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.

• AFLP
• Ascomycete
• Colletotrichum lindemuthianum
• HMG
• MAT1-2

We thank Luis Herrera-Estrella for critical reading of the manuscript, Dr James Kelly, Michigan State University, for the kind gift of G. lindemuthiana isolates MU 01, 02 and 03, Dr Rosmary Bryson for making her doctoral thesis available to us, CONACyT, Mexico, for financial support under grant number 28275SIM and CONACyT-SAGARPA for financial support under grant number K159-A9702.