A New Source of Resistance to Pseudocercosporella herpotrichoides, Cause of Eyespot Disease of Wheat, Located on Chromosome 4V of Dasypyrum villosum.

Resistance to Pseudocercosporella herpotrichoides in five wheat cultivars, accession W6 7283 of Dasypyrum villosum, and Chinese Spring disomic addition lines of the D, villosum chromosomes 1V, 2V, 4V, 5V, 6V and 7V, was evaluated in seedlings by measuring disease progress 6 weeks after inoculation with a figlucuronidase-transformed strain of the pathogen and by visual estimates of disease severity. D, villosum and the disomic addition line of chromosome 4V were as resistant as wheat cultivars 'VPM-1 ' and 'Cappelle I)esprez', but less resistant than 'Rendezvous'. Resistance of the chromosome 4V disomic addition line was equivalent to that of D. villosum. 'Chinese Spring' and disomic addition lines of 1V, 2V, 5V, 6V and 7V were all susceptible, These results confirm SPRAGUF's (1936) report of resistance in D. villosum to P. herpotrichoides and establish the chromosomal location for the genes controlling resistance. The presence of chromosome 4V in the addition line and its homoeology to chromosome 4 in wheat were confirmed by Southern analysis of genomic DNA using chromosome group 4-specific clones. This genetic locus is not homoeologous with other known genes for resistance to P. herpotrichoides located on chromosome group 7, and thus represents a new source of resistance to this pathogen. [ABSTRACT FROM AUTHOR]