Potato domestication

From: The potato treasure of the Andes

Mercedes Ames

Outline

• Introduction

• Classification of cultivated potatoes

• The origin of the cultivated potato

• Single domestication based on AFLP

• Domestication traits

• The potato in the Andes and Europe

Solanaceae family

4th crop in production worldwide

Range of ploidy: 2X, 3X, 4X and 5X

High morphological diversity with a great variety of shapes and colors of tubers

Morphology similarities between wild and cultivated potatoes

Introduction

Introduction

Native of the Andes of South America

Landraces growing from western Venezuela to northern Argentina and South Central Chile

Landrace populations in Mexico are post-Columbian introductions

“The potato eaters” Vincent Van Gogh 1885

Classification of cultivated potatoes

3 artificial groups based on use: - Wild (highly diverse)- Cultivated indigenous (Andes and southern Chile)- Modern cultivars

Ploidy became a taxonomic trait for cultivated potatoAndean fields contain mixtures of landracesHybridization with wild potatoes

Most accepted taxonomic treatment

S. ajanhuiri (2n=2x=24)S. chaucha (2n=3x=36)S. curtilobum (2n=5x=60)S. juzepczukii (2n=3x=36)S. phureja (2n=2X=24)S. goniocalyx (2n=2X=24)S. stenotomum (2n=2X=24)S. tuberosum

ssp. tuberosum (2n=4X=48)ssp. andigenum (2n=4X=48)

Poor morphological support for previous classifications

S. tuberosum

Only species because: - Reticulate origins- Multiple origins- Continuous hybridization

Ajanhuiri group Chaucha groupCurtilobum group Juzepczukii group Phureja groupStenotomum groupChilotanum group= ssp. tuberosumAndigenum group

Groups classification:

Spooner and Huaman, 2002)

From Dr. Marc Ghislain’s presentation at the 2nd Solanaceae Genome workshop 2005, Ischia - Italy

Evidences for structure in cultivated potato:4x adg+tbr(chi) – 2x phu+stn+gon+sol – 2x ajh – 3x juz – 5x cur

Gene pool structure analyses I

From Dr. Marc Ghislain’s presentation at the 2nd Solanaceae Genome workshop 2005, Ischia - Italy

Cluster analysis on 531 landraces x 24 SSR markers:

From Dr. Marc Ghislain’s presentation at the 2nd Solanaceae Genome workshop 2005, Ischia - Italy

Arguments about the origins of the potato:

Chilean potato landraces originated from indigenous primitive chilean 4X wild species

Juzepczuk and Bukasov

Salaman

S. tuberosum ssp. tuberosum in Chile arose from ssp. andigenum from the Andes directly or through a cross with an unidentified wild species

• Cytoplasmic types of chilean landraces of S. tuberosum and modern potatoes were identical

• 9 cytoplasmic factors that separate spp. andigenum from ssp. tuberosum that cause sterility in the presence of specific chromosomal genes, abnormal anthers and pollen, anthers fused to styles, and female sterility. Factors only expressed : tbr x adg

(Crosses not succeed ) and not when adg x tbr (crosses succeed)

Grunorigin of the cultivated potato through selection from a brevicaule-complex and subsequent hybridization events involving a number of unknown diploid species.

Hawkes identifies S. leptophyes as the progenitor of S. stenotomum, the species he designated as the most primitive of the cultivated species.

Thus the cultivated potato seems to have originated from a group of wild tuber-bearing Solanum species such as S. brevicaule, S. leptophyes, S. canasense and others.

Arguments about the origins of the potato:

Wild species

Cultivated species

S. acaule (4X)

S. sparsipilum (2X)

S. leptophyes (2X)

S. megistacrolobum (2X)

S. tuberosum ssp. andigena (4X)

S. stenotomum (2X)

S. ajanhuiri (Yari) (2X)

(Ajawiri)

S. curtilobum (5X)

S. juzepczukii (3X)

S. chaucha (3x)

S. phureja (2X)

Hawkes 1990. The potato: Evolution, Biodiversity and Genetic Resources

Hosaka : The cpDNA evidences

5 cpDNA genotypes: A, C, S, T and W

Non of them specie-specific, but present in different frequency

Andigenum: mostly type A

Stenotomum: all types but type S more frequent

Overlap of types in: Stenotomum, S. bukasovii, S. canasense, S. candolleanum, S. multidissectum and S. leptophyes

Stenotomum: most primitive

Ancestral species complex

Tuberosum: T type

S. tarijense: T-type possible female progenitor of Tuberosum.

W

T

C

A

S

Van Den Berg et al. 1988. Am.Journal of Bot. 85(1):92-109

First recognized by Ugent as a taxonomically confusing group of putative ancestors of the cultivated potato.

Endemic to central Peru, Bolivia and northern Argentina.

