Brittle culm15 encodes a membrane-associated chitinase-like protein required for cellulose biosynthesis in rice.
Plant chitinases, a class of glycosyl hydrolases, participate in various aspects of normal plant growth and development, including cell wall metabolism and disease resistance. The rice (Oryza sativa) genome encodes 37 putative chitinases and chitinase-like proteins. However, none of them has been characterized at the genetic level. In this study, we report the isolation of a brittle culm mutant, bc15, and the map-based cloning of the BC15/OsCTL1 (for chitinase-like1) gene affected in the mutant. The gene encodes the rice chitinase-like protein BC15/OsCTL1. Mutation of BC15/OsCTL1 causes reduced cellulose content and mechanical strength without obvious alterations in plant growth. Bioinformatic analyses indicated that BC15/OsCTL1 is a class II chitinase-like protein that is devoid of both an amino-terminal cysteine-rich domain and the chitinase activity motif H-E-T-T but possesses an amino-terminal transmembrane domain. Biochemical assays demonstrated that BC15/OsCTL1 is a Golgi-localized type II membrane protein that lacks classical chitinase activity. Quantitative real-time polymerase chain reaction and β-glucuronidase activity analyses indicated that BC15/OsCTL1 is ubiquitously expressed. Investigation of the global expression profile of wild-type and bc15 plants, using Illumina RNA sequencing, further suggested a possible mechanism by which BC15/OsCTL1 mediates cellulose biosynthesis and cell wall remodeling. Our findings provide genetic evidence of a role for plant chitinases in cellulose biosynthesis in rice, which appears to differ from their roles as revealed by analysis of Arabidopsis (Arabidopsis thaliana).
Key Laboratory of Plant Genomics, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China.
Bin
B
Wu
Baocai
B
Zhang
Yan
Y
Dai
Lei
L
Zhang
Keke
K
Shang-Guan
Yonggang
Y
Peng
Yihua
Y
Zhou
Zhen
Z
Zhu
D001696:Biomechanical Phenomena; D002473:Cell Wall / Q000378:metabolism; D002482:Cellulose / Q000096:biosynthesis*; D002688:Chitinases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D003001:Cloning, Molecular; D057075:Enzyme Assays; D004926:Escherichia coli / Q000378:metabolism; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant / Q000235:genetics; D056426:Genetic Loci / Q000235:genetics; D006031:Glycosylation; D006056:Golgi Apparatus / Q000201:enzymology; D008565:Membrane Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D009154:Mutation / Q000235:genetics; D012275:Oryza / Q000201:enzymology* / Q000235:genetics; D010940:Plant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D021381:Protein Transport; D015398:Signal Transduction / Q000235:genetics
D008565:Membrane Proteins; D010940:Plant Proteins; D002482:Cellulose; D002688:Chitinases