Functional Analyses Of AmDREB2and AmRD22Genes From Ammopiptanthus Mongloicus

DREB (Dehydration responsive element binding) transcription factors and RD22proteins play key roles in plant response and resistance to multiple abiotic stresses. Ammopiptanthus mongolicus shows very strong resistance to cold, drought and high salinity. In this paper, a DREB2-like gene, namely AmDREB2, was cloned from A. mongolicus, and the expression patterns of both AmDREB2and AmRD22that was cloned from this plant previously were analyzed under different abiotic stresses. Moreover, the functional analyses of AmDREB2and AmRD22were performed by their transgenic Arabidopsis. The main results are as follows:(1)The complete coding region cDNA of AmDREB2was cloned by PCR method. Its predicted polypeptide consists of175amino acids and has a molecular weight of19.96KDa and an isoelectric point of7.26. It belongs to the DREB2-type transcription factor and was predicted to be suloble protein with strong hydrophilicity and most probably located in cell nucleus.(2)The expression of AmDREB2was significantly induced by high salinity, drought and low temperature, and especially continued to increase under drought and salinity stresses.(3) The cDNA fragment of AmDREB2was successfully ligased to plant expression vector pCAMBIA3301and was promoted by the promoter of rd29A. Then the gene fragment was introduced into Arabidopsis by Agrobacterium-mediated transformation. The transgenic plants were identified and propagated, and the homozygous lines of T3generation were obtained.(4)Through phenotypic characterization of the T3lines under multiple abiotic stresses like drought, low temperature, high salinity and exogenous abscisic acid (ABA), it was suggested that AmDREB2functions as a positive regulator of drought and salt resistance and a negative regulator of exogenous ABA sensitivity.(5)The expression of AmRD22was obviously induced by drought and high salinity but weakly induced by low temperature.(6)AmRD22gene was introduced into Arabidopsis by Agrobacterium-mediated transformation and the transgenic plants were identified and propagated. The phenotypic characterization of homozygous lines of T3generation were carried out under drought, low temperature, high salinity and exogenous ABA, and it was suggested that AmRD22mainly plays an important role in resistance to high salinity stress.