@article{HuuKellerContietal.2020,
  author    = {Huu, Cuong Nguyen and Keller, Barbara and Conti, Elena and Kappel, Christian and Lenhard, Michael},
  title     = {Supergene evolution via stepwise duplications and neofunctionalization of a floral-organ identity gene},
  series = {Proceedings of the National Academy of Sciences of the United States of America (PNAS)},
  volume    = {117},
  journal   = {Proceedings of the National Academy of Sciences of the United States of America (PNAS)},
  number    = {37},
  publisher = {National Academy of Sciences},
  address   = {Washington},
  issn      = {0027-8424},
  doi       = {10.1073/pnas.2006296117},
  pages     = {23148 -- 23157},
  year      = {2020},
  abstract  = {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, their roles remain unclear, as does the evolutionary buildup of the S locus. Here we demonstrate that the MADS-box GLOBOSA2 (GLO2) gene at the S locus determines anther position. In Primula forbesii S-morph plants, GLO2 promotes growth by cell expansion in the fused tube of petals and stamen filaments beneath the anther insertion point; by contrast, neither pollen size nor male incompatibility is affected by GLO2 activity. The paralogue GLO1, from which GLO2 arose by duplication, has maintained the ancestral B-class function in specifying petal and stamen identity, indicating that GLO2 underwent neofunctionalization, likely at the level of the encoded protein. Genetic mapping and phylogenetic analysis indicate that the duplications giving rise to the style-length-determining gene CYP734A50 and to GLO2 occurred sequentially, with the CYP734A50 duplication likely the first. Together these results provide the most detailed insight into the assembly of a plant supergene yet and have important implications for the evolution of heterostyly.},
  language  = {en}
}
@misc{KappelCuongNguyenHuuLenhard2017,
  author    = {Kappel, Christian and Cuong Nguyen Huu, and Lenhard, Michael},
  title     = {A short story gets longer: recent insights into the molecular basis of heterostyly},
  series = {Journal of experimental botany},
  volume    = {68},
  journal   = {Journal of experimental botany},
  publisher = {Oxford Univ. Press},
  address   = {Oxford},
  issn      = {0022-0957},
  doi       = {10.1093/jxb/erx387},
  pages     = {5719 -- 5730},
  year      = {2017},
  abstract  = {Heterostyly is a fascinating adaptation to promote outbreeding and a classical paradigm of botany. In the most common type of heterostyly, plants either form flowers with long styles and short stamens, or short styles and long stamens. This reciprocal organ positioning reduces pollen wastage and promotes cross-pollination, thus increasing male fitness. In addition, in many heterostylous species selfing and the generation of unfit progeny due to inbreeding depression is limited by a self-incompatibility system, thus promoting female fitness. The two floral forms are genetically determined by the S locus as a complex supergene, namely a chromosomal region containing several individual genes that control the different traits, such as style or stamen length, and are held together by very tight linkage due to suppressed recombination. Recent molecular-genetic studies in several systems, including Turnera, Fagopyrum, Linum, and Primula have begun to identify and characterize the causal heterostyly genes residing at the S locus. An emerging theme from several families is that the dominant S haplotype represents a hemizygous region not present on the recessive s haplotype. This provides an explanation for the suppressed recombination and suggests a scenario for the chromosomal evolution of the S locus. In this review, we discuss the results from recent molecular-genetic analyses in light of the classical models on the genetics and evolution of heterostyly.},
  language  = {en}
}