Gene Expression, Subcellular Localization Of Arabidopsis Annexing And Ab Iotic Stress Respons Of AnnAt3

Ca²⁺, an important intracellular messenger, functions in plant growth and developmentby involving in various signaling pathway. Eukaryotic cells contain many kinds ofCa²⁺-effectors that mediate cellular responses to intracellular Ca²⁺signaling. Annexin, whichcan bind to certain membrane phospholipids in a Ca²⁺-dependent manner, is a linker betweenCa²⁺signaling and membrane functions. It has been reported that Annexins havemultifunctional functions in animal cells, such as membrane trafficking, ion transport, mitoticsignaling, cytoskeleton re-arrangement, and DNA replication. Annexins have now beendescribed in many plant species. However, the detailed information and functionalcharacterization of plant Annexins are waiting for further investigated. In this study, weanalyzed the gene expressions, protein subcellular location of Arabidopsis Annexin family（AnnAt1-AnnAt8） and physiological functions of AnnAt3. The results were as follows:（1） The patterns of gene expression of AnnAt1-AnnAt8were different in various tissuesand developmental stages. AnnAt1/6/7was expressed at most developmental stages andtissues; however, the expression patterns of AnnAt2/3/4/5/8had tissue specificity. Forexample, the expression of AnnAt3was detected mainly in leaves, hypocotyls and calyx,AnnAt4in hypocotyls, AnnAt5in hypocotyls and stamen filaments, and AnnAt8in leaves andseeds. AnnAt3/6/7/8were detected in guard cells.（2）The subcellular localizations of AnnexinAts were determined by using of transientexpression in tobacco leaf epidermis and stable expression in Arabidopsis. The results showedthat AnnAt2, AnnAt3, and AnnAt6were localized in cytosol and nucleus. The localization ofAnnAt5was observed in peroxisomes, and AnnAt7was only located in cytosol. The differentsubcellular localizations indicated that the members of Annexins of Arabidopsis play differentcell functions.（3） By using quantitative real-time reverse transcription-PCR （qRT-PCR） we analyzedthe expressions of AnnAt3. We found that the expression level of AnnAt3was increased after treated with the salt and MV. Moreover the increased AnnAt3expression was mainly takenplace in the roots of transgenic Arabidopsis （AnnAt3promoter::GUS） by GUS staininganalysis. The root length of seedlings grown on medium containing100mM NaCl or0.6μMABA was investigated. We found that the root length of the transgenic plants overexpressingAnnAt3was shorter than that of the wildtype. Our data revealed that AnnAt3may be involvedin Arabidopsis response to abiotic stress by ABA dependent way.（4） We observed the dynamics of actin filaments in annAt2and annAt3mutants labeledusing GFP-ABD2-GFP. The actin filaments localization and the bundle changed in hypocotylcells of annAt2and annAt3mutants compared with that of the wild type. This result suggestedthat AnnAt2and AnnAt3may be involved in actin dynamic regulation in vivo.In this study, we investigated the gene expression models and protein subcellularlocalizations of the Annexin family members in Arabidopsis. Moreover we analyzed thefunction of AnnAt3in response to the abiotic stress and regulations of actin filaments. Ourresults provide a detailed picture of functional sites of Annexins, and provide importantinformation for future investigation on their functions and mechanism.