Function of Mitochondrial Electron Transfer Chain in Oxygen and Sugar Deficiency Responses in Rice

• Main Authors: Yu-Ping Chen, 陳郁屏
• Other Authors: Su-May Yu
• Format: Others
• Language: zh-TW
• Published: 2012
• Online Access: http://ndltd.ncl.edu.tw/handle/14441911445862636098

碩士 === 國立陽明大學 === 生命科學系暨基因體科學研究所 === 100 === Flooding is a widespread natural disaster that leads to oxygen (O2) and energy deficiency in terrestrial plants reduce their productivity. Rice (Oryza sativa) is unusually tolerant to flooding and germination. They involve a CIPK15-SnRK1A-αAmy3 pathway under water. However, the underlying mechanism of sensing O2 and sugar depletion in rice is still not fully understood. Since rice CIPK15 is an important component for CIPK15-SnRK1A-αAmy3 pathway on submergence tolerance of rice. It belongs to CBL-CIPK network in plants. The CBL-CIPK network connects a Ca2+ sensor and the kinase signaling transduction, which is important for various stress responses in plants. Ca2+ signals are the cellular secondary messenger in many different cell responses. In maize root cells, the hypoxia specifically induces the mitochondrial Ca2+ releasing. In mammalian cells, hypoxia can induce the mitochondrial ROS and organelle Ca2+ releasing then sequentially triggers the APMK-dependent pathway and down stream gene expression. These evidences indicate that the Ca2+ signals releasing from mitochondria that is induced by oxygen deprivation. Mitochondrial electron transfer chain (mtETC) plays a major role for oxidative respiration and direct responses to carbohydrate and oxygen levels in cells. In this study, we used rice T-DNA insertion mutants of mtETC complex I NADH-b17 gene and plant specific complex III AOX-1a gene to identify their gene functions under sugar starvation and oxygen deprivation. In this report, we demonstrated that the mtETC could regulate the CIPK15-SnRK1A-αAmy3 pathway under sugar starvation in rice suspension cells. It indicated that this retrograde pathway from mitochondria to nucleus is important for sugar response in rice. These results demonstrate that the mtETC could be a sensing system for carbohydrate starvation or oxygen deprivation. It is also important for submergence tolerance during seed germination and developing in water.