Sources of Resistance to Pear Rust

Abstract

The results of the study of the resistance to rust (Gymnosporangium sabinae (Dicks.) G. Winter) of pear cultivars, forms and intergeneric hybrids with different genetic origin as well as economical and biological characteristics of identified absolutely resistant genotypes are given. The studies were carried out in 2012-2020 in the pear collection orchard with the aim of to reveal genetic donors and sources of absolute resistance to rust for the further use in breeding programs. The work was carried out in accordance with the Program and Methods of Fruit, Berry and Nut Crop Breeding and Program and Methods of Fruit, Berry and Nut Crop Variety Investigation. Four intergeneric hybrids (Malopyrus № 1, Pyromalus № 818, Sorbopyrus auricularis, Sorbopyrus Kuryanovii); 114 pear genotypes of different genetic origin including pear cultivars and forms of Pyrus communis L., Pyrus pyrifolia (Burm) Nakai, Pyrus ussuriensis Maxim.; cultivars that are interspecific hybrids of Pyrus communis and Pyrus ussuriensis; Pyrus salicifolia Pall. and Pyrus calleryana Decne. as well as 2800 hybrid seedlings were used as objects for the research. As a result it was determined that all cultivars and hybrid seedlings used in the work regardless of their genetic origin were susceptible to pear rust: cultivars and forms derived from Pyrus communis, Pyrus ussuriensis, Pyrus pyrifolia and interspecific hybrids within the Pyrus L. genus. Intergeneric hybrids of pear with apple, apple with pear, pear with mountain ash and pear with whitebeam showed absolute resistance to the pathogen. Four intergeneric hybrids Malopyrus № 1, Pyromalus № 818, Sorbopyrus auricularis, Sorbopyrus Kuryanovii were allocated as sources for future use in breeding for high resistance to pear rust.