Abstract
The temporary callose layer surrounding the tetrads of microspores is critical for male gametophyte development in flowering plants, as abnormal callose deposition can lead to microspore abortion. A sophisticated signaling network regulates callose biosynthesis but these pathways are poorly understood. In this study, we characterized a rice male-sterile mutant, oslecrk5, which showed defective callose deposition during meiosis. OsLecRK5 encodes a plasma membrane-localized lectin receptor-like kinase, which can form a dimer with itself. Moreover, normal anther development requires the K-phosphorylation site (a conserved residue at the ATP-binding site) of OsLecRK5. In vitro assay showed that OsLecRK5 phosphorylates the callose synthesis enzyme UGP1, enhancing callose biosynthesis during anther development. Together, our results demonstrate that plasma membrane-localized OsLecRK5 phosphorylates UGP1 and promotes its activity in callose biosynthesis in rice. This is the first evidence that a receptor-like kinase positively regulates callose biosynthesis.
A G‐type lectin receptor‐like kinase regulates the perception of oomycete apoplastic expansin‐like proteins
