Functional Analysis Of Apple Transcription Factor MdbZIP26 Genes

Apple(Malus domestica Borkh.)is one of the most economically important fruit crops in china,and the apple industry play a significant role in agricultural production and national economy.However,the growth and development of it is seriously affected by a range of biotic and abiotic stresses(such as drought,high salt),which cause significant economic losses,as well as a reduction in fruit yield、quality and forage-livestock system every year.During the past decade,extensive attention has been given to understanding the resistance of AREB transcription factors to a variety of stresses.It is very important to cultivate good varieties of resistance to adverse environment.Previously,our team analyzed expression patterns of MdbZIP26 genes by quantitative real-time PCR(q RT-PCR),revealed that the gene was obviously up-regulated after treating with drought,salt or ABA.We’re guessing Mdb ZIP26 gene may play an important role in tolerance to adversity stresses.Our research first isolated Mdb ZIP26 gene from M.domestica cv.“yanfu-3”,and constructed the over-expression vector of p CAMBIA2300-35S-Mdb ZIP26,then transferred it into the Arabidopsis thaliana.Finally,T3 generation of homozygous transgenic lines and wild type(WT)were treated with salt,drought or ABA,for further explore the function and possible mechanism of Mdb ZIP26 gene.The main results were as follows:1.The cDNA sequence of MdbZIP26 was isolated from M.domestica “yanfu-3” using Reverse Transcription-Polymerase Chain Reaction(RT-PCR),the open reading flame(ORF)were predicted to have 1296 bp nucleic acids,which encodes 431 amino acids(Transcript ID:MDP0000248567).The protein also was found to have one conserved b ZIP domain,a Pfam and a HNS domain.Analysis of the deduced amino acid sequence alignment indicated that Mdb ZIP26 was most closely to Arabidopsis thaliana ABF family and Vitis vinifera L..2.Overexpression vector ‘p CAMBIA2300-35S-Mdb ZIP26’ was constructed and transformed to the model plant Arabidopsis thaliana.Results revealed that,compared with WT plants,Mdb ZIP26-expressing Arabidopsis lines increased tolerance to osmotic stress during germination,seedlings and mature plants stage.The seed germination、greening cotyledonrates、root length and number of lateral roots were higher in transgenic lines compared to control plants.Moreover,stomatal aperture of Mdb ZIP26-expressing lines was smaller.Small clusters of dead cells and localized superoxide production in transgenic lines.The activity of antioxidant enzymes in transgenic lines was significantly higher than that in wild type,accompanied by low electrolyte leakage and MDA content.Mdb ZIP26 also enhances plant resistance to osmotic stress by transcriptional regulation of the expression of stress-related genes.According to this study we indicated that Mdb ZIP26 may also be involved in,or have a function upstream of,the ABA biosynthetic pathway.