@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}
}
@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}
}