Planta (2010) 232:95–108 DOI 10.1007/s00425-010-1145-6 123 ORIGINAL ARTICLE Rice BRITTLE CULM 3 (BC3) encodes a classical dynamin OsDRP2B essential for proper secondary cell wall synthesis Ko Hirano · Toshihisa Kotake · Kumiko Kamihara · Kahori Tsuna · Tsutomu Aohara · Yasuko Kaneko · Hiroshi Takatsuji · Yoichi Tsumuraya · Shinji Kawasaki Received: 23 January 2010 / Accepted: 25 February 2010 / Published online: 6 April 2010  Springer-Verlag 2010 Abstract “Brittle culm” mutants found in Gramineae crops are suitable materials to study the mechanism of secondary cell wall formation. Through positional cloning, we have identiWed a gene responsible for the brittle culm phenotype in rice, brittle culm 3 (bc3). BC3 encodes a member of the classical dynamin protein family, a family known to function widely in membrane dynamics. The bc3 mutation resulted in reductions of 28–36% in cellulose con- tents in culms, leaves, and roots, while other cell wall com- ponents remained unaVected. Reductions of cell wall thickness and birefringence were observed in both Wber (sclerenchyma) and parenchymal cells, together with blur- ring of the wall’s layered structures. From promoter-GUS analyses, it was suggested that BC3 expression is directly correlated with active secondary cell wall synthesis. These results suggest that BC3 is tightly involved in the synthesis of cellulose and is essential for proper secondary cell wall construction. Keywords Brittle culm · Cell wall · Cellulose · Dynamin · Rice Abbreviations bc Brittle culm CesA Cellulose synthase catalytic subunit DRP Dynamin-related protein PH domain Pleckstrin homology domain GED GTPase eVector domain GUS -Glucuronidase PRD Proline-rich domain Introduction Plant cell walls constitute the predominant component of the earth’s biomass, mostly in the form of secondary walls, which function as the skeletal frameworks of plants. Sec- ondary cell walls are also the basis for the lumber and tex- tile industries, and are indispensable for good crop yield and quality. Although earlier biochemical approaches to study cell wall biosynthesis were hampered by the diYculty of isolating cell wall polysaccharide synthases, advances in molecular genetic techniques have facilitated the study of plant cell wall biogenesis over the past decade (for review, see Somerville et al. 2004). Indeed, cellulose synthase catalytic subunit (CesA) genes have been cloned through molecular genetic analyses on Arabidopsis mutants with defects in mechanical strength and/or morphology. Arabidopsis xylem-collapsed mutants, K. Hirano and T. Kotake contributed equally to this work. Electronic supplementary material The online version of this article (doi:10.1007/s00425-010-1145-6) contains supplementary material, which is available to authorized users. K. Hirano · K. Kamihara · H. Takatsuji · S. Kawasaki (&) Division of Plant Sciences, National Institute of Agrobiological Sciences, 2-1-2 Kannondai, Tsukuba, Ibaraki 305-8602, Japan e-mail: kawasa@nias.affrc.go.jp T. Kotake · K. Tsuna · T. Aohara · Y. Tsumuraya Division of Life Science, Graduate School of Science and Engineering, Saitama University, Sakura-ku, Saitama 338-8570, Japan Y. Kaneko Department of Science Education, Faculty of Education, Saitama University, Sakura-ku, Saitama 338-8570, Japan Present Address: K. Hirano Bioscience and Biotechnology Center, Nagoya University, Nagoya 464-8601, Japan