TABLE 1.

Spinach progeny populationsegregating for downy mildew response following inoculation with race 13 of P. effusa.

Parents	Resistant	Susceptible	Total	χ2	P
Resistance from Swan
Whale × Swan	58	45	103	1.64	0.20
GBSa	34	34	68
Polka × Swan	40	38	78	0.05	0.82
GBS	4	9	13
Resistance from Squirrel
Squirrel × Polka	23	41	64	5.06	0.02
GBS	8	10	18
Whale × Squirrel	19	43	62	9.29	0.00
GBS	18	12	30
Resistance from Tonga
Polka × Tonga	28	64	92	14.09	0.00
GBS	10	9	19
Resistance from T-Bird
Polka × T-Bird	17	57	74	21.62	0.00
GBS	14	7	21
GBS additional sources
Parents and controls	6	7	13
Other unknowns	–	–	8
Total Phenotyped	185	288	473
Total (GBS)b	94	88	190
Filtering
Other unknowns			8
Individual missing			6
High heterozygosity			2
Total (Association panel)c	89	85	174
Association panel	32	33	65
(Whale × Swan)d

Cultivar Swan, Squirrel, Tonga, and T-Bird are resistant to race 13 of P. effusa, and Polka and Whale are susceptible cultivars. Chi-square goodness of fit test was for a 1:1 ratio. ^aNumber of progeny lines pursued to genotype using the genotyping by sequencing (GBS) approach (Elshire et al., 2011). ^bTotal number of lines pursued to genotype. ^cTotal number of lines pursued to conduct association analysis that remained after filtering for lines that were not phenotyped the same time with all other panels, high missing SNP data, and high heterozygosity. ^dProgeny lines from a cross of Whale and Swan were only used to perform independent association analysis to identify resistant loci specific to cultivar Swan.