Fitness components of Monosporascus cannonballus isolates from northeastern Brazilian melon fields

Abstract

Monosporascus root rot and vine decline caused by Monosporascus cannonballus is one of the most important melon yieldlimiting diseases in northeastern Brazil. This study investigated the fitness components of 57 isolates of M. cannonballus obtained from Brazilian melon fields by evaluating: i) their mycelial growth rate (MGR), and perithecia and ascospore production (PP and AP) on potato dextrose agar (PDA); ii) their sensitivity to the fungicide fluazinam; and iii) their virulence to melon seedlings. All M. cannonballus isolates showed variability in their MGR, PP and AP values. They were sensitive to the fungicide fluazinam, showing some degree of mycelial growth inhibition (MGI), and were pathogenic to melon seedlings, with a mean disease severity index (DSI) of 62.1%. By univariate analysis, the formation of groups of similarity amongst the isolates of M. cannonballus within each variable was not limited by the area of origin of each isolate, given that in most situations, different isolates of the same area were distributed into distinct groups of similarity. A multivariate cluster analysis allowed the separation of the 57 M. cannonballus isolates in 18 groups of similarity. The fitness variability among M. cannonballus isolates found in this study should be considered when possible sources of resistance are evaluated in melon breeding programs.

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

“…Subsequently, Correia et al. () investigated the fitness components of 57 isolates of M. cannonballus obtained from Brazilian melon fields by evaluating their mycelial growth rate, perithecia and ascospore production, sensitivity to the fungicide fluazinam and virulence to melon seedlings. A multivariate cluster analysis allowed the separation of these isolates in 18 groups of similarity.…”

“…The differences in pathogenicity exhibited by the two M. cannonballus isolates on cucurbit species may be due to genetic variability, a factor that can configure specific and differentiated degrees of virulence. According to Bruton (1998) Correia et al (2014) investigated the fitness components of 57 isolates of M. cannonballus obtained from Brazilian melon fields by evaluating their mycelial growth rate, perithecia and ascospore production, sensitivity to the fungicide fluazinam and virulence to melon seedlings. A multivariate cluster analysis allowed the separation of these isolates in 18 groups of similarity.…”

Characterization of Five New Monosporascus Species: Adaptation to Environmental Factors, Pathogenicity to Cucurbits and Sensitivity to Fungicides

“…There is some knowledge about the adaptability of M . cannonballus populations to different environmental factors such as temperature, hydrogen potential (pH) and salinity [ 1 , 3 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 ]. In fungi, these factors profoundly affect their growth rate but also can act as triggers in development pathways [ 27 ].…”

“…of fluazinam were also effective in inhibiting the in vitro mycelial growth of 57 Brazilian isolates of M . cannonballus [ 25 ]. Azoxystrobin, prochloraz, and pyraclostrobin + boscalid exhibited high and similar efficacies in the control of M. cannonballus in field experiments, but fludioxonil was less effective than azoxystrobin and, in certain cases, showed some phytotoxicity to melon plants [ 31 ].…”

Adaptabilidade de isolados de Monilinia fructicola com diferentes níveis de sensibilidade à azoxistrobina

“…(STAMMLER et al, 2013;HINCAPIE et al, 2014 (LIBERATO, 1995). Essa técnica multivariada é amplamente utilizada na área de melhoramento vegetal (CORREIA et al, 2014;SILVA et al, 2014;VIVAS et al, 2015), enquanto que na área de resistência de fungos a fungicidas ainda são raros os trabalhos (POMERANTZ et al, 2014) , 2005;FERNANDEZ-ORTUÑO et al, 2008). Apesar da via AOX produzir pouca energia, ela auxilia o fungo a continuar se desenvolvendo dentro do hospedeiro (AVILA-ADAME; KOLLER, 2002KOLLER, , 2003b ), germinação (%), diâmetro no meio com fungicida (cm) e taxa de crescimento micelial (cm.dia -1 ) no meio sem fungicida dos isolados resistentes (SP08345 e SP09839) e sensível (PR09839) de Monilinia fructicola nas respectivas transferências que foi realizada a avaliação de cada variável Médias seguidas pela mesma letra maiúscula na linha e pela mesma letra minúscula na coluna não diferem entre si pelo teste de Tukey, ao nível de 5 % de probabilidade.…”