Abstract
The availability of cloned genes that control sexual reproduction (mating type genes) in higher fungi has allowed us to consider the causes of failure to mate in asexual fungi. We report here that the asexual fungusBipolaris sacchari has a homolog of theMAT-2 gene of its sexual ascomycete relativeCochliobolus heterostrophus. TheB. sacchari MAT-2 sequence is highly similar to that ofC. heterostrophus MAT-2 and, in fact, functions in transgenicC. heterostrophus. Thus, the asexual nature ofB. sacchari is not due to absence or mutation ofMAT. When either of theC. heterostrophus MAT genes was transformed intoB. sacchari, the recipient could neither self nor cross with otherB. sacchari strains, in contrast to transgenicC. heterostrophus strains which can do both. Persistent asexuality ofB. sacchari, in spite of the presence of complementary functionalMAT genes, suggests that this fungus lacks genes other thanMAT which are essential for mating. Notably, the transgenicB. sacchari strains were sometimes able to initiate, but not complete, sexual development in interspecific pairings withC. heterostrophus. Transcript analysis showed that theB. sacchari MAT-2 gene is expressed in transgenicC. heterostrophus and that theC. heterostrophus MAT genes are expressed in transgenicB. sacchari. No transcript of the nativeB. sacchari MAT-2 gene was detected under any growth condition tested.
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Communicated by C. A. M. J. J. van den Hondel
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Sharon, A., Yamaguchi, K., Christiansen, S. et al. An asexual fungus has the potential for sexual development. Molec. Gen. Genet. 251, 60–68 (1996). https://doi.org/10.1007/BF02174345
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DOI: https://doi.org/10.1007/BF02174345