All of them show: (1) pinnately dissected leaves (2) round fruits (3) rotate to rotate-pentagonal corollas (4) largely sexually compatible (5) EBN matches ploidy (6) 2X, 3X, 6X (7) grow as weeds and in complexes with cultivated potatoes

Only 3 wild taxa recognized:

a) The peruvian populationsb) The Bolivian and the Argentinianc) S. oplocense (Bolivia and Argentina)

The brevicaule-complex: the wild ancestors of the cultivated potato

Materials and Methods:

362 accessions total

261 wild98 landraces

S. etuberosum S. palustre

Sect. Petota

Sect. Etuberosum

Wild: S. brevicaule complexS. stoloniferum (4x)

Cultivated: Phureja group (2X)Stenotomum group (2X)Andigenum group (4X)Chilotanum group (4X)

AFLP genotyping Phylogenetic analysis

A single domestication for potato based on AFLPs (Spooner et al, 2005 PNAS 102:41)

Results:

Concordance with morphology defining:- Northern: species from Peru + S. achacasense (northern Bolivia)- Southern: species from Bolivia and northern Argentina

• Fail to resolve many species within the complex

Northern:- S. abancayense, S. bukasovii, S. canasense, S. leptophyes, S. marinasense

S. multidissectum, S. multiinterruptum- S. candolleanum and S. pampasense (form clades)

Southern:- S. ambosinum, S. brevicaule, S. canasense, S. leptophyes, S. oplocense, S.

sparsipilum, S. sucrense- S. avilesii, S. hoopesii, S. incamayonense, S. spegazzinii, S. ugentii, S. verneii,

S. vidaurrei (form clades)

S. tarijense previously hypothesized as the likely maternal contributor to the Chilotanum group, was group in a different clade with other related species: S. berthaultii and S. chacoense

Strict consensus parsimony cladogram

Southern Brevicaule group plus other species

Cultivated species

Northern Brevicaule group

Clade 3

Outgroups

Summarizing the tree

Single domestication for potato

• All landrace (diploids and polyploids) form a monophyletic clade derived from the northern members of the S. brevicaule complex.

• S. brevicaule northern group poorly defined, maybe they can be reduced to a single species as S. bukasovii.

• This single origin differs from previous domestication hypotheses in:

(i) a single origin supported here rather than a series of multiple independent origins.

(ii) the origin is confined to the northern component of the S. brevicaule complex, rather than to other southern complex species that have been commonly mentioned as progenitors (S. sparsipilum and S. vernei)

• “Single” origin meaning an origin from a single species , or its progenitor S. bukasovii in the broad area of southern Peru.

• Potatoes were spread through the Andes from Peru both north and south

Points of discussion

• The use of anonymous markers data to infer crop origins ?

• Not all the cultivars groups were included in this analysis: what about Ajanhuiri Curtilobum Chaucha and Juzepczukiigroups?

• cp DNA data? Is the effect of gene flow? hibridizations?

• What about the relationships among the different groups, this origin involved an ancestral group ? S. stenotomum? polyploidization?

Domestication syndrome traits in some Solanaceae

Seems to be controlled by a limited number of genes

Trait Crop

Growth habit / plant architecture/height Tomato

Fruit size Tomato, Egg plant

Fruit morphology Tomato, Egg plant

Plant prickliness Eggplant

It seems that domestication of the Solanaceae has been driven by mutations in a very limited number of target loci with major phenotypic effects

Potato domestication

Selection for above-ground characters:

Higher vigor

Selection for underground characters:

Shorter stolons

Larger tubers

Colored and shaped tubers

Reduction of bitter tuber glycoalcaloids

α-solanina and α-chaconina levels in wild species from Series Tuberosa (S. bukasovii in particular) is consistent with the occurrence of these compounds in S. stenotomum and S. tuberosum (chilotanum) (Johns and Alonso, 1989)

But reduction of glycoalcaloid content not necessarily had to be direct, either selection for size (+ tuber size - concentration of glycoalcaloids to increase in water and carbohydrate) or reduced toxicity. (Johns and Alonso, 1989)

The potato treasure of the Andes: from Agriculture to Culture

The Potato in the Andes

1st cultivated potatoes from central Andes of Peru and Bolivia 6000 – 1000 years ago

Preferences and selection by individual farmers may explain some of the diversity of potato

Cultural factors, culinary preferences and the place of the potato in the Andean folklore are significant

Folk taxonomy is accurate but it seems to underestimate the actual diversity

The potato in Europe

First records of potato out of south America 1562 in Canary Islands, Spain

Second record: 1570 Sevilla, Spain

Great social influence

Hypotheses:

1. 1st European modern cultivars were introductions of chilean landraces2. 1st modern potatoes were introduced from the Andes to Europe as S. tuberosum ssp.

andigenum, which in Europe rapidly evolve into a wider leaf morphology with long-day adaptation.Late blight (Phytophtora infestans (Mont.)) killed most tuberosum-evolved andigenum clones in 1840’s, modern potato was mass selected and bred for blight

3. Early introduction were from both the Andes and from Chile, the Chilean introductions became the prominent type before the 1840’s.

The potato eaters (www.vggallery.com)

Now is almost everywhere….With the development of modern cultivars….

Thank you!!

Fondazione Slow Food per la Biodiversità