No abstract

A serious problem for Paan-lime production in Thailand is a citrus canker disease caused by the bacterium Xanthomonas citri subsp. citri (Xcc). The use of antagonist against pathogenic Xcc is increasingly becoming popular. In this study, we investigated the effect of pathogenic Xcc and a bacterial antagonist on defense-related gene expression of Paan-lime. The ability of Xcc and the antagonist Pseudomonas aeruginosa SWUC02 to induce defense-related gene expression, including PR-1, Pt14, LRR8, and LOX gene, was assessed. We assured that all four defense-related genes are present in Paan-lime by analyzing the similarity of nucleotide sequences in parts of the genes against other citrus species. Using reverse-transcription PCR (RT-PCR), we showed that the antagonist is able to induce the expression of LRR8 gene at 24 hours post-inoculation, while Xcc induces PR-1 and LOX gene expression at the same time. Our results suggest that these defense-related genes alter their expressions in response to canker disease infection. Thus, we could use this group of genes as a biomarker for screening canker-resistance Paan-lime tree.