Quantifying host response of different barley (Hordeum vulgare) types to loose smut (Ustilago nuda)

Abstract

Ustilago nuda, the causal agent of loose smut, is an internal seed-borne fungus that induces significant yield and quality losses by constituting systemic infection in barley. This study aimed to quantify host response of different barley types (2-row, 6-row, spring, winter and facultative) to U. nuda by considering five agronomic characteristics (plant height, spike length, grain weight, root weight and biomass) of barley. Experiments were conducted in a greenhouse in two consecutive years by applying floret injecting technique for spike inoculations. As a result, compared to healthy plants, U. nuda infections caused significant (P<0.01) reductions in the examined agronomic characteristics of barley. Based on infection rates, four reaction types (highly resistant, resistant, moderately resistant and moderately susceptible) were determined among the tested barley cultivars. Infection rates were positively correlated with the mean reductions in plant height, grain weight, root weight and biomass. To the current state of knowledge, this is the first detailed study that quantifies host response of Turkish barley germplasm to U. nuda and suggests new resistance sources not only for conventional farming but also organic farming and breeding programs.