RESUMO
Commelinid monocotyledons are a monophyletic clade differentiated from other monocotyledons by the presence of cell wall-bound ferulate and p-coumarate. The Poaceae, or grass family, is a member of this group, and most of the p-coumarate in the cell walls of this family acylates lignin. Here, we isolated and examined lignified cell wall preparations from 10 species of commelinid monocotyledons from nine families other than Poaceae, including species from all four commelinid monocotyledon orders (Poales, Zingiberales, Commelinales, and Arecales). We showed that, as in the Poaceae, lignin-linked p-coumarate occurs exclusively on the hydroxyl group on the γ-carbon of lignin unit side chains, mostly on syringyl units. Although the mechanism of acylation has not been studied directly in these species, it is likely to be similar to that in the Poaceae and involve BAHD acyl-coenzyme A:monolignol transferases.
Assuntos
Parede Celular/química , Lignina/metabolismo , Magnoliopsida/química , Propionatos/metabolismo , Acilação , Commelinaceae/química , Commelinaceae/citologia , Cotilédone/citologia , Ácidos Cumáricos , Hidrólise , Lignina/química , Espectroscopia de Ressonância Magnética , Magnoliopsida/citologia , Parabenos/química , Parabenos/metabolismo , Células Vegetais/química , Células Vegetais/metabolismo , Propionatos/química , Zingiberales/química , Zingiberales/citologiaRESUMO
Viscosity reduction has a great impact on the efficiency of ethanol production when using roots and tubers as feedstock. Plant cell wall-degrading enzymes have been successfully applied to overcome the challenges posed by high viscosity. However, the changes in cell wall polymers during the viscosity-reducing process are poorly characterized. Comprehensive microarray polymer profiling, which is a high-throughput microarray, was used for the first time to map changes in the cell wall polymers of sweet potato (Ipomoea batatas), cassava (Manihot esculenta), and Canna edulis Ker. over the entire viscosity-reducing process. The results indicated that the composition of cell wall polymers among these three roots and tubers was markedly different. The gel-like matrix and glycoprotein network in the C. edulis Ker. cell wall caused difficulty in viscosity reduction. The obvious viscosity reduction of the sweet potato and the cassava was attributed to the degradation of homogalacturonan and the released 1,4-ß-d-galactan and 1,5-α-l-arabinan.
Assuntos
Parede Celular/química , Ensaios de Triagem em Larga Escala , Análise em Microsséries , Raízes de Plantas/química , Tubérculos/química , Polímeros/química , Ipomoea batatas/química , Ipomoea batatas/citologia , Manihot/química , Manihot/citologia , Oxirredução , Viscosidade , Zingiberales/química , Zingiberales/citologiaRESUMO
Banana bunchy top nanovirus has a multicomponent, circular single-stranded DNA genome comprising at least six integral components, BBTV DNA-1 to -6, which have been consistently associated with bunchy top disease worldwide. At least three other components, BBTV S1, S2 and Y, which have been isolated from Taiwanese BBTV isolates, do not appear to be integral components. We show here that both BBTV DNA-1 and S1, which encode replication initiation (Rep) proteins, were capable of self-replication when bombarded into banana embryogenic cell suspensions. However, only BBTV DNA-1 was capable of directing the replication of two other BBTV genomic components, namely BBTV DNA-3 which encodes the coat protein, and DNA-5 which encodes a retinoblastoma binding-like protein. These results indicate that (i) BBTV DNA-1 is the minimal replicative unit of BBTV and encodes the 'master' viral Rep and (ii) BBTV S1 is possibly a satellite DNA which is unable to replicate integral BBTV components.
Assuntos
Proteínas do Capsídeo , DNA Helicases/genética , Vírus de DNA/genética , DNA Viral/biossíntese , DNA Viral/genética , Proteínas de Ligação a DNA , Vírus de Plantas/genética , Transativadores/genética , Replicação Viral , Zingiberales/virologia , Biolística , Capsídeo/genética , DNA Helicases/metabolismo , Vírus de DNA/crescimento & desenvolvimento , DNA Satélite/genética , DNA Viral/administração & dosagem , Vírus de Plantas/crescimento & desenvolvimento , Transativadores/metabolismo , Proteínas Virais/genética , Proteínas Virais/metabolismo , Zingiberales/citologia , Zingiberales/embriologiaRESUMO
A 1369 bp DNA fragment (Sc) was isolated from a full-length clone of sugarcane bacilliform badnavirus (ScBV) and was shown to have promoter activity in transient expression assays using monocot (banana, maize, millet and sorghum) and dicot plant species (tobacco, sunflower, canola and Nicotiana benthamiana). This promoter was also tested for stable expression in transgenic banana and tobacco plants. These experiments showed that this promoter could drive high-level expression of the beta-glucuronidase (GUS) reporter gene in most plant cells. The expression level was comparable to the maize ubiquitin promoter in standardised transient assays in maize. In transgenic banana plants the expression levels were variable for different transgenic lines but was generally comparable with the activities of both the maize ubiquitin promoter and the enhanced cauliflower mosaic virus (CaMV) 35S promoter. The Sc promoter appears to express in a near-constitutive manner in transgenic banana and tobacco plants. The promoter from sugarcane bacilliform virus represents a useful tool for the high-level expression of foreign genes in both monocot and dicot transgenic plants that could be used similarly to the CaMV 35S or maize polyubiquitin promoter.
