Bihon, WubetuWingfield, Michael J.Slippers, BernardDuong, Tuan A.Wingfield, Brenda D.2014-09-232014-09-232014-01Bihon, W, Wingfield, MJ, Slippers, B, Duong, TA & Wingfield, BD 2014, 'MAT gene idiomorphs suggest a heterothallic sexual cycle in a predominantly asexual and important pine pathogen', Fungal Genetics and Biology, vol. 62, pp. 55-61.1087-1845 (print)1096-0937 (online)10.1016/j.fgb.2013.10.013http://hdl.handle.net/2263/42076Diplodia pinea (=Sphaeropsis sapinea) is a well-known and economically important latent pathogen of Pinus spp. in many parts of the world. Despite intensive scrutiny, its sexual state has never been observed and the fungus has thus been considered exclusively asexual. It was, therefore, surprising that a recent population genetics study showed high genotypic diversity and random association of alleles in a number of populations, suggesting that the pathogen has a cryptic sexual stage. Using the genome sequence of two individual D. pinea isolates, we interrogated the structure of the MAT locus in this fungus. The results suggested that D. pinea is heterothallic (self-sterile) with complete and apparently functional copies of the MAT genes containing the a-1 and HMG domains present in different isolates. In addition to the MAT1-2-1 and MAT1-1-1 genes, we found a MAT1-1-4 gene in the MAT1-1 idiomorph and a novel MAT1-2-5 gene in the MAT1-2 idiomorph. Importantly, the frequencies of occurrence of both idiomorphs in populations examined were not significantly different from a 1:1 ratio, which would be expected in sexually reproducing populations. Although the sexual state has never been observed, the results strongly suggest that D. pinea has a cryptic, heterothallic sexual cycle.en© 2013 Elsevier Inc. All rights reserved. Notice : this is the author’s version of a work that was accepted for publication in Fungal Genetics and Biology. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Fungal Genetics and Biology, vol. 62, pp. 55-61, 2014. doi : 10.1016/j.fgb.2013.10.013.Diplodia pineaEndophyteHeterothallicMating typeIdiomorphCryptic sexPostprint Article