title: Reduced lignin content and altered lignin composition in the warm season forage grass Paspalum dilatatum by down-regulation of a Cinnamoyl CoA reductase gene.
abstract: C4 grasses are favoured as forage crops in warm, humid climates. The use of C4 grasses in pastures is expected to increase because the tropical belt is widening due to global climate change. While the forage quality of Paspalum dilatatum (dallisgrass) is higher than that of other C4 forage grass species, digestibility of warm-season grasses is, in general, poor compared with most temperate grasses. The presence of thick-walled parenchyma bundle-sheath cells around the vascular bundles found in the C4 forage grasses are associated with the deposition of lignin polymers in cell walls. High lignin content correlates negatively with digestibility, which is further reduced by a high ratio of syringyl (S) to guaiacyl (G) lignin subunits. Cinnamoyl-CoA reductase (CCR) catalyses the conversion of cinnamoyl CoA to cinnemaldehyde in the monolignol biosynthetic pathway and is considered to be the first step in the lignin-specific branch of the phenylpropanoid pathway. We have isolated three putative CCR1 cDNAs from P. dilatatum and demonstrated that their spatio-temporal expression pattern correlates with the developmental profile of lignin deposition. Further, transgenic P. dilatatum plants were produced in which a sense-suppression gene cassette, delivered free of vector backbone and integrated separately to the selectable marker, reduced CCR1 transcript levels. This resulted in the reduction of lignin, largely attributable to a decrease in G lignin.
authors: Department of Environment and Primary Industries, AgriBio Centre for AgriBioscience, 5 Ring Road, Bundoora, VIC, 3083, Australia.
authors: Andrea
authors: A
authors: Giordano
authors: Zhiqian
authors: Z
authors: Liu
authors: Stephen N
authors: SN
authors: Panter
authors: Adam M
authors: AM
authors: Dimech
authors: Yongjin
authors: Y
authors: Shang
authors: Hewage
authors: H
authors: Wijesinghe
authors: Karen
authors: K
authors: Fulgueras
authors: Yidong
authors: Y
authors: Ran
authors: Aidyn
authors: A
authors: Mouradov
authors: Simone
authors: S
authors: Rochfort
authors: Nicola J
authors: NJ
authors: Patron
authors: German C
authors: GC
authors: Spangenberg
mesh_terms: D000445:Aldehyde Oxidoreductases / Q000096:biosynthesis* / Q000235:genetics; D057231:Climate Change; D018076:DNA, Complementary / Q000235:genetics; D018506:Gene Expression Regulation, Plant; D008031:Lignin / Q000235:genetics / Q000378:metabolism*; D031781:Paspalum / Q000235:genetics* / Q000254:growth & development; D030821:Plants, Genetically Modified / Q000235:genetics* / Q000254:growth & development; D012621:Seasons
chemical_list: D018076:DNA, Complementary; D008031:Lignin; D000445:Aldehyde Oxidoreductases; C019904:cinnamoyl CoA reductase