Doubled haploid populations from 5 carefully selected wheat (Triticum aestivum L.) crosses were established in order to produce genetic maps. The characterisation of the parental material included pedigree analyses to define the extent of the genetic relationships among the lines and to determine the occurrence of alien chromosome segments that may contribute to segregation distortion. The characterisation of the parents also defined the range of grain quality traits that could be examined in the lines derived from each cross. Populations of up to 321 lines were produced using wide cross-mediated doubled haploid production from F1 plants. Assessment of the lines for heterogeneity was carried out using readily identifiable phenotypic markers and electrophoresis of seed storage proteins, with 2.3–11.6% of the lines being removed from further analysis. Segregation distortion was estimated in several populations where sufficient information from genetic markers was available. In a Sunco/Tasman doubled haploid population, heterogeneity was detected between the first 51 lines and the remainder of the mapping population and this could be traced to F1 plants that were produced from an earlier set of crosses. χ2 tests on the mapping data available for the Cranbrook/Halberd, CD87/Katepwa, and Sunco/Tasman doubled haploid populations revealed segregation distortion at rates of 1.8%, 5.1%, and 12.5% respectively. Whereas the wide-cross doubled haploid protocol does not appear responsible for the bulk of the non-Mendelian segregation observed, several potential sources were identified. In particular, clustering of distorted loci at specific chromosome regions appeared to be associated with the presence of alien introgressions in one of the parents. This was especially marked in the Sunco/Tasman population. Providing such distortions are recognised in the models used, these populations provide powerful tools for extensive mapping studies to determine the genetic factors controlling grain quality traits and other wheat characters of interest.

A wheat_maize induced doubled haploid population that segregates at the Awned locus for awned and awnless phenotypes were studied at two field sites using a genetic linkage map. Interval QTL analysis indicated that significant QTLs for wheat flour water absorption and protein content were located on a linkage group associated with the morphological marker, awns. The QTL peak for flour water absorption was located at the Awned locus (B1, 5AL), whilst the QTL peak for protein content was located nearby, 10.1 cm away from the Awned locus. The locations of those QTL were confirmed by analysing data from two independent field trials conducted under different environment conditions. The QTL identified for water absorption controlled 12% and 11% of the observed variance at the two field trials, whilst for flour protein content the QTL explained 7% and 19% of the variance respectively. Variance component analysis indicated that the QTL for water absorption controlled approximately 14.8-25.0% and 13.6-23% of the genetic variance at the two sites studied (Roma and imbour) whilst the QTL for protein content explained between 12.8% and 30.4% of the genetic variance at Roma and 34.7-82.6% at Jimbour. Cross-site analysis with composite interval mapping approach resulted in significant LOD values of 6.12 and 9.94 for water absorption and protein content, respectively. The QTL for water absorption was independent from the hardness locus.

Because of the importance of BYDV in wheat production worldwide, and given the difficulties of bioassaying for resistance, a molecular marker was developed for the resistance known as Bdv2 that originates on the long arm of chromosome 7Ai1 of Thinopyrum intermedium. This resistance was identified in a partial amphiploid line TAF46, a disomic addition line to wheat (L1), a telosomic addition line (7Ai1 L), and a series of recombinants and translocations. A RAPD (random amplified polymeric DNA) marker for the resistant germplasm was cloned and sequenced, and primers were designed against that sequence to produce a sequence characterised amplified region (SCAR) marker. A single PCR product is produced only with genotypes carrying the resistance from any of the available recombinants. The cloned sequence, recommended primers, and PCR protocols are described. The usefulness of the marker has been demonstrated for following Bdv2 in segregating wheat breeding germplasm, with the imminent release of a BYDV-resistant cultivar.

The segregation of both high and low molecular weight glutenin subunits across 7 F1 wheat (Triticum aestivum L.) × maize (Zea mays L.) derived doubled haploid populations was examined. The F1 wheats used in each population were produced from parents of interest to Australian wheat breeding programs. The parents varied by up to 5 glutenin subunit loci. Examination of subunits individually within each population using a chi-square analysis revealed that all but 2 of the 26 pairs of alleles analysed fitted the expected 1 : 1 segregation ratio. Glutenin profiles were examined for each cross individually and all but one (Sonalika/Hartog) fitted the expected Mendelian segregation pattern. The analysis of allele distribution of the 6 glutenin loci across all 7 crosses showed all falling well within expected segregation ratios. Closer examination of parental lines and populations revealed irregularities which conflict with original assumptions and provide a valid explanation for the few segregation distortions observed. It is concluded that wheat × maize-derived doubled haploid populations represent a unbiased assortment of parental gametes on both arms of Group 1 chromosomes.

Abstract. The aim of this study was to assess whether the recent finding that 4 Prime Hard wheat varieties grown at southern sites provided flour of comparable quality to that from northern sites is likely to be generally applicable to other varieties, as this is especially important as new varieties are developed. The grain, dough processing, and baking properties of samples from 4 sets of lines, each grown over 2 seasons at 2 northern and 2 southern sites, was assessed. The samples included 2 sets of doubled haploid lines (one derived from Hartog × Klasic, differing only at Glu-A3, and the other Hartog × CD-87, differing at 5 glutenin loci), and 2 sets of F 8 crossbred lines (from Janz/Hartog and Janz*2/Dollarbird, permitting an additional comparison of effects of allelic variation at the Glu-D1 locus). Approximately similar grain protein contents were obtained at one pair of northern and southern sites (respectively Narrabri and Ariah Park, 12-14%) and a second pair of northern and southern sites (respectively Roma and Walpeup, 14-17%, although the latter was consistently higher). The results demonstrated that the grain, dough, and baking properties of the lines were broadly similar at each protein content, and that in general, grain from the southern sites had comparable quality characteristics to that from the northern sites. However, in 1997, the Walpeup southern site suffered very dry conditions late in grain filling, and several of the grain samples were of low size and poor flour milling extraction rate and colour. In 1998, wet conditions late in the season meant that the grain at Ariah Park was lower in protein content and doughs were of lower extensibility and produced depressed loaf volumes. The variation in glutenin subunit composition also permitted the conduct of a detailed comparison of allelic influences on flour processing and baking properties at 4 sites and in 4 backgrounds. This revealed significant effects of allelic variation at Glu-B1, Glu-D1, and Glu-B3 on dough properties, with the effect of Glu-B1 differing between sets of lines.A R 0 1 2 0 5 H i g h q u a l i t y , h i g h p r o t e i n wh e a t i n s o u t h e r n A u s t r a l i a J . H . S k e r r i t t e t a l .