Recognition of Phytophthora infestans in potato (Solanum tuberosum L.): Scr74 gene as an example

Abstract

Phytophthora infestans is the causal agent of late blight, the most devastating disease of potato worldwide. The P. infestans genome encodes potentially polymorphic genes that evolve continually to evade the recognition of plant R genes, though it has hundreds of predicted and conserved effector proteins recognised by the plant. The gene Scr74 encodes a predicted 74-amino acid secreted cysteine-rich protein belonging to a highly polymorphic gene family within P. infestans. This study screened the recognition of Scr74 genes in wild potato genotypes from August 2013 to January 2014 in the Plant Breeding Laboratory of Wageningen University, the Netherlands. To identify the recognition of the Scr74 gene, we grew potato genotypes in the green house for PVX assays, detached leaf assays and molecular work. Twenty-seven good-quality sequences of the Scr74 gene variant with a length of 74 amino acids were found and more frequent amino acid variation was detected on the mature protein. Seventeen Scr74 constructs were identified as diversified and two effectors were strongly recognised by wild S. verrucosum genotypes via effectoromics from the PVX assay. A strong plant cell death hypersensitive response (HR) was recorded on wild S. verrucosum and S. tuberosum genotypes from the detached leaf assay. This recognition seems to be a useful indicator for the presence of a resistance gene (s) to the polymorphic effectors of P. infestans (as it has seen on Scr74 gene) in the wild potato genotypes.

Keywords

• phytophthora infestans
• polymorphic gene
• phytotoxin-like protein
• scr74 gene
• apoplastic effectors
• effectoromics