The Molecular Mechanism Of Drought Resistance Regulated Of BpERF111 Transcription Factor From Betula Platyphylla

Plants always suffer from biotic stress and abiotic stress in the process of growth and development,including drought,salt and low temperature stress.AP2/ERF is one of the largest transcription factor families,involved in plant development and respond to abiotic stress.The drought resistance function of BpERF111 in Betula platyphylla was studied.The total length of CDS of BpERF111 is 1098 bp,encoding 365 amino acids,belonging to the AP2/ERF family.The expression of BpERF111 was induced by drought stress,and the highest expression of BpERF111 was observed at 4 h,indicating that BpERF111 might be involved in drought stress regulation of Betula platyphylla and BpERF111 has tissue specificity and the highest expression in the stem.The transgenic birches（OE）was obtained by leaf-disk mediated by Agrobacterium Tumefaciens.Three high expression lines（OE-5,OE-10,and OE-12）were selected for follow-up study.The wild-type birches and overexpressed birches were subjected to drought stress respectively,and the phenotypes of overexpressed birches were analyzed.The results showed that the overexpressed birches were more resistant to drought stress.Physiological analysis of the overexpressed birches showed that the activities of POD and SOD,the content of Proline,ROS,MDA and Relative Electrical Conductivity were significantly increased after drought stress,compared with wild-type birches,indicating that the overexpression of BpERF111 can improve the scavenging ability of Reactive Oxygen,thus reducing the degree of cell damage.Reduce cell death and improve the drought resistance of Betula platyphylla.The phosphorylation of BpERF111 is regulated by drought stress.Further studies showed that drought stress could phosphorylate Ser²³⁰ of BpERF111,but the phosphorylation level disappeared when the site was mutated to alanine（Ala）.By using Protein Capture Based on biolistic transformation（PCa B）method to identify BpHAP5A,the upstream regulator of BpERF111,EMSA confirmed that BpHAP5A can bind to the promoter of BpERF111.By Ch IP-q PCR and RT-q PCR,the transcription factor was found to bind to the BpERF111 promoter and induce its expression in Betula platyphylla.