Regions of the Genome that Affect Agronomic Performance in Two‐Row Barley

Abstract

Quantitative trait locus (QTL) main effects and QTL by environment (QTL × E) interactions for seven agronomic traits (grain yield, days to heading, days to maturity, plant height, lodging severity, kernel weight, and test weight) were investigated in a two-row barley (Hordeura vulgare L.) cross, Harrington/TR306. A 127-point base map was constructed from markers (mostly RFLP) scored in 146 random double-haploid (DH) lines from the Harrington/TR306 cross. Field experiments involving the two parents and 145 random DH lines were grown in 1992 and/or 1993 at 17 locations in North America. Analysis of QTL was based on simple and composite interval mapping. Primary QTL were declared at positions where both methods gave evidence for QTL. The number of primary QTL ranged from three to six per trait, collectively explaining 34 to 52% of the genetic variance. None of these primary QTL showed major effects, but many showed effects that were consistent across environments. The addition of secondary QTL gave models that explained 39 to 80% of the genetic variance. The QTL were dispersed throughout the barley genome and some were detected in regions where QTL have been found in previous studies. Eight chromosome regions contained pleiotropic loci and/or linked clusters of loci that affected multiple traits. One region on chromosome 7 affected all traits except days to heading. This study was an intensive effort to evaluate QTL in a narrow-base population grown in a large set of environments. The results reveal the types and distributions of QTL effects manipulated by plant breeders and provide opportunities for future testing of marker-assisted selection. M OLECULAR MAPS of plant genomes, used in conjunction with phenotypic measurements, can provide information about chromosome regions that affect quantitative traits. Although knowing whether such regions represent individual quantitative trait loci (QTL)

Molecular basis of barley quality

“…QTLs for a given trait have been detected in multiple mapping populations and environments. For example, several important malting quality QTLs are always detectable in the similar region of chromosome 5H in several experiments (Hayes et al 1993;Han et al 1995;Oziel et al 1996;Tinker et al 1996Li et al 2002, Paris et al 2002. The QTL × environment interaction only results in differences in the magnitude of QTL effects.…”

Genetics of phenotypic plasticity: QTL analysis in barley, Hordeum vulgare

“…Each population was derived from a cross between two inbred parental lines in the following: The Harrington  TR306 (HT) population (n ¼ 145 doubled haploids) was the subject of prior QTL mapping reports Tinker and Mather, 1994;Tinker et al, 1996;Mather et al, 1997;Spaner et al, 1998). The Steptoe  Morex (SM) population (n ¼ 150 doubled haploids), first reported by Kleinhofs et al (1993), was also the subject of prior QTL reports Hayes and Iyamabo, 1994).…”

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

“…The majority of QTLs analyses for yield and yield component traits in barley were conducted with early balanced populations (Hayes et al 1993, Thomas et al 1995Tinker et al 1996;Bezant et al 1997, Yin et al 1999, Marquez-Cedillo 2000, while only four QTLs analyses have so far been conducted in advanced backcross barley populations (Matus et al 2003;Pillen et al 2003, Li et al 2004. Some QTLs in classical QTL studies consistently mapped to the same genomic regions despite a wide range of different germplasms used.…”