Malting barley improvement.

Hayes, P.

Abstract
Although tremendous improvements in malting barley quality have been achieved over the past century or so, traditional breeding methods are laborious, time consuming and dependent on the vagaries of natural genetic processes. However, recent advances in genetics offer the potential for much greater control, enabling new varieties to be systematically "designed" and certain problems of traditional breeding to be overcome. It is well known that desirable and undesirable heritable characteristics are often closely linked; for instance, barley varieties with outstanding agronomic properties, such as yield and adaptability to varying climates and soils, often have poor malting quality and vice versa. Attempts to combine two sets of desirable characteristics often fail because the genes for all the traits in question are close together on the same chromosome, and tend to be inherited together; the occasional natural recombinants often do not breed true. "Doubled haploid" techniques, in which one set of chromosomes in a hybrid is eliminated and the remaining one duplicated, so that the resulting plant has two identical sets and if self pollinated can only produce offspring genetically identical to itself, can be used to stabilise new gene combinations. Such plants are also useful in genetic mapping. By analysis of DNA variation between different genetically uniform lines which differ in relevant characteristics, the genes governing these traits can be located and genetic markers associated with desirable properties identified. The use of recombinant techniques, e.g. to confer high malting quality on a high yielding variety previously only usable as feed barley, would be greatly facilitated by this means. It might also become possible to introduce desirable genes from other species.
Keywords : barley breeding genetic mapping genetic marker hybridisation recombination