Cotton J. E.(Jed) and Bonnie McClellan © 2005 California Academy of Sciences © 2006 Matt Below Katie Konchar – UW Department of Botany

“The fabric of our Lives” Oils, Balls, Q-tips ™, Bandages, Tissue, Paper, Napkins, Socks, Shirts, Shorts, Sweaters, Pants, Coats, Towels, Linen, Cushions, Drapery, Upholstery, Rugs, Carpet, Comforters, Mattresses, Insulation, Filtration Southern Illonois University Ethnobotanical Leaflet

Country School of Menomonie A collection of cotton products from the boll to the finished product, hung in the kindergarten of an old Menomonie school house.

Gossypium Phylum Magnoliophyta Class Magnoliopsida Order Malvales Family Malvaceae Tribe Gossypieae Lysigenous glands contain sesquiterpenes collectively called gossypol n = 26 © 2006 Matt Below

Diversity Annual, biennial or perennial Herbaceous, short shrub or small tree Primary axis, alternate Leaves have varying texture, shape, hairiness Showy cream, yellow, red or purple flowers axilary, terminal or solitary with typically 5 petals

Seed Hairs Unicellular outgrowths of the epidermis of the seed or seed coat Unique convolutions and spiral twists causes the fibers to cling together when spun Steve Hurst. Provided by ARS Systematic Botany and Mycology Laboratory. Cyprus.

Four Independently Domesticated Species!! African-Asian diploids: G. herbaceum G. arboreum New World tetraploids: G. barbadense G. hirsutum Annualized Longer, stronger fiber Higher yield, abundant fiber Ease of harvest Time of maturity Day length neutral Disease resistance Glandless seed

Modern Mechanized Production Modern Cotton Gin Stand USDA

Jonathan Wendel Iowa State University Ecology, Evolution, and Organismal Biology Gene expression Genome size evolution Phylogenetics

Wendel and Cronn, 2003: Figure 1

From Chapter 70: Figure 70.1 “Line of Domestication” 6-11 mya

Two parental diploid groups on opposite sides of the world! How did Gossypium disperse over such a long distance? Where humans involved? When did the divergence of A and D genomes occur? And, when did the chance recombination of these genomes lead to allopolyploidization?

Cretaceous Hypothesis: Based on the observation of global distribution and impressive morphological variation within the tribe Evidence points to progenitor diploid species lines which are in currently in different hemispheres The continents where the progenitors may have originated have shifted due to the movements of tectonic plates separating the African and South American continents Rationally suggests that allopolyploidy must be ancient! Hybridization must have occurred before the splitting of the supercontinents and therefore can be dated back to the Cretaceous or early Tertiary

Hypotheses for Recent Origin of Allopolyploidy in Cotton: Agronomically advanced fiber probably only developed once Origin must have involved human transfer of the A genome cultigen to the New World Followed by hybridization of the A genome cultigen with a New World D genome species So…allopolyploid cotton formed during agricultural times, within the last 6 millennia!

Other proposals: Endrezzi et al. Thermal stability measurements and hybridization experiments: –Argue for Miocene origin (5-18 mya) –Calculations based on an early Cretaceous divergence of parental diploid groups Phillips 1963 Review of cytogenetic evidence –Argues for mid-Pleistocene –Two germinal lines of anciently diverging tribes recently combined to form tetraploids

A Pleistocene Origin Evolutionary implications of a recent origin of allopolyploidy: Divergence and speciation of Gossypium tetraploids Diploid parentage of the tetraploids Biogeography How can the progenitors have dispersed?

Rapid diversification and speciation Phylogenetic analyses demonstrate radiation into 3 lineages involving 5 tetraploid species Supported by low levels of interspecific divergence in nuclear genes -Island endemics must have originated after additional dispersal events

Concerning diploid parentage Cytogenetic studies indicate G. raimondii as the closest living relative of D genome parental donor Hutchinson et al., 1947 –used 5 D-genome species in crosses with G. hirsutum or G. barbadense –Indicated G. raimondii as closer to the D-genome than other species tested –Innovative approach involving comparative analysis of diverse synthetic allohexaploids Liu et al., 2001b –G. raimondii is the sister group to clade of all 5 allopolyploid species

A-genome perspectives A-genome of allopolyploid cotton is more similar to the A-genome diploids than the D-genome of the allopolyploid is to that of the D-genome diploids! G. arboreum and G. herbaceum better models of the progenitor A-genome diploid than G. raimondii is of the D-genome diploid G. herbaceum more likely the A-genome donor than G. arboreum

Biogeographical Theories Theories, based on cytogenetic data, suggested that polyploidization occurred after a Trans-Atlantic dispersal of a species similar to G. herbaceum Wendel and Albert, 1992: Suggest pre-Pleistocene A-genome radiation into Asia, followed by trans-Pacific dispersal to the Americas Supported by biogeography of D-genome species Recent arrival of G. raimondii in Peru

Allopolyploidization of Cotton Occurred Only Once All New World tetraploid cottons contain Old World Cytoplasm Must have been one single seed plant in the initial hybridization event So, how did it get there? By Evert at

Transoceanic Voyages But How!? Seeds of many species of Gossypium are tolerant to long periods of immersion in salt water Capable of germination after many years of immersion But, only retain their buoyancy for a couple months Stephens, 1966 suggested long distance dispersal may have been accomplished on naturally floating debris. Long distance dispersals are characteristic of Gossypieae Important in diversification and speciation