Bacterial spot caused by Xanthomonas vesicatoria devastated tomato production of Khyber Pakhtunkhwa-Pakistan

Abstract

In Khyber Pakhtunkhwa (KP) province-Pakistan, bacterial spot caused by Xanthomonas campestris pv. vesicatoria (Xcv) has decimated commercial tomato production. Field surveys were conducted in 2017 and 2018 to analyse the effects of the bacterial spot in tomato producing areas of KP, including Swat, Lower Dir, and Mansehra. During the growing seasons, diseased samples were collected from tomato fields, and disease incidence and severity were documented. The pathogen was isolated, purified, and morphologically and biochemically characterised. Most of the morphological and biochemical characteristics such as yellow colonies, were like those of Xanthomonas spp. Further, the pathogen was confirmed using XV1F/XV1R pair of species-specific primers, which amplify the atpD gene sequence solely in Xanthomonas vesicatoria. Out of 30 isolates, 16 isolates were confirmed to be Xcv. In these agro-ecological zones, this was the first report on the presence of Xcv. Furthermore, humidity and temperature were found to impact the incidence and severity of bacterial spot substantially. Most isolates grew at high temperatures and low humidity; however, some prefered high-temperature and low-humidity environments. In conclusion, bacterial spot disease caused by Xcv has now spread throughout all tomato-producing areas of KP province. To avert future plant epidemics, ongoing climate and pest monitoring is required to build an effective disease warning system for producers and other agriculture-related agencies.

Chemical and Molecular Detection of New Strains of Xanthomonas Campestris pv. Vesicatoria and Pseudomonas putida Associated with Tomato Crop

“…The results were negative for Starch hydrolysis, Indole test, Gelatin hydrolysis, and KOH Solubility. These findings are consistent with previous studies [16,19,31].…”

“…However, other tests such as the Oxidase test, Arginine Hydrolysis, KOH test, Starch hydrolysis, and Indol test produced negative results. These findings indicate that the isolates exhibit the characteristics and traits of the campestris type, aligning with previous studies[16,19].…”

“…These tests included the Catalase test, Oxidase test, Arginine hydrolysis, Motility test, UV fluorescence, Starch hydrolysis, Indole test, Gelatin liquefaction, and KOH solubility. The references [15,16,20] guided the execution of these tests.…”

“…These tests included the Catalase test, Gelatin hydrolysis, Motility test, Aesculin hydrolysis, Oxidase test, Arginine hydrolysis, KOH solubility, and Starch hydrolysis. The references[15,16,19] guided the execution of these tests.2.7. Microscopic and Visual Identification of Pseudomonas Putida Bacteria2.7.1.…”

Genomic and phenotypic insight into Xanthomonas vesicatoria strains with different aggressiveness on tomato

“…X. vesicatoria and X. euvesicatoria were historically considered the predominant bacterial spot lineages worldwide, although X. perforans and X. gardneri are increasingly isolated from areas in America, Africa, the Middle East, and the Indian Ocean ( Vancheva et al, 2021 ). However, the disease caused by X. vesicatoria continues to be a worldwide problem due to the seedborne nature of this pathogen ( Kebede et al, 2014 ; Potnis et al, 2015 ; Berrueta et al, 2016 ; Roach et al, 2018 ; Osdaghi et al, 2021 ; Potnis, 2021 ; Ahmad and Ahmad, 2022 ).…”