The expert consultations on the use of crop wild relatives for pre-breeding in potato was a workshops organized by the Global Crop Diversity Trust in collaboration with CIP and took place from the 22nd – 24th of February 2012.

1. A perspective on major
historical milestones
Shelley Jansky
USDA-ARS
University of Wisconsin-Madison

4. 1570‟s

5. 1700
1621
1610

6. 1900‟s

7.  By 1800, potato was a major crop in England and
Ireland
 “Degeneration” was a problem
 Selection of cultivars from open-pollinated
seedling populations was productive
 First deliberate hybridization
◦ Knight, England, 1807

8.  Daber
◦ Brought to Germany in 1830
◦ Immune to wart; high starch
◦ Probably from Chile
 Rough Purple Chile
◦ Brought to US in 1851 (from Chile via Panama)
 Progeny
 include Garnet Chili, Early Rose, and Burbank
 were used as parents in Europe after Irish potato famine
 are in >250 N. Am and European cultivars
 Most cultivars are in Chilean cytoplasm

9.  Germplasm collection
◦ Russia, Germany, UK, US
 W-races
◦ Breeding lines developed in Germany, Belgium, U.S.
◦ Late blight resistance from S. demissum
 Backcross progenies resembled cultivars
 Yield increases were observed as a “side-
effect” of introgressing disease resistance
 An important feature of successful parents
was male fertility

10.  Base broadening
◦ Mass selection for adaptation
 Neotuberosum from adg (Simmonds, Glendinning,
Plaisted)
 Long day phu-stn (Carroll, Haynes)
◦ B populations (CIP)
 Late blight resistance and other traits
 Sexual polyploidization
◦ 4x from 4x x 2x and 2x x 2x crosses
 Yield heterosis
 Processing quality
◦ Lenape contains S. chacoense germplasm

11.  S. demissum (6x, 4EBN)
◦ 1900‟s – found to be resistant
◦ Initially used as a source of major genes
 In pedigrees of cultivars developed in mid-
1900‟s – in many countries
 Resistance broke down in 1960‟s
◦ But minor genes also exist
 Also contributed hybrid vigor

12.  Cultivated
◦ „Villaroela‟
 Native cultivar, Chiloe
 Introduced to U.S. for virus resistance
 In pedigrees of British and N. American cultivars
◦ Adg CPC 1673 and 1960 (H1gene)
 Wild
◦ S. vernei (2x, 2EBN)
 Somatically doubled and crossed to cultivars
 Quantitative resistance

13.  S. stoloniferum (4x, 2EBN)
◦ MPI61.303/34
 Sto-tbr hybrid – Max Planck
 Durable resistance –Rysto
 In pedigrees of many European cultivars
◦ sto-tbr hybrids
 Male sterile
 Field resistance to late blight

14.  1960‟s, U.S.
 S. chacoense (2x, 2EBN)
◦ Grandparent of Lenape
◦ In pedigrees of most N. Am. processing CVs
 S. berthaultii (2x, 2EBN)
◦ In pedigrees of White Pearl and Kalkaska
 High dry matter content
 Low reducing sugar accumulation in storage

15.  Traits from CWRs can be easily transferred to
cultivars
◦ “When trying to transfer genes from the mentioned
wild species, we never were faced with
unsurmountable difficulties.” (Ross, 1966)
◦ “It was possible to transfer any property so far
tested of a wild species into a cultivar.” (Ross, 1978)
◦ “…virtually any potato species can be utilized for
the introgression of desirable genes into S.
tuberosum.” (Bradshaw et al., 2006)

16.  CWRs contribute to yield heterosis
◦ “…it looks as though potato breeding has generally
been rather unsuccessful. … The reason most
probably lies in the narrowness of the genetic base
of our north temperate breeding stocks.”
(Simmonds, 1971)
◦ “Three-fourths of the varieties developed from
species hybrids are reported to possess high or
very high yielding quality.” (Rieman et al., 1954)
◦ “Beyond the planned transfer of distinctive major
genes, there is a heterotic effect on yield…”
(Ross, 1979)

17.  No unfavorable traits prohibit the use of
CWRs for cultivar development
◦ “There is no unfavorable trait known that would
prohibit the utilization of a wild species.” (Ross,
1979)
◦ “The suppression of the glycoalkaloid synthesis is
inherited in a dominant way.” (Ross, 1966)

18.  CWRs may contribute multiple desirable
traits
◦ “It is noteworthy that when primitive cultivars or
wild species have been used in modern
breeding, in spite of the procedure used being
designed to eliminate most of their contributions
apart from the specific characters for which they
were chosen for use, they have frequently
contributed useful characters in addition to those
intended.” (Glendinning, 1983)

19.  Few generations of backcrossing are needed
to return to cultivar types
◦ “…after the first backcross already a remarkable
shift to the behavior of S. tuberosum varieties has
taken place.” (Rudorf, 1958)
◦ “…seedling lines appeared among the backcross
progenies coming very close to cultivated varieties
in yield and other properties.” (Ross, 1979)

20.  Despite attempts by many programs over
several decades to introgress wild species
germplasm into cultivars, the genetic base of
potato is still primarily S. tuberosum.
 Scotland (Bradshaw, 2009)
◦ Access to 80 species
 7 species in cultivar pedigrees
 S. demissum (late blight)
 S. vernei (cyst nematode)
 S. microdontum (PVY)
 S. multidissectum, S. commersonii, S. maglia, S. acaule