The sugar beet multi-talented resistance protein Rz2

Abstract

Sugar beets infected with the Beet necrotic yellow vein virus show a massive proliferation of rootlets, leaf vein yellowing, and necrosis and can lead to 80 % sugar yield loss. Transmitted by the protist Polymyxa betae control of the virus is achieved by using two dominant resistance genes, Rz1 and Rz2. The focus of the presented work was to study the molecular characteristics of the resistance protein Rz2. In the first instance, we were able to confirm Rz2 as an independent monogenic resistance gene, which is mainly expressed in the root tissue of the natural host Beta vulgaris. Additionally, the TGB1 from BNYVV and other sugar beet infecting virus species were identified as avr determinant by using the experimental host N. benthamiana and transient Agrobacterium-mediated leaf infiltration as test system. In a second approach, Rz2 was functionally transferred into N. benthamiana by leaf-disk transformation to generate transgenic plants constitutively expressing Rz2. Moreover, the interaction between the two proteins was investigated by different approaches but due to experimental problems, no validated results were obtained. Furthermore, the ability of BNYVV to adapt to the resistance by evading recognition due to mutations was investigated but no virus variants were detected indicating their ability to break Rz2 mediated resistance.