Phylogeography and population structure analysis reveals diversity by mutations in Lasiodiplodia theobromae with distinct sources of selection

Abstract

ABSTRACT. Lasiodiplodia theobromae is a plant pathogen with a worldwide distribution, with low host specificity, causing stem cankers, dieback diseases, and fruit rot in several species of plants. In coconut, this pathogen is reported as the etiological agent of "coconut leaf blight" (CLB) disease, causing several losses in fruit production. The CLB is an important disease for this crop in Brazil. In our study, we used a phylogeographic approach through the molecular characterization of the translation elongation factor 1-α (TEF1-α) to elucidate the pathogen distribution in Brazil and other countries, besides, search information about diversity sources of this pathogen in coconut palm tree at Brazilian northern, northeast, and southeast. We found that L. theobromae diversity is within populations (locations), and populations that are located closest to the center of the tropical zone have more variability as Central Africa, Brazilian Southeast, and Northeast. The widespread distribution could be in part related with long-distance dispersal via global trade of plants and plant products. The entrance route of L. theobromae in Brazil probably occurred from Africa route and not occurred once. In Brazil, the diversity of this pathogen in coconut tree could be linked to two agents of selection: high host diversity (in Northeast) and distinct management measures adopted in Southeast. These different sources of selection, mainly the mutations, could be one of the reasons that we found distinct reactions to "coconut leaf blight" chemical control in these regions.

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

“…The lack of diversity found in this study emphasizes the low genetic diversity of the pathogen in northeastern Brazil. This is in contrast with results from population genetics of L. theobromae from coconut trees in Brazil and other countries based on EF1‐α sequence analysis (Santos et al ., ). In that study, relatively high levels of genetic diversity were observed in populations from northeastern and southeastern Brazil.…”

“…In that study, relatively high levels of genetic diversity were observed in populations from northeastern and southeastern Brazil. However, according to those authors, the variability of L. theobromae haplotypes could be associated with selection pressures experienced by the pathogen due to high host diversity and control management strategies adopted by different regions in Brazil (Santos et al, 2017).…”

“…However, there are still few studies involving the population genetics of this pantropical pathogen (Burgess et al, 2003;Shah et al, 2011;Begoude et al, 2012;Mehl et al, 2017). Although recent research has studied the identity, distribution and pathogenicity of L. theobromae in Brazil (Netto et al, 2014;Correia et al, 2016;Coutinho et al, 2017), currently there is only a single study about the genetic diversity and structure of this pathogen isolated from coconut tree populations at a regional level, and compared with other countries (Santos et al, 2017).…”

Phylogeographic distribution of Asperisporium caricae isolates in brazilian southeastern and northeastern coastal regions

“…Interactions between plant genotypes and fungal isolates throughout the evolution of living beings can bring harm to the host. It is possible setting effective disease control strategies when the variations between different pathogen isolates are known (SANTOS et al, 2017b). A practical example of it can be seen when fungi with pathogenic potential keep their ancestral ability to explore other hosts as endophytes.…”

“…Phylogeographic studies about fungi, although scarce, may contribute to the knowledge about the pathogen diversity and help understanding the geographical distribution of genealogical lineages, mainly of the ones within and among closely-related species (AVISE, 2000;SANTOS et al, 2017b). The literature still lacks studies relating the geographic and phylogenetic distribution of the fungal species A. caricae.…”