Breeding for resistance to insect-transmitted viruses in barley - an emerging challenge due to global warming

Due to global warming longer periods of higher temperature in autumn and winter are expected which may result in an increasing importance of insect-transmitted viruses. Investigations carried out in Saxony-Anhalt from 1998 to 2008 on the incidence of Barley yellow dwarf virus (BYDV) and Wheat dwarf virus (WDV) revealed a clear relation between the number of infection days in autumn and the BYDV-attack in winter barley fields in the following spring. In additional experiments carried out in growth chambers under controlled conditions it turned out that 10°C is the minimum temperature for an efficient transmission of BYDV by Rhopalosiphum padi. In order to enhance the level of resistance to BYDV, Ryd2, Ryd3 and a QTL derived from the cultivar ‘Post’ located on chromosome 2HL were combined using DH-lines and molecular markers. Concerning symptom expression and virus extinction first results indicate a reduction in those lines combining especially Ryd2 and Ryd3. Concerning WDV extensive screening programmes were conducted, but tolerance was only detected in cv. ‘Post’. First results of genetic analysis using DH-lines give hint that this tolerance is inherited in a quantitative manner.