Summary
A novel mechanism for increasing vegetative biomass and grain yield has been identified in wheat (Triticum aestivum). RNAi‐mediated down‐regulation of Glucan, Water‐Dikinase (GWD), the ...primary enzyme required for starch phosphorylation, under the control of an endosperm‐specific promoter, resulted in a decrease in starch phosphate content and an increase in grain size. Unexpectedly, consistent increases in vegetative biomass and grain yield were observed in subsequent generations. In lines where GWD expression was decreased, germination rate was slightly reduced. However, significant increases in vegetative growth from the two leaf stage were observed. In glasshouse pot trials, down‐regulation of GWD led to a 29% increase in grain yield while in glasshouse tub trials simulating field row spacing and canopy development, GWD down‐regulation resulted in a grain yield increase of 26%. The enhanced yield resulted from a combination of increases in seed weight, tiller number, spikelets per head and seed number per spike. In field trials, all vegetative phenotypes were reproduced with the exception of increased tiller number. The expression of the transgene and suppression of endogenous GWD RNA levels were demonstrated to be grain specific. In addition to the direct effects of GWD down‐regulation, an increased level of α‐amylase activity was present in the aleurone layer during grain maturation. These findings provide a potentially important novel mechanism to increase biomass and grain yield in crop improvement programmes.
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BFBNIB, DOBA, FZAB, GIS, IJS, IZUM, KILJ, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBMB, UILJ, UKNU, UL, UM, UPUK
Flours from engineered wheat grain overexpressing a single α‐amylase type 3 (TaAMY3) were compared to flour from germinated grains to study the impact of elevated levels of α‐amylase on small‐scale ...noodle quality. The results showed that α‐amylase alone significantly reduced cooking time and increased cooking loss but had no detrimental effect on flour color, noodle color, or firmness. Noodles produced from sprouted grains were significantly detrimentally affected for all the above quality characteristics, in particularly after 24 and 48 h imbibition. A strong correlation was observed between the decrease in unextractable polymeric protein (UPP) levels, and noodle firmness. These findings raise important questions as to the supposition that α‐amylase is the source of the adverse effects of pre‐harvest sprouting (PHS) and late maturity α‐amylase (LMA) on Asian white‐salted noodles and highlights the usefulness of applying biotechnology in elucidating how flour components affect end product quality.
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Flours from engineered wheat grain overexpressing a single alpha-amylase type 3 (TaAMY3) were compared to flour from germinated grains to study the impact of elevated levels of alpha-amylase on ...small-scale noodle quality. The results showed that alpha-amylase alone significantly reduced cooking time and increased cooking loss but had no detrimental effect on flour color, noodle color, or firmness. Noodles produced from sprouted grains were significantly detrimentally affected for all the above quality characteristics, in particularly after 24 and 48h imbibition. A strong correlation was observed between the decrease in unextractable polymeric protein (UPP) levels, and noodle firmness. These findings raise important questions as to the supposition that alpha-amylase is the source of the adverse effects of pre-harvest sprouting (PHS) and late maturity alpha-amylase (LMA) on Asian white-salted noodles and highlights the usefulness of applying biotechnology in elucidating how flour components affect end product quality.
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Dietary fibre lowers the risk of coronary heart disease and colorectal cancer. This survey quantifies mixed link β-glucan (MBG) and arabinoxylan (AX) in wheat and investigates relationships between ...the grain carbohydrates. MBG and AX contents were measured in 500 and 200 wheat accessions respectively, including diploid, tetraploid and hexaploid genotypes comprising primitive, synthetic and elite lines. Overall, MBG contents ranged between 1.8 and 18.0 g kg... grain dry weight. In wheat-barley addition lines and triticale hexaploids the levels were 9.0-11.3 and 3.5-9.6 g kg... respectively. The amounts in synthetic wheats were nearer their tetraploid parents than their diploid parents. AX and total non-starch polysaccharide (NSP) contents ranged from 23.7 to 107.5 g kg... and from 31.7 to 136.7 g kg... respectively. Linear regressions showed that the relationships of starch and grain weight with NSP glucose were stronger than those with AX. The results indicated insufficient genetic diversity in the germplasm surveyed to initiate a breeding programme to increase the amount of MBG in wheat grain to 20 g kg..., a level considered high enough to confer a 10-15% reduction in blood cholesterol. (ProQuest: ... denotes formulae/symbols omitted.)
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
White clover (Trifolium repens L.) is an important pasture legume that does not normally accumulate fructan as a storage carbohydrate. We have generated transgenic white clover plants that accumulate ...fructan, by expressing the fructosyltransferase (Ftf) enzyme from the bacterium Streptococcus salivarius under the control of the cauliflower mosaic virus (CaMV) 35S promoter. Fructan accumulated in leaves, petioles, stolons, flowers, and roots of transgenic plants. Levels of fructan up to approximately 2% dry weight were measured in leaves. The fructan was of high molecular mass ( > 5000 kDa), typical of bacterial fructans. Ftf enzyme activity up to 120 nmol min–1 g–1 fresh weight was determined in leaf extracts of the transformed plants, and appeared to be stable throughout leaf development. Most transformed lines appeared normal, flowered and produced seed, but the growth rate of some transformed lines decreased. Photosynthetic carbon assimilation and levels of endogenous carbohydrates (hexoses, sucrose and starch) were not substantially changed in a clonal line with relatively low fructan. However, in a clonal line with relatively high fructan accumulation, plant growth was reduced, leaf photosynthesis was decreased by 60%, and carbohydrate contents were reduced. The results are discussed in the context of manipulating soluble carbohydrate composition in pasture species to improve nutritive quality for grazing animals.
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