Ocimum basilicum plants or germplasm having tolerance or improved tolerance to Peronospora belbahrii infection, comprising in its genome the single nucleotide polymorphisms (SNPs) of SEQ ID NOs:1-630 or having approximately 90% to 0.5% of said SNPs in said Ocimum basilicum genome are disclosed. Further embodiments include methods of producing, selecting, and evaluating the responses of Ocimum basilicum plants or germplasm having tolerance or improved tolerance to Peronospora belbahrii infection； said plants comprised of at least one dominant allele and at least one recessive allele in the homozygous state that produce higher levels of tolerance to Peronospora belbahrii； seeds, plants, plant parts, methods for producing basil plants by crossing said basil plant with itself or with another basil plant, methods for producing sweet basil plants having higher tolerance to Peronospora belbahrii, plants and plant parts produced by those methods and methods for producing interspecific basil plants having tolerance to Peronospora belbahrii.
