Establishment and characterisation of wheat genetic mapping populations

Abstract

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.

Molecular discrimination of Bx7 alleles demonstrates that a highly expressed high-molecular-weight glutenin allele has a major impact on wheat flour dough strength

“…respectively The results from this work bear importance, also regarding the genetic mapping of the CD87 Katepwa DH population due to the re-designation of CD87 and resulting DH lines as over-expressing Bx7. In retrospect, this can be deemed as an initial inaccuracy in polymorphism scoring, and could well be one source of segregation distortion, as discussed by Kammholz et al (2001). The development of this new marker now creates the opportunity for an improved method of polymorphism scoring in populations derived from CD87, and should be evaluated for use in other populations containing highexpressing Bx7 alleles, bearing in mind that the 18 bp duplication should not be assumed to be an unambiguous marker for the over-expression of the Bx7 allele.…”

“…Doubled-haploid lines (n=156 progeny lines) were derived from a CD87 Katepwa F1 cross and subsequent wheat maize doubledhaploid system; plants grown at Wongan Hills and Horsham were produced by the National Wheat Molecular Marker Program in Australia (NWMMP) (Kammholz et al 2001). The parents of this population were chosen for their contrasting physiological and functional features, specifically the high extensibility of CD87 as compared to that of Katepwa.…”

Quantitative trait loci and molecular markers associated with wheat allelopathy

“…This present study on the genetic markers associated with allelopathic activity was performed using the existing doubled-haploid mapping population Sunco Tasman, initially developed for studying wheat quality traits, such as flour colour and texture (Kammholz 2001). Although cv Tasman was strongly allelopathic, cv Sunco belonged to the intermediate allelopathic groups (Wu et al 2000a).…”

“…The doubled-haploid (DH) wheat population of SuncoTasman, consisting of 271 DH lines, was produced using the wheat maizederived DH production technique from F 1 plants by Kammholz et al (2001), and kindly supplied by Mr. John Sheppard of Leslie Research Centre, Queensland Department of Plant Industries, Australia.…”

"Perfect" markers for the Rht-B1b and Rht-D1b dwarfing genes in wheat

“…All lines scored positive for either the tall or the semi-dwarf allele. The genotypes were incorporated in an existing genetic map (Kammholz et al 2001). The markers were located to homoeologous regions of chromosomes 4B and 4D, respectively (Fig.…”