Population structure of Monosporascus cannonballus isolated from melons produced in Northeastern Brazil based on mycelial compatibility groups

Abstract

ABSTRACT. The population structure of Monosporascus cannonballus, which causes vine decline in melons, was assessed based on the determination of mycelial compatibility groups (MCGs) in a collection of 58 isolates obtained from seven melon fields in three municipalities of Northeastern Brazil. For comparison, an additional 11 isolates of M. cannonballus from Spain were included in the analysis. MCGs were determined through comparisons of paired isolates growing on PDA culture media in the dark at 30ºC in various combinations. The Brazilian isolates were assigned into four MCGs: MCG-1 (n = 35 isolates), MCG-2 (n = 20), MCG-3 (n = 2), and MGC-4 (n = 1). MCG-1 and MCG-2 included isolates from all surveyed areas. The Spanish isolates were assigned into six different MCGs, and none of them were compatible with the Brazilian isolates. The genetic structure was determined using the frequencies of MCGs and genotypic diversity indices. The maximum genotypic diversity was 6.9 and 54.5% for the Brazilian and Spanish populations, respectively. The low level of genetic diversity in the M. cannonballus population from Northeastern Brazil suggests that breeding melons for disease resistance may be a promising strategy for the region.Keywords: Cucumis melo, melon, vine decline, soilborne pathogen, genetic diversity.Estrutura populacional de Monosporascus cannonballus isolados de melão produzido no Nordeste brasileiro com base em grupos de compatibilidade micelial RESUMO. A estrutura populacional de Monosporascus cannonballus, que causa o declínio das ramas do meloeiro, foi avaliada com base em grupos de compatibilidade micelial (MCGs) determinados numa coleção de 58 isolados obtidos de sete áreas de cultivo de meloeiro em três municípios do Nordeste brasileiro. Adicionalmente, 11 isolados de M. cannonballus da Espanha foram incluídos para comparação. Os MCGs foram determinados pelo pareamento das culturas em todas as combinações possíveis em meio BDA no escuro a 30ºC. Os isolados brasileiros foram distribuídos em quatro MCGs: MCG-1 com 35 isolados, MCG-2 com 20 isolados, MCG-3 com dois isolados e MCG-4 com um isolado. Os MCG-1 e MCG-2 incluíram isolados brasileiros de todas as áreas de meloeiro. Os isolados espanhóis foram distribuídos em seis diferentes MCGs e nenhum destes foi compatível com os isolados brasileiros. A estrutura genética foi estimada com base na frequência de MCGs e em índices de diversidade genotípica. A porcentagem máxima de diversidade genotípica da população brasileira foi de 6,9% comparada com 54,5% da população espanhola. A pequena diversidade genética na população de M. cannonballus no Nordeste brasileiro indica que um programa de melhoramento de cultivares resistentes tem grande chance de sucesso no controle da doença na região.Palavras-chave: Cucumis melo, melão, declínio das ramas, patógeno habitante do solo, diversidade genética.

Cotton, cowpea and sesame are alternative crops to cucurbits in soils naturally infested with Monosporascus cannonballus

“…In a similar study, Bezerra et al. () assigned 58 isolates obtained from seven melon fields in three municipalities of north‐eastern Brazil into four MCGs. Subsequently, Correia et al.…”

“…(Aleandri et al., ; de Cara et al., ; Stanghellini & Misaghi, ; Stanghellini, Mohammadi, & Adaskaveg, ) Pythium spinosum Swada and Rhizoctonia solani Kühn (Al‐Sadi et al., ) and Plectosphaerella melonis (Watan & Sato) Phillips, Carlucci & Raimondo (Armengol et al., ; Bruton, Davis, & Gordon, ). In Brazil, this syndrome is considered an important limiting factor for cucurbit cultivation (Bezerra et al., ).…”

“…melonis (Watan & Sato) Phillips, Carlucci & Raimondo (Armengol et al, 1998;Bruton, Davis, & Gordon, 1995). In Brazil, this syndrome is considered an important limiting factor for cucurbit cultivation (Bezerra et al, 2013).…”

Fitness components of Monosporascus cannonballus isolates from northeastern Brazilian melon fields

“…In recent years, the expansion of the cultivated area, coupled with intensive and continuous cultivation of melon without crop rotation, has contributed to the increased incidence of fungal diseases affecting the root system. Monosporascus root rot and vine decline (MRRVD) caused by the soilborne ascomycete Monosporascus cannonballus Pollack & Uecker is one of the most important melon yield-limiting diseases in the Brazilian northeast (Silva et al, 2010;Bezerra et al, 2013), as in other melon-production regions located in hot semi-arid to arid regions, as well as subtropical environments worldwide (Martyn & Miller, 1996;Cohen et al, 2000;Cohen et al, 2012;Ben Salem et al, 2013).…”