小粒咖啡AP2/ERF家族全基因组鉴定及抗寒基因CaDREB2的功能分析OA

To address the Coffea arabica industry in Yunnan being chronically constrained by low-temperature stress,this study systematically conducted the genome-wide identification of the AP2/ERF transcription factor family and functional analysis of the key cold-resistant gene CaDREB2.As the core coffee-producing region in China,Yunnan frequently suffers from severe cold damage such as leaf browning,defoliation,and even branch dieback caused by low-temperature invasions during winter and spring,which directly affects coffee yield and quality.Therefore,based on the genomic data of C.arabica,combined with bioinformatics analysis and Arabidopsis genetic transformation tech-nology,this research deeply elucidated the characteristics of AP2/ERF family members and the cold resistance regula-tory mechanism of CaDREB2.First,using HMMER software retrieval and joint verification with multiple databases,a total of 187 CaAP2/ERF family genes were identified in C.arabica(hereafter referred to as CaAP2/ERF)and classified into five subfamilies according to phylogenetic relationships:ERF(97),DREB(51),AP2(26),RAV(11)and soloist(2).Expression profile analysis showed that the genes in this family exhibited significant tissue specificity,with the largest number of expressed genes in roots(156),while 43 genes reached peak expression at 120 days of fruit development.Further focusing on the core subpopulation responding to low temperature,six CBF genes were screened out,among which CaDREB2 was most significantly up-regulated under low-temperature stress and shared the closest genetic rela-tionship with the Arabidopsis cold-resistant gene AtDREB1A.Functional verification indicated that after constructing CaDREB2-overexpressing Arabidopsis lines and treating them at 4℃for 72 h,the wilting degree of transgenic plants was significantly slighter than that of the wild type.Physiological index measurements showed that the superoxide dis-mutase(SOD)activity of transgenic lines increased by 85.0%compared with the wild type,proline content accumulated 1.39 times,and malondialdehyde content was significantly lower than that of the wild type,confirming that CaDREB2 enhances cold resistance by strengthening the antioxidant system and osmotic regulation capacity.Molecular mechanism studies revealed that CaDREB2 could simultaneously activate the expression of downstream stress-resistant genes(such as AtCOR15 and AtCOR78)in both ABA-dependent and ABA-independent pathways,forming a synergistic regulatory network.This study completed the genome-wide identification of the CaAP2/ERF family for the first time,clarified that CaDREB2 was the key gene positively regulating coffee cold tolerance,revealed its molecular mechanism of enhancing cold resistance by regulating antioxidant enzyme activity,osmotic regulator accumulation,and downstream mul-ti-pathway gene expression,and would provide core gene resources and a theoretical basis for coffee cold-resistant mo-lecular breeding.