Patterns of Diversity in Populations of the Turfgrass Pathogen Colletotrichum cereale as Revealed by Transposon Fingerprint Profiles

Abstract

Anthracnose disease of cool‐season turfgrasses, caused by the fungus Colletotrichum cereale, has recently emerged as one of the most significant pathogens of Poa annua Here we investigated the utility of four repetitive transposable elements as molecular markers for the analysis of C. cereale populations. Southern blot hybridization analysis revealed lineage‐specific polymorphisms and distribution patterns for these transposons. Comparative phylogenetic analysis of three nonrepetitive protein coding DNA sequences against the transposon restriction fragment length polymorphisms indicated that the transposon sequences have similar evolutionary histories to those found in the sampled C. cereale population, despite the alteration of several transposon copies by repeat‐induced point mutation. The variability and ubiquity of the Ccret2A15 transposon in C. cereale genomes suggest that this element could be used as a reliable DNA marker to discriminate between lineages of the fungus, identify hybrid genotypes, and analyze genetic diversity in populations of this turfgrass pathogen.

Influence of Host and Geographic Locale on the Distribution of Colletotrichum cereale Lineages

“…The sexual cycle for C. cereale has never been documented [3], yet gene flow is known to have occurred between clades A and B, and between several populations of this species [2], [6]–[8]. Several other Colletotrichum species ( e.g.…”

“…Both clades are responsible for anthracnose disease in turfgrass, and have also been associated with Pooid grasses as endophytes [2] . Despite substantial evidence for lineage diversification, significant levels of gene flow link clades A and B, indicating that they are of a single species [6] – [8] . Clade A is subdivided into ten subpopulations, each corresponding with a single host ( P. annua or A. stolonifera ) or ecosystem (turfgrass, cereal crops, or prairie) [2] .…”

“…While the subdivision of clade A into subpopulations appears to be driven by host specialization, the factors shaping the earlier diversification of C. cereale into clade A and clade B are unknown. Clade A has traditionally been found in higher numbers and encompassing a larger geographic area than clade B isolates [2] , [6] , [8] . However, this pattern may reflect a bias in sampling rather than structure of natural populations.…”

Development of new molecular markers for the Colletotrichum genus using RetroCl1 sequences

“…Currently, different transposon-based DNA fingerprinting techniques have been used for analysis genetic diversity, such as: S-SAP (Sequence-Specific Amplified Polymorphism) (Waugh et al 1997), RBIP (Retrotransposon-Based Insertion Polimorphism;Flavell et al 1998), IRAP (Inter-Retrotransposon Amplified Polymorphism; Kalendar et al 1999), REMAP (REtrotransposon-Microsatellite Amplified Polymorphism; Kalendar et al 1999), IMP (Inter-MITE Polymorphism; Chang et al 2001), and RFLP (Crouch et al 2008a). In fungi, among these techniques, IRAP and REMAP are the most used.…”

“…The CgT1 (He et al 1996) and Cgret (Zhu and Oudemans 2000) elements can be used for the study of population structure, genome dynamics and evolution in Colletotrichum gloeosporioides. The Ccret2A15 transposon of Colletotrichum cereale could be used in the discrimination of strains, hybrid identification and genotypes, to analyze genetic diversity in population and may even be used to study populations of the economically important plant pathogens Colletotrichum sublineolum and Colletotrichum falcatum (Crouch et al 2008a). Three other transposons (Collect1 I29 , Ccret1 DBP6 and Ccret2 DBP16 ) were described in C. cereale, but these elements showed high level of RIP mutations (Crouch et al 2008a, b).…”