1) The study tested resistance to several pathogens and pests in potato species across different taxonomic groupsings and found significant differences in resistance both within and among species. 2) No single taxonomic grouping perfectly predicted the most resistant species, but some biogeographic parameters sometimes correlated with resistance trait distributions. 3) Several species, including S. bukasovii, S. bulbocastanum, S. chacoense, and S. commersonii, showed resistance to multiple pathogens and pests tested.

1. Tests of taxonomic and
biogeographic predictivity
Shelley Jansky, USDA
Reinhard Simon, CIP
David Spooner, USDA

2. Background
“[Prediction] means that one can describe a
trait as characteristic of all members of a
taxon before it has been verified for all.”
(Warburton, 1967)
“A primary function of classification is to
construct classes about which we can make
inductive generalizations.” (Gilmour, 1951)
“One of the greatest assets of a sound
classification is its predictive value.” (Mayr, 1969)

3. Germplasm
~40 species (~150 accessions)
14 of Hawkes’ 19 series
4 plastid-based clades + 1 outgroup
1, 2, 4, EBN
2x, 4x, 6x

4. Tests of predictivity
White mold
– Sclerotinia sclerotiorum
– Foliar fungus
Early blight
– Alternaria solani
– Foliar fungus
Colorado potato beetle
– Leptinotarsa decemlineata
– Defoliating insect
Soft rot
– Pectobacterium carotovorum
– Bacterium
Potato virus Y

5. Resistance to White Mold
S. commersonii (Commersoniana, 4, 1, 2x)
S. palustre (outgroup, O, 1, 2x)
S. schenckii (Demissa, 4, 4, 6x)
Species (series, clade, EBN, ploidy)
S. violaceimarmoratum (Conicibaccata, 4, 2, 2x)
S. etuberosum (outgroup, O, 1, 2x)
S. sparsipilum (Tuberosa, 4, 2, 2x)
S. pinnatisectum (Pinnatisecta, 1, 1, 2x)
S. chacoense (Yungasensa, 4, 2, 2x)
S. tarijense (Yungasensa, 4, 2, 2x)
S. bulbocastanum (Bulbocastana, 2, 1, 2x)
S. acaule (Acaulia, 4, 2, 4x)
S. chomatophilum (Conicibaccata, 3, 2, 2x)
S. raphanifolium (Megistacroloba, 4, 2, 2x)
S. jamesii (Pinnatisecta, 1, 1, 2x)
S. demissum (Demissa, 4, 1, 2x)
0 500 1000 1500 2000 2500 3000 3500 4000
(Crop Sci 2006 46:2561) Mean Rank Score

6. Resistance to Early Blight
S. neorossii (Tuberosa, 4, ?, 2x)
S. commersonii (Commersoniana, 4, 1, 2x)
Species (series, clade, EBN, ploidy)
S. tarijense (Yungasensa, 4, 2, 2x)
S. raphanifolium (Megistacroloba, 4, 2, 2x)
S. bulbocastanum (Bulbocastana, 2, 1, 2x)
S. andreanum (Tuberosa, 3, 2, 2x)
S. sparsipilum (Tuberosa, 4, 2, 2x)
S. megistacrolobum (Megistacroloba, 4, 2, 2x)
S. acaule (Acaulia, 4, 2, 4x)
S. demissum (Demissa, 4, 1, 2x)
S. brevicaule (Tuberosa, 4, 2, 2x)
S. microdontum (Tuberosa, 4, 2, 2x)
S. paucijugum (Conicibaccata, 3, 2, 4x)
S. albicans (Acaulia, 4, 4, 6x)
S. bukasovii (Tuberosa, 4, 2, 2x)
0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6
(Phytopath 2008 98:680) Early Blight Score

