New sources of partial resistance to bacterial spot race T2 in processing tomatoes

María C Berrueta,Guillermo A Galván,Gustavo Giménez,Alejandra Borges

doi:10.1590/s0102-05362016003004

María C Berrueta, Guillermo A Galván + Show 2 more

Open Access

https://doi.org/10.1590/s0102-05362016003004

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Abstract

ABSTRACT Bacterial leaf spot of tomato is caused by four Xanthomonas species, among which Xanthomonas vesicatoria race T2 predominates in Uruguay. Difficulties in integrated disease management and the rapid spread of the pathogen led to investigations of genetic resistance. This study aimed to identify resistance sources to bacterial leaf spot race T2 in tomato for processing. Twelve genotypes were evaluated under field conditions in 2010 and 2011. Plants were spray-inoculated with a suspension of bacteria (108 cfu/mL) 15 days after transplantation. Incubation period, disease severity on leaves, and the percentage of fruits with symptoms at harvest were determined. The incubation period did not differ among the genotypes. The genotype 'Hawaii 7981' had the lowest leaf severity on the leaves, followed by 'Loica'. The lines (derived from the cultivar 'Loica') LB97, LB99, LB60, and LB76, and the cultivar 'Ohio 8245' showed intermediate levels of severity on leaves, whereas 'H9997', 'Cuyano', LB85, and 'NUN6011' presented higher severities. The differences in disease severity of the leaves were similar over the years, while incidence of symptoms in fruit was more variable. Next to 'Hawaii 7981', the cultivars 'Loica' and 'Ohio 8245' were identified as new sources of partial resistance to bacterial spot race T2.

Highlights

A mancha bacteriana do tomateiro é causada por quatro espécies de Xanthomonas, sendo Xanthomonas vesicatoria raça T2 a predominante no Uruguai
O objetivo do presente trabalho foi identificar fontes de resistência à mancha bacteriana foliar raça T2 do tomateiro para indústria
In Uruguay, race T2 (X. vesicatoria) is the most widespread according to field survey data, and X. gardneri is present (Montelongo, 2012)

Summary

Introduction

A mancha bacteriana do tomateiro é causada por quatro espécies de Xanthomonas, sendo Xanthomonas vesicatoria raça T2 a predominante no Uruguai. Incubation period, leaf severity, and fruit incidence were measured in the evaluation of tomato resistance to bacterial spot. The high mean incidence of bacterial spot on fruits (37% in 2010 and 22% in 2011) demonstrates the importance of the disease in Uruguay, and confirms the severe yield losses this disease can cause.

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