The effect of selection for protein and isozyme loci on quantitative traits in a doubled haploid population of barley

Abstract

Doubled haploid families extracted from the F1 hybrid of the spring barley cross (Dissa x Sabarlis) by the Hordeum bulbosum technique were scored for the segregation of alleles at isozyme Joel. Isozyme and protein loci on all seven pairs of barley chromosomes were examined and five out of the seven pairs of barley chromosomes (2!, 31,41, 6! and 7!) were shown to possess polymorphic isozyme and protein loci. The systems tested did not deviate significantly from the expected 1: 1 ratio and esterase loci on chromosome 3 were mapped intra-chromosomally. The relationship between marker loci and quantitative trait loci (QTL) was examined. A comparison of the mean scores for each allelic class revealed significant differences in the expression of a range of quantitative traits. Thus, by selecting for isozyme and protein phenotypes one can significantly affect the expression of certain QTL in barley. For example, allelic variation at the a-Amy-I locus makes a large contribution to the genetic variation available for selection in the case of single plant yield. The advantage of using DH families for gene mapping and in dissecting QTL are discussed.

Chromosome location of genes controlling tolerance to salt (NaCl) and vigour in Hordeum vulgare and H. chilense

“…The disadvantage of the group 6 or group 7 addition lines over euploid wheat is their lack of true breeding due to poor transmission of the extra chromosomes, particularly in the pollen. The positive effects of chromosome 6H on grain yield has also been noted in a barley doubled haploid population derived from the cross Dissa x Sabarlis (Powell et a!., 1990). Increased yields of doubled haploid lines were found to be associated with the a-amylase-1 phenotype of Sabarlis; the a-Amy-i gene is located on the long arm of 6H and this may provide a means of marking genes which influence vigour in barley (Powell et al, 1990).…”

AB-QTL analysis in spring barley: II. Detection of favourable exotic alleles for agronomic traits introgressed from wild barley (H. vulgare ssp. spontaneum)

“…These are predominantly yield QTLs identified on chromosome arms 2HS, 3HL and 6HL. Their effect on yield are commonly explained by pleiotropic effects of the photoperiod response gene Ppd-H1 on 2HS (Li et al 2004), the dwarfing gene denso on 3HL (Thomas et al 1995), and linkage to the Amy1 locus on 6HL (Powell et al 1990;Bezant et al 1997). These genomic regions also revealed significant effects on yield in this study (QYld.S42-2H.a, QYld.S42-3H.b and QYld.S42-6H.a) with the favourable QTL allele contributed by the elite parent.…”

Segregation of genetic markers among wheat doubled haploid lines derived from wheat x maize crosses

“…Powell et al (1986) reported that the microspore-derived DH lines showed distorted segregation ratios in three of the five loci investigated, whereas the DH lines obtained through the H. bulbosum technique, in only one. No deviation was observed in seven markers among the DH lines obtained through the H. bulbosum technique from a different combination (Powell et al, 1990). Kjaer et al (1991) reported that the DH lines obtained through the H. bulbosum technique showed no significant deviation from the expected ratio in nine out of the ten markers.…”