Origin of AP2 Gene Family and Cotton AP2 Transcription Factors′ Roles in Plant Resistance

棉花学报 Cotton Science 2005，17(6)：366-370

Origin of AP2 Gene Family and Cotton AP2 Transcription Factors′ Roles in Plant Resistance
QIN Jie¹，WANG Wu²，ZUO Kai-jing¹，TANG Ke-xuan¹
(1.Plant Biotechnology Centre，Shanghai Jiaotong University， Shanghai 200030，China；2.Key Laboratory of Cotton Genetic Improvement，Ministry of Agriculture，Cotton Research Institute， Chinese Academy of Agricultural Sciences，Anyang，He'nan 455000，China)

Abstract：AP2 gene family firstly found in Arabidopsis has been isolated from yanobacterium (Trichodesmium erythraeum)，ciliate (Tetrahymena thermophila) and virus (Bacteriophage Felix 01 andEnterbacteria phage RB49 ). A horizontal transfer of an HNH-AP2 endonuclease from bacteria or viruses into plants may led to the origin of the AP2/ERF family of transcription factors via transposition and homing processes. Bioinformatics analysis showed that over 150 AP2 genes in Arabidopsis could be divided into five subfamilies on the basis of number of repetition and sequence of AP2 domain： ERF (ethylene response factor) and DREB subfamily with one single AP2 domain and a conserved WLG motif; AP2 subfamily with two AP2 domains; Rav subfamily containg a B3 DNA binding domain following the AP2 domain; other subfamilies have a single AP2 domain but lack the WLG motif.
Among them， AP2/ERF subfamily could specifically bind the GCC-box presenting in many PR genes to modulate their expression and participate in disease resistance signaling pathways. ERF genes can express in biotic and abiotic stresses and it may play roles in the cross-talking of multi signal pathway. Over-expression of ERF genes showed broad-spectrum pathogen resistance in transgenic plants， which suggest a potential application of ERF genes in molecular breeding. Two ERF genes from seaisland cotton by SSH and cDNA screening could also be induced by ET and ABA. Over-expression of GbERF1 can enhance transgenic tobacco resistance to Pseudomonas syringae pv tabaci and alter some GCC-box and non GCC-box ethylene inducible genes' expression. So，studying the AP2 gene family would help us understand the evolutionary genetics of environmental stress responses，the components and regulatory structure of individual pathways in cotton.
Key words：AP2 gene family；transcriptional regulation；origin；disease resistance
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