| 1 | Distribution,structure and biosynthetic gene families of(1,3;1,4)-β-glucan in Sorghum bicolor显示文摘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 fl uorescence and transmission electron microscopy. Micrographs showed a variable distribution of(1,3;1,4)-b-glucan in fl uenced 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 de fined.Transcript pro filing of these genes across sorghum tissues was carried out using real-time quantitative polymerase chain reaction, indicating that, as in other cereals, Csl F6 transcripts dominated. | 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 | 2015 | Journal of Integrative Plant Biology2015，57，4： | 2 |
| 4 | Ecological succession following forest decline in a xeric oak forest of south-central United States显示文摘Aims The loss of canopy trees associated with forest decline can greatly influence the species composition and structure of a forest and have major impacts on the ecosystem.We studied the changes in forest composition and structure 1 and 5 years following nearly total canopy mortality on several hundreds of hectares of xeric oak forests in south-central United States.Because the forests were within an ecotonal vegetation type composed of a mosaic of forest,savanna and grassland,we sought to learn whether forest decline areas would recover to forest or change to more open savanna and grassland conditions in the landscape pattern of vegetation.Because low intensity fire shaped the vegetation type,we sought to learn whether fire would keep the decline areas open.Methods The study was conducted in a xeric oak forest in east-central Oklahoma,USA.Randomly located vegetation and regeneration surveys were conducted in decline and non-decline stands 1 and 5 years following nearly total canopy mortality.Diameter at breast height(DBH),regeneration and sprout origin were recorded for all woody species.Important FindingsThe major canopy species post oak(Quercus stellata Wangenh.),blackjack oak(Quercus marilandica Muenchh.)and black hickory(Carya texana Buckl.)suffered 85-92%mortality;however,minor canopy components experienced limited mortality.Mortality affected all size classes of canopy trees except those below 5 cm breast height diameter.There was abundant regeneration of all species and fire seemed to maintain a high level of sprouting.Decline appeared to decrease the relative importance of stump sprouting and increase other types including root sprouts.Decline areas had abundant true seedlings,with stem origin from a root with the same diameter as the stem,which is very unusual for xeric oak forests.Regeneration height in decline areas was twice that of non-decline forests.Our findings suggest that forest decline may lead to:(i)reduced oak dominance and species change in the canopy,(ii)change in reproduction type to increase success of true seedlings and maintain genetic diversity of oaks. | Devin P.Bendixsen Stephen W.Hallgren Jesse A.Burton | 2016 | Journal of Plant Ecology2016，9，4： | 0 |
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