TY  - GEN
A1  - Huu, Cuong Nguyen
A1  - Plaschil, Sylvia
A1  - Himmelbach, Axel
A1  - Kappel, Christian
A1  - Lenhard, Michael
T1  - Female self-incompatibility type in heterostylous Primula is determined by the brassinosteroid-inactivating cytochrome P450 CYP734A50
T2  - Current biology
N2  - 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)
KW  - heteromorphic self-incompatibility
KW  - heterostyly
KW  - Primula forbesii
KW  - brassinosteroid
KW  - CYP734A50
KW  - supergene
KW  - pleiotropy
Y1  - 2022
U6  - https://doi.org/10.1016/j.cub.2021.11.046
SN  - 0960-9822
SN  - 1879-0445
VL  - 32
IS  - 3
SP  - 671
EP  - 676, E1-E5
PB  - Cell Press
CY  - Cambridge, Mass.
ER  -