IAA From IAM Pathway And Its Response To Stress In Arabidopsis

Auxin (IAA), one of the most important plant hormone, regulates multiple processesof plant growth and development, and is related to plant resistance under the adverseenvironments. In this study, two vectors carrying iaaH gene and GFP or RFPrespectively were co-transformed into Arabidopsis of Columbia wild-type orArabidopsis with the auxin-response DR5promoter. The CRE/loxP recombinationsystem activated iaaH and GFP co-expression, and various amount of GFP showed thatthere were different concentrations of auxin in plant.We detected the indole-3-acetamide(IAM)-dependent pathway of IAA biosynthesis and anlazyed the roles of IAA inresponse to adverse stresses in Arabidopsis. The main results are as follow.The co-transformation materials of different vector combinations ofpI-GFP/pGII-iaaH and pGI-RFP/pGII-iaaH were further purified. With different stresstreatments of100mM,150mM NaCl and150mM,300mM Mannitol separately,transgenic plants grew better than the control plants, especially in its longer and agreater number of lateral roots, it reveals that the expression of iaaH has improved salttolerance and drought resistance in plants.Mixed vectors carrying different plasmid constructs of pGI-RFP and pGII-iaaHwere co-transformed into Arabidopsis carrying the auxin-response DR5promoter,added substrate indole-3-acetamide (IAM) of iaaH to MS Medium, the transgenicplants growth was inhibited less than the control plants under150mMNaCl. Under the0,5μMIAM,8μMIAM,150mM NaCl,150mM NaCl+5μMIAM and150mMNaCl+8μMIAM conditions, we detected that the results of expression level of GFP indifferent Media on the cellular level and the expression of three auxin early responsegenes of NTM2、IAA30、GH3.5by RT-PCR showed great divergence. It confirmed theexistence of the indole-3-acetamide (IAM)-dependent pathway of IAA biosynthesis inplants. It reveals that a certain concentration of IAA can enhance plant growth andlateral root formation and improve the salt tolerance of plants as well. The studyprovided an important basis for showing the mechanism of auxin in the regulation ofplant stress response.