Response of barley immunodeficient mutants tweaky spike to salicylic acid in field conditions

Abstract

Salicylic acid (SA) serves as a signaling molecule for activation of Severas plant defense responses including systemic acquired resistance to pathogens. The action of SA was tested in field conditions on six barley allelic mutants tweaky spike (tw) and two mutants branched ear (be) induced in two different cltuvars, ‘Auksiniai II’ and ‘Auksiniai 3’ whese, were also tested as WT. Immunodeficiency of tw type mutants to fungal pathogens is manifested by increased susceptibility to Ustilago nuda and Claviceps purpurea, as well as by an increased frequency of moldy germinating grains. Field conditions were unfavorable to C. purpurea and U. nuda, but even in these conditions susceptibility of the tw mutant to U. nuda increased and the positive action of SA was observed. Susceptibility to Puccinia hordei and Drechslera teres is determined not by the genotype of the test mutants, but by the basic WT genotype of initial cultivars. Cv. ‘Auksiniai II’ was exclusively sensitive to D. teres. Seed-treatment of cv. ‘Auksiniai II’ and of the mutant tw increased plant resistance to that pathogen. Both the initial cultivars as well as all mutants arisen from them were resistant to powdery mildew (Blumeria graminis). Keywords: induced immunity response, salicylic acid, barley mutants, immunodeficiency