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Abstract:
This programme aims to optimise end user quality traits in wheat
and barley. Milling yield is dependent on size and shape of
grains and on the proportion of endosperm to the other tissues
in the grain. The recessed ventral groove of wheat is a
particular obstacle to the efficient extraction of the white
flour and the adoption of new de-branning technology in UK mills
has further increased the importance of crease morphology. For
barley, a short, fat grain is desirable to assist water uptake
and rapid starch mobilisation during malting. We will use
forward and reverse genetics approaches combined with knowledge
of seed development in model systems to improve our
understanding of grain size and shape. This programme involves
the major laboratories presently engaged in research in grain
and seed development in the UK, together with a leading group
working on milling technology allowing the benefits of altered
grain shape to milling yield and malting quality to be assessed.
We have shown that UK wheat varieties differ in grain morphology
and will extend our analysis to broader germplasm including T.
aestivum sphaerococcum which has rounded grains and a reduced
crease. Introgression of the "sphaerococcum" phenotype into
elite UK material will allow the effects on de-branning and
milling yield to be determined. The segregation of QTLs for
grain shape will be studied in different populations to identify
linked markers. We will also map and identify genes that may be
controlling a similar (globosum) phenotype in barley. Our work
in the model species Arabidopsis and maize is resolving the
processes and genes that are involved in cell proliferation and
differentiation in the endosperm. We hypothesise that cereal
orthologues of these genes may underlie QTLs for grain size and
shape. The expression of selected candidates will be altered in
transgenic wheat or through TILLING in barley and an assessment
of grain morphology and quality traits compared to parental
lines.
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