Small-interfering Rnas From Natural Antisense Transcripts Derived From A Cellulose Synthase Gene Modulate Cell Wall Biosynthesis In Barley

摘要

Small-interfering RNAs (siRNAs) from natural cis-antisense pairs derived from the 3'-coding region of the barley (Hordeum vulgare) CesA6 cellulose synthase gene substantially increase in abundance during leaf elongation. Strand-specific RT-PCR confirmed the presence of an antisense transcript of HvCesA6 that extends ≥ 1230 bp from the 3' end of the CesA-coding sequence. The increases in abundance of the CesA6 antisense transcript and the 21-nt and 24-nt siRNAs derived from the transcript are coincident with the down-regulation of primary wall CesAs, several Csl genes, and GT8 glycosyl transferase genes, and are correlated with the reduction in rates of cellulose and (1 →3),(1 →4)-β-D-glucan synthesis. Virus induced gene silencing using unique target sequences derived from HvCesA genes attenuated expression not only of the HvC-esA6 gene, but also of numerous nontarget Csls and the distantly related GT8 genes and reduced the incorporation of D-~(14)C-Glc into cellulose and into mixed-linkage (1 → 3),(1 →4)-β-D-glucans of the developing leaves. Unique target sequences for CsIF and CslH conversely silenced the same genes and lowered rates of cellulose and (1 →3),(1 →4)-β-D-glucan synthesis. Our results indicate that the expression of individual members of the CesAlCsl superfamily and glycosyl transferases share common regulatory control points, and siRNAs from natural c/s-antisense pairs derived from the CesA/Csl superfamily could function in this global regulation of cell-wall synthesis.