Heterothallic mating observed between Mexican isolates of Glomerella lindemuthiana

Abstract

Although several reports have described the occurrence of the teleomorphic state of Glomerella lindemuthiana (anamorph, Colletotrichum lindemuthianum), there has been a lack of continuity in this research. To identify G. lindemuthiana isolates capable of developing the teleomorphic state, 19 Mexican isolates were analyzed. Three types of response were observed: (i) negative, where only mycelial growth with or without acervuli was observed; (ii) potential, where in addition to the above, spherical perithecia-like structures were observed; (iii) positive, where perithecia containing asci and ascospores were observed. All strains were self-sterile and only one combination of strains produced fertile perithecia. From this fertile combination 168 individual ascospore cultures were isolated, including five from a single ascus. Forty-four monoascospore cultures were characterized with AFLP, confirming that these individuals were progeny from a sexual cross between the original two G. lindemuthiana isolates and that sexual reproduction in G. lindemuthiana is heterothallic in nature. Analysis of the parental strains with degenerate PCR primers indicated that sequences homologous to the HMG box of the MAT1-2 idiomorph are present in both parental isolates. This supports previous observations in other Glomerella species where the standard ascomycete configuration of distinct idiomorphs at the MAT locus does not hold true. The significance of these results is discussed.

The Genomics of Colletotrichum

“…These experiments, performed by multiple laboratories, focused on detection of the highly conserved alpha DNA binding domain that characterizes the Mat1-1 idiomorph in other ascomycete fungi. None of these approaches provided any evidence for the presence of a Mat1-1 gene, even from homothallic strains of Colletotrichum (Crouch et al 2006;Du et al 2005, Rodríguez-Guerra et al 2005García-Serrano et al 2008). BLAST searches of the four Colletotrichum genome sequences confirmed the absence of any sequence with significant identity to the Mat1-1 gene.…”

“…Colletotrichum does not conform to this system. To date, only the Mat1-2 idiomorph, with the characteristic conserved high mobility group (HMG) binding domain, is known from any Colletotrichum species surveyed, regardless of whether the strains are heterothallic or homothallic (Crouch et al 2006;Du et al 2005, Rodríguez-Guerra et al (2005; García-Serrano et al (2008); Vaillancourt et al 2000b). However, genetic evidence does point to at least two unlinked loci acting as mating determinants in crosses involving C. graminicola strains M1.001 and M5.001 (Vaillancourt et al 2000a).…”

Symptoms and Prepenetration Events Associated with the Infection of Common Bean by the Anamorph and Teleomorph ofGlomerella cingulataf.sp.phaseoli

“…phaseoli . During the past 20 years, a number of genetic studies using morphological and molecular markers have demonstrated the formation of recombinant forms during the sexual phase (Batista and Chaves, 1982; Bryson, 1990; Mendes‐Costa, 1996; Rodriguez‐Guerra et al., 2005; Camargo et al., 2007; Luna‐Martinez et al., 2007), results which may explain the remarkable variability that has been observed amongst different populations of the fungus (Rodriguez‐Guerra et al., 2005; Camargo et al., 2007). The meiospore producing form of the ascomycete has been observed in field‐collected isolates maintained under laboratory conditions in the absence of artificial inducers (Camargo et al., 2007; Damasceno e Silva et al., 2007; Souza et al., 2007).…”

Mate Limitation in Fungal Plant Parasites Can Lead to Cyclic Epidemics in Perennial Host Populations

“…The Gibberella fujikuroi species complex counts at least eight different heterothallic species pathogenic on pine, maize, rice, banana in both temperate and tropical conditions, with massive socio-economic effects (Steenkamp et al, 2000;Nirenberg and O'Donnell, 1998). Colletotrichum lindemuthianum, responsible for black spot disease of common bean, is considered heterothallic as well as many strains in the Colletotrichum genus (Rodríguez-Guerra et al, 2005;Cannon et al, 2012). More generally, with the advent of genomes studies, more and more species once classified as asexual, are now recognized as having retained the machinery for sexual reproduction and in some cases as having operational heterothallism genes (Ene and Bennett, 2014).…”