POSTULATION OF YR RESISTANCE GENES TO STRIPE RUST IN 12 COMMERCIAL WHEAT CULTIVARS OF RUSSIAN BREEDING

Abstract

Stripe rust (Puccinia striiformis f. sp. tritici) is a common wheat disease of economic importance in all world wheat production regions. In most of the regions stripe rust causes yield losses of 10-70 %, depending on the time infection occur, host susceptibility, disease development, and the duration of the epidemics. In South Russia even in unfavourable conditions for the pathogen, stripe rust occurred in the region every year, and in some areas there are foci of the disease with of up to 50% severity. Phytopathological testing is one of the least expensive and most effective methods for the rapid identification of juvenile resistance genes in varieties against pathogens. It allows to obtain detailed information about the genetics of the host and pathogen in a short time. In the research Yr resistant genes and its combinations were postulated in winter wheat varieties of Russian breeding to North-Caucasus population of stripe rust by this method. Purpose of this study was identification of known stripe rust resistance genes in 12 commercial winter wheat cultivars by phytopathological testing. Material and methods: The postulation of known resistance genes was carried out in a greenhouse complex (seedling stage) and at the research station (adult plant stage) of the Laboratory of Plant Immunity to Diseases of the Federal Scientific Center for Biological Plant Protection (Krasnodar). For postulation, we chose the method by Dubin et al. (1989), based on the comparison of response types of differential cultivars and studied varieties to Pst isolates. Results. In 10 out of 12 winter wheat varieties of Russian breeding, 13 stripe rust resistance genes and their combinations were postulated.: Yr3, Yr3a, Yr6, Yr32, Yr2+6, Yr2+9, Yr39+Alp, Yr4+12, Yr4b, Yr3a+4a+H46, YrA, YrSp, YrSU. The following resistance genes have not been identified: Yr2, Yr5, Yr10, Yr10+Mor, Yr24, Yr27, Yr25+32, since no isolates virulent to carriers of these genes were isolated from the North Caucasian population of P. striiformis; and they are highly effective against this population. Highly effective (Yr3, Yr2+9, Yr3a, Yr4+12, Yr3a+4a+H46) resistance genes were identified in the Kurs, Morozko, and Step’ varieties. We note a combination of effective Yr2+6 genes in the Gurt variety. In field conditions, high resistance (degree of damage up to 10%) to the North Caucasian population of the stripe rust pathogen was shown by lines and differential cultivars containing the following resistance genes: Yr2, Yr3, Yr8, Yr10, Yr24, Yr25, Yr27, Yr10+Mor, Yr3a, Yr25+32, Yr3a+4a+H46, Yr3с+Min, Yr4+12, Yr7+25, Yr8+19, 8+6+25, YrSp. Due to the low degree of damage, these genes and their combinations are classified as highly effective and can be involved in the breeding process to create new resistant varieties. Varieties containing these genes can also be recommended for breeders and used in production for effective disease control.

Keywords

• gene postulation
• genetic resistance
• pathotype
• puccinia striiformis
• resistance
• stripe rust
• wheat