Three distinct rice cellulose synthase catalytic subunit genes required for cellulose synthesis in the secondary wall.
Several brittle culm mutations of rice (Oryza sativa) causing fragility of plant tissues have been identified genetically but not characterized at a molecular level. We show here that the genes responsible for three distinct brittle mutations of rice, induced by the insertion of the endogenous retrotransposon Tos17, correspond to CesA (cellulose synthase catalytic subunit) genes, OsCesA4, OsCesA7 and OsCesA9. Three CesA genes were expressed in seedlings, culms, premature panicles, and roots but not in mature leaves, and the expression profiles were almost identical among the three genes. Cellulose contents were dramatically decreased (8.9%-25.5% of the wild-type level) in the culms of null mutants of the three genes, indicating that these genes are not functionally redundant. Consistent with these results, cell walls in the cortical fiber cells were shown to be thinner in all the mutants than in wild-type plants. Based on these observations, the structure of a cellulose-synthesizing complex involved in the synthesis of the secondary cell wall is discussed.
Tanaka
Katsuyuki
K
Institute of the Society for Techno-innovation of Agriculture, Forestry and Fisheries, Tsukuba, Ibaraki 305-0854, Japan.
Murata
Kazumasa
K
Yamazaki
Muneo
M
Onosato
Katsura
K
Miyao
Akio
A
Hirochika
Hirohiko
H
D000595:Amino Acid Sequence; D029681:Arabidopsis Proteins; D020134:Catalytic Domain / Q000235:genetics; D002473:Cell Wall / Q000201:enzymology; D002482:Cellulose / Q000096:biosynthesis*; D015971:Gene Expression Regulation, Enzymologic; D018506:Gene Expression Regulation, Plant; D005964:Glucosyltransferases / Q000235:genetics* / Q000378:metabolism; D008855:Microscopy, Electron, Scanning; D008969:Molecular Sequence Data; D009154:Mutation; D012275:Oryza / Q000201:enzymology* / Q000235:genetics; D010802:Phylogeny; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D018520:Plant Shoots / Q000235:genetics / Q000378:metabolism / Q000648:ultrastructure; D018626:Retroelements / Q000235:genetics; D017386:Sequence Homology, Amino Acid
D029681:Arabidopsis Proteins; D010940:Plant Proteins; D018626:Retroelements; D002482:Cellulose; D005964:Glucosyltransferases; C457769:PRC1 protein, Arabidopsis; C028634:cellulose synthase (UDP-forming)