Homologues of a single resistance‐gene cluster in potato confer resistance to distinct pathogens: a virus and a nematode

Abstract

SummaryThe isolation of the nematode-resistance gene Gpa2 in potato is described, and it is demonstrated that highly homologous resistance genes of a single resistance-gene cluster can confer resistance to distinct pathogen species. Molecular analysis of the Gpa2 locus resulted in the identi®cation of an R-gene cluster of four highly homologous genes in a region of approximately 115 kb. At least two of these genes are active: one corresponds to the previously isolated Rx1 gene that confers resistance to potato virus X, while the other corresponds to the Gpa2 gene that confers resistance to the potato cyst nematode Globodera pallida. The proteins encoded by the Gpa2 and the Rx1 genes share an overall homology of over 88% (amino-acid identity) and belong to the leucine-zipper, nucleotide-binding site, leucine-rich repeat (LZ-NBS-LRR)-containing class of plant resistance genes. From the sequence conservation between Gpa2 and Rx1 it is clear that there is a direct evolutionary relationship between the two proteins. Sequence diversity is concentrated in the LRR region and in the C-terminus. The putative effector domains are more conserved suggesting that, at least in this case, nematode and virus resistance cascades could share common components. These ®ndings underline the potential of protein breeding for engineering new resistance speci®cities against plant pathogens in vitro.

The Impact of Plant-Parasitic Nematodes on Agriculture and Methods of Control

“…These include the Mi-1 gene from Solanum peruvianum (formerly Lycopersicon peruvianum) [75], Hs1 pro-1 from sugar beet [76] and Gpa2 and Gro1-4 from potato [77,78].…”

NLR network mediates immunity to diverse plant pathogens

“…Sw5b, a gene from the wild tomato species Solanum peruvianum, mediates resistance against TSWV in tomato (21). Furthermore, introgression of Rx and Gpa2 into potato confers resistance to potato virus X (PVX) and potato cyst nematode, respectively (22,23).…”

Potato chromosomes IX and XI carry genes for resistance to potato virus M

“…lycopersici located on tomato chromosome 11 (Simons et al 1998). The marker UBC878 962 tightly linked to Gm shared high identity with sequences upstream of both the Rx1 gene for resistance to PVX and the Gpa2 gene for resistance to the potato cyst nematode Globodera pallida (van der Vossen et al 2000). Both resistance genes are physically tightly linked (van der Vossen et al 2000;Bakker et al 2003) and reside in a resistance hotspot on potato chromosome XII (Gebhardt and Valkonen 2001).…”

“…The marker UBC878 962 tightly linked to Gm shared high identity with sequences upstream of both the Rx1 gene for resistance to PVX and the Gpa2 gene for resistance to the potato cyst nematode Globodera pallida (van der Vossen et al 2000). Both resistance genes are physically tightly linked (van der Vossen et al 2000;Bakker et al 2003) and reside in a resistance hotspot on potato chromosome XII (Gebhardt and Valkonen 2001). Additionally, UBC878 962 was homologous to the promoter region of the patatin gene (Liu et al 1991) located on chromosome VIII (Gebhardt et al 1991).…”

“…This marker was cloned, sequenced (AY960860) and compared to the sequence database with the BLASTN program. UBC878 962 shared 94% sequence identity with a S. tuberosum genomic region on chromosome XII containing the Rx1 gene for resistance to potato virus X (PVX) (van der Vossen et al 2000), and 84% identity with the 5¢' nontranslated region of the Gpa2 gene (AF195939.1) for resistance to the potato cyst nematode Globodera pallida which is physically tightly linked to Rx1 (van der Vossen et al 2000). Additionally, UBC878 962 shared 87% identity with the promoter region of the patatin gene (Liu et al 1991) located on chromosome VIII (Gebhardt et al 1991).…”