Stigma receptors control intraspecies and interspecies barriers in Brassicaceae

[摘要] Flowering plants have evolved numerous intraspecific and interspecific prezygotic reproductive barriers to prevent production of unfavourable offspring(1). Within a species, self-incompatibility (SI) is a widely utilized mechanism that rejects self-pollen(2,3) to avoid inbreeding depression. Interspecific barriers restrain breeding between species and often follow the SI x self-compatible (SC) rule, that is, interspecific pollen is unilaterally incompatible (UI) on SI pistils but unilaterally compatible (UC) on SC pistils(1,4-6). The molecular mechanisms underlying SI, UI, SC and UC and their interconnections in the Brassicaceae remain unclear. Here we demonstrate that the SI pollen determinant S-locus cysteine-rich protein/S-locus protein 11 (SCR/SP11)(2,3) or a signal from UI pollen binds to the SI female determinant S-locus receptor kinase (SRK)(2,3), recruits FERONIA (FER)(7-9) and activates FER-mediated reactive oxygen species production in SI stigmas(10,11) to reject incompatible pollen. For compatible responses, diverged pollen coat protein B-class(12-14) from SC and UC pollen differentially trigger nitric oxide, nitrosate FER to suppress reactive oxygen species in SC stigmas to facilitate pollen growth in an intraspecies-preferential manner, maintaining species integrity. Our results show that SRK and FER integrate mechanisms underlying intraspecific and interspecific barriers and offer paths to achieve distant breeding in Brassicaceae crops.

[关键词] POLLEN-PISTIL INTERACTIONS;SELF-INCOMPATIBILITY;ARABIDOPSIS-THALIANA;S-NITROSYLATION;COAT PROTEINS;PLANT;KINASE;COMPATIBILITY;GENERATION;MECHANISM