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. ∆aptA and ∆aptB but not ∆aptC 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.

中文翻译：

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构巢曲霉的正常子囊孢子产生和紫外线防护需要有性孢子色素曲黄素

许多真菌同时产生无性和有性孢子，作为传播和/或重组遗传性状的繁殖体。无性孢子通常色素沉着，这种色素沉着可以防止紫外线照射。然而，对于可能用于性孢子的任何目的色素沉着知之甚少。子囊菌构巢曲霉模型产生绿色无性孢子（分生孢子）和红色有性孢子（子囊孢子）。在这里，我们发现先前表征的红色素 asperthecin 是构巢曲霉的子囊孢子色素。asperthecin 生物合成基因簇由三个基因组成：aptA、aptB 和 aptC，其中 aptA（编码聚酮合酶）或 aptB（编码硫酯酶）的缺失会产生小的、畸形的透明子囊孢子；而 aptC 的缺失（编码单加氧酶）会产生形态正常但紫色的子囊孢子。ΔaptA 和 ΔaptB 但不是 ΔaptC 或野生型子囊孢子对紫外线极为敏感。我们发现两个历史上的子囊孢子颜色突变体 clA6 和 clB1 分别具有 aptA 和 aptB 序列的突变。