Identification and phylogeny determination of pathogens-associated with leaf blight of cotton.
Bacterial blight of cotton (BBC) is known to be a destructive bacterial disease affecting all cotton growing regions of the world including Pakistan. Infected cotton leaves with typical BBC symptoms were collected from three districts (Multan, Burewala and Bahwalpur) of Punjab, Pakistan. Morphological and basic biochemical tests (Gram staining, KOH Test, Tween 80 hydrolysis Test, Fluorescent Pigment Test and Kovacs' Oxidase Test) confirmed isolated bacteria to be gram negative. Genome of four bacterial isolates M5, M8, Bo7 and B10 were sequenced using next generation sequencing (NGS) protocol Illumina HiSeq 4000. Multigene phylogenetic and Average Nucleotide Identity (ANI) analysis has revealed three different Pantoea species; Pantoea anthophila, P. eucrina and P. dispersa to be responsible for BBC in Punjab, Pakistan. Inoculation of four bacterial isolates (M5, M8, Bo7 and B10) on susceptible cotton variety Acala Maxxa in greenhouse conditions has confirmed these isolates to be responsible for BBC. Bacterial isolate from Bahwalpur region (B10) produced highest number of lesions on cotton leaves followed by Bo7 and M8. Discovery of these Pantoea species instead of Xanthomonas citri pv. malvacearum (Xcm) as a pathogen of BBC in Pakistan emphasize the fact that we need to understand etiology of this disease to develop better management practices.