RESUMO
During sexual reproduction of flowering plants, the pollen tube grows fast and over a long distance within the pistil to deliver two sperms for double fertilization. Growing plant cells need to communicate constantly with external stimuli as well as monitor changes in surface tension of the cell wall and plasma membrane to coordinate these signals and internal growth machinery; however, the underlying mechanisms remain largely unknown. Here we show that the rice member of plant-specific receptor-like kinase CrRLK1Ls subfamily, Ruptured Pollen tube (RUPO), is specifically expressed in rice pollen. RUPO localizes to the apical plasma membrane and vesicle of pollen tubes and is required for male gamete transmission. K+ levels were greater in pollen of homozygous CRISPR-knockout lines than wild-type plants, and pollen tubes burst shortly after germination. We reveal the interaction of RUPO with high-affinity potassium transporters. Phosphorylation of RUPO established and dephosphorylation abolished the interaction. These results have revealed the receptor-like kinase as a regulator of high-affinity potassium transporters via phosphorylation-dependent interaction, and demonstrated a novel receptor-like kinase signaling pathway that mediates K+ homeostasis required for pollen tube growth and integrity.
Assuntos
Proteínas de Membrana/genética , Oryza/genética , Proteínas de Plantas/genética , Tubo Polínico/genética , Antiportadores de Potássio-Hidrogênio/genética , Receptores Proteína Tirosina Quinases/genética , Arabidopsis/genética , Proteínas de Arabidopsis/genética , Flores/genética , Flores/crescimento & desenvolvimento , Regulação da Expressão Gênica de Plantas , Germinação/genética , Homeostase , Magnoliopsida/genética , Magnoliopsida/crescimento & desenvolvimento , Proteínas de Membrana/biossíntese , Oryza/crescimento & desenvolvimento , Fosforilação , Pólen/genética , Pólen/crescimento & desenvolvimento , Tubo Polínico/crescimento & desenvolvimento , Polinização/genética , Antiportadores de Potássio-Hidrogênio/biossíntese , Proteínas Quinases/genéticaRESUMO
Acquisition and distribution of metal ions support a number of biological processes. Here we show that respiratory growth of and iron acquisition by the yeast Saccharomyces cerevisiae relies on potassium (K(+)) compartmentalization to the trans-Golgi network via Kha1p, a K(+)/H(+) exchanger. K(+) in the trans-Golgi network facilitates binding of copper to the Fet3p multi-copper ferroxidase. The effect of K(+) is not dependent on stable binding with Fet3p or alteration of the characteristics of the secretory pathway. The data suggest that K(+) acts as a chemical factor in Fet3p maturation, a role similar to that of cations in folding of nucleic acids. Up-regulation of KHA1 gene in response to iron limitation via iron-specific transcription factors indicates that K(+) compartmentalization is linked to cellular iron homeostasis. Our study reveals a novel functional role of K(+) in the binding of copper to apoFet3p and identifies a K(+)/H(+) exchanger at the secretory pathway as a new molecular factor associated with iron uptake in yeast.
