Abstract:

Based on the information of transcriptome database derived from Xanthomon asaxonopodis pv. citri（Xac）infected citrus，the cDNA sequences of WRKY22，WRKY50，WRKY72-1 and WRKY72-2 were cloned from Newhall（Citrus sinensis Osbeck）and Calamondin. Sequence analysis showed that the full length of cDNAs were 1 123，1 312，1 809 and 2 208 bp，with 921，480，1 809 and 1 767 bp open reading frames（ORF），respectively. Those cDNAs encode 306，159，602 and 588 amino acids，respectively. Analysis of amino acid sequences and protein structures indicated that the 4 CsWRKYs belonged to the group Ⅱ WRKY proteins. The results of phylogenetic analysis showed that the 4 CsWRKY genes had a close relationship with TcWRKY and VvWRKY family from Theobroma cacao and Vitis vinifera，respectively. Subcellular localization analysis indicated that the 4 CsWRKY proteins were located in the nucleus. The expression of these genes in Newhall navel orange and Calamondin after Xac inoculation revealedthat WRKY22 was involved in the susceptible response of the host，while WRKY50 was involved in the immune response of Xac resistance. Xac inhibited the WRKY72-1- and WRKY72-2- mediated host basal immunity. Results of SA and MeJA treatments indicated that none of the 4 WRKY genes was involved in the disease and stress resistance of host mediated by SA and MeJA.

Key words: Citrus, CsWRKY, gene cloning, expression analysis