|Prevalence of puroindoline grain hardness genotypes among historically significant North American spring and winter wheats. Crop Science 41:218-228
|Morris C.F., Lillemo M., Simeone M.C., Giroux M.J., Babb S.L. and Kidwell K.K.
USDA-ARS Western Wheat Quality Lab, Washington State University Dept. Crop and Soil Sciences, Agricultural University of Norway Dept. Horticulture and Crop Science, Montana State University Dept. of Soil and Environmental Sciences
|Grain hardness ("hard" or "soft"
kernel texture) is the single most important trait in determining the utilization
and marketing of wheat (Triticum aestivum L.). Puroindoline a and b proteins
represent the molecular basis for this trait. This study surveyed the prevalence
of puroindoline hardness mutations (alleles) among North American spring and
winter wheat varieties with emphasis on those that are historically important.
Each variety was assessed for kernel texture using the Single Kernel Characterization
System; Hardness alleles were defined by puroindoline gene sequence and
the presence or absence of puroindoline a protein on polyacrylamide gels. A
total of 90 spring wheats were examined: nine were soft and possessed wild-type
("soft") puroindoline sequences, 10 were mixed hardness, and the remaining 71
were uniformly hard. Of these hard spring wheats, 18 carried the Pina-D1b
hardness allele (null for puroindoline a protein), 47 the Pinb-D1 b allele
(Gly-46-Ser-46), and four the Pinb-D1c allele (Leu-60-Pro-60). Two hard
spring wheats possessed a new allele, designated Pinb-D1e, which involves
a single nucleotide change in Trp-39 to a "stop" codon. Lastly, among the spring
wheats, a new hardness allele was found in the hard component of the variety
'Utac' which was mixed. This allele, Pinb-D1f, also involved a single
nucleotide change such that Trp-44 became a "stop" codon. A total of 62 winter
wheat varieties were examined, of which five were soft and three were of mixed
hardness. Of interest, the three mixed hardness wheats were 'Turkey', 'Kharkof',
and 'Weston'. The hard component of each carried the Pinb-D1b allele.
Of the 54 remaining wheats, all of which were hard, all but two carried the
same Pinb-D1b allele. 'Chiefkan' winter wehat carried the same Pinb-D1e
as 'Canadian Red' and 'Gehun' spring wheats. 'Andrews' hard red winter wheat
possessed a new allele, designate d Pinb-D1g, which was a single nucleotice
change in Cys-56 to a "stop" codon. In conclusion, hard grain phenotype results
from one of various mutations in either of the puroindoline proteins. To-date,
seven hardenss alleles have been discovered and characterized in hexaploid wheat.
All but one occur in the puroindoline b gene coding sequence and result from
single nucleotide changes. These molecular markers are useful in characterizing
lineages and analyzing ancestral relationships.
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