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Expression Profiling and T-DNA Mutational Analysis of the Arabidopsis Annexin Gene Family.  S.J. Roux1, G.B. Clark1, A.Cantero-Garcia1, S.-H. Kim2. 1Molecular Cell & Developmental Biology, University of Texas, Austin, Texas 78712, USA, and 2Dept. of Biology Education, Korea National Univ. of Education, Chungbuk 363-791, Korea.

   Recent data indicate plant annexins are key participants in the process of secretion of newly synthesized plasma membrane and wall materials during plant growth and development. Annexins are preferentially distributed on the faster side of gravitropically bending hypocotyls and roots coincident with higher secretory activity on these sides. In Arabidopsis, there are eight different annexins, which range from 30% to 82% in deduced amino acid sequence identity. In order to better evaluate the role of annexins in growth we have assayed annexin expression levels for all eight annexins using real time quantitative RT-PCR in dry and germinating seeds and in 5-day old etiolated seedlings after red and far red light treatments. All eight annexins are expressed at varying levels in germinating seeds and expression levels for certain annexins are modulated by red light. We are also assessing the function of each of the eight Arabidopsis annexins by analyzing the phenotype of mutants for each individual annexin gene. To achieve this goal, we have obtained T-DNA insertions for all eight Arabidopsis annexin genes and are determining which of these lead to gene disruption for a particular annexin using real time quantitative RT-PCR. Thus far we have confirmed T-DNA insertion lines that have mutant alleles for most of the Arabidopsis annexins. To further test potential roles of individual annexins during seedling growth, we are testing the confirmed annexin mutants for altered gravitropic growth, etiolated hypocotyl growth, root and root hair growth, and lateral root density.

 (Supported byNASA: NAG2-1586 to SJR and GBC.)