The Genetic Transformation And Preliminary Functional Of AP2 From Betula Platyphylla Suk.

APETALA2/ethylene-responsive element binding protein(AP2/EREBP)gene family is a class of transcription factor family,this transcription factors family present in all plant,which was involved in many biological processes,including plant growth and flower development,fruit development,seed development,injuries,bacteria defense,response to high salt and drought stress and so on.The main function of the AP2 subfamily is regulation of development of flowers,ovules,and seeds.The AP2 gene belongs to the A-class gene of homeotic genes,involved in floral meristem characteristics,regulation of floral organ identity.Unlike the other highly characterized floral homeotic proteins containing MADS domains,AP2 has two DNA-binding domains referred to as the AP2 domains.The AP2 domain has 60-70 conservative arruno acids.It contains three antiparallel ?-pleated sheet and a amphiphilic alpha helix,Which is similar to the zinc finger structure.The AP2 gene cloned into the plant expression vector pBI121 under the control of CaMV35S promoter.With agrobacterium mediated genetic transformation method is obtained the transgenic birch and transgenic Arabidopsis thaliana.The PCR with the characteristic primer BplAP2,primer NPT? and primer GUS showed that two birch lines and fifteen arabidopsis lines were positive.Through resistance screening,we got 4 homozygous transgenic arabidopsis lines.From the morphological results,the ap2 mutant flower organs are distinguished by the presence of stigmatic papillae and multiple ovules along the margin of esch organ.The lateral sepals are either absent or develop into leaflike.Second whorl organs,which normally develop into petals.Third whorl stamens are reduced in number from six in wild type to between two and four organs.The positions of the flowers,side branches and cauline leaves in BplAP2 transgenic plants were changed.Compared with the wild type,ap2 mutant plants rosette leaf number,the diameter of the rosette leaves and the number of pod reduce,an increase in the seed number of single pod and seed weight;in BplAP2 transgenic plant,the number of rosette leaf,the diameter of the rosette leaves and the number of pod increases,the seed number of single pod changes a little,seed weight reduce.It is speculated that BplAP2 gene can regulate the development of flower organs and involved in the development of side branches,rosette leaves and seeds.Determination of the soluble protein anf free fatty content in seeds showed that:the ratio of the two substances in the ap2 mutant seeds were increased,and the ratio of the two substances in the ap2 mutant seeds were decreased.It is speculated that BplAP2 gene is involved in the regulation of synthesis of protein and fatty acid,so,it affect the weight of seed.Unlike most other flower homeotic genes AP2 is also expressed at the mRNA level in both stem and leaf.qRT-PCR analysis of BpIAP2 gene in Arabidopsis and birch analysis showed that,the BplAP2 gene expression was significantly increased of the roots,stems and leaves in overexpression BplAP2 gene birch,and it has the high expression in transgenic Arabidopsis flowers and the low expression in teansgenic Arabidopsis stems.The expression analysis of flower development genes related the BplAP2 gene showed that:the expression of TFL1?API and AG were up-regulated in BplAP2 transgenic Arabidopsis roots and steams;the expression of TFL1 and LFY were up-regulated and API and AG were down-regulated in BplAP2 transgenic Arabidopsis leaves and siliques and the expression of API were up-regulated TFL1 and AG were down-regulated in BplAP2 transgenic Arabidopsis flowers.It is speculated that BplAP2 gene can regulate the development of vegetative organs by interaction with AP1,LFY,TFL1 and AG,in addition to involved in the development of floral organs.