1.1.3
RESISTANCE EVALUATION OF BARLEY TO PUCCINIA HORDEI AND PYRENOPHORA TERES, AND CHARACTERIZATION OF GENES BY MEANS OF CLASSICAL AND MOLECULAR METHODS

D KOPAHNKE1, U WALTHER1, S KICHERER1, A GRANER2 and O AFANASENKO3

1Federal Centre for Breeding Research on Cultivated Plants, Institute for Epidemiology and Resistance, Theodor-Roemer-Weg 4, 06449 Aschersleben, Germany; 2Institute of Plant Genetics and Crop Plant Research, Corrensstraße 3, 06466 Gatersleben, Germany; 3All-Russian Institute of Plant Protection (VIZR), Podbelsky shosse 3, St Petersburg-Pushkin 189620, Russia

Background and objectives
Leaf rust caused by Puccinia hordei and net blotch caused by Pyrenophora teres are very important diseases in barley. The breeding of resistant barley is considered to be the most economical and environmentally safe method to reduce yield losses. The basis of this strategy is the availability of effective genes for resistance. Because the genes selected in Hordeum vulgare have previously been overcome by leaf rust, the evaluation work was continued in Hordeum spontaneum.

Materials and methods
A collection of 1000 samples of H. spontaneum was tested in the greenhouse (leaf rust - seedling stage, 10 defined isolates; net blotch - leaf segment test, four isolates) and in the field (artificial infection, four replications, recorded by AUDPC) [2]. In the field all samples were tested for quantitative and qualitative resistance to leaf rust and only samples with a high level of resistance in the leaf segment test to net blotch were followed up. Highly resistant lines of H. spontaneum were crossed with susceptible parents. F1 and F2 populations were investigated in the seedling stage respectively by leaf segment test. By means of five F2 populations RFLP markers for leaf rust resistance were developed [1]. Every year, as a prerequisite for evaluation, tests were carried out on the virulence of pathogen populations by the production of single-spore isolates.

Results and conclusions
Forty-one accessions with qualitative resistance and 220 with a high level of quantitative resistance to leaf rust were selected [3]. Tests with Rph7-virulent isolates in Israel showed that the qualitative resistance was different from Rph7. Genetical analyses were carried out on crosses of H. spontaneum with the susceptible parent L94. The following inheritance of resistance was proposed: one dominant gene (one line), one recessive gene (12 lines), two dominant genes (two lines) and two recessive genes (10 lines). Five F2 populations were investigated by molecular methods. Following analysis with P. teres, 93 accessions were resistant in the leaf segment test and 45 of them showed a high resistance level in the field. Genetical analysis of crosses of H. spontaneum lines with susceptible parents indicated the presence of: one dominant gene (one line), one dominant and one recessive gene (three lines), two dominant genes (one line). In addition the resistant materials were tested against powdery mildew and stripe rust. A relatively high number of accessions were found with complex resistance to leaf rust and net blotch as well as race-specific resistance to powdery mildew and stripe rust.

References
1. Kicherer S, Backes G, Jahoor A et al., 1996. Proceedings of the 9th European and Mediterranean Cereal Rusts and Mildew Conference, 2-6 September 1996, Lunteren,The Netherlands.
2. Kopahnke D, Nachtigall M, Wolf GA, 1997. Journal of Applied Genetics 38B, 161-166.
3. Müller D, Prochnow J, Walther U, 1996. Proceedings of the 9th European and Mediterranean Cereal Rusts and Mildew Conference, 2-6 September 1996, Lunteren,The Netherlands, p. 228.