Cloning Of NAC4 And NAC27 Genes From Soybean And Genetic Transformation Of Arabidopsis And Rice

Abiotic stresses such as drought and soil salinization have a severe impact on soybean's yield and quality. A lot of researches reveal that the NAC transcription factor family plays an important role on plant abiotic stress response. Our previous research showed considerable variation on the soybean NAC4 gene during the domestication and breeding process, demonstrating that the soybean NAC4 might have been subjected to artificial selection. We carried out the studies about clone and genetic transformation of the soybean NAC4 gene and the NAC27 gene homologous to soybean NAC4 in soybean, in order to explore the possible role of two NAC transcription factors, our results are as follows:1. We identified genes homologous to soybean NAC4 in Arabidopsis using BLAST analysis. The homology of soybean NAC4 with Arabidopsis ANAC055 reaches 60.9%. Using three primers method. The T–DNA insertion was found within the 3'-UTR region. Detected by RT-PCR showing that the ANAC055 was expressed with the highest level in leaves, followed by flowers and stems, but not in roots and pods. In addition, the ANAC055 was Compared with wild Arabidopsis thaliana, the ANAC055 gene expression in Arabidopsis thaliana mutant was down-regulated, with the highest level of down-regulation in flowers(more than 70%) and lower in leaves and stems(leaves about 40% and stems are about 50%). Under the conditions of salt stress(NaCl simulation) and drought stress(mannitol simulation), the inhibition of the root length of the homozygous Arabidopsis thaliana mutant was slightly higher than that of the wild type, indicate that ANAC055 may play a certain action on the process of resistance to drought and salt stress.2. We obtained the NAC4, NAC27 cDNA fragment from gandou No. 4 and successfully constructed vectors expressing soybean NAC4 and NAC27, which were then transformed into wild type Arabidopsis thaliana and homozygous Arabidopsis thaliana mutants using Agrobacterium-mediated transformation method. Homozygous NAC4 and NAC27 overexpressing Arabidopsis thaliana plants and homozygous transgenic Arabidopsis thaliana plants presumably complement the mutant phenotype were identidied. Under the conditions of salt stress(NaCl simulation) and drought stress(mannitol simulation), the root growth of the NAC4 and NAC27 overexpression Arabidopsis thaliana plants was less inhibited compared to that of the wild type. Under drought stress, the root growth of transgenic Arabidopsis thaliana plants presumably complement the mutant phenotype, which was the same as wild Arabidopis thaliana, was less inhibited than the Arabidopsis mutants. On the contrary, under salt stress, the root growth of tansgenic Arabidopsis thaliana plants presumably complement the mutant phenotype similar as that of the Arabidopsis mutants were more inhibited than the wild types.3.We aslo successfully tansformed those vectors expressing soybean NAC4 and NAC27 into rice(zhonghua 11). Positive tansgenic rice lines were obtained from T1 transgenic rice plants.These results indicate that NAC4 and NAC27 gene may play a role on the response to drought and salt stress, and their function need a further study.