Identification and characterization of a barley yellow dwarf virus resistance gene in maize

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Barley yellow dwarf is the most widely spread viral disease of cereals. It is caused by the Barley yellow dwarf virus (BYDV) and the Cereal yellow dwarf virus (CYDV), where the first is causing more severe damages than the second. Maize plays an important role in the epidemiology of BYDV and is as well damaged by the virus. With increasing global temperatures, viral diseases in general and BYDV in specific are expected to become prominent problems in cereal and maize cultivation. The control of the virus itself is not possible and insecticides to control the BYDV-transmitting aphids are not certificated in Germany. Resistant maize can break the transmission cycle of BYDV and therewith could as well contribute to a reduction of the BYDV problems in other cereals. In an earlier study, we detected a BYDV resistance factor at the bottom of chromosome ten, which explained considerable proportions of the phenotypic variance of the traits virus concentration and disease symptoms. Based on these experiments, the gene GRMZM2G018027 is the best candidate as BYDV resistance gene. The homolog of this gene in Arabidopsis thaliana is OXS3 that is described to be involved in the production of H2O2. As H2O2 is known to play an important role in pathogen defense, GRMZM2G018027 could be involved in a general pathogen defense reaction. One of the objectives of the proposed project is to identify and validate the BYDV resistance gene in maize. This will be reached with the help of five so called heterogeneous inbred families. Artificial inoculation experiments and experiments characterizing the sucking behavior of aphids on recombinant plants of the heterogeneous inbred families as well as genotypes that were created by transforming the maize inbred A188 with different alleles of GRMZM2G018027 will be used to improve our understanding of the molecular function of the BYDV resistance gene. Furthermore, we plan to quantify the contribution of the BYDV resistance gene to variation of other viral diseases.