VALIDATION OF DIASTATIC POWER QTL IN WESTERN SPRING SIX-ROWED BARLEY GERMPLASMS.

Authors: Hoffman, David; Obert, Donald; Hang, An

Submitted to: North American Barley Research Workshop Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 7/17/2005
Publication Date: 7/17/2005
Citation: Hoffman, D.L., Obert, D.E., Hang, A. 2005. Validation of diastatic power qtl in western spring six-rowed barley germplasms. North American Barley Research Workshop Proceedings.

Interpretive Summary: Barley is a major commodity in the western U.S., especially when utilized for malt production. Spring six-rowed barley germplasm adapted to the western U.S. is often low in diastatic power (DP), an important malting trait. DP quantitative trait loci (QTL) and linked markers have been identified in a spring six-rowed mapping population grown in western environments, but these QTL have not been validated in elite western six-rowed backgrounds and the QTL are based on restriction fragment length polymorphism (RFLP) markers. The objectives of this study were to validate DP QTL in populations containing elite western germplasm and to identify polymerase chain reaction (PCR)-based markers linked to select DP QTL. Low DP spring six-rowed cultivars or elite lines were crossed to ‘Morex’, a high DP 6-rowed barley, or to SM#42, a high DP line of the ‘Steptoe’/Morex mapping population. F1 plants were backcrossed to the adapted low DP lines two or three times, and segregating lines were developed from the backcrossed populations. The low DP parents and backcross-derived segregating lines were genotyped with PCR-based markers closely aligned to five DP QTL with large effects on chromosomes 1H, 4H, and 7H. Lines homozygous for the PCR-based markers and parental checks were planted in 4-m rows at Aberdeen, ID. Quality analysis to determine DP levels was performed by the Cereal Crops Research Unit, Madison, WI. Nearly all the low DP parental lines had marker alleles that resembled either Steptoe or Morex with regard to DNA fragment size. Two lines from Utah State University had DP-negative marker alleles for all loci except the one on the short arm of chromosome 4H. Some had more DP-positive alleles with a few DP-negative alleles, while others had similar numbers of DP-positive and DP-negative alleles. Also, some heterogeneity within lines was detected. We plan to determine if relationships between marker genotype and DP can be identified in the advanced populations and if other traits are affected by DP marker selection. This study should provide useful information for the development of six-rowed malting barleys in the western U.S

Technical Abstract: Barley is a major commodity in the western U.S., especially when utilized for malt production. Spring six-rowed barley germplasm adapted to the western U.S. is often low in diastatic power (DP), an important malting trait. DP quantitative trait loci (QTL) and linked markers have been identified in a spring six-rowed mapping population grown in western environments, but these QTL have not been validated in elite western six-rowed backgrounds and the QTL are based on restriction fragment length polymorphism (RFLP) markers. The objectives of this study were to validate DP QTL in populations containing elite western germplasm and to identify polymerase chain reaction (PCR)-based markers linked to select DP QTL. Low DP spring six-rowed cultivars or elite lines were crossed to ‘Morex’, a high DP 6-rowed barley, or to SM#42, a high DP line of the ‘Steptoe’/Morex mapping population. F1 plants were backcrossed to the adapted low DP lines two or three times, and segregating lines were developed from the backcrossed populations. The low DP parents and backcross-derived segregating lines were genotyped with PCR-based markers closely aligned to five DP QTL with large effects on chromosomes 1H, 4H, and 7H. Lines homozygous for the PCR-based markers and parental checks were planted in 4-m rows at Aberdeen, ID. Quality analysis to determine DP levels was performed by the Cereal Crops Research Unit, Madison, WI. Nearly all the low DP parental lines had marker alleles that resembled either Steptoe or Morex with regard to DNA fragment size. Two lines from Utah State University had DP-negative marker alleles for all loci except the one on the short arm of chromosome 4H. Some had more DP-positive alleles with a few DP-negative alleles, while others had similar numbers of DP-positive and DP-negative alleles. Also, some heterogeneity within lines was detected. We plan to determine if relationships between marker genotype and DP can be identified in the advanced populations and if other traits are affected by DP marker selection. This study should provide useful information for the development of six-rowed malting barleys in the western U.S