Identification of Genetic Sources of Resistance to the Seed-Born Leaf Stripe Disease of Barley (Pyneophera graminea Ito & Kurib)

Leaf stripe disease of barley is caused by the seed transmitted hemi-biotrophic fungus Pyneophera graminea which has spread in to important areas of barley production in Iran especially in Khorasan Razavi province. The fungus survives as a mycelium in the pericarp, the hull and the seed coat, but not in the embryo. During the seed generation, its growing mycelium penetrates the coleorhiza and it colonized the plant systematically starting from the root tip. Once infection spreads into the young leaves, growth switches to a necrotrophic phase with the production of a host-specific glycosyl toxin that causes longitudinal dark brown necrotic stripe between the leaf veins, as well as spike sterility. Finally become necrotic, lead to severe yield reduction when seed infection is high, especially in organic farming systems. The aim of the present study was to evaluate the resistance of domesticated commercial cultivars (23 cultivars), promising candidate genotypes (23 genotypes) and foreign genetic resources (30 cultivars).

In this study, the resistance of 46 commercial cultivars and promising genotypes with 30 cultivars resistant to barley leaf stripe reported in scientific sources to leaf stripe disease with six morphological traits including days to heading, plant height, number of seed in spike, one-thousand grains weight and days to maturity was evaluated in randomized complete block design with three replications during two cropping years (2017-2019) in Mashhad Agricultural and Natural Resources Research and Education Center. Infection of plants occurred naturally. Evaluation of resistance of genotypes by Delogo method was calculated based on the percentage of infected plants as well as components of variance, heritability, genetic and phenotypic coefficients using SPSS software and formula.

All of the traits were significant and highly significant among the genotypes during two years. The highest coefficient of genetic diversity was observed in the number of rows in spike and the number of seeds per spike and the lowest was observed in the number of days to flowering. Heritability above 90% was obtained for most of traits. A positive correlation was shown between most of the traits. The highest coefficient of variation is belonged to disease incidence. The percentage of infection in the first year varied between 0 and 54.5% and in the second year ranged from one to 64.5%. Disease incidence for first year was observed, 23 highly resistant genotypes, two resistant genotypes, 13 moderately resistant genotypes and eight susceptible genotypes and also for second years evaluated 21 highly resistant genotypes, five resistant genotypes, 13 moderately resistant genotypes and seven sensitive genotypes.

Leaf stripe disease has a significant effect on reducing barley yield, so it can be managed by identifying resistant cultivars. Based on the results, the studied cultivars and genotypes showed various reactions to disease, ranging from susceptible to highly resistant. Most genotypes were observed as highly resistant and moderately resistant. According to results two-row genotypes had a higher resistance level than six-row genotypes to leaf stripe. Based on the results, a number of commercial cultivars, including Walfajre, Dasht, Bahman, Behrokh and Nik have been resistant or semi-resistant to this disease