Cloing And Functional Identification Of The Copper Resistance Gene CopB In Xanthomonas Gardneri

Bacterial Spot is a general kind of disease, which happens in the region of the world. It causes serious damage on fruits of tomato and pepper. It significantly reduces the yields of fruits and seriously affects the quality of their fruits. Xanthomonas gardneri is one kind of pathogen of Bacterial Spot disease. Through analyzing the growth condition of Xv1O strain on SPA medium contained diffifrent concentration of CUSO4, Xv10strain grew well on SPA medium contained CUSO4of which the concentration was100μg/ml,150μg/ml,200μg/ml,250μg/ml,300μg/ml or400μg/ml. We conclude that CUSO4(650μg/ml) suppress the growth of Xv10strain; Xv-10strain can be depressed by CuSO4780μg/ml). In order to prevent and control the disease, researching on pathogenic mechanism of the pathogen through molecular means is very important.With the whole genome sequence of pathogen of Bacterial Spot disease announced, it provides favorable conditions for us to study the pathogenesis mechanism.There are two genes named copA and copB in Xanthomonas gardneri. The length of cop A is1782bp and the length of cop B is1095bp. CopA is made up of593aminoacid; CopB is made up of364aminoacid. The amino acid sequence of CopB of Xanthomonas gardneri is88%similar to that of CopB of Xanthomonas axonopodis pv. citri and49%similar to that of CopB of Pseudomonas syringe pv.tomato. Copper resistance mechanism of Xanthomonas gardneri is similar to that of Pseudomonas syringe pv.tomato. But there are not copR and copS in Xanthomonas gardneri.This article will mainly research on colonling copB, analyzeing the sequence of copB, deletion mutation of copB, complementation analysis and doing related tests. This article have constructed△copBxv and△copBxv-C, done pathogenic tests and copper resistance tests on Xv10,△copBxv and△copBxv-C, dedtcted exocellular polysaccharides secretion of Xv10,△copBxv and△copBxv-CIt can be concluded that the nucleotide sequence copB is highly conserved in Xanthomonas gardneri by analyzing the gene copB of Xv10. The nucleotide sequence of copB of Xanthomonas gardneri is highly similar to that of Xanthomonas axonopodis pv. citrumelo and Xanthomonas oryzae pv. oryzae.Through inoculating bacterial suspension of△copBxv on tomato, disease degree of tomato seedlings got slighted. It indicated that copB had an effect on plant pathogenicity.Growth forth of△copBxv on LB medium containing100μg/ml CUSO4became weake, but gene complementary could recovery some growth forth of AcopBxv. It indicated that copB had an effect on copper resistance.Exocellular polysaccharides production or secretion of△copBxv hardly changed. There was little difference among exocellular polysaccharides production or secretion of Xv10,△copBxv and△copBxv-C. It can be concluded that copB hardly affected production or secretion of exocellular polysaccharides.