Three Distinct Rice Cellulose Synthase Catalytic Subunit Genes Required for Cellulose Synthesis in the Secondary Wall

Abstract

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.

Molecular characterization, expression pattern, and function analysis of the OsBC1L family in rice

“…In addition, osbc1l4 shows similar mutant phenotype and expression pattern with some cellulose synthase genes (OsCESA4, OsCESA7, and OsCESA9; Tanaka et al 2003). These genes also exhibited a dwarf mutant phenotype and decreased secondary wall synthesis and were expressed in seedlings, culms, panicles, and roots, but not in mature leaves (Tanaka et al 2003). Therefore, we infer that OsBC1L4 might be involved in the biosynthesis of cell wall and cellulose in rice.…”

“…So far, several members of the COBRA gene family have been found to be involved in the synthesis of cellulose, which is responsible for the expansion and formation of the cell wall (Schindelman et al 2001;Li et al 2003;Brown et al 2005;Ching et al 2006). In addition, osbc1l4 shows similar mutant phenotype and expression pattern with some cellulose synthase genes (OsCESA4, OsCESA7, and OsCESA9; Tanaka et al 2003). These genes also exhibited a dwarf mutant phenotype and decreased secondary wall synthesis and were expressed in seedlings, culms, panicles, and roots, but not in mature leaves (Tanaka et al 2003).…”

Complexes with Mixed Primary and Secondary Cellulose Synthases Are Functional in Arabidopsis Plants

“…Phylogenetic analysis revealed six distinct CESA clades found in seed plants, each corresponding to one of the six required components of the primary and secondary cellulose synthase complexes in Arabidopsis (Holland et al, 2000;Samuga and Joshi, 2002;Tanaka et al, 2003;Burton et al, 2004;Djerbi et al, 2005;Nairn and Haselkorn, 2005;Ranik and Myburg, 2006;Suzuki et al, 2006;Kumar et al, 2009;Carroll and Specht, 2011). The interaction between the different CESA proteins in the primary and secondary rosettes has been characterized previously by coimmunoprecipitation and yeast two-hybrid methods, showing interaction patterns with similarities between primary and secondary CESAs (Taylor et al, 2000;Desprez et al, 2007;Wang et al, 2008;Atanassov et al, 2009;Timmers et al, 2009).…”

Structure, organization, and functions of cellulose synthase complexes in higher plants

“…At least three types of CESA isoforms, called α 1 , α 2 , and β, may be necessary for the spontaneous arrangement of CESAs in each CelS Ding and Himmel, 2006). Consistent with this hypothesis, different types of CesA isoforms have been found to be coexpressed in Arabidopsis thaliana: AtCesA4, AtCesA7, and AtCesA8 (Taylor et al, 2003); barley: HvCesA1, HvCesA2, and HvCesA6 (Burton et al, 2004); poplar: PtrCesA1, PtrCesA2, and PtrCesA3 Bhandari et al, 2006); and rice: OsCesA4, OsCesA7, and OsCesA9 (Tanaka et al, 2003). However, expression of several CesA isoforms in the same cell does not necessarily indicate that they interact and are part of the same CelS.…”