The sexual spore pigment asperthecin is required for normal ascospore production and protection from UV light in Aspergillus nidulans
| Authors: | Jonathan M. Palmer, Philipp Wiemann, Claudio Greco, Yi Ming Chiang, Clay Wang, Daniel Lindner, Nancy P. Keller |
| Year: | 2021 |
| Type: | Scientific Journal |
| Station: | Northern Research Station |
| DOI: | https://doi.org/10.1093/jimb/kuab055 |
| Source: | Journal of Industrial Microbiology and Biotechnology |
Abstract
Many fungi develop both asexual and sexual spores that serve as propagules for dissemination and/or recombination of genetic traits. Asexual spores are often heavily pigmented and this pigmentation provides protection from UV light. However, little is known about any purpose pigmentation that may serve for sexual spores. The model Ascomycete Aspergillus nidulans produces both green pigmented asexual spores (conidia) and red pigmented sexual spores (ascospores). Here we find that the previously characterized red pigment, asperthecin, is the A. nidulans ascospore pigment. The asperthecin biosynthetic gene cluster is composed of three genes: aptA, aptB, and aptC, where deletion of either aptA (encoding a polyketide synthase) or aptB (encoding a thioesterase) yields small, mishappen hyaline ascospores; while deletion of aptC (encoding a monooxygenase) yields morphologically normal but purple ascospores. ΔaptA and ΔaptB but not ΔaptC or wild type ascospores are extremely sensitive to UV light. We find that two historical ascospore color mutants, clA6 and clB1, possess mutations in aptA and aptB sequences, respectively.