Project description:The effect of plant growth-promoting bacteria inoculation on plant growth and the sugar content in Agave americana was assessed. The bacterial strains ACO-34A, ACO-40, and ACO-140, isolated from the A. americana rhizosphere, were selected for this study to evaluate their phenotypic and genotypic characteristics. The three bacterial strains were evaluated via plant inoculation assays, and Azospirillum brasilense Cd served as a control strain. Phylogenetic analysis based on the 16S rRNA gene showed that strains ACO-34A, ACO-40 and ACO-140 were Rhizobium daejeonense, Acinetobacter calcoaceticus and Pseudomonas mosselii, respectively. All of the strains were able to synthesize indole-3-acetic acid (IAA), solubilize phosphate, and had nitrogenase activity. Inoculation using the plant growth-promoting bacteria strains had a significant effect (p<0.05) on plant growth and the sugar content of A. americana, showing that these native plant growth-promoting bacteria are a practical, simple, and efficient alternative to promote the growth of agave plants with proper biological characteristics for agroindustrial and biotechnological use and to increase the sugar content in this agave species.
Project description:Agave americana L. is a highly productive, drought-tolerant species being investigated as a feedstock for biofuel production. Some Agave spp. yield crop biomass in semi-arid conditions that are comparable to C3 and C4 crops grown in areas with high rainfall. This study evaluates the bioethanol yield potential of A. americana by (1) examining the relationship between water use efficiency (WUE) and plant carbohydrates, (2) quantifying the carbohydrate and energy content of the plant tissue, and (3) comparing the products of enzymatic hydrolysis to that of other candidate feedstocks (Miscanthus x giganteus Greef et Deuter, Sorghum bicolor (L.) Moench, and Panicum virgatum L.). Results indicate that (1) WUE does not significantly affect soluble and insoluble (i.e., structural) carbohydrate composition per unit mass in A. americana; (2) without pretreatment, A. americana biomass had the lowest gross heat of combustion, or higher heating/calorific value, compared to high yielding C4 crops; and (3) after separation of soluble carbohydrates, A. americana cellulosic biomass was most easily hydrolyzed by enzymes with greater sugar yield per unit mass compared to the other biomass feedstocks. These results indicate that A. americana can produce substantial yields of soluble carbohydrates with minimal water inputs required for cultivation, and fiber portions of the crop can be readily deconstructed by cellulolytic enzymes for subsequent biochemical fermentation.
Project description:We report here the complete genome sequence of Rhizobium sp. strain ACO-34A, isolated from Agave americana L. rhizosphere. No common nod genes were found, but there were nif genes for nitrogen fixing. A low average nucleotide identity to reported species supports its designation as a novel Rhizobium species that has a complete ribosomal operon in a plasmid.
Project description:Agave plants are important crassulacean acid metabolism (CAM) plants with multiple agricultural uses, such as being used in tequila and fiber production. Agave hybrid H11648 ((A. amaniensis Trel. and Nowell × A. angustifolia Haw.) × A. amaniensis) is the main cultivated Agave species for fiber production in large tropical areas around the world. In this study, we conducted a transcriptome analysis of A. H11648. About 49.25 million clean reads were obtained by Illumina paired-end sequencing. De novo assembly produced 148,046 unigenes with more than 40% annotated in public databases, or matched homologs in model plants. More homologous gene pairs were found in Asparagus genome than in Arabidopsis or rice, which indicated a close evolutionary relationship between Asparagus and A. H11648. CAM-related gene families were also characterized as previously reported in A. americana. We further identified 12 cellulose synthase genes (CesA) in Asparagus genome and 38 CesA sequences from A. H11648, A. americana, A. deserti and A. tequilana. The full-length CesA genes were used as references for the cloning and assembly of their homologs in other Agave species. As a result, we obtained CesA1/3/4/5/7 genes with full-length coding region in the four Agave species. Phylogenetic and expression analysis revealed a conserved evolutionary pattern, which could not explain the distinct fiber traits in different Agave species. We inferred that transcriptional regulation might be responsible for Agave fiber development. This study represents the transcriptome of A. H11648, which would expand the number of Agave genes and benefit relevant studies of Agave fiber development.
Project description:Agave species are important crassulacean acid metabolism (CAM) plants and widely cultivated in tropical areas for producing tequila spirit and fiber. The hybrid H11648 of Agave ((A. amaniensis × A. angustifolia) × A. amaniensis) is the main cultivar for fiber production in Brazil, China, and African countries. Small Auxin Up-regulated RNA (SAUR) genes have broad effect on auxin signaling-regulated plant growth and development, while only few SAUR genes have been reported in Agave species. In this study, we identified 43, 60, 24, and 21 SAUR genes with full-length coding regions in A. deserti, A. tequilana, A. H11648, and A. americana, respectively. Although phylogenetic analysis revealed that rice contained a species-specific expansion pattern of SAUR gene, no similar phenomena were observed in Agave species. The in silico expression indicated that SAUR genes had a distinct expression pattern in A. H11648 compared with other Agave species; and four SAUR genes were differentially expressed during CAM diel cycle in A. americana. Additionally, an expression analysis was conducted to estimate SAUR gene expression during different leaf developmental stages, abiotic and biotic stresses in A. H11648. Together, we first characterized the SAUR genes of Agave based on previously published transcriptome datasets and emphasized the potential functions of SAUR genes in Agave's leaf development and stress responses. The identification of which further expands our understanding on auxin signaling-regulated plant growth and development in Agave species.
Project description:Plant biomass from different species is heterogeneous, and this diversity in composition can be mined to identify materials of value to fuel and chemical industries. Agave produces high yields of energy-rich biomass, and the sugar-rich stem tissue has traditionally been used to make alcoholic beverages. Here, the compositions of Agave americana and Agave tequilana leaves are determined, particularly in the context of bioethanol production. Agave leaf cell wall polysaccharide content was characterized by linkage analysis, non-cellulosic polysaccharides such as pectins were observed by immuno-microscopy, and leaf juice composition was determined by liquid chromatography. Agave leaves are fruit-like--rich in moisture, soluble sugars and pectin. The dry leaf fiber was composed of crystalline cellulose (47-50% w/w) and non-cellulosic polysaccharides (16-22% w/w), and whole leaves were low in lignin (9-13% w/w). Of the dry mass of whole Agave leaves, 85-95% consisted of soluble sugars, cellulose, non-cellulosic polysaccharides, lignin, acetate, protein and minerals. Juice pressed from the Agave leaves accounted for 69% of the fresh weight and was rich in glucose and fructose. Hydrolysis of the fructan oligosaccharides doubled the amount of fermentable fructose in A. tequilana leaf juice samples and the concentration of fermentable hexose sugars was 41-48 g/L. In agricultural production systems such as the tequila making, Agave leaves are discarded as waste. Theoretically, up to 4000 L/ha/yr of bioethanol could be produced from juice extracted from waste Agave leaves. Using standard Saccharomyces cerevisiae strains to ferment Agave juice, we observed ethanol yields that were 66% of the theoretical yields. These data indicate that Agave could rival currently used bioethanol feedstocks, particularly if the fermentation organisms and conditions were adapted to suit Agave leaf composition.