Divergence of evolutionary ways among common sym genes: CASTOR and CCaMK show functional conservation between two symbiosis systems and constitute the root of a common signaling pathway.
In recent years a number of legume genes involved in root nodule (RN) symbiosis have been identified in the model legumes, Lotus japonicus (Lotus) and Medicago truncatula. Among them, a distinct set of genes has been categorized as a common symbiosis pathway (CSP), because they are also essential for another mutual interaction, the arbuscular mycorrhiza (AM) symbiosis, which is evolutionarily older than the RN symbiosis and is widely distributed in the plant kingdom. Based on the concept that the legume RN symbiosis has evolved from the ancient AM symbiosis, one issue is whether the CSP is functionally conserved between non-nodulating plants, such as rice, and nodulating legumes. We identified three rice CSP gene orthologs, OsCASTOR, OsPOLLUX and OsCCaMK, and demonstrated the indispensable roles of OsPOLLUX and OsCCaMK in rice AM symbiosis. Interestingly, molecular transfection of either OsCASTOR or OsCCaMK could fully complement symbiosis defects in the corresponding Lotus mutant lines for both the AM and RN symbioses. Our results not only provide a conserved genetic basis for the AM symbiosis between rice and Lotus, but also indicate that the core of the CSP has been well conserved during the evolution of RN symbiosis. Through evolution, CASTOR and CCaMK have remained as the molecular basis for the maintenance of CSP functions in the two symbiosis systems.
Division of Plant Sciences, National Institute of Agrobiological Sciences, Tsukuba, Ibaraki, 305-8602, Japan.
Mari
M
Banba
Caroline
C
Gutjahr
Akio
A
Miyao
Hirohiko
H
Hirochika
Uta
U
Paszkowski
Hiroshi
H
Kouchi
Haruko
H
Imaizumi-Anraku
D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000235:genetics / Q000378:metabolism*; D003001:Cloning, Molecular; D018744:DNA, Plant / Q000235:genetics; D019143:Evolution, Molecular; D017343:Genes, Plant; D005816:Genetic Complementation Test; D000070116:Lotus / Q000235:genetics / Q000378:metabolism / Q000382:microbiology; D016254:Mutagenesis, Insertional; D009154:Mutation; D038821:Mycorrhizae / Q000502:physiology; D012275:Oryza / Q000235:genetics* / Q000378:metabolism / Q000382:microbiology; D010641:Phenotype; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D053204:Root Nodules, Plant / Q000235:genetics / Q000378:metabolism; D016415:Sequence Alignment; D013559:Symbiosis
D018744:DNA, Plant; D010940:Plant Proteins; D017871:Calcium-Calmodulin-Dependent Protein Kinases