capsicum phylogeny and domestication

CapsicumPhylogeny and Domestication

Brian Walsh

Family: Solanaceae

Subfamily: Solanoideae

Tribe: Capsicinae (since 1999)•Estimated 25 species (my count =37)

•Native to South and Central America

•Current distribution is global

•One of the most utilized spice in the world

•Part of human diet for 9000 years

•All diploid

•Typically self-fertilize

•Most n=12 (some n=13)

One of the most diversely utilized plants

• Spice• Food• Dye• Medicine• Weapons• Poison• Drinks• Deterrent• Insecticide/Pesticide• Preservative• Snuff

• Rituals• Tribute• Town Names• Punishment

Domestication

•Davenport (1970) proposes all five domesticated species arose from a single ancestor (C. frutescens L.) (Lumper) (based on morphology)

•Heiser (1971) proposes each domesticated species arose from its own unique wild ancestor (Splitter) (hybridization studies)

Pickersgill (1972) agrees with Heiser - different cultivated species show a combination of characters suggesting domestication by different groups of people living in different areas.

•Eshbaugh (1983) argues at least three distinct domesticated lineages based on morphology, plant breeding and enzyme analysis (C. chacoense is plesiomorphic)

View from 1000000 km above 5°18’S 63°55’W

Agricultural Centers of the New World and the theoretical flow of speciation

Based on C. chacoense

Domesticated Characters in Capsicum

• Gigantism of fruit• Altered fruit shape• Fruit color other

than red• Retained on

peduncle a maturity• Variable capsaicin

levels

• small fruit• Fruit round• Red fruit

• Peduncle dehiscence at maturity

• High capsaicin levels

Domesticated Wild

Capsicum annuum

Capsicum annuum complex

C. annuum var. annuum

C. annuum var. avicular

C. frutescens

C. chinense

C. chacoense

Capsicum baccatum group

C. baccatum var. praetermissum

C. baccatum var. pendulum

C. baccatum var. baccatum

Capsicum eximium complex

C. pubescens

C. eximium

C. cardenasii

white flowers

white flowers with yellow spots

purple flowers

Total species=8

Eshbaugh’s breakdown into flower color categories (why?)

Tabasco

C. frutescens

C. baccatum var. praetermissum

Capsicum eximium

Capsicum eximium

C. baccatum var. praetermissum

Capsicum cardenasii

Only species that strictly outcrosses

Flower color classification of Capsicum

•Color categories inaccurate (too many exceptions)

•Only a fraction of total species included

•Doesn’t agree with molecular data

Current phylogenetic questions

• Monophyly of genus

• Resolving species relationships

Capsicum Monophyletic?

Modified from Bohs & Olmstead 1997

A B C

A A C

A B C

=

Monophyletic

A A C

=

Not Monophyletic

Walsh 2001

(chloroplast atpB-rbcL spacer data)

Walsh 2001

(chloroplast atpB-rbcL spacer data)

n=12/13

Walsh 2001

combined atpB-rbcL spacer and waxy data

Walsh 2001

(chloroplast atpB-rbcL spacer data)

Capsicum monophyly

• Intact for the time being

• Odd C. ciliatum seems to be the weak link

(n=13)

Mascone’s missing treeMascone 2003

Flow cytometry and Feulgen densitometry

1C-value of DNA = an equation for calculating genome size in absolute units

Genome size in Mbp

Capsicum anuum complex

C. annuum var. annuum

C. annuum var. avicular

C. frutescens

C. chinense

C. chacoense

white flowers

United by similar DNA amount and little heterochromatin

Visualization of Mascone’s results

C. annuum var. annuum

C. frutescens

C. chinense

C. chacoense

1C G

3.35 3273

3.38 3312

3.40 3332

3.42 3352

Capsicum baccatum group

C. baccatum var. praetermissum

C. baccatum var. pendulum

C. baccatum var. baccatum

white flowers with yellow spots

Similar DNA amounts – not surprising

C. baccatum var. umbilicatum New variety described in 1998

Domesticated status unknown

C. baccatum var. pendulum

C. baccatum var. baccatum

C. baccatum var. umbilicatum

Interpreted from data – not explicitly stated

C. annuum var. annuum

C. frutescens

C. chinense

C. chacoense

1C G

3.35 3273

3.38 3312

3.40 3332

3.42 3352

3.69 3621

3.71 3636

3.76 3636

Capsicum eximium complex

C. pubescens

C. eximium

C. cardenasii

purple flowers

C. eximium has DNA content intermediate between C. baccatum and C. pubescens, but genome size supports close relationship to C. pubescens as well as isozyme and cross studies

C. parvifolium synonym with C. cardenasii? (but description is off – tree?)

C. parvifolium only compared to C. campylopodium

C. campylopodium groups with C. pubescens – large genome size, and large amounts of heterochromatin forming complex patterns (tone implies trepidation)

points out distantly related and nothing more

C. baccatum var. pendulum

C. baccatum var. baccatum

C. baccatum var. umbilicatum

C. pubescens

C. eximium

C. parvifolium/cardenasii

C. campylopodium

?

?

C. annuum var. annuum

C. frutescens

C. chinense

C. chacoense

1C G

3.35 3273

3.38 3312

3.40 3332

3.42 3352

3.69 3621

3.71 3636

3.76 3636

4.06 3979

4.47 4381

5.14 5032

5.77 5655

However, Mascone claims his data supports his hypothesis

• Increase in DNA amount is evolutionary advancement

• C. chacoense most plesiomorphic (ancestral)• C. campylopodium most advanced• n=13 in more recently evolved

C. baccatum var. pendulum

C. baccatum var. baccatum

C. baccatum var. umbilicatum

C. pubescens

C. eximium

C. parvifolium/cardenasii

C. campylopodium

?

Mascone tree rooted

Least DNA

Most DNA x=13

C. annuum var. annuum

C. frutescens

C. chinense

C. chacoense

C. baccatum var. pendulum

C. baccatum var. baccatum

C. baccatum var. umbilicatum

C. pubescens

C. eximium

C. parvifolium/cardenasii

C. campylopodium

?

Mascone

Least DNA

Most DNA x=13

C. annuum var. annuum

C. frutescens

C. chinense

C. chacoense

?

ancestral

molecular

X=13 species• C. ciliatum• C. buforum• C. campylopodium• C. cornutum• C. schottianum• C. villosum• C. pereirae *• C. friburguense *• 3 unnamed Capsicum

Capsicum flexuosum

n = 13

n = 12

•Capsicum needs more research

•Appears to be an x=12/x=13 split in distant past

•research hindered by incomplete sampling

•Difficult to study domestication when phylogeny unresolved

•6 new species identified in last 8 years

Conclusion

Naga Morich

Following Photos unused in presentation

Cherrapeño

Bolivian rainbow

Cherry Pepper

Chilaca Fluorescent

Fredrik from Amalfi

Jalapeño - Biker Billy

Lemon black pepper

Little nubian

O'odham Indian Piquin

Peter Pepper Pimenta-Doce

Poblano Suryamukhi

Tepin Variegata

Naga Jolokia / Tezpur

C. Frutescens

Tabasco PI451762

Antillerna (Paris)

C. chinense

C02466

Capsicum galapagoense

PI560944 - Putapario

C. chacoense

C. Pubescens

praetermissum

Capsicum eximium

C. ciliatum

Capsicum Cardenasii

C. tovarii