Linked morphological and molecular markers associated with common root rot reaction in barley

Abstract

Selection of common root rot [Cochliobolus sativus (Ito & Kurib.) Drechsl. ex Dastur] resistant barley germplasm is difficult due to the influence of environment on disease expression and the quantitative nature of resistance. Morphological and molecular markers associated with common root rot resistance could be used to increase the efficiency of selection of resistant germplasm and facilitate transfer to desirable barley genotypes Forty-five morphological marker sets consisting of four to six backcross-derived lines for each marker in a common background (cultivar Bowman) were planted in disease nurseries at two locations in each of 3 yr. Disease reactions of the back-cross-derived lines were tested for a difference from the disease reaction of Bowman, which indicated a putative association between the marker and common root rot reaction. An association was obtained between common root rot reaction and one set of backcross-derived lines that contained two linked markers: glossy-sheath (gs4) and orange lemma (o). A RAPD marker closely linked to gs4 and o was also associated with common root rot reaction. The RAPD marker was associated with the allele for resistance, while gs4 and o were associated with the allele for susceptibility. The RAPD marker would be most useful in the selection of common root rot resistant germplasm and the transfer of this resistance to other genotypes. Key words: Common root rot, Cochliobolus sativus, barley, morphological markers, molecular markers