Distribution, structure and biosynthetic gene families of (1,3;1,4)-b-glucan in Sorghum bicolor

• Published in: 植物学报（英文版） 2015 (4), p.429-445
• Main Authors: Riksfardini A. Ermawar, Helen M. Collins, Caitlin S. Byrt, Natalie S. Betts, Marilyn Henderson, Neil J. Shirley, Julian Schwerdt, Jelle Lahnstein, Geoffrey B. Fincher, Rachel A. Burton
• Format: Article
• Language: English
• ISSN: 1672-9072
• DOI: 10.1111/jipb.12338

In cereals, the presence of soluble polysaccharides including (1,3;1,4)-b-glucan has downstream implications for human health, animal feed and biofuel applications. Sorghum bicolor (L.) Moench is a versatile crop, but there are limited reports regarding the content of such soluble polysaccharides. Here, the amount of (1,3;1,4)-b-glucan present in sorghum tissues was measured using a Megazyme assay. Very low amounts were present in the grain, ranging from 0.16%–0.27%(w/w), while there was a greater quantity in vegetative tissues at 0.12–1.71%(w/w). The fine structure of (1,3;1,4)-b-glucan, as denoted by the ratio of cellotriosyl and cellotetraosyl residues, was assessed by high performance liquid chromatography (HPLC) and ranged from 2.6–3:1 in the grain, while ratios in vegetative tissues were lower at 2.1–2.6:1. The distribution of (1,3;1,4)-b-glucan was examined using a specific antibody and observed with fluorescence and transmission electron micro-scopy. Micrographs showed a variable distribution of (1,3;1,4)-b-glucan influenced by temporal and spatial factors. The sorghum orthologs of genes implicated in the synthesis of (1,3;1,4)-b-glucan in other cereals, such as the Cellulose synthase-like (Csl) F and H gene families were defined. Transcript profiling of these genes across sorghum tissues was carried out using real-time quantitative polymerase chain reaction, indicating that, as in other cereals, CslF6 transcripts dominated.