Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/23/2009
Publication Date: 4/12/2010
Citation: Filichkin, T.P., Vinje, M.A., Budde, A.D., Corey, A.E., Duke, S.H., Gallagher, L., Helgesson, J., Henson, C.A., Obert, D.E., Ohm, J.B., Petrie, S.E., Ross, A.S., Hayes, P.M. 2010. Phenotypic Variation for Diastatic power, ß-Amylase Activity, and ß-Amylase Thermostability vs. Allelic Variation at the Bmy1 Locus in a Sample of North American Barley Germplasm. Crop Science. 50:826-834. Interpretive Summary: Crop improvement is always a complex endeavor and improvement of malting barley is made even more difficult by the need to improve both a suite of agronomic/production traits and an even larger number of malting quality traits, the latter of which are typically ill-defined and frequently change in order to meet industry's needs. Malting barley breeding programs are in need of accurate, easily used markers of high quality. To this end, many discrete genetic changes in genes known to be important in malting quality have been examined for their potential as molecular markers. This study specifically examines the genetic and functional variation of one of the most important components of malting quality, beta-amylase, in germplasm relevant to North America. This study demonstrates that the molecular markers for beta-amylase that are useful in some other barley growing regions of the world are not, in fact, useful in the germplasm studied here, which is adapted for growth and production in North America. The impact of the dissemination of this knowledge is two fold. First is that North American barley breeders will not waste resources on markers with no utility and, second, it clearly demonstrates the need for knowledge of the functional variation in target genes in the germplasm array undergoing selection for improvement in order to make informed decisions on implementation of marker assisted selection.
Technical Abstract: Malting quality data including diastatic power, ß-amylase activity, and ß-amylase thermostability, were collected on malts from three barley (Hordeum vulgare L.) breeding program trials containing two growth habits and 165 lines grown in multiple environments. We attempted to identify causal polymorphisms within the coding and intron III regions of the Bmy1 gene and by extension identify useful markers for marker assisted selection. The third intron of Bmy1 and the coding region for the parents of the spring barley germplasm arrays are identical despite having an abundant amount of malting quality variation. The entire gene was subsequently sequenced and no polymorphisms were found that correlated to malting quality phenotypes indicating the genetic basis for the observed variation must reside outside the Bmy1 gene. One of the parents of the winter barley germplasm array had a novel Bmy1 allele (Sd1a) even though it contained no intron III polymorphisms. However, there were amino acid substitutions found in the Sd1a allele that are considered candidates as causative agents for the phenotypic variation. The Sd1a allele, which is associated with low diastatic power, was present in only three of the 51 lines, presumably due to preceding generations being selected for high diastatic power. Marker assisted selection against the Sd1a allele may be successful but the lack of prevalence in the North American germplasm renders this marker irrelevant. This research illustrates the importance of having complete allele sequence and more importantly knowledge of functional polymorphisms in target genes before embarking on a breeding program based on marker assisted selection.