The Preliminary Study On UF1 Response To Abiotic Stress In Arabidopsis

Abscisic acid(ABA) and microfilament cytoskeleton participate in plant responses to abiotic stress. Here we studied an unknown function gene UF1 which was induced by ABA,NaCl and actin-depolymerizing drug latrunculin B in Arabidopsis. The expression patterns of UF1, the subcellular localization of UF1 protein, the sensitivities of seed germination and seedling growth to NaCl and ABA stress, the relative expression levels of ABI1, SnRK2.6,ABI5 and RD29 A in uf1 mutant, UF1 overexpression line and wild-type(WT) Arabidopsis with ABA treatment and the dynamic changes of microfilament cytoskeleton in uf1 mutant treated with salt stress. The results were as follows:(1) UF1 was expressed in various vegetative organs and reproductive organs we detected,especially in seedling, stem, flower, slique and seed.(2) We observed that the Green fluorescence was located in the cytosol of leaf epidermal cells, hypocotyl cells and root cells in the region of meristem and maturation in transgenic35S::UF1-GFP Arabidopsis plants.(3) UF1 functions in response to salt stress in Arabidopsis. Seed germination of the uf1 mutants was delayed compared with that of the WT plants with 175 mM NaCl treatment,whereas the UF1-overexpressing lines showed less sensitive to NaCl than WT plants,suggesting that UF1 can response to NaCl stress.(4) UF1 is involved in ABA signaling pathway in Arabidopsis. The expression of UF1 was up-regulated by ABA in our qRT-PCR and GUS staining expriments. The seed germination rate and cotyledon greening rate of uf1 mutants were lower than WT with 1.0μM ABA treatment, and the root length of uf1 mutants was shorter than WT plants. On the contrary, the UF1-overexpressing lines showed less sensitive to ABA than WT plants. The relative expression levels detected by qRT-PCR of various ABA-responsive genes, ABI1,SnRK2.6, ABI5 and RD29 A, in uf1 mutant and UF1-overexpressing line after 100μM ABAtreatment were higher or lower than in WT plants. These results indicate UF1 is involved in ABA signaling pathway.(5) The microfilament in bundles of uf1 mutant was in a low degree compared with that of WT Arabidopsis. The long microfilament bundles of uf1 mutant were severed into small fragments and depolymerized more quickly than WT plants with 200 mM NaCl treatment within 1h.(6) Yeast two-hybrid experiment result showed the UF1 interacted with UF2, another protein of unknown function.