Identification of Xanthomonas species associated with bacterial leaf spot of tomato, capsicum and chilli crops in eastern Australia

R. Roach,C. G. Gambley,R. Mann,B. Rodoni,R. G. Shivas

doi:10.1007/s10658-017-1303-9

R. Roach, C. G. Gambley + Show 3 more

Open Access

https://doi.org/10.1007/s10658-017-1303-9

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Abstract

Several species of Xanthomonas cause bacterial leaf spot, a disease that affects solanaceous crops worldwide. The diversity of 64 Australian isolates of Xanthomonas spp. associated with bacterial leaf spot in tomato, capsicum and chilli crops in eastern Australia was determined using multi-locus sequence analysis of atpD, dnaK, efp and gyrB genes, species-specific PCR assays and biochemical analyses. At least five species of Xanthomonas associated with bacterial leaf spot were identified in Australian tomato, capsicum and chilli crops and their pathogenicity assessed. Phylogenetic and biochemical analyses identified X. euvesicatoria, X. perforans and X. vesicatoria as the most frequently recovered pathogenic species. Non-pathogenic and weakly pathogenic species were also identified. The suitability of the identification methods used and the implications of the detection of these species will be discussed.

Highlights

Bacterial leaf spot (BLS) is a disease of solanaceous crops that occurs worldwide, especially in warm and humid climates (Jones et al 2014)
Type strains for X. euvesicatoria (NCPPB 2968), X. gardneri (NCPPB 881), X. perforans (NCPPB 4321) and X. vesicatoria (NCPPB 422) were imported under permit from the National Collection of Plant Pathogenic Bacteria (NCPPB)
Fifty-seven Xanthomonas-like bacteria isolated from symptomatic tomato, capsicum and chilli crops plants from Qld and New South Wales (NSW) from 2012 to 2015 and an additional

Summary

Introduction

Bacterial leaf spot (BLS) is a disease of solanaceous crops that occurs worldwide, especially in warm and humid climates (Jones et al 2014). Several species of Xanthomonas are reported to cause BLS of tomato (Solanum lycopersicum), capsicum and chilli (Capsicum annuum) (Potnis et al 2015). The symptoms of BLS are small, brown, angular, water-soaked lesions on leaves, stems and fruit, and result in defoliation and direct fruit damage. Species reported to cause BLS all produce similar symptoms on their hosts, making precise diagnosis difficult from visual symptoms alone. Control of BLS is achieved primarily through the use of resistant lines, antibiotic application and copper sprays. Reliance on a limited range of chemicals has seen copper and antibiotic resistance develop rapidly in Xanthomonas populations (Griffin et al 2017; Martin et al 2004; Minsavage et al 1990)

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