|Identification and characterization of near-isogenic hard and soft hexaploid wheats. Crop Science 41:211-217
|Morris,C.F., King,G.E., Allan,R. E. and Simeone,M.C.
USDA-ARS Western Wheat Quality Lab and Washington State University Dept. Crop and Soil Sciences
|A complete understanding of the
physical-chemical mechanism and underlying genetic control of wheat (Triticum
aestivum L.) endosperm texture will contribute to defining optimal grain
utilization while assisting the breeding and development of new cultivars. World
trade in wheat grain primarily is based on the two main market classes, "soft"
and "hard", which are mostly determined by the expression of the puroindoline
genes at the Hardness (Ha) locus. Here we identify and charcterize new
genetic stocks (Near Isogenic Lines, NILs) in four different genetic backgrounds
(20 NILs total, 9 hard and 11 soft). Methods included identifying homogenous
or mixed texture libes by Single Kernel Characterization System, and Near-Infrared
Reflectance Spectroscopy. Puroindoline genes and Ha allels were determined
through nucleic acid sequence analysis. The four different genetic sources for
NILs were: 1) accessions of 'Gamenya' cultivar which were physical mixtures
of hard and soft types; 2) existing near-isogenic lines from the cultivars Heron
and Falcon, 3) advanced-generation backcross lines involving 'Paha' and 'Early
Blackhull', and 4) 'Nugaines' and 'Early Blackhull Derivative'. The NILs reported
here provide new genetic materials for the study of wheat grain texture and
the effect of puroindolines and the Hardness gene on end-use quality.
Two of the four sets of NILs possess the Gly-46 to Ser-46 Pinb-D1b hardness
allele which has not been previously available in NILs. The results corroborate
a model of wheat grain texture that identifies two major haradness classes,
as opposed to one that accomodates intermediate texture classes such as "semi-hard"
and "medium-soft". A direct role on the puroindoline proteins in conferring
soft grain phenotype is supported; conversely, no genetic basis for intermediate
hardness was found. Rather intermediate hardness resulted from mixtures of the
soft and hard classes.
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