Cytoplasmic male sterility-related protein kinase, OsNek3, is regulated downstream of mitochondrial protein phosphatase 2C, DCW11

• Published in: Plant and cell physiology Vol. 50; no. 4; pp. 828 - 837
• Main Authors: Fujii, S.(Tohoku Univ., Sendai (Japan)), Yamada, M, Toriyama, K
• Format: Journal Article
• Language: English
• Published: Japan Oxford University Press 01.04.2009; Oxford Publishing Limited (England)
• Subjects: CYTOPLASMIC MALE STERILITY; ESTERILIDAD MASCULINA CITOPLASMICA; EXPRESION GENICA; EXPRESSION DES GENES; GENE EXPRESSION; Gene Expression Regulation, Plant; Gene Knockout Techniques; Genes, Plant; MITOCHONDRIA; Mitochondria - enzymology; Mitochondrial retrograde signaling; MITOCHONDRIE; MITOCONDRIA; Mutation; NIMA-related kinase; Oryza - genetics; Oryza - metabolism; ORYZA SATIVA; Oryza sativa L; Phosphoprotein Phosphatases - metabolism; Plant Infertility - genetics; Plant Proteins - genetics; Plant Proteins - metabolism; POLEN; POLLEN; Pollen - genetics; Pollen - metabolism; PROTEIN KINASE; Protein Phosphatase 2C; Protein-Serine-Threonine Kinases - genetics; Protein-Serine-Threonine Kinases - metabolism; PROTEINA QUINASA; PROTEINE KINASE; RNA, Plant - genetics; STERILITE MALE CYTOPLASMIQUE; Pollen; NIMA-related kinase; L; Protein phosphatase 2C; Cytoplasmic male sterility; Mitochondrial retrograde signaling
• ISSN: 0032-0781; 1471-9053
• DOI: 10.1093/pcp/pcp026

OsNek3 (Oryza sativa L. NIMA-related kinase) and DCW11 encoding a mitochondrial putative protein phosphatase 2C were found in our previous microarray study as down-regulated genes in the rice CW-CMS line, which lacked pollen germination ability. Further analysis of DCW11 revealed that DCW11 is strongly correlated with CW-CMS occurrence. Here we show the relationship between OsNek3 and DCW11. OsNek3 was preferentially expressed in mature pollen. A knockout mutant with Tos17 inserted into OsNek3 did not show any pollen-defective phenotype. On the other hand, plants overexpressing OsNek3 occasionally produced a peculiar pollen structure in which the outer cell wall of four pollen grains fused together even at the mature pollen stages, which resembled that of quartet mutants in Arabidopsis. OsNek3 was shown to interact with a LIM domain-containing protein, OsPLIM2b, whose expression was strongly specific in mature pollen, suggesting that OsNek3 might play a role in pollen germination. OsNek3 was shown to be down-regulated in DCW11-knockdown lines, whereas osnek3 mutation did not result in DCW11 down-regulation. These results suggest that OsNek3 is downstream of DCW11 in retrograde signaling from the mitochondria to the nucleus and is involved in CW-CMS.