Molecular, morphological and pathogenic diversity ofSclerotinia sclerotiorumisolates from common bean (Phaseolus vulgaris) fields in Argentina

Abstract

a Consejo Nacional de Investigaciones Cient ıficas y T ecnicas (CONICET) CCT-Salta, J.M. Leguizam on 366,White mould, caused by Sclerotinia sclerotiorum, is one of the most threatening fungal diseases occurring across major bean production regions worldwide. In Argentina, under favourable weather conditions, up to 100% seed yield losses occur on susceptible common bean cultivars. The aim of this study was to characterize the diversity of S. sclerotiorum isolates from six dry bean fields in the main production area of Argentina by means of molecular, morphological (mycelium colour, number and pattern of sclerotia distribution) and pathogenic approaches. Among 116 isolates analysed, high genotypic and morphological variability was observed. A total of 52 mycelial compatibility groups (MCGs) and 59 URPs (universal rice primers) molecular haplotypes were found. All the MCGs were location specific, while only 12% of the URP haplotypes were shared among locations. The molecular analysis of variance revealed a significant differentiation among populations, with higher genetic variability within the populations analysed than among them. The aggressiveness of the isolates towards bean seedlings was assessed in the greenhouse. Most of the isolates were highly aggressive, while no variation among locations was observed. The information generated in the present study provides, for the first time, information on the variability of S. sclerotiorum associated with white mould in the main common bean production area in Argentina. In addition, the findings suggest the occurrence of both clonal and sexual reproduction in the populations analysed. This work contributes to the development of sustainable management strategies in bean production aimed to minimize yield losses due to white mould.

Interannual dynamics, diversity and evolution of the virome in Sclerotinia sclerotiorum from a single crop field

“…However, beyond abiotic and host factors, we speculated that the virulence of the S. sclerotiorum population taken as a whole was also greatly affected by mycoviruses for the following reasons. First, the isolates of S. sclerotiorum collected from a single crop field showed significant virulence variation ( Attanayake et al 2013 ; Abán et al 2018 ), and a wide variety of mycoviruses have been discovered in S. sclerotiorum ( Jiang et al 2013 ; Marzano et al 2016 ; Mu et al 2017 ). Secondly, some mycoviruses could not only confer hypovirulence on S. sclerotiorum but also have the potential to convert S. sclerotiorum into an endophyte and enhance the resistance of rapeseed against the phytopathogens, for example Botrytis cinerea and S. sclerotiorum ( Zhang et al 2020 ).…”

Genetic structure of Sclerotinia sclerotiorum populations from sunflower and cabbage in West Azarbaijan province of Iran

“…Despite the clonality in the studied S. sclerotiorum populations, the frequencies of the most prevalent MLGs were not high, and the overall proportion of distinct MLGs was 0.62. Molecular marker studies of S. sclerotiorum populations have revealed MLG proportions of 0.12 for various crops in New York 36 , 0.29 for canola in northern Iran 27 , 0.45 for dry bean in the USA, France, Australia, and Mexico 37 , 0.51 for common bean in Argentina 21 , 0.58 for rapeseed in China 20 , 0.59 for various crops and meadow buttercup in the UK 16 , 0.59 for common bean in Brazil 18 and 0.61 for various crops in England, Wales, Scotland, Norway and Australia 17 . Furthermore, in the present study, proportions of MLGs ranged from 0.62 to 1 in geographic populations and were 0.70 and 0.63 in the samples collected from sunflower and cabbage, respectively.…”

“…A thorough understanding of the role of each determinant on genetic structure can assist in predicting the potential risk of a fungal pathogen and improving control strategies 6 . Genetic structure of S. sclerotiorum from different hosts and geographic regions has been studied using mycelial compatibility group (MCG) 7 – 10 and various molecular markers such as inter-simple sequence repeat (ISSR) 11 , random amplified polymorphic DNA (RAPD) 12 , restriction fragment length polymorphism (RFLP) 7 – 10 , sequence-related amplified polymorphism (SRAP) technique 13 , simple sequence repeat (SSR) 14 – 20 , and universal rice primers (URP) 21 . Results of several population genetic analyses have been consistent with homothallic mating and sclerotia production of S. sclerotiorum and found a clonal genetic structure with low genotypic diversity, linkage disequilibrium at marker loci, and dominance of one or a few multilocus genotypes (MLGs) over time and space 8 – 10 , 22 , 23 .…”

“…Results of several population genetic analyses have been consistent with homothallic mating and sclerotia production of S. sclerotiorum and found a clonal genetic structure with low genotypic diversity, linkage disequilibrium at marker loci, and dominance of one or a few multilocus genotypes (MLGs) over time and space 8 – 10 , 22 , 23 . However, a number of studies have found high genotypic diversity within populations and random association of marker alleles and concluded that recombination (outcrossing) infrequently occurs in the life cycle of S. sclerotiorum and contributes to the population structure of the pathogen in the studied regions 14 – 17 , 21 , 24 – 28 .…”

Characterization of fungal pathogens and germplasm screening for disease resistance in the main production area of the common bean in Argentina

“…Some of the major economic crops affected include dry bean, potato, soybean [ Glycine max (L.) Merr. ], sunflower ( Helianthus annuus L.), canola ( Brassica napus L.), lettuce ( Lactuca sativa L.), carrot ( Daucus carota L.), and pea ( Pisum sativum L.) ( Carpenter et al, 1999 ; Mert-Türk et al, 2007 ; Hemmati et al, 2009 ; Attanayake et al, 2013 ; Lehner et al, 2015 ; Abán et al, 2018 ; Panullo et al, 2018 ). In Argentina, WM has been detected in all bean production areas, reaching seed yield and quality losses up to 80–100% on susceptible common bean cultivars under favorable weather conditions ( Singh and Schwartz, 2010 ).…”