Function Analysis Of Two ACS Genes In Arabidopsis Thaliana To Biologic And Abiotic Stress Responses

ACC synthas is key enzyme in biosynthetic pathway of ethylene, and respond to biologic and abiotic stress, such as infection of pathogen, injury and extreme temperature et al. We constructed RNAi expressing vector of ACS9 genes and acquire the transgenic plant with inhibition of ACS9 expression, preliminary proved that ACS9 is related to disease responses in arabidopsis. The objective of the present study is, to investigate the function of ACS6 and ACS9 in arabidopsis biologic and abiotic stress responses, transgenic plant of ACS9 gene and ACS6 T-DNA mutant were used to be conducted with analysis on stress resistance and relative physiological under stress. The expression patterns of genes relating to stresses and ethylene biosynthesis were also detected. The main results are as follows:1. The germination detection indicated that the acs6 mutant and ACS9i-2 lines more sensitive than wild-type plan to stress, the germination of acs6 mutant was lowest. The wild-type grew stronger than ACS9i-2 lines at 150 mmolL-1 NaCl , which indicatesalt ability of salt tolerance was reduce in ACS9i-2lines; The growth was not distint deal with PEG6000.2. Acs6 mutant displayed much stronger disease symptoms compared with wild to Sclerotinia sclerotiorum and the disease symptoms progressed and led to complete decay of the at 3 d post inoculation. Compared to wild, the transgenic lines could maintain lower activities of SOD,POD and CAT, highter content of MDA after inoculation.3. Compared to wild, ACS9i-2 lines could accumulate lower free proline and more MDA under salt stress, so the osmotic adjustment ability reduced, and most of the leaves became brown and growing repressed with 200 mmolL-1 NaCl for 20 d.4. The water loss rates of ACS9i-2 lines were significantly highter than those of Col and acs6 mutant; The osmotic rate of ACS9i-2 lines leaves increased most rapidly with 10% PEG6000 among three lines.5. Grow two weeks Acs6 plants displayed leaves yellowing led to complete decay at 42℃for 24 h;all almost of four weeks acs6 and ACS9i-2 lines were wither after 72h ,the center leaives of wild arabidopsis still grown green.6. The expressions of PDF1.2 gene and PR3 gene were lower than in wild-type after Sclerotinia sclerotiorum inoculated; Some marker genes such as RD29A, P5CS1, P5CS2 were induced when plants suffered from abiotic stresses. In acs6 and ACS9i-2 lines, the expressions of P5CS1 and RD29A were lower than that in wild-type plants under various of abiotic stresses.7. Ethylene biosynthesis of ACS9i-2 lines was highest among three lines in 35d arabidopsis, acs6 mutant the second, wild arabidopsis lowest, but ethylene biosynthesis of acs6 mutant and ACS9i-2 lines are similar to the wild among 60 d mature.