title: Calcium signalling mediates self-incompatibility response in the Brassicaceae.
abstract: Self-incompatibility in the Brassicaceae is controlled by multiple haplotypes encoding the pollen ligand (S-locus protein 11, SP11, also known as S-locus cysteine-rich protein, SCR) and its stigmatic receptor (S-receptor kinase, SRK). A haplotype-specific interaction between SP11/SCR and SRK triggers the self-incompatibility response that leads to self-pollen rejection, but the signalling pathway remains largely unknown. Here we show that Ca(2+) influx into stigma papilla cells mediates self-incompatibility signalling. Using self-incompatible Arabidopsis thaliana expressing SP11/SCR and SRK, we found that self-pollination specifically induced an increase in cytoplasmic Ca(2+) ([Ca(2+)]cyt) in papilla cells. Direct application of SP11/SCR to the papilla cell protoplasts induced Ca(2+) increase, which was inhibited by D-(-)-2-amino-5-phosphonopentanoic acid (AP-5), a glutamate receptor channel blocker. An artificial increase in [Ca(2+)]cyt in papilla cells arrested wild-type (WT) pollen hydration. Treatment of papilla cells with AP-5 interfered with self-incompatibility, and Ca(2+) increase on the self-incompatibility response was reduced in the glutamate receptor-like channel (GLR) gene mutants. These results suggest that Ca(2+) influx mediated by GLR is the essential self-incompatibility response leading to self-pollen rejection.
authors.affiliation: Graduate School of Biological Sciences, Nara Institute of Science and Technology, Ikoma 630-0192, Japan.
authors.forename: Megumi
authors.identifier: http://orcid.org/0000-0002-5280-1649
authors.initials: M
authors.lastname: Iwano
authors.affiliation: Graduate School of Biological Sciences, Nara Institute of Science and Technology, Ikoma 630-0192, Japan.
authors.forename: Kanae
authors.initials: K
authors.lastname: Ito
authors.affiliation: Graduate School of Biological Sciences, Nara Institute of Science and Technology, Ikoma 630-0192, Japan.
authors.forename: Sota
authors.initials: S
authors.lastname: Fujii
authors.affiliation: Graduate School of Biological Sciences, Nara Institute of Science and Technology, Ikoma 630-0192, Japan.
authors.forename: Mitsuru
authors.initials: M
authors.lastname: Kakita
authors.affiliation: Graduate School of Biological Sciences, Nara Institute of Science and Technology, Ikoma 630-0192, Japan.
authors.forename: Hiroko
authors.initials: H
authors.lastname: Asano-Shimosato
authors.affiliation: Graduate School of Biological Sciences, Nara Institute of Science and Technology, Ikoma 630-0192, Japan.
authors.forename: Motoko
authors.initials: M
authors.lastname: Igarashi
authors.affiliation: Graduate School of Biological Sciences, Nara Institute of Science and Technology, Ikoma 630-0192, Japan.
authors.forename: Pulla
authors.initials: P
authors.lastname: Kaothien-Nakayama
authors.affiliation: Graduate School of Biological Sciences, Nara Institute of Science and Technology, Ikoma 630-0192, Japan.
authors.forename: Tetsuyuki
authors.initials: T
authors.lastname: Entani
authors.affiliation: Graduate School of Biological Sciences, Nara Institute of Science and Technology, Ikoma 630-0192, Japan.
authors.forename: Asaka
authors.initials: A
authors.lastname: Kanatani
authors.affiliation: Graduate School of Biological Sciences, Nara Institute of Science and Technology, Ikoma 630-0192, Japan.
authors.forename: Masashi
authors.initials: M
authors.lastname: Takehisa
authors.affiliation: Graduate School of Biological Sciences, Nara Institute of Science and Technology, Ikoma 630-0192, Japan.
authors.forename: Masaki
authors.initials: M
authors.lastname: Tanaka
authors.affiliation: Graduate School of Biological Sciences, Nara Institute of Science and Technology, Ikoma 630-0192, Japan.
authors.forename: Kunihiko
authors.initials: K
authors.lastname: Komatsu
authors.affiliation: Graduate School of Biological Sciences, Nara Institute of Science and Technology, Ikoma 630-0192, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Shiba
authors.affiliation: The Institute of Scientific and Industrial Research, Osaka University, Ibaraki, Osaka 567-0047, Japan.
authors.forename: Takeharu
authors.initials: T
authors.lastname: Nagai
authors.affiliation: Brain Science Institute, The Institute of Physical and Chemical Research (RIKEN), Wako, Saitama 351-0198, Japan.
authors.forename: Atsushi
authors.initials: A
authors.lastname: Miyawaki
authors.affiliation: Graduate School of Biological Sciences, Nara Institute of Science and Technology, Ikoma 630-0192, Japan.
authors.forename: Akira
authors.initials: A
authors.lastname: Isogai
authors.affiliation: Graduate School of Biological Sciences, Nara Institute of Science and Technology, Ikoma 630-0192, Japan.
authors.forename: Seiji
authors.initials: S
authors.lastname: Takayama