Pathogenic variability and genetic diversity using BOX -PCR of Xanthomonas campestris pv campestris isolated from cole crops

摘要

Xanthomonas campestris pv campestris (Xcc) (Pammel) Dowson causes black rot disease in crucifers, which is one of the most important diseases in India and occurs in all parts of the country including the states of West Bengal, Odisha, Maharashtra, Uttar Pradesh, Uttarakhand, Himachal Pradesh, Rajasthan, Delhi, Meghalaya and Jammu and Kashmir (Singh and Shri Dhar 2011). The disease is vascular disease and typical symptoms of the disease in the field are V-shaped chlorotic to necrotic lesions startingfrom leaf margins and with blackening of the veins and vascular tissues. Xanthomonas campestris possesses interspecies variations on the level of pathovars, haplotypes, serogroups and based on the interaction of various isolates of X. campestris pv campestris with different Brassica species, a total of seven pathogenic races of X. campestris pv campestris have been reported (Jensen etal. 2010). PCR-based DNA-fingerprinting is a fast, reliable and comparatively low cost method to study the genetic diversity of bacteria (Zaccardelli et al. 2007, Valverade et al. 2007), which is better than conventional methods of characterization. Several methods for assessment of genetic diversity of bacteria employing PCR with different primers homologous to repetitivesequences under three families of repetitive sequences (Rep) including repetitive extragenic palindromic (REP) sequences, enterobacterial repetitive intergenic consensus (ERIC) sequences and BOX element were identified and their use as primers for PCR leads to selective amplification of distinct genomic regions including highly polymorphic intergenic regions of bacteria (Zaccardelli et al. 2007, Singh et al. 2011).