Abstract
The receptor protein kinase 2 (RPK2), an Arabidopsis LRR receptor-like kinase (LRR-RLK), is the only homolog of the receptor protein kinase 1 (RPK1) which is a key regulator of ABA signaling in Arabidopsis. Two RPK2 knockout mutants (rpk2-1 and rpk2-2) showed male-sterility and bushy shoot growth. Abnormal lignification was observed on the surface of rpk2 anther and it might cause the defect of anther dehiscence. Tapetum abnormally fatted in rpk2 anther after meiosis and normal pollen maturation was inhibited. We identified 255 downregulated genes (fold decrease > 3) in rpk2 flowers by a microarray experiment and revealed that many genes for lignin biosynthesis and cell wall degradation enzymes were downregulated. Furthermore, several genes for ABA- or stress-related proteins, such as RD20 and LEA proteins, are also downregulated. These results indicate that RPK2 is essential for floral development and that RPK2 may be involved in ABA signaling pathway.
