Occurrence of Pseudomonas syringae pv. Tomato race 1 in Italy on Pto Gene‐Bearing Tomato Plants

Abstract

Bacterial speck symptoms on leaves of the tomato cultivar Erminia Fl (Petoseed), heterozygous for the Pto resistant gene, were observed in June 1995 in Northern Italy. Using individual-lesion isolation, 8 bacterial isolates were obtained from the affected leaves, which were identified as Pseudomonas syringae pv. tomato by biochemical, physiological, nutritional and pathogenicity tests. When the differential cultivar Otitario 7710, homozygous for the Pto gene, was inoculated with the bacterial isolates, 4 of them provoked the typical bacterial speck symptoms and therefore belonged to race 1. This is the first occurrence of P. syringae pv. tomato race 1 in Italy and the first time this race has been isolated on a Pto gene-bearing tomato cultivar grown in open field. Zusammenfassung DasVorkommen von Pseudomonas syringae pv. tomato Rasse 1 in Itatien an Tomatenpflanzen mit dem Pto-Gen Im Juni 1995 wurden in Nortalien Symptome der Tupfelschwarze an Blattern der Tomatensorte Erminia Fl (Petoseed), die fur das Pto Resistenzgen heterozygotisch ist, beobachtet. Aus einzeinen Blattlasionen wurden 8 Bakterienisolate gewonnen, die anhand von biochemischen, physiologischen, Nahrmediumverwertungssowie Pathogenitatstests als Pseudomonas syringae pv. tomato bestimmt werden konnten. Nach einer Inokulation der Differentialsorte Ontario 7710, die filr das Pto-Gtn homozygotisch ist., mit diesen Baktedenisolaten wurden Syptome der Tupfelschwarze durch 4 Isolate hervorgerufen, ein Zeichen dafur, dafi diese Isolate zu Rasse 1 gehoren. Damit wird zum ersten Mai tiber das Vorkommen von P. syringae pv. tomato in Itahen und uber die Isolierung dieser Rasse aus einer im Freiland wachsenden Tomatensorte mit dem Pjo-Gen beschrieben.

A Review of the Most Common and Economically Important Diseases That Undermine the Cultivation of Tomato Crop in the Mediterranean Basin

“…Two Pst races (0 and 1) have been identified so far, based on the different responses of tomato cultivars with or without resistance gene to Pseudomonas syringae pv. tomato (Pto) and based on the Pst expression of the avirulence (avr) genes (avrPto and avrPtoB) [188]; so far, the more virulent race 1 has been reported in Italy and Portugal and Tunisia [189][190][191][192]. Pst is favoured by a temperature range of 13-28 • C, with a high humidity and even with free water on leaves [40].…”

Pto update: recent progress on an ancient plant defence response signalling pathway

“…In California, 40% of the tomato acreage now contains Pto (G. Martin, personal communication). There have been two reports of race 1 strains causing disease in fields of Pto ‐bearing tomato plants (Arredondo and Davis, 2000; Buonaurio et al ., 1996), but only one of these was associated with significant damage. Unfortunately, neither was characterized with respect to their origin or possible mutations in avrPto , and it is not clear whether the strains arose from a race 0 population in response to selection by Pto , or were introduced.…”

Zinc phosphate protects tomato plants against Pseudomonas syringae pv. tomato

“…It also remains difficult to control. Although tomato genotypes with high or intermediate resistance to Pst are available on the market, as the pathogen has been shown to overcome this resistance (Buonaurio et al 1996;Kunkeaw et al 2010;Lin and Martin 2007;Thapa and Coacker 2016), there is the need for further methods of control.…”