The Genomes of the Secondary and Tertiary Gene Pools of Barley

Abstract

In plant breeding, crop wild relatives are usually a valuable genetic resource for crop improvement. Thereby, wild relatives of a plant are divided into three different gene pools, depending on how difficult it is to produce hybrids between a species and the crop itself. In barley (Hordeum vulgare spp. L), the primary gene pool consists of barley itself, landraces and H. spontaneum. These germplasms are easy to utilize and were frequently used for barley improvement. By contrast, species of the secondary and tertiary gene pool are much more difficult to access and have thus not yet been reported to be utilized for barley breeding. H. bulbosum is the only member within the secondary gene pool. A relatively large set of hybrids, substitution and introgression lines between barley and H. bulbosum have been produced and characterized on a physiological and molecular level. Recently, the latest molecular tools such as genotyping-by-sequencing and Exome Capture have been utilized to unlock these genetic resources. While about 31 highly diverse species belong to the tertiary gene pool, not much success has been reported so far to access them.