Tai Wang’ group reveals a novel receptor-like kinase signaling pathway that mediates K+ homeostasis required for pollen tube growth and integrity
Figure 1. Homozygous bi-allelic mutant pollen tubes burst in pistils. (A to D) Pollen tube growth in pistils of wild-type (A,E), heterozygous T-DNA mutant rupo+/- (B,F), mono-allelic mutant (C,G) and bi-allelic mutant (D,H). White arrowheads indicate the putative positions of micropyles. All ovules were targeted by pollen tubes except for ovules from the bi-allelic mutant. Inserts in (E,F,G,H) are close-ups of representative pollen tubes in wild-type (E), rupo+/- (F), mono-allelic (G) and bi-allelic (H) stigmas. Red arrows in (H) indicate callus spots.
During sexual reproduction of flowering plants, the pollen loaded onto the stigma of pistils generates a directionally grew pollen tube. The tube grows fast and over a long distance within the pistil to deliver two sperms to activate double fertilization and embryo development. The feature requires pollen tubes communicate with female tissues and maintain their integrity before sperm discharge, but underlying molecular mechanisms are still remained largely unknown. Tai Wang’ group finds pollen tube plasma membrane-localized receptor-like kinase RUPO is one important component of signaling pathways for pollen tube growth and integrity in rice. RUPO is expressed specifically in pollen, and loss-of-function of RUPO led to significantly high K+ levels and pollen tube rupture immediately after germination. RUPO interacted 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.
This study have been published in PLoS Genetics in July 22, 2016, and was supported by “973”project from the Ministry of Science and Technology.
Figure 2. A proposed RUPO-potassium transporter signaling model to control pollen tube growth and integrity via regulating K+ homeostasis.
During sexual reproduction of flowering plants, the pollen loaded onto the stigma of pistils generates a directionally grew pollen tube. The tube grows fast and over a long distance within the pistil to deliver two sperms to activate double fertilization and embryo development. The feature requires pollen tubes communicate with female tissues and maintain their integrity before sperm discharge, but underlying molecular mechanisms are still remained largely unknown. Tai Wang’ group finds pollen tube plasma membrane-localized receptor-like kinase RUPO is one important component of signaling pathways for pollen tube growth and integrity in rice. RUPO is expressed specifically in pollen, and loss-of-function of RUPO led to significantly high K+ levels and pollen tube rupture immediately after germination. RUPO interacted 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.
This study have been published in PLoS Genetics in July 22, 2016, and was supported by “973”project from the Ministry of Science and Technology.
Figure 2. A proposed RUPO-potassium transporter signaling model to control pollen tube growth and integrity via regulating K+ homeostasis.