Isolation and characterization of Xanthomonas campestris pv. campestris from cabbage and its Inhibition using endophytic bacteria
摘要
The plant pathogenic bacterium Xanthomonas campestris pv. campestris (Xcc) is a seed borne bacterium that causes black rot of cabbage and causes huge loss in yield. In the present study Xcc were isolated from cabbage and characterized by morphological features, biochemical tests, pathogenicity test and molecular analysis. A total of five Xcc isolates were obtained from five different cabbage fields around Mysuru region of Karnataka. When cultured on YDC media, the isolates showed typical yellow, raised, translucent, mucoid colonies. The biochemical analysis showed that the bacteria were negative for Gram’s staining, oxidase reaction and nitrate reduction, and positive for starch hydrolysis, gelatin hydrolysis, KOH solubility, catalase test, indole production and H2S production. In pathogenicity test, all the isolates showed typical black rot symptoms characterized by V-shaped lesions that progressed from yellow to brown along the leaf margins, accompanied by the blackening of veins. The molecular identification of the isolates was carried out by amplification of 16s rRNA region and hrpF gene. Further, endophytic bacteria were isolated from cabbage and screened for their ability to inhibit Xcc. A total of five endophytic bacteria were obtained and among them four isolates showed inhibitory effect on Xcc. The isolate P3 showed maximum inhibition with inhibition zone of 28 ± 0. 14 mm and was identified as Bacillus safensis by amplification of 16s rRNA region. The results provide insights on characterization of Xcc and indicate that Bacillus safensis could play an important role in biocontrol of Xcc on further characterization.