@misc{HuuPlaschilHimmelbachetal.2022,
  author    = {Huu, Cuong Nguyen and Plaschil, Sylvia and Himmelbach, Axel and Kappel, Christian and Lenhard, Michael},
  title     = {Female self-incompatibility type in heterostylous Primula is determined by the brassinosteroid-inactivating cytochrome P450 CYP734A50},
  series = {Current biology},
  volume    = {32},
  journal   = {Current biology},
  number    = {3},
  publisher = {Cell Press},
  address   = {Cambridge, Mass.},
  issn      = {0960-9822},
  doi       = {10.1016/j.cub.2021.11.046},
  pages     = {671 -- 676, E1-E5},
  year      = {2022},
  abstract  = {Most flowering plants are hermaphrodites, with flowers having both male and female reproductive organs. One widespread adaptation to limit self-fertilization is self-incompatibility (SI), where self-pollen fails to fertilize ovules.(1,2) In homomorphic SI, many morphologically indistinguishable mating types are found, although in heteromorphic SI, the two or three mating types are associated with different floral morphologies.(3-6) In heterostylous Primula, a hemizygous supergene determines a short-styled S-morph and a long-styled L-morph, corresponding to two different mating types, and full seed set only results from inter morph crosses.(7-9) Style length is controlled by the brassinosteroid (BR)-inactivating cytochrome P450 CYP734A50,(10) yet it remains unclear what defines the male and female incompatibility types. Here, we show that CYP734A50 also determines the female incompatibility type. Inactivating CYP734A50 converts short S-morph styles into long styles with the same incompatibility behavior as L-morph styles, and this effect can be mimicked by exogenous BR treatment. In vitro responses of S-and L-morph pollen grains and pollen tubes to increasing BR levels could only partly explain their different in vivo behavior, suggesting both direct and indirect effects of the different BR levels in S-versus L-morph stigmas and styles in controlling pollen performance. This BR-mediated SI provides a novel mechanism for preventing self-fertilization. The joint control of morphology and SI by CYP734A50 has important implications for the evolutionary buildup of the heterostylous syndrome and provides a straightforward explanation for why essentially all of the derived self-compatible homostylous Primula species are long homostyles.(11)},
  subject      = {heteromorphic self-incompatibility},
  language  = {en}
}
@article{KappelIllingHuuetal.2020,
  author    = {Kappel, Christian and Illing, Nicola and Huu, Cuong Nguyen and Barger, Nichole N. and Cramer, Michael D. and Lenhard, Michael and Midgley, Jeremy J.},
  title     = {Fairy circles in Namibia are assembled from genetically distinct grasses},
  series = {Communications biology},
  volume    = {3},
  journal   = {Communications biology},
  number    = {1},
  publisher = {Springer Nature},
  address   = {London},
  issn      = {2399-3642},
  doi       = {10.1038/s42003-020-01431-0},
  pages     = {8},
  year      = {2020},
  abstract  = {Fairy circles are striking regularly sized and spaced, bare circles surrounded by Stipagrostis grasses that occur over thousands of square kilometres in Namibia. The mechanisms explaining their origin, shape, persistence and regularity remain controversial. One hypothesis for the formation of vegetation rings is based on the centrifugal expansion of a single individual grass plant, via clonal growth and die-back in the centre. Clonality could explain FC origin, shape and long-term persistence as well as their regularity, if one clone competes with adjacent clones. Here, we show that for virtually all tested fairy circles the periphery is not exclusively made up of genetically identical grasses, but these peripheral grasses belong to more than one unrelated genet. These results do not support a clonal explanation for fairy circles. Lack of clonality implies that a biological reason for their origin, shape and regularity must emerge from competition between near neighbor individuals within each fairy circle. Such lack of clonality also suggests a mismatch between longevity of fairy circles versus their constituent plants. Furthermore, our findings of lack of clonality have implications for some models of spatial patterning of fairy circles that are based on self-organization. Christian Kappel et al. examine the genetic composition of fairy circles, regular circular patterns of grasses in the Namib Desert, using ddRAD-seq. They find that these grasses are made up of multiple unrelated genets rather than genetically identical grasses, suggesting non-clonality.},
  language  = {en}
}
@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}
}