|Scofield, Steven - Steve|
Submitted to: Proceedings of the National Academy of Sciences (PNAS)
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/24/2008
Publication Date: 12/12/2008
Citation: Held, M.A., Penning, B., Kessans, S.A., Yong, W., Scofield, S.R., Brandt, A.S., Carpita, N.C. 2008. Small-Interfering RNAs from Natural Antisense Transcripts Derived from a Cellulose Synthase Gene Modulate Cell Wall Biosynthesis in Barley. Proceedings of the National Academy of Sciences. 105:20534-10539.
Interpretive Summary: This manuscript provides the first evidence for a system that could act to coordinate the expression of suites of CesA/Csl genes, which encode the enzymes that produce major plant cell wall components. This work demonstrates the existence of naturally occurring antisense RNAs homologous to the CesA genes of barley. Together the sense and antisense RNAs form double-stranded RNA that is cleaved for 21 and 24 base small interfering RNAs (siRNAs). A functional role in the regulation of CesA/Csl gene expression is strongly supported by the finding that the accumulation of the 21 and 24b CesA siRNAs is inversely proportional to the expression of CesA mRNA. Understanding this mechanism has significant implications for the manipulation of specific aspects of cell wall biosynthesis, and it will be central to efforts to engineer crops for efficient production of cellulosic biofuels.
Technical Abstract: Viral-induced gene silencing of members of the cellulose synthase/cellulose synthase-like (CesA/Csl) gene superfamily in barley (Hordeum vulgare cv. Blackhulless) using the Barley Stripe Mosaic Virus reduced theincorporation of D-14C-Glc into cellulose and into mixed-linkage (1'3),(1'4)-'-D-glucans of the developing leaves. Expression of a primary wall-associated HvCesA6 gene, as well as numerous other non-target Csls and those of unrelated glycosyltransferases, was attenuated by unique target sequences derived from HvCesA6. Plants silenced with unique targets from CslF and CslH gene families also had reduced incorporation of D-14C-Glc into leaf cellulose and mixed-linkage (1'3), (1'4)-'-D-glucan. The expression of a secondary wall-associated HvCesA8 was unaffected by silencing of HvCesA6. We observed that 21-nt and 24-nt small interfering RNAs from natural cis-antisense pairs derived from the c-terminal coding region of a CesA gene increase substantially in abundance during barley leaf elongation, coincident with the down-regulation of primary wall CesA6, CslF, and GT8 genes. Our results indicate that the expression of individual members of the CesA/Csl family share common regulatory control points, and small interfering RNAs from natural cis-antisense pairs derived from CesAs may function in this regulation.