Quantitative Trait Loci Associated with Milling and Baking Quality in a Soft X Hard Wheat Cross Kimberley

Hybridization between soft and hard wheat creates new associations among loci. Advantages include an increase Interclass hybridization between soft and hard wheat (Triticum in genetic diversity, a potential increase in grain yield, aestivum L.) results in new genetic combinations of potential value. and transfer of pest resistance genes. Both May et al. We investigated whether interclass hybridization could improve enduse quality of both classes. Our objectives were to analyze quality (1989) and Carver (1996) indicated that recovery of soft traits in a population of recombinant inbred lines (RILs) derived from or hard wheat quality characteristics was possible in a cross between the good quality soft white wheat NY6432-18 (NY18), interclass single crosses if genetic variation for grain and good quality hard white wheat Clark’s Cream (CC), identify quality was maintained at a high level within the segrequantitative trait loci (QTLs) for those traits, and use linkage analysis gating population. A better understanding of the underto determine which parent was contributing favorable alleles at spelying genetic structure influencing wheat quality would cific QTLs for a given trait. The population was assessed for milling, hasten the development of unique wheats possessing protein and dough mixing, hydration, cookie and loaf traits. Traits value-added traits as well as wheats suited to convenwere measured in two to six environments grown over three seasons tional end-uses. Specifically, we wondered if interclass in Ithaca, NY. The molecular map for the population contains 370 hybridization could create new associations among loci molecular markers including restiction fragment length polymorthat would actually improve end-use quality of both phisms (RFLPs), microsatellites, and markers derived from known function genes in wheat. Linkage groups have been located to all the hard and soft wheat. wheat chromosomes except for 7D. Pinb derived from the puroindoWheat flour is classified for use in baking on the basis line b gene on chromosome 5DS was the major QTL for milling, of its texture (soft vs. hard) and chemical properties hydration, and cookie baking traits. The major QTL for mixograph (primarily protein). In the USA, the main use of hard peak time was at the Glu-Dy1 marker, derived from Glu-D1-2 gene wheat flour is for bread baking and the main use of on chromosome 1DL. The Glu-Ax1 and Glu-By1 markers were QTLs soft wheat flour is for cookie baking. Cookie flour is for mixograph peak height and tolerance, respectively. QTLs for flour characterized by low water absorption, fine particleprotein quantity were detected on chromosome 2B. With the excepsize, and low protein content as compared with bread tion of the hydration traits, multiple regression models included alleles flour milled from hard wheat (Hoseney, 1988). During from both parents. Interclass hybridization may be an underexploited the initial milling step, soft wheat endosperm fractures wheat breeding strategy for improvement of agronomic and quality through cell walls and hard wheat endosperm fractures traits in wheat. at the cell wall. As a consequence, soft wheat flour particles are finer than those in hard wheat flours. SubF wheat breeders routinely practice hybridizasequent milling passes released intact starch granules in tions among wheat classes because of the difficulty soft wheat flour. Starch wheat granules in hard wheat in recovering desired end-use quality characteristics. flour are fractured. The amount of damaged starch in flour is highly correlated with increased kernel hardness. The amount of water required by bread dough, or K.G. Campbell, USDA-ARS Wheat Genetics, Quality, Physiology, & Disease Research Unit, Washington State Univ., Pullman, WA 99164the dough water absorption value, depends on damaged 6420; C. Bergman, USDA-ARS Rice Research Unit, Beaumont, TX, starch and protein content (Miller et al., 1997). The 77713; D. Gualberto and P.L. Finney, USDA-ARS Soft Wheat Quality damaged starch is of value in yeast-leavened products Lab., Wooster OH, 44691; J. Anderson, Dep. of Agronomy and Plant because in addition to absorbing water, it acts as a subGenetics, Univ. of Minnesota, St. Paul, MN 55116; M. Giroux, Dep. strate for -amylase and creates a favorable environof Plant Sciences, Montana State Univ., Bozeman, MT 59715; D. Siritunga, Dep. of Plant Biology, The Ohio State Univ., Columbus OH ment for yeast growth. In contrast, chemical-leavened 43210; J. Zhu and M. Sorrells, Dep. of Plant Breeding and Biometry, soft wheat products have better texture if they are made Cornell Univ., Ithaca, NY 14853; F. Gendre, C. Roué and A. Vérel, from flour with small particle-size and low water retenDanone Vitapole-15, Avenue Galileé, 92350 Le Plessis Robinson, FRANCE. Mention of trade names does not connote endorsement Abbreviations: AWRC, alkaline water retention capacity; CC, Clark’s of products by The USDA-ARS, Cornell Univ., Montana State Univ., Cream; HMW, high molecular weight; LMW, low molecular weight; The Ohio State Univ. or The Univ. of Minnesota. Received 25 Jan. NY18, NY 6432-18; QTL, quantitative trait locus; RIL, recombinant 2000. Corresponding author (kgcamp@wsu.edu). inbred line; LOD, likelihood of odds; RFLP, restriction fragment length polymorphism. Published in Crop Sci. 41:1275–1285 (2001). 1276 CROP SCIENCE, VOL. 41, JULY–AUGUST 2001 tion capacity. Therefore damaged starch is undesirable in flour protein content, dough water absorption, dough mixing time, bread loaf volume, and bread loaf crumb in soft wheat flour (Bass, 1988). The bread-baking potential of wheat is typically asscore among a set of recombinant inbred hard spring wheat lines. The combined additive effects of the HMW sessed on the basis of flour protein quantity, through the use of physical dough mixing and recording instruments glutenin loci accounted for an average of just 13% of the parental differences in bread-baking quality, indicating such as the mixograph, and through experimental breadbaking procedures. An interrelationship between mixothat other loci were involved. For example, Prasad et al. (1999) recently identified a QTL on 2DL that explained graph peak time, peak height, tolerance, and flour protein quantity exists. Good bread flours have strong 18% of the variation in grain protein content in a cross between two Indian wheat cultivars. A chromosome gluten which is indicated by high protein quantity, long peak time, high peak height, and long or less negative segment on 6BS in Triticum turgidum L. subsp. dicoccoides increased protein quantity (Joppa et al., 1997). tolerance values. A combination of short peak time, high peak height, and very negative tolerance is a charThat chromosome segment was subsequently transferred and mapped in hexaploid wheat (Khan et al., acteristic of weak gluten flour. Weak gluten flours can also have short peak time, low peak height, and less 2000). Law et al. (1978) noted that 5DL influenced grain protein content in ‘Chinese Spring’/‘Hope’ chromosome negative tolerance. That type of flour could have good cookie baking qualities if it was soft with low protein substitution lines. Quantiative trait loci for grain protein content have been identified on 4B, 5A, 6A, 6B, and quantity. Cookie baking potential is assessed based upon water absorption as measured by the alkaline wa7B in durum wheat (Blanco et al., 1996). Wheat genetic stocks have been used to locate wheat ter retention capacity (AWRC) test, which mimics the high pH environment of chemical leavened batters. quality loci to chromosome arms. Mansur et al. (1990) reported that dough water absorption was increased by AWRC has a strong negative correlation with cookie diameter (Yamazaki, 1953). Experimental cookie bak‘Cheyenne’ chromosomes 1A, 1B, 1D, 2D, and 3B in a study of recombinant chromosome substitution lines of ing procedures are also used (Bloksma and Bushuk, 1988). the hard wheat Cheyenne into a Chinese Spring background. Loaf volume was increased by Cheyenne chroFlour yield from a small experimental mill is correlated with the straight grade flour yield from commercial mosomes 1A, 1B, 1D, 3A, 3B, 7A, and 7B. Mixing time was increased by chromosomes 1D and 7A. Flour promills. Higher flour yield is preferred for both hard and soft wheat. Softness equivalent is a measure of flour tein content was increased by Cheyenne chromosomes 1A, 4A, and 5D, and decreased by chromosomes 1B, particle-size and is correlated to the yield of break flour from of commercial mills (Finney and Andrews, 1986). 2A, 6B, and 7B. Zemetra et al. (1987) studied flour mixing time and mixing tolerance (a measure of a Break flour is released during the first pass of the wheat kernels through the mill break rolls. Wheats are either dough’s ability to resist breakdown) in a set of reciprocal substitution lines between the hard wheat cultivars classified as hard or soft. Intermediate texture is not desired. Wichita and Cheyenne. Significant effects on flour mixing time were noted for chromosome 1B and 2D. ChroSpecific genes with major effects on wheat end-use quality have been discovered. Kernel texture is conmosome 1B also influenced mixing tolerance as did 3B and 7B. trolled by a single locus Ha located on the short arm of chromosome 5D (Symes, 1965). Recently, Giroux Previous studies investigated the genetic control of milling and baking traits in crosses between good and and Morris (1998) reported that hard wheats do not have the puroindoline A (PINA) protein and do possess poor quality hard wheat cultivars or between a good quality hard wheat cultivar and a poor quality soft wheat a glycine to serine mutation in the puroindoline B (PINB) protein. The loci for Pina and Pinb are tightly cultivar like Chinese Spring. Bergman et al. (1998) reported heritabilities and genetic correlations for quality linked to each other on chromosome 5DS and probably function together as the Ha gene. Althou