Genome analysis of a single R-gene cluster in potato revealed two highly homologous resistance genes, Gpa2 and Rx1. The two genes confer resistance to fully unrelated pathogens, namely the potato cyst nematode Globodera pallida and the potato virus X. To get more insight into the evolutionary relationship between the two resistance genes, three new homologues mapping to the same cluster on chromosome 12 of the diploid potato clone SH83 were identi¿ ed by using a single LRR-based primer pair. cDNA analysis resulted in the identi¿ cation of the ORFs for two out of the three new homologues. To investigate the diversi¿ cation process within this cluster, DNA sequence data were analysed; the remarkable sequence conservation between the effector domains of Gpa2 and Rx1 points at the activation of a similar resistance mechanism. On the other hand, infection studies and histological observations revealed a relatively slow resistance response for Gpa2, while Rx1 results in an extreme resistance. To gain more insight in the mechanism underlying nematode and virus resistance structure-function analysis of GPA2 and RX1 are currently under investigation.
|Title of host publication||Nematology Symposium abstracts|
|Place of Publication||Leiden|
|Publisher||Brill Academic Publishers|
|Publication status||Published - 2002|