|Assessing Genotypic Softness in Single Wheat Kernels Using Starch Granule-Associated Friabilin as a Biochemical Marker. Euphytica 86:65-72
|Bettge,A.D., Morris,C.F. and Greenblatt,G.A.
|The end-use quality of wheat (Triticum
aestivum L.) is determined in large part by the texture of the grain (soft or
hard). Endosperm texture is currently determined by several empirical methods.
These methods are limited because they use bulk grain lots, as opposed to individual
kernels; assess phenotypic, as opposed to genotypic hardness; require a quantity
of grain greater than that generally available in the early generations of wheat
breeding programs, and are destructive. Recent approaches that use single kernels
address the problems associated with bulk grain lots, but suffer the other limitations
of providing only the phenotype and being destructive. An objective method for
determining the texture genotype of single kernels of wheat was developed using
starch granule-associated friabilin, a family of closely related 15 kDa proteins,
as a biochemical marker. The occurrence of friabilin on water-washed wheat starch
granules is apparently unaffected by the environment and is perfectly correlated
(no exceptions) with grain softness. The technique presented here can detect
friabilin on as little as 0.2 mg of starch and provides a 250-fold improvement
in friabilin detection compared to previous methods. The method uses only a
portion of the endosperm of F1 heterozygotes from hard x soft and
soft x hard crosses. Further, the method uses only a portion of the endosperm
kernel and therefore accommodates embryo propagation and high molecular weight
glutenin subunit characterization. This single kernel method also facilitates
the genetic characterization of mixed, bulk grains.
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