New sources of resistance for stripe rust in barley

Eight spring barley accessions from the gene bank in Gatersleben, Germany, and 10 cultivars were tested for stripe rust resistance. Tests were performed at the seedling stage in the growth chamber and as adult plants in the field. All accessions and six cultivars were scored as resistant against race 24 under all test conditions, with very few plants as exceptions, while the susceptible control cultivars ‘Karat’ and ‘Certina’, and four other cultivars were attacked in all cases. Differences between accessions and between cultivars were detected after infection with isolates from ‘Trumpf’ and ‘Bigo’ (seedling tests only). Infection structures within seedling leaves without pustules and for the first time within leaves of adult plants from the field were analysed by fluorescence microscopy. With this method additional genetic Differences in the resistance reaction could be detected which could not to be seen in the resistance test. Crosses between the accessions and the susceptible cultivar ‘Karat’ led to segregating F₂ progenies. The percentage of resistant plants varied between the accessions. This also indicates a different genetic basis of resistance in the accessions. The infection structures observed by fluorescence microscopy stopped earlier in leaves of the two accessions HOR 8979 and HOR 8991 than in leaves of other accessions in all the tests. These accessions were the only ones with more than 50% resistant plants in all F₂ tests. In general, the accessions from the gene bank can be used as new resistance sources against stripe rust.