Detection of Xanthomonas campestris pv. Campestris in Imported Germplasm of Cabbage during Post Entry Quarantine

Black rot is a devastating bacterial disease causing considerable yield losses in cabbage. Xanthomonas campestris pv. campestris ( Xcc ) is a regulated non-quarantine pest for India and detection of Xcc in imported germplasm is very important to prevent the introduction and spread of pathogen in the country. A total of 175 germplasm accessions of cabbage were imported by Syngenta India Pvt. Ltd. from China and grown in post entry quarantine (PEQ) growing area of Syngenta Farm, Karnal. During PEQ inspection of crop, 35 accessions showed typical black rot symptoms. Out of 35 accessions, eight representative accessions were used and found to be positive for Xcc based on mophological, cultural and biochemical assay. Xcc specific primers gave a specific band of 769 base pairs, which confirmed the presence of Xcc in the infected samples. 16S rRNA sequencing of one isolate ( XccP1 ) was used to further confirm the presence of the pathogen. 16S rRNA sequence showed 100% sequence similarity with Xcc strains already deposited in NCBI database. Black rot infected germplasm accessions grown in PEQ area were up-rooted and incinerated to prevent further spread of disease.