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.

Analysis of the MAT1-2-1 gene of Colletotrichum lindemuthianum

“…Sacc.) and more recent reports on different species within the genus Glomerella (Cisar et al 1996;Cisar and TeBeest 1999;Vaillancourt and Hanau 1999;Vaillancourt et al 2000;Rodríguez-Guerra et al 2005) suggest that control of sexual reproduction within this genus is different from that described for other fi lamentous ascomycetes.…”

“…Amplifi cation of the conserved HMG region of the MAT1-2-1 gene in C. lindemuthianum isolates MU 03 and DGO 02 revealed that the MAT1-2-1 idiomorph was present in both partners of the mating pair (Rodríguez-Guerra et al 2005). To extend this result, isolates of Colletotrichum from different plant species were analyzed using degenerate primers, and the MAT1-2-1 gene was found to be present in all isolates tested (Fig.…”

“…These strains are no longer capable of completing the sexual cycle by themselves, but on contact with another strain carrying a different mutation, complementation may occur and sexual reproduction achieved (Wheeler 1954). More recent molecular data on the MAT1 locus in Glomerella have shown that in contrast to other fi lamentous ascomycetes, both members of a mating pair carry the MAT1-2 idiomorph (Vaillancourt et al 2000;Rodríguez-Guerra et al 2005). This situation could arise under the model of Wheeler if different mutations either in the MAT1-2 idiomorph or in other genes involved in the mating process occurred in each mating partner and were complemented Received: December 4, 2007/ Accepted: May 6, 2008 Abstract A single MAT1-2-1 gene was identifi ed from a mating pair of the fi lamentous ascomycete Colletotrichum lindemuthianum.…”

“…A 780-bp fragment obtained by polymerase chain reaction (PCR) using oligonucleotides C3 and C5 (see Table 1) was used as a probe. Amplifi cation of the MAT1-2-1 HMG domain from C. lindemuthianum using specifi c primers (HMGCLF/HMGCLR; Table 1) was carried out under the same conditions (Rodríguez-Guerra et al 2005). The thermal asymmetrical interlaced (TAIL)-polymerase chain reaction (PCR) technique (Liu and Whittier 1995) was used to characterize the MAT1-2-1 gene sequences fl anking the conserved MAT1-2-1 HMG domain from both MU 03 and DGO 02 strains.…”

“…DNA was obtained by the method of Raeder and Broda (1985) as described by González et al (1998). The degenerate primers for amplifi cation of the MAT1-2 HMG domain reported by Arie et al (1997) (HMGDF and HMGDR; Table 1) were used to amplify the MAT1-2-1 HMG domain from the parental MU 03 and DGO 02 strains and from other Colletotrichum isolates obtained from different plant species, as described in Rodríguez-Guerra et al (2005). Amplifi cation products were separated on a 2% agarose gel and visualized by staining with ethidium bromide.…”