Ds. Douches et al., Evaluation of wild Solanum species for resistance to the US-8 genotype of Phytophthora infestans utilizing a fine-screening technique, AM J POTATO, 78(2), 2001, pp. 159-165
Greenhouse assays were carried out to characterize Solanum accessions previ
ously reported to be late blight resistant and to identify individuals with
in the accessions with high levels of resistance to late blight. Foliage of
wild Solanum species accessions or hybrid cultivated potato x wild species
(diploid or tetraploid) from Mexico, Russia, or South America was inoculat
ed with Phytophthora infestans (US-8) and was scored for severity of foliar
symptoms at 7 and 14 days after inoculation (DAI). Mexican accessions (S.
brachycarpum, S. pinnatisectum, S. guerreroense, and S. fendleri) were sign
ificantly more resistant (1.1% infection at 14 DAI) than either Russian (59
.1% infection at 14 DAI) or South American (53.4% infection at 14 DAI) acce
ssions. Moreover, the genotypes within the Mexican accessions tended to be
more uniformly resistant whereas genotypes within the Russian and South Ame
rican accessions tended to segregate for resistance. The more resistant gen
otypes of Russian and South American accessions (176/546) were retested, an
d 56 genotypes were identified as having potential for use in potato breedi
ng programs for resistance to late blight. Fifty percent of the selected ge
notypes were from S. microdontum accessions PI498124, PI595510, and PI59551
1. The potential of these species for incorporation into breeding programs
for late blight resistance is discussed.