Piece de resistance: novel classes of plant disease resistance genes

Cloning of four new plant resistant (R) genes gives an insight into the molecular components of plant-pathogen interactions. The four R genes are RPS2 from Arabidopsis, N from tobacco, Cf-9 from tomato and L6 from flax. The diversity in R genes can be attributed to structural differences in genome organization at the loci of R genes. Recombination is mediated by R gene sequences, which might give rise to novel, altered or aberrently regulated R genes due to intragenic recombination or unequal crossing over.