Quantitative Trait Loci for Germination and Malting Quality Characters in a Spring Barley Cross

Abstract

Absence of dormancy and good malting quality are significant targets of many barley (Hordeum vulgare L.) breeding programs. Expression of dormancy is strongly affected by the environment, and malting quality assays are expensive. Both groups of characters would therefore be suitable for marker‐assisted selection. The objective of this study was to identify quantitative trait loci (QTL) controlling germination and malting quality characters in a cross between the spring barley genotypes ‘Blenheim’ and E224/3 as an initial step in the development of a marker‐assisted selection scheme. The characters were measured on a random sample of doubled haploid lines from the cross grown in replicated trials each year from 1989 to 1992. The QTL were revealed by regression analysis of the data with marker scores from 120 mapped polymorphic loci. The QTL controlling hot water extract were located on barley Chromosomes 2, 3, and 7. Milling energy was largely controlled by a factor on Chromosome 7, a region also associated with extract viscosity. The denso dwarfing gene on Chromosome 3 was associated with a reduction in grain N but this was found to be a dilution effect as the locus had previously been found to be associated with an increase in grain yield. The germination characters showed little relationship with each other, possibly reflecting different mechanisms of control.

Analysis of quantitative traits in barley by the use of Amplified Fragment Length Polymorphisms

“…Good overall agreement in the location of QTL to chromosomal segments is observed between previous (Thomas et a!., 1995b(Thomas et a!., , 1996 studies based on RAPD and RFLP maps, and the present study which included AFLPs (Fig. 2).…”

“…With these possible exceptions, this confirms the dispersion of QTLs between parents leading to the transgressive segregation reported in previous studies of this cross (Thomas et a!., 1995b(Thomas et a!., , 1996. More than 67 per cent of the phenotypic variation accounted for by the sCIM analysis was attributable to main effects for most of the characters, the exceptions being GE4, 1GE8, DP and HWEc (Table 5).…”

“…The percentages of phenotypic variation accounted for by the main effects and interactions were less than those detected in the previous studies for HD, Ht, TGW, IGE8, ON and HWEc (Thomas The Genetical Society of Great Britain, Heredity, 79, 48-59. Table 5 Numbers of QTLs detected by MQTL using primary and secondary inferences for each character and the percentages of phenotypic variation accounted for by QTL main effects and QTL x E interactions compared to the average amount detected by single environment regression analysis (Thomas et aL, 1995b(Thomas et aL, , 1996 Main 6 + and -indicate the effect of alleles from Blenheim upon a trait. indicates a cross-over interaction where significant effects from Blenheim were positive in one environment and negative in another.…”

“…In the second cycle the program attempts to insert these markers but with the same restriction that if the JUMP threshold is exceeded, they are excluded. In the third cycle (Thomas et al, 1995b(Thomas et al, , 1996. In this paper, we will consider a subset of those characters (Table 2).…”

Quantitative Trait Loci Controlling Vegetative Growth Rate in the Edible Basidiomycete Pleurotus ostreatus

“…However, no quantitative analyses have been performed to determine exhaustively the number, positions, and effects of the genes involved. Quantitative trait locus (QTL) analysis has been applied widely to commercially important plant crops (22,32,33) but is rare in studies of mushrooms. Only for Agaricus bisporus has a QTL analysis of resistance to Pseudomonas tolaasii been described (24).…”