A pith necrosis caused by Xanthomonas perforans on tomato plants

Abstract

Pith necrosis is a common disease of tomato in Europe, mainly caused by Pseudomonas corrugata and other soil-borne species of Pseudomonas. During 2011-2012 a survey was conducted in soil-grown tomato crops in southeastern Sicily (Italy). Plants showed pith necrosis, brown discolouration of the vascular tissues, leaf chlorosis and sometimes wilting of leaves. Thirty bacterial isolates from symptomatic tissues, forming colonies on NA and KB, were identified by morphological, biochemical and physiological tests. Among them, seven isolates were analyzed for their 16S rDNA and 16S-23S spacer region sequence that resulted in 99 % identity to that of the Xanthomonas perforans type strain (GenBank accession number GQ46173over 2.085 bp.). Additional sequences of fusA, gapA, gltA, gyrB, lacF, and lepA from one selected isolate were 100% identical to sequences of the Xanthomonas perforans type strain. X. perforans local isolates showed similar genomic patterns with REP-PCR and fAFLP, and were clearly distinguished from other Xanthomonas spp. type strains. In steminoculation assays, bacteria isolated from symptomatic tomato plants identified as P. fluorescens, P. putida, P. marginalis, P. citronellolis, P. straminea, and Pantoea agglomerans induced discolouration of vascular tissues, while Pectobacterium carotovorum subsp. atrosepticum isolates induced soft rot. Conversely, the isolates here identified as Xanthomonas perforans were able to induce pith necrosis, vascular discolouration, longitudinal splits and external lesions on stems. This report of X. perforans causing pith necrosis on tomato represents a potentially serious problem that may limit the productivity of tomato crops.

Tomato susceptibility to Fusarium crown and root rot: Effect of grafting combination and proteomic analysis of tolerance expression in the rootstock

“…radicis-lycopersici (FORL), is one of the most destructive diseases worldwide (Jones et al, 1991). This fungus, together with other emerging and wellestablished soilborne pathogens (Aiello et al, 2013;Dimartino et al, 2011;Vitale et al, 2011), represents a serious threat for tomato production in South Italy and, particularly, in South-eastern Sicily, where FCRR can cause yield losses up to 40%. The current disinfestation measures to control FORL, such as chemicals or soil solarization, have various limitations related to poor efficacy, pathogen thermo-tolerance and high costs (Jones et al, 1991;Vitale et al, 2013).…”

Scientific Opinion on the pest categorisation of Xanthomonas campestris pv. vesicatoria (Doidge) Dye

“…Spots increase in size and cracks appear at the centres, which become darker and later necrotising. Recently, pith necrosis has been associated with the presence of X. perforans (Aiello et al, 2013). The symptoms observed resemble those caused by the pathogenic bacterium Pseudomonas corrugata: pith discoloration and necrosis, hollowing of the centre of the stem and swollen stems with the production of numerous adventitious roots.…”

“…Precise and detailed information concerning the current distribution in EU Member States of each of the four newly described Xanthomonas spp. is not available but, very recently, the presence of X. perforans was reported in Sicily (Aiello et al, 2013). Moreover, according to former comprehensive studies performed on a worldwide collection of isolates and based on serology, metabolic features and fatty acid methylester profiles (FAME), X. euvesicatoria (X. campestris pv.…”

Pith Necrosis of Tomato Caused by Pseudomonas viridiflava May Not Decrease Production

“…Besides P. viridiflava [1], the bacteria Pseudomonas agglomerans [4], Pseudomonas corrugata [5], Pseudomonas mediterranea [6], Pseudomonas marginalis [7], Pseudomonas cichorii [8], Pseudomonas fluorescens and Xanthomonas perforans [9] may cause the pith necrosis of tomato. Up to now, only Pseudomonas corrugata, P. viridiflava and Pseudomonas mediterranea were reported as the etiological agent of tomato pith necrosis in Brazil.…”