Plant and Cell Physiology Advance Access originally published online on October 6, 2009
Plant and Cell Physiology 2009 50(11):1886-1897; doi:10.1093/pcp/pcp133
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Rice BRITTLE CULM 5 (BRITTLE NODE) is Involved in Secondary Cell Wall Formation in the Sclerenchyma Tissue of Nodes
1Division of Life Science, Graduate School of Science and Engineering, Saitama University, 255 Shimo-okubo, Sakura-ku, Saitama, 338-8570 Japan
2Faculty of Education, Saitama University, 255 Shimo-okubo, Sakura-ku, Saitama, 338-8570 Japan
3Plant Science Division, National Institute of Agrobiological Sciences, Tsukuba, Ibaraki, 305-8602 Japan
*Corresponding author: E-mail, kawasa{at}nias.affrc.go.jp; Fax, +81-29-838-7416.
| Abstract |
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Several brittle culm (bc) mutants known in grasses are considered excellent materials to study the process of secondary cell wall formation. The brittle phenotype of the rice bc5 (brittle node) mutant appears exclusively in the developed nodes, which is distinct from other bc mutants (bc1, 2, 3, 4, 6 and 7) that show the brittle phenotype in culms and leaves. To address the defects of the rice bc5 mutant in node-specific cell wall formation, we analyzed tissue morphology and cell wall composition. The bc5 mutation was found to affect the cell wall deposition of node sclerenchyma tissues at 1 week after heading, the stage at which the cell wall sugar content is reduced, in the bc5 nodes, compared with wild-type nodes. Moreover, decreased accumulation of lignin and thickness of cell walls in the sclerenchyma tissues were also observed in the bc5 nodes. The amounts of cellulose and hemicellulose were reduced to 53 and 65% of those in the wild-type plants, respectively. Sugar composition and glycosidic linkage analyses of the hemicellulose showed that the accumulation of glucuronosyl arabinoxylan in bc5 nodes was perturbed by the mutation. The bc5 locus was narrowed to an approximately 3.1 Mb region of chromosome 2, where none of the other bc genes is located. The bc5 mutation appeared to reduce the expression levels of the OsCesA genes in the nodes after heading. The results indicate that the BC5 gene regulates the development of secondary cell walls of node sclerenchyma tissues.
Keywords: Cellulose Glucuronosyl arabinoxylan Lignin Rice node Sclerenchyma tissue Secondary cell walls
Abbreviations: AH, after heading; L-Ara, L-arabinose; bc, brittle culm; BH, before heading; CesA, cellulose synthase catalytic subunit; fra, fragile fiber; L-Fuc, L-fucose; Gal, galactose; GalA, galacturonic acid; Glc, glucose; GlcA, glucuronic acid; GT, glycosyltransferase; HPAEC-PAD, high-performance anion-exchange chromatography with pulsed amperometric detection; irx, irregular xylem; Man, mannose; NST, NAC SECONDARY WALL THICKENING PROMOTING FACTOR; Os, Oryza sativa; PAL, phenylalanine ammonia-lyase; L-Rha, L-rhamnose; RT–PCR, reverse transcription–PCR; SND, SECONDARY WALL-ASSOCIATED NAC DOMAIN; VND, VASCULAR-RELATED NAC DOMAIN; WAH, week after heading; Xyl, xylose.
(Received August 3, 2009; Accepted September 24, 2009)
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