Genetic structure and demographic history of Colletotrichum gloeosporioides sensu lato and C. truncatum isolates from Trinidad and Mexico

Abstract

BackgroundC. gloeosporioides sensu lato is one of the most economically important post-harvest diseases affecting papaya production worldwide. There is currently no information concerning the genetic structure or demographic history of this pathogen in any of the affected countries. Knowledge of molecular demographic parameters for different populations will improve our understanding of the biogeographic history as well as the evolutionary and adaptive potential of these pathogens. In this study, sequence data for ACT, GPDH, β-TUB and ITS gene regions were analyzed for C. gloeosporioides sensu lato and C. truncatum isolates infecting papaya in Trinidad and Mexico in order to determine the genetic structure and demographic history of these populations.ResultsThe data indicated that Mexico is the ancestral C. gloeosporioides sensu lato population with asymmetrical migration to Trinidad. Mexico also had the larger effective population size but, both Mexico and Trinidad populations exhibited population expansion. Mexico also had greater nucleotide diversity and high levels of diversity for each gene. There was significant sub-division of the Trinidad and Mexico populations and low levels of genetic divergence among populations for three of the four gene regions; β-TUB was shown to be under positive selection. There were also dissimilar haplotype characteristics for both populations. Mutation may play a role in shaping the population structure of C. gloeosporioides sensu lato isolates from Trinidad and from Mexico, especially with respect to the ACT and GPDH gene regions. There was no evidence of gene flow between the C. truncatum populations and it is possible that the Mexico and Trinidad populations emerged independently of each other.ConclusionsThe study revealed relevant information based on the genetic structure as well as the demographic history of two fungal pathogens infecting papaya, C. gloeosporioides sensu lato and C. truncatum, in Trinidad and Mexico. Understanding the genetic structure of pathogen populations will assist in determining the evolutionary potential of the pathogen and in identifying which evolutionary forces may have the greatest impact on durability of resistance. Intervention strategies that target these evolutionary forces would prove to be the most practical.

Characterization of Colletotrichum truncatum from papaya, pepper and physic nut based on phylogeny, morphology and pathogenicity

“…In agreement with this, in a previous work conducted by Rampersad et al . (), the genetic structure of C. gloeosporioides and C. truncatum was analysed using sequence data for ACT , GAPDH , β ‐TUB and ITS gene regions. The results indicated that, among the four sequences analysed, GAPDH exhibited the highest percentages of molecular variance within populations (95%) for C. truncatum .…”

“…Recently, molecular methods have been used conjointly with morphological studies. Of these, comparison of multiple nucleotide sequences, such as the nuclear rDNA internal transcribed spacer (ITS) region, β‐tubulin ( TUB2 ), actin ( ACT ), glutamine synthetase ( GS ) and glyceraldehyde 3‐phosphate dehydrogenase ( GAPDH ), have provided substantial information regarding the phylogenetic relationship among individuals and the genetic structure of the population (Rampersad et al ., ). Previous reports have suggested the usefulness of a polyphasic approach to determine the greatest variability among closely related Colletotrichum species (Cai et al ., ) and even among individuals of the same species (Katoch et al ., ).…”

Utility of internally transcribed spacer region of rDNA (ITS) and β‐tubulin gene sequences to infer genetic diversity and migration patterns of Colletotrichum truncatum infecting Capsicum spp.

“…Long‐term, stable control of disease depends on thoughtful integration of these epidemiological and population genetic factors (Milgroom ).The findings of this study should lead to a more thorough understanding of natural constraints on pathogen populations and how these can be exploited to develop novel and perhaps shared control strategies (Rampersad et al. ).…”

Metageographic population analysis of Colletotrichum truncatum associated with chili fruit rot and other hosts using ITS region nucleotide sequences

“…Information on variation in the species at wide geographical level is a prerequisite for the development of disease management strategies i.e. identification of resistance sources, pesticide use, predicting resistance breakdown, development and deployment of disease resistant varieties and in streamlining cultural practices (McDonald and Linde 2002;Rampersad et al 2013). Presently, metageographic population study of Colletotrichum and related pathogen in the literature is scanty.…”

“…Knowledge of population genetic structure, levels of intra species divergence, gene flow among wide geographic populations of the species help in the understanding of biogeographic history, evolutionary and adaptive potential of the pathogenic species (McDermott and McDonald 1993;McDonald 1997;Rampersad et al 2013). Information on variation in the species at wide geographical level is a prerequisite for the development of disease management strategies i.e.…”