Genetic diversity and population structure of Lasiodiplodia theobromae from different hosts in northeastern Brazil and Mexico

Abstract

Lasiodiplodia theobromae is one of the most frequent fungal pathogens associated with dieback, gummosis, leaf spot, stem‐end rot and fruit rot symptoms in cashew, mango, papaya and grapevine. In this study, the variation in the genetic diversity of 117 L. theobromae isolates from northeastern Brazil (n = 100) and Mexico (n = 17), which were collected from these four crops, was analysed using microsatellite markers. The results revealed low genetic diversity among L. theobromae populations and the existence of two genetic groups. All Mexican isolates were grouped with Brazilian isolates, suggesting a low level of differentiation between these populations. Furthermore, no evident host or climate‐based population differentiation was observed for L. theobromae in Brazil. The populations studied were mostly clonal, but additional studies are needed to better understand the mode of reproduction of the pathogen. The low genetic diversity of L. theobromae populations in northeastern Brazil suggests that resistant cultivars could be used as a durable management strategy to reduce the impact of the diseases caused by this pathogen.

Genetic variation, vegetative compatibility, and aggressiveness diversity of Diplodia bulgarica isolates from apple orchards in West Azarbaijan province of Iran

“…Among the geographic populations of D. bulgarica, UR had the highest gene and genotypic diversity as well as genotype richness, suggesting that this population may have been the initial founding population and served as a source for subsequent Linde, 2002;Milgroom, 1996). Therefore, high genotypic diversity in populations of supposedly asexual fungi has been considered as an indirect evidence for occurrence of recombination during parasexual or cryptic sexual cycles (Baskarathevan et al, 2012;Bihon et al, 2012aBihon et al, , 2012bRêgo et al, 2019). The high levels of genotypic diversity and richness observed in the present study as well as the low levels of CF, absence of widely distributed dominant genotype, and presence of reticulations in Neighbor-Net could suggest that D. bulgarica populations have not been under strict asexual reproduction and genetic recombination has occurred in the life cycle of the pathogen.…”

“…However, genetic diversity in a number of Botryosphaeriaceae species belonging to Botryosphaeria , Diplodia , Lasiodiplodia , and Neofusicoccum have been evaluated using various molecular markers such as amplified fragment length polymorphism (AFLP; Al‐Sadi et al, 2013), inter‐simple sequence repeat (ISSR; Elena et al, 2015; Qiu et al, 2015), simple sequence repeat (SSR) or microsatellite (Begoude Boyogueno et al, 2012; Bihon et al, 2011, 2012b; Rêgo et al, 2019), and universally primed polymerase chain reaction (UP‐PCR; Baskarathevan et al, 2012; Billones‐Baaijens et al, 2013). Most of the studies have revealed low genetic differentiation among populations collected from different woody plants or geographic regions (Al‐Sadi et al, 2013; Begoude Boyogueno et al, 2012; Elena et al, 2015; Rêgo et al, 2019), although significant genetic differentiation has also been reported in D. pinea (Bihon et al, 2012b) and D. seriata (Qiu et al, 2015) populations in South Africa and Australia, respectively. Despite homogeneity across regions, marker analyses have revealed distinct genetic clusters within populations of D. seriata (Elena et al, 2015) and L. theobromae (Rêgo et al, 2019).…”

“…Most of the studies have revealed low genetic differentiation among populations collected from different woody plants or geographic regions (Al‐Sadi et al, 2013; Begoude Boyogueno et al, 2012; Elena et al, 2015; Rêgo et al, 2019), although significant genetic differentiation has also been reported in D. pinea (Bihon et al, 2012b) and D. seriata (Qiu et al, 2015) populations in South Africa and Australia, respectively. Despite homogeneity across regions, marker analyses have revealed distinct genetic clusters within populations of D. seriata (Elena et al, 2015) and L. theobromae (Rêgo et al, 2019). The results also indicated that gene and genotypic diversity of the studied species differ considerably and vary from low (Rêgo et al, 2019) to high (Al‐Sadi et al, 2013; Baskarathevan et al, 2012; Begoude Boyogueno et al, 2012; Bihon et al, 2012a; Elena et al, 2015; Qiu et al, 2015).…”

“…Despite the importance of D. bulgarica, genetic diversity of this pathogen has never been studied as yet, and information on its biology is lacking. However, genetic diversity in a number of Botryosphaeriaceae species belonging to Botryosphaeria, Diplodia, Lasiodiplodia, and Neofusicoccum have been evaluated using various molecular markers such as amplified fragment length polymorphism (AFLP; Al-Sadi et al, 2013), inter-simple sequence repeat (ISSR; Elena et al, 2015;Qiu et al, 2015), simple sequence repeat (SSR) or microsatellite (Begoude Boyogueno et al, 2012;Bihon et al, 2011Bihon et al, , 2012bRêgo et al, 2019), and universally primed polymerase chain reaction (UP-PCR; Baskarathevan et al, 2012;Billones-Baaijens et al, 2013).…”

“…Due to the fact that the sexual stage in the majority of Diplodia species is unknown, they were believed to reproduce strictly asexually in the field (Bihon et al, 2011). However, the identification of a large number of genotypes with randomly associated alleles at marker loci provided indirect evidence for the occurrence of recombination events in the studied populations (Baskarathevan et al, 2012;Bihon et al, 2012aBihon et al, , 2012bRêgo et al, 2019). Furthermore, recent identification of mating type (MAT) idiomorphs in the genome of several Diplodia species (Lopes et al, 2018) and confirmation of hyphal fusion between isolates of D. pinea (Bihon et al, 2011) and D. seriata (Elena et al, 2015) provided additional support for possible occurrence of sexual or parasexual cycles, respectively, in the studied species.…”