Leaf scald resistance genes in Hordeum vulgare and Hordeum vulgare ssp. spontaneum: parallels between cultivated and wild barley

Abstract

The prerequisite for breeding barley varieties with durable scald resistance is a diversity of genes each with molecular markers for their manipulation in crosses. Here we compare the outcomes of genetic analysis of scald resistance in 5 doubled haploid mapping populations of cultivated barley with 9 third-backcross families that derive from a set of diverse wild barley populations. In all cases, resistance was assessed as seedling infection type responses, but the Sloop/Halcyon population was also tested for adult plant resistance in field trials at two sites. In the latter case, the major quantitative trait locus for field resistance was coincident with that for seedling response on chromosome 3H. Most of the other cultivated barley sources of resistance in this study (1 cultivar and 3 breeders populations synthesised for resistance) also resolved to markers in the region of this 3H locus. In contrast, the genetic basis of resistance in wild barley populations resolved to at least 5 chromosome locations (1HS, 3H, 6HS, 7HL, and 7HS). Useful markers were of several kinds including proteins, isozymes, PCR based on RFLPs, AFLP, and SSR loci. Thus, wild barley increases the range of options for pyramid breeding and provides linked molecular markers that will be useful in manipulating those genes, or in the analysis of resistance in new sources.