Genetic Loci Related to Kernel Quality Differences between a Soft and a Hard Wheat Cultivar

processing and end-use characteristics, which depend on protein hydration and development through mixing. Hybridizations between hard and soft wheat types could be a source Hard wheat is generally used for making bread-type of novel variation for wheat quality improvement. This study was conducted to identify genomic regions related to differences in milling and products, and soft wheat is generally preferred for baking quality between a soft and a hard cultivar of hexaploid wheat pastry-type products. Hard grain requires more energy (Triticum aestivum L.). A population of 101 double-haploid lines was to be reduced to flour than soft grain, and its starch generated from a cross between Grandin, a hard spring wheat variety, granules are damaged more during milling. Damaged and AC Reed, a soft spring wheat variety. The genetic map included starch granules absorb more water, thereby altering sev320 markers in 43 linkage groups and spanned 3555 cM. Quadrumateral baking properties (Mok and Dick, 1991). milled flour yield, softness equivalent, flour protein content and alkaline Hybridizations between hard and soft wheat types water retention capacity were evaluated for three locations and one year, could expand the genetic base of wheat breeding and and Allis-Chalmers milling, mixograph, and cookie baking tests were create new possibilities for combinations of desirable completed without replication. The effect of qualitative variation for alleles from both germplasm subgroups. However, this kernel texture, caused by the segregation of the Hardness gene, was controlled by regression on texture class. The residual variance was used type of cross is not common practice in wheat breeding for composite interval mapping, and QTLs on 1A, 1B, 1A/D, 2A, 2B, because the two classes have distinct quality goals. 2D, 3A/B, 4B, 5B and 6B were detected. The effect of some QTLs was Carver (1996) compared interclass hybrids, backcrosses opposite to the direction expected on the basis of parental phenotypes. and progeny from a hard hard cross, and concluded The hard wheat parent contributed alleles favorable for soft wheat variethat the interclass crosses resulted in progenies with ties at QTLs on 1AS,L, 1BL-2, and 6B, whereas the soft parent contribhigher grain yield but lower flour yield and larger variuted alleles for higher protein content at QTLs on 2BL-1, 4B-1, and 6B ability for quality traits, and that recovering the quality and higher flour yield on 2BL-2 and 4B-2. These results indicated that profile of the hard type through intensive selection would hard soft wheat crosses have considerable potential for improving be feasible. Identification of quantitative trait loci (QTL) milling and baking quality of either class. related to quality differences between classes could help in planning complementary crosses and backcrosses, and in designing selection schemes to recover the quality charT texture of grain of hexaploid wheat is either acteristics needed in either class. hard or soft, each resulting in flour with different Major genes controlling the difference in kernel texture between soft and hard wheat were mapped on the F. Breseghello, Embrapa, C.P. 179, Santo Antonio de Goias, GO, 75375, short arm of chromosome 5D (Sourdille et al., 1996), Brazil; J. Tanaka and M.E. Sorrells, Dep. of Plant Breeding and Genetics, and as a group are named Ha or Hardness locus (Baker, 240 Emerson Hall, Cornell Univ., Ithaca, NY 14853; P.L. Finney, Roman 1977). The product of that locus is called friabilin, which Meal Co., 2101 S. Tacoma Way, Tacoma, WA 98409; C. Gaines and L. is a composite of related proteins that include puroindoAndrews, USDA, Soft Wheat Quality Lab., Williams Hall, 1680 Madison Ave. Wooster, OH 44691; G. Penner, NeoVentures Biotechnology Inc., line a and puroindoline b (Giroux and Morris, 1998). 69 Mary Street, Guelph, ON, Canada, N1G 2A9F. We thank the NaOther QTLs, with minor effects on kernel texture within tional Council for Scientific and Technological Development-CNPq, the hard wheat type, were detected on chromosomes Brazil for the studentship granted to F. Breseghello. This paper is part 1A and 6D (Perretant et al., 2000). of his PhD dissertation. Also, we wish to express our gratitude to Populations derived from crosses between hard and Danone for the extended support of this research. Financial support was also provided by USDA Hatch Project 149419, and by USDAsoft genotypes have higher expected marker polymorIFAFS Competitive Grant No. 2001-04462. Received 19 May 2004. phism because of the divergence between the two breed*Corresponding author ([email protected]). ing groups, which can facilitate building a linkage map, compared with other elite elite crosses. Additionally, Published in Crop Sci. 45:1685–1695 (2005). Crop Breeding, Genetics & Cytology doi:10.2135/cropsci2004.0310 © Crop Science Society of America Abbreviations: AWRC, Alkaline water retention capacity; CIM, Composite interval mapping; SMR, Single marker regression analysis. 677 S. Segoe Rd., Madison, WI 53711 USA 1685 Published online August 1, 2005