Cloning And Charaterization Of Aux/Iaa Encoding Gene CmIAA1from Chrysanthemum Morifolium

Chrysanthemum(Chrysanthemum morifolium) is domestic to China, whose ornamental character is valuable, is one of the ten most famous flowers in China. And it is important for the flower production. The diversity of chrysanthemum floral and morphologic types indicates that the growth and development of chrysanthemum are regulated by plenty of factors. The auxin indole-3-acetic acid (IAA) is one of the foremost phytohormone, so there must be tightly relationship among the cells and auxin signal pathway. In recent years, the transgenic technology is becoming more and more reliable so that scientists can research a single gene precisely. Research of CmIAAl, a member of auxin response protein family, is to discover more details on the auxin signal pathway. Here come the main results.In this study, a full length cDNA of auxin response protein gene named CmIAAl was isolated from Chrysanthemum via RT-PCR and RACE, the degenerate primer used in this experiment were designed according to the conservative sequences of other auxin response proteins promulgated in GeneBank. The full length cDNA of CmIAAl was1017bp, and the ORF was711bp which encoded a polypeptide of237amino acids residues. Sequence analysis showed that CmIAAl contained4typical domains. CmIAAl had a similar sequence with RcAUX28which came from Ricinus communis, and the identity was49.73%. Phylogenetic tree analysis showed that CmIAAl and other auxin response proteins with4domains were grouped into the same branch.Quantitive real-time PCR (qRT-PCR) showed that CmIAAl transcript abundance increased obviously in response to20-200μg/ml IAA at12h after IAA treatment. But CmIAAl transcript abundance reduced within24h under treatments of10μg/ml GA,100μg/ml ABA,30μg/ml6-BA and10mg/L ethylene.A plant expression vector for CmIAAl gene pCAMBIA-1301-CmIAAl was constructed in this report, which was introduced into Arabidopsis thaliana via an Agrobacterium tumefaciens EHA105-mediated floral dip method. Two independent transgenic lines overexpressing CmIAAl were selected for further investigations and contrasted to wild-type Arabidopsis. The transgenic lines developed a shorter taproot, and the transgenic lines grew slower and are smaller compared with the wild type plants. Both decapitated35S::CmIAAl lines plants generated more lateral roots than WT. the results of decapitating, adding exogenous IAA and using the NPA treatments on Arabidopsis proved that CmIAAlwas a member of the IAA signal pathway. And we found that10-7M IAA could recover taproot growth of the transgenic Arabidopsis, while for WT was10-9M IAA.10-5,10-7M IAA could promote the lateral root genesis of both transgenic lines, which indicated CmIAAl participated the IAA signal pathways as an inhibitor.