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Gossypium
	Flower of Gossypium herbaceum
Scientific classification
Kingdom:	Plantae
Clade:	Tracheophytes
Clade:	Angiosperms
Clade:	Eudicots
Clade:	Rosids
Order:	Malvales
Family:	Malvaceae
Subfamily:	Malvoideae
Tribe:	Gossypieae
Genus:	Gossypium; L.
Type species
	Gossypium arboreum; L.
Species
	See text.
Synonyms
	Erioxylum Rose & Standl.; Ingenhouzia DC.; Notoxylinon Lewton; Selera Ulbr.; Sturtia R.Br.; Thurberia A.Gray; Ultragossypium Roberty;

Gossypium (/ɡɒˈsɪpiəm/)^[2] is a genus of flowering plants in the tribe Gossypieae of the mallow family, Malvaceae, from which cotton is harvested. It is native to tropical and subtropical regions of the Old and New Worlds. There are about 50 Gossypium species,^[3] making it the largest genus in the tribe Gossypieae, and new species continue to be discovered.^[3] The name of the genus is derived from the Arabic word goz, which refers to a soft substance.^[4]

Cotton is the primary natural fibre used by humans today, amounting to about 80% of world natural fibre production.^[5] Where cotton is cultivated, it is a major oilseed crop and a main protein source for animal feed. Cotton is thus of great importance for agriculture, industry and trade, especially for tropical and subtropical countries in Africa, South America and Asia. Consequently, the genus Gossypium has long attracted the attention of scientists.

The origin of the genus Gossypium is dated to around 5–10 million years ago.^[6] Gossypium species are distributed in arid to semiarid regions of the tropics and subtropics. Generally shrubs or shrub-like plants, the species of this genus are extraordinarily diverse in morphology and adaptation, ranging from fire-adapted, herbaceous perennials in Australia to trees in Mexico.^[3] Most wild cottons are diploid, but a group of five species from America and Pacific islands are tetraploid, apparently due to a single hybridization event around 1.5 to 2 million years ago.^[6] The tetraploid species are G. hirsutum, G. tomentosum, G. mustelinum, G. barbadense, and G. darwinii.

Cultivated cottons are perennial shrubs, most often grown as annuals. Plants are 1–2 m high in modern cropping systems, sometimes higher in traditional, multiannual cropping systems, now largely disappearing. The leaves are broad and lobed, with three to five (or rarely seven) lobes. The seeds are contained in a capsule called a "boll", each seed surrounded by fibres of two types. These fibres are the more commercially interesting part of the plant and they are separated from the seed by a process called ginning. At the first ginning, the longer fibres, called staples, are removed and these are twisted together to form yarn for making thread and weaving into high quality textiles. At the second ginning, the shorter fibres, called "linters", are removed, and these are woven into lower quality textiles (which include the eponymous lint). Commercial species of cotton plant are G. hirsutum (97% of world production), G. barbadense (1–2%), G. arboreum and G. herbaceum (together, ~1%).^[7] Many varieties of cotton have been developed by selective breeding and hybridization of these species. Experiments are ongoing to cross-breed various desirable traits of wild cotton species into the principal commercial species, such as resistance to insects and diseases, and drought tolerance. Cotton fibres occur naturally in colours of white, brown, green, and some mixing of these.

Selected species

Subgenus Gossypium

Gossypium anomalum Wawra & Peyr.
Gossypium arboreum L. – tree cotton (India and Pakistan)
Gossypium herbaceum L. – Levant cotton (southern Africa and the Arabian Peninsula)

Subgenus Houzingenia

Gossypium raimondii Ulbr. – one of the putative progenitor species of tetraploid cotton, alongside G. arboreum
Gossypium thurberi Tod. – Arizona wild cotton (Arizona and northern Mexico)

Subgenus Karpas

Gossypium barbadense L. – Creole cotton/Sea Island Cotton (tropical South America)
Gossypium darwinii G.Watt – Darwin's cotton (Galápagos Islands)
Gossypium hirsutum L. – upland cotton (Central America, Mexico, the Caribbean and southern Florida)
Gossypium mustelinum Miers ex G.Watt
Gossypium tomentosum Nutt. ex Seem – Maʻo or Hawaiian cotton (Hawaii)

Subgenus Sturtia

Gossypium australe F.Muell (northwestern Australia)
Gossypium sturtianum J.H. Willis – Sturt's desert rose (Australia)^[8]^[9]

Formerly placed in genus Gossypium

Gossypioides brevilanatum (Hochr.) J.B.Hutch. (as G. brevilanatum Hochr.)
Gossypioides kirkii (Mast.) J.B.Hutch. (as Gossypium kirkii Mast.)
Kokia drynarioides (Seem.) Lewton (as G. drynarioides Seem.)^[9]

Gossypium genome

A public genome sequencing effort of cotton was initiated^[10] in 2007 by a consortium of public researchers. They agreed on a strategy to sequence the genome of cultivated, allotetraploid cotton. "Allotetraploid" means that the genomes of these cotton species comprise two distinct subgenomes, referred to as the At and Dt (the 't' for tetraploid, to distinguish them from the A and D genomes of the related diploid species). The strategy is to sequence first the D-genome relative of allotetraploid cottons, G. raimondii, a wild South American (Peru, Ecuador) cotton species, because of its smaller size due essentially to less repetitive DNA (retrotransposons mainly). It has nearly one-third the number of bases of tetraploid cotton (AD), and each chromosome is only present once.^{[clarification needed]} The A genome of G. arboreum, the 'Old-World' cotton species (grown in India in particular), would be sequenced next. Its genome is roughly twice the size of G. raimondii's. Once both A and D genome sequences are assembled, then research could begin to sequence the actual genomes of tetraploid cultivated cotton varieties. This strategy is out of necessity; if one were to sequence the tetraploid genome without model diploid genomes, the euchromatic DNA sequences of the AD genomes would co-assemble and the repetitive elements of AD genomes would assemble independently into A and D sequences, respectively. Then there would be no way to untangle the mess of AD sequences without comparing them to their diploid counterparts.

The public sector effort continues with the goal to create a high-quality, draft genome sequence from reads generated by all sources. The public-sector effort has generated Sanger reads of BACs, fosmids, and plasmids, as well as 454 reads. These later types of reads will be instrumental in assembling an initial draft of the D genome. In 2010, two companies (Monsanto and Illumina), completed enough Illumina sequencing to cover the D genome of G. raimondii about 50x.^[11] They announced they would donate their raw reads to the public. This public relations effort gave them some recognition for sequencing the cotton genome. Once the D genome is assembled from all of this raw material, it will undoubtedly assist in the assembly of the AD genomes of cultivated varieties of cotton, but a lot of hard work remains.

Cotton pests and diseases

Pests

Boll weevil, Anthonomus grandis
Cotton aphid, Aphis gossypii
Cotton stainer, Dysdercus koenigii
Cotton bollworm, Helicoverpa zea, and native budworm, Helicoverpa punctigera, are caterpillars that damage cotton crops.
Some other Lepidoptera (butterfly and moth) larvae also feed on cotton – see list of Lepidoptera that feed on cotton plants.
Green mirid (Creontiades dilutus), a sucking insect
Spider mites, Tetranychus urticae, T. ludeni and T. lambi
Thrips, