The Preliminary Study On Arabidopsis Annexin3Responsing To Drought Stress

Phytohormone ABA is a key regulator in controlling water status and stomatal movement, and it plays a critital role in plants response to abiotic stress. The response of guard cells to ABA is activated by a series of molecular transduction cascade, including ABA binding to its receptors, activating SnPK2s by releasing the inhibitor PP2Cs (notably ABI1and ABI2), and eventually leading to water lose in guard cells and stomatal closure. As cytoskeleton of plants, actin is the supporter of plant morphological structure and final executor of stomatal movement. Stomatal movement is accompanied by rearrangement of actin in guard cells. It has been known that ABA-induced stomatal closure can be inhibited by preventing the disruption of actin filaments. At present, a lot of signal components involved in microfilament rearrangement have been discovered, including actin binding proteins.Annexins are multimember and multifunctional Ca2+depended soluble lipid-binding proteins. Annexins have been evidenced playing an important role in resistant to stress in plants, and act as a bridge between cytoskelenton and membrane in animal. AtANN1and AtANN4interact with each other and are involved in regulating the process of responsing to drought and salt stress in arabidopsis, and qRT-PCR results revealed that AtANN3is13-fold up-regulated by dehydration.In this paper, we took the model plant Arabidopsis thaliana as materials to explore the expression patterns and function of Arabidopsis annexin3(AtANN3):(1) We obtained two T-DNA insertion mutants of AtANN3(named annS-1and ann3-2) and selected two lines of AtANN3overexpression plants for drought stress treatment.(2) In order to know the expression pattern of AtANN3,pAtANN3::GUS was constructed. GUS staining analysis showed that AtANN3expressed high levels in guard cells and7d old seedling (consistent with the predictions of the website), so we speculate that AtANN3may take part in stomatal movement. (3) AtANN3-mCherry and GFP-ABD2-GFP showed a clear co-localization in Arabidopsis. We hypothesize that AtANN3and actin work with each other, which shows AtANN3may be involved in regulating actin dynamics changes.(4) Dehydration experiments evidenced that AtANN3OE was more sensitive to drought stress and detached leaves of AtANN3OE exhibited a phenotype of faster water lost than wild type. But no obvious difference was observed between mutants and wild type.(5) No difference of stomatal aperture was observed between wild type and AtANN3OE plants in normal condition. When treated with ABA, AtANN3OE showed insensitive response to ABA than wild type. Guard cell movement was inhibited in AtANN3OE plants.(6) We checked the relative expression level in AtANN3OE and WT plants via qRT-PCR. We found that ABI1and ABI2expressed in the same level between wild type and AtANN3OE plants in normal condition. However, they were increased3.25-fold and3.43-fold respectively under ABA treatment in AtANN3OE, compared to wild type.