Assessment of Barley Accessions PI 382313, PI 382474, PI 382915, and PI 382976 for Stem Rust Resistance

Abstract

New sources of resistance to Puccinia graminis Pers. f. sp. tritici Erikss. and Henn. in barley(Hordeum vulgare L.) should be identified and incorporated into breeding programs to ensure the continued resistance of barley to this pathogen. The objective of this study was to identify resistance to stem rust in barley accessions from the USDA Wiebe collection and determine the relationship of this resistance to resistance conferred by the T gene. Four accessions, PI 382313, PI 382474, PI 382915, and PI 382976, were selected as having good field resistance at the Winnipeg Agriculture Canada Research Station, Glenlea rust nursery in 1986. The field resistance of these four accessions was reconfirmed in the 1987 rust nursery and was found to be as effective as, or more effective than, that conferred by T. Seedling and adult plant tests were conducted in controlled environments with six races (C5, C10,C 17,C 25,C 35, and C53). In seedling tests, PI 382313 was resistant or moderately resistant to all six races. Both PI 382474 and PI 382915 were moderately susceptible to C35 and susceptible to the other five races. The PI 382976 was moderately resistant to C35 and C53, and moderately susceptible or susceptible to the other races. In adult plant tests, PI 382474 was resistant to C35 and PI 382313 was resistant to C17. Both PI 382915 and PI 382979 displayed little resistance as adults to the six races. Genetics studies with PI 382313 indicated that the field resistance of this accession was conferred by a single dominant gene that was different from T.

Components of resistance in barley to stem rust: receptivity, urediniospore production, latent period, and infection response in adult plants

“…The mode and range of infection responses (coded on a 0 -10 scale of Jedel et al 1989) on adult plants inoculated with 4 mg/mL urediniospores of races QCC, QFC, and TPM are shown in Table 5. With all three races.…”

“…In greenhouse tests, barley seedlings commonly produce mesothetic reactions (different infection types on the same plant) to many races of P. g. tritici, which makes distinction between resistant and susceptible genotypes difficult (Jedel et al 1989;Miller and Lambert 1955;Patterson et al 1957;Steffenson et al 1985). Statistically significant differences, however, can be detected among barley genotypes by using weighted infection types or by counting the number of uredinia produced per unit of leaf area (Fox and Harder 19956;Jedel et al 1989;Steffenson et al 1985;Steffenson and Wilcoxson 1987).…”

“…Statistically significant differences, however, can be detected among barley genotypes by using weighted infection types or by counting the number of uredinia produced per unit of leaf area (Fox and Harder 19956;Jedel et al 1989;Steffenson et al 1985;Steffenson and Wilcoxson 1987). Although there are specific resistance gene effects in the barley -stem rust interaction (Jin et al 1994;Steffenson et al 1993), the variable expression of resistance in barley makes the detection of race-specific genes difficult.…”

“…Infection responses on the plants were recorded 14-15 days after inoculation. A numerical scale of 0-10 (Jedel et al 1989), which is based on percent of plant infected, uredinial size, and degree of chlorosis, was employed to calculate means from replicates to determine the relationship of infection response with the other components. The barley line 4 2 1 861, which showed very low receptivity at the inoculum concentration of 4 mg urediniospores/mL oil, was further evaluated for receptivity and urediniospore production by inoculation with race QCC at concentrations of up to 16 mg urediniospores/mL oil.…”

“…Genes for stem rust resistance in addition to Rpgl have been detected in barley: gene Rpg2, effective in the adult plant stage, was found in the line Hietpas 5 (CI 7124) (Patterson 1951;Patterson et al 1957); gene Rpg3 in PI 382313 (Jedel et al 1989;Jedel 1990); gene rpg4, a recessive gene in the line 421861 (Jin et al 1994); and a gene, temporarily designated as RpgU, has been detected in several barley cultivars (Fox and Harder 1995~). These genes individually confer only low to moderate levels of resistance, and the resistance conferred by gene rpg4 becomes ineffective at temperatures The results were obtained from 2 years of observations of QCC at Brandon, Man., and for the race composite at Glenlea, Man.…”