Testing Taxonomic Predictivity of Foliar and Tuber Resistance to Phytophthora infestans in Wild Relatives of Potato

Abstract

Potato late blight, caused by the oomycete phytopathogen Phytophthora infestans, is a devastating disease found in potato-growing regions worldwide. Long-term management strategies to control late blight include the incorporation of host resistance to predominant strains. However, due to rapid genetic changes within pathogen populations, rapid and recurring identification and integration of novel host resistance traits is necessary. Wild relatives of potato offer a rich source of desirable traits, including late blight resistance, but screening methods can be time intensive. We tested the ability of taxonomy, ploidy, crossing group, breeding system, and geography to predict the presence of foliar and tuber late blight resistance in wild Solanum spp. Significant variation for resistance to both tuber and foliar late blight was found within and among species but there was no discernable predictive power based on taxonomic series, clade, ploidy, breeding system, elevation, or geographic location. We observed a moderate but significant correlation between tuber and foliar resistance within species. Although previously uncharacterized sources of both foliar and tuber resistance were identified, our study does not support an assumption that taxonomic or geographic data can be used to predict sources of late blight resistance in wild Solanum spp.

The wild tomato speciesSolanum chilenseshows variation in pathogen resistance between geographically distinct populations

“…The mosaic-like structure of our results indicates that these resistances are likely caused by a multitude of factors. These findings are in line with several inter-species studies in wild potato, where no correlation could be found between geographical location of the species and resistance against P. infestans (Khiutti et al, 2015) or A. solani (Jansky, Simon & Spooner, 2008). To further unravel the combination of factors contributing to local variations, new sampling excursions would be required, that not just collect plant and pathogen, but also measure local geographic and climatic parameters.…”

Peer Review #1 of "The wild tomato species Solanum chilense shows variation in pathogen resistance between geographically distinct populations (v0.1)"

“…These findings are in line with several inter-species studies in wild potato, where no correlation could be found between geographical location of the species and resistance against P. infestans (Khiutti et al, 2015) or A. solani (Jansky, Simon & Spooner, 2008).…”

Potato Germplasm Enhancement Enters the Genomics Era

“…Potato Genebank, for example, maintains 167 accessions of S. chacoense. To address this challenge, a series of studies was carried out to determine whether taxonomic or biogeographic data could be used to predict the distribution of disease and pest resistance phenotypes in wild relatives of potato [119][120][121][122][123][124][125]. These studies were designed to test prediction at the section and species level without prior knowledge of phenotypes.…”