Supergene evolution via stepwise duplications and neofunctionalization of a floral-organ identity gene

作者：Cuong Nguyen Huu, B. Keller, E. Conti, C. Kappel, Michael Lenhard · 发表于：Proceedings of the National Academy of Sciences of the United States of America · 年份：2020 · DOI：10.1073/pnas.2006296117 · 被引用次数：69 · 研究领域：Biology、Medicine

Significance Heterostyly is an adaptation to promote outbreeding in plants. In heterostylous primroses, plants form flowers either with long styles and low anthers or with short styles and high anthers. This difference is due to a chromosomal segment containing five predicted genes, yet their roles and the evolution of this segment remain unclear. Here we identify the gene responsible for raising the anthers in short-styled flowers. This gene arose by duplication from a classical floral-organ identity gene and gained a novel function. Surprisingly, the responsible chromosomal segment appears to have evolved by stepwise gene duplications rather than duplication of an entire chromosomal block. These findings thus provide detailed insight into the evolution of complex polymorphisms involving different individual traits. Heterostyly represents a fascinating adaptation to promote outbreeding in plants that evolved multiple times independently. While l-morph individuals form flowers with long styles, short anthers, and small pollen grains, S-morph individuals have flowers with short styles, long anthers, and large pollen grains. The difference between the morphs is controlled by an S-locus “supergene” consisting of several distinct genes that determine different traits of the syndrome and are held together, because recombination between them is suppressed. In Primula, the S locus is a roughly 300-kb hemizygous region containing five predicted genes. However, with one exception, the...