Abstract
We report isolation and characterization of a fragile culm mutant fc116 that displays reduced mechanical strength caused by decreased cellulose content and altered cell wall structure in rice. Map-based cloning revealed that fc116 was a base substitution mutant (G to A) in a putative beta-1,6-N-acetylglucosaminyltransferase (C2GnT) gene (LOC_Os05g07790, allelic to BC10). This mutation resulted in one amino acid missing within a newly-identified protein motif “R, RXG, RA.” The FC116/BC10 gene was lowly but ubiquitously expressed in the all tissues examined across the whole life cycle of rice, and slightly down-regulated during secondary growth. This mutant also exhibited a significant increase in the content of hemicelluloses and lignins, as well as the content of pentoses (xylose and arabinose). But the content of hexoses (glucose, mannose, and galactose) was decreased in both cellulosic and non-cellulosic (pectins and hemicelluloses) fractions of the mutant. Transcriptomic analysis indicated that the typical genes in the fc116 mutant were up-regulated corresponding to xylan biosynthesis, as well as lignin biosynthesis including p-hydroxyphenyl (H), syringyl (S), and guaiacyl (G). Our results indicate that FC116 has universal function in regulation of the cell wall polymers in rice.
Highlights
Plant cell walls are complex, dynamic cellular structures essential for plant growth, development, physiology, and adaptation
We found that extension force (EF) of the fc116 mutant in culms was reduced by 67% comparing to its wild type at the heading stage (Figure 1F)
We found that most negatively co-expressed genes of FC116 belonged to Modules in close vicinity of modules 44 that typically were for secondary cell wall (SCW), whereas the positively co-expressed genes distributed to the modules including the modules 24 that typically were for primary cell wall
Summary
Plant cell walls are complex, dynamic cellular structures essential for plant growth, development, physiology, and adaptation. Cell walls can be classed as primary or secondary, depending upon whether they are extendable or non-extendable during organ growth (Lee et al, 2011). Primary cell wall is a flexible matrix that mainly composed of cellulose, hemicelluloses, pectins, and proteins, allowing directed cell growth. OsFC116 Involving in Cell Wall Biosynthesis (Smook, 1992). Hemicelluloses include polysaccharides such as xyloglucans, xylans, mannans, and glucomannans, and β(1,3-1,4)-glucans (Scheller and Ulvskov, 2010). Lignin is an amorphous polymer of phenylpropane units with three major monomers: p-hydroxyphenyl (H), guaiacyl (G), and syringyl (S), laid down during secondary cell wall formation (Zhao and Dixon, 2011; Sun et al, 2012)
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