7. Resistant to Early Blight
Susceptible to Early Blight

8. Resistance to Colorado Potato Beetle
S. pinnatisectum (Pinnatisecta, 1, 1, 2x)
S. immite (Tuberosa, 3, 1, 2x)
S. polyadenium (Polyadenia, 1, 1, 2x)
Species (series, clade, EBN, ploidy)
S. albornozii (Piurana, 3, 2, 2x)
S. chacoense (Yungasensa, 4, 2, 2x)
S. neorossii (Tuberosa, 4, ?, 2x)
S. jamesii (Pinnatisecta, 1, 1, 2x)
S. tarijense (Yungasensa, 4, 2, 2x)
S. commersonii (Commersoniana, 4, 1, 2x)
S. chomatophilum (Conicibaccata, 3, 2, 2x)
S. stenophyllidium (Pinnatisecta, 1, 1, 2x)
S. demissum (Demissa, 4, 1, 2x)
S. palustre (outgroup, O, 1, 2x)
S. violaceimarmoratum (Conicibaccata, 4, 2, 2x)
S. lesteri (Polyadenia, 1, 1, 2x)
0 100 200 300 400 500 600 700 800 900
(J Econ Entomol 2009 102:422) AUDPC

9. Resistance to Soft Rot
S. paucijugum (Conicibaccata, 3, 2, 4x)
S. brevicaule (Tuberosa, 4, 2, 2x)
S. commersonii (Commersoniana, 4, 1, 2x)
Species (series, clade, EBN, ploidy)
S. violaceimarmoratum (Conicibaccata, 4, 2, 2x)
S. verrucosum (Tuberosa, 4, 2, 2x)
S. bukasovii (Tuberosa, 4, 2, 2x)
S. microdontum (Tuberosa, 4, 2, 2x)
S. colombianum (Conicibaccata, 4, 2, 4x)
S. sparsipilum (Tuberosa, 4, 2, 2x)
S. boliviense (Megistacroloba, 4, 2, 2x)
S. megistacrolobum (Megistacroloba, 4, 2, 2x)
S. chacoense (Yungasensa, 4, 2, 2x)
S. chomatophilum (Conicibaccata, 3, 2, 2x)
S. cardiophyllum (Pinnatisecta, 2, 1, 2x)
S. albicans (Acaulia, 4, 4, 6x)
0 5 10 15 20 25 30 35 40 45 50
(Phytopathol 2010 101:205) Mean Rank Score

10. Resistance to Potato Virus Y
(Phytopath 2011 101:1074)

12. Accessions evaluated for Accessions with resistance
resistance to potato virus Y to potato virus Y

13. WM EB CPB SR PVY
S. bukasovii (2x, 2)
X X X
S. bulbocastanum (2x,1)
X X X X
S. chacoense (2x, 2)
X X X X
S. chomatophilum (2x, 2)
X X X
S. commersonii (2x, 1)
X X X X
S. demissum (2x, 1)
X X X
S. jamesii (2x, 1)
X X X
S. microdontum (2x, 2)
X X X
S. pinnatisectum (2x, 1)
X X X
S. sparsipilum (2x, 2)
X X X
S. tarijense (2x, 2)
X X X
S. violaceimarmoratum (2x, 2)
X X X

14. WM EB CPB SR PVY
S. bukasovii (2x, 2)
X X X
S. bulbocastanum (2x,1)
X X X X
S. chacoense (2x, 2)
X X X X
S. chomatophilum (2x, 2)
X X X
S. commersonii (2x, 1)
X X X X
S. demissum (2x, 1)
X X X
S. jamesii (2x, 1)
X X X
S. microdontum (2x, 2)
X X X
S. pinnatisectum (2x, 1)
X X X
S. sparsipilum (2x, 2)
X X X
S. tarijense (2x, 2)
X X X
S. violaceimarmoratum (2x, 2)
X X X

15. Conclusions
Significant differences among accessions
and genotypes within a species
Significant differences among species,
series, clades, EBN, and ploidy levels
No taxonomic grouping criterion identified
the most resistant species
Some biogeographic parameters
sometimes predicted the distribution of
resistance traits