础和应用依据。

储藏根采后生理性变质(PPD)是木薯特有的生物学现象，发生迅速并导致储藏根变质，收获后72 小时内必须加工，因此是当前木薯产业化面临的主要瓶颈之一。PPD 是由氧化激发的储藏根薄壁细胞生理生化衰变的过程，其发生与活性氧（ROS）有着密切的关系。本课题通过分析ROS 转换与清除密切相关的超氧化物歧化酶（MeCu/ZnSOD）、过氧化氢酶（MeCAT1）及抗坏血酸过氧化物酶(MeAPX2)在PPD 发生中的功能，采用偶联提高清除超氧根离子和H2O2 能力的思路，构建了双价表达MeCu/ZnSOD 与MeCAT1 及MeCu/ZnSOD 与MeAPX2 的表达载体，获得了SOD+CAT1及SOD+APX2的转基因木薯植株，研究了上调这些基因的表达对PPD进程的生理生化影响，结合Solexa高通量表达谱分析了MicroRNA，深入了解了ROS及褪黑素调控PPD的发生机制并利用新技术延缓PPD的发生，为基因工程培育耐储藏木薯建立了理论基础和应用依据。项目共发表标注论文9篇，包括SCI论文5篇，申请专利3项，培养2名博士生和3名工程硕士生。