The role of carbonic anhydrase in photosynthesis in Arabidopsis

该项目将研究碳酸酐酶（CA），一种催化二氧化碳和HCO3-相互转化的酶，是否有助于进行C3光合作用的植物的二氧化碳固定。Moroney et al. (2001) Plant, Cell Environ. 24: 141报道拟南芥具有至少14个CA基因。初步结果表明，一个双突变体缺失两个细胞质CAs， &#946；CA2 and &#946；CA3表现出生长减少和对CO2的亲和力降低，表明这些CAs在CO2固定中起着不可或缺的作用。本项目的总体目标是确定不同CA酶在C3植物光合作用中的作用和重要性。这项工作将涉及拟南芥叶片CAs的分子特征和反向遗传学方法，以获得缺失一种或多种CA亚型的敲除拟南芥植株。利用敲除植株，将通过测量整个植株的气体交换、叶肉电导和同位素识别来确定特定CA亚型的生理作用。最近，Zhu et al. (2010) Ann Rev. Plant Biol. 61: 235指出C3植物对CO2固定的一个重要限制是对CO2从叶肉细胞向叶绿体扩散的抗性。这个研究项目将增加我们对影响二氧化碳固定的因素的理解，使科学家能够更好地制定策略来改善二氧化碳的输送和作物产量，特别是在面对大气中二氧化碳增加的情况下。本课题将成为研究生和本科生教育的重要组成部分。在路易斯安那州立大学，有许多项目促进不同学生群体参与实践研究，为这些学生在工业、医学和学术领域取得成功提供了一个框架。

This project will investigate whether carbonic anhydrase (CA), an enzyme that catalyzes the interconversion of CO2 and HCO3-, facilitates CO2 fixation in plants that perform C3 photosynthesis. Moroney et al. (2001) Plant, Cell Environ. 24: 141 reported that Arabidopsis possesses at least 14 CA genes. Preliminary results showed that a double mutant missing two cytosolic CAs, βCA2 and βCA3, exhibited reduced growth and a reduced affinity for CO2 indicating these CAs play an integral role in CO2 fixation. The overall goal of this project is to determine the roles and importance of different CA enzymes for photosynthesis in C3 plants. The work will involve a molecular characterization of leaf CAs in Arabidopsis and a reverse genetics approach to obtain knockout Arabidopsis plants missing one or more CA isoforms. Using the knock-out plants, the physiological roles of the specific CA isoforms will be determined by measuring gas exchange, mesophyll conductance, and isotopic discrimination in whole plants. Recently, Zhu et al. (2010) Ann Rev. Plant Biol. 61: 235 pointed out that a significant limitation to CO2 fixation in C3 plants is the resistances to the diffusion of CO2 from outside mesophyll cells to chloroplasts. This research project will increase our understanding of the factors that affect CO2 fixation allowing scientists to better formulate strategies to improve CO2 delivery and crop yield particularly in the face of increasing atmospheric CO2. This project will be an important component in the education of graduate and undergraduate students. At LSU, there are many programs to foster participation of a diverse group of students in hands-on research, providing a framework for these students to go on to successful careers in industry, medicine and academics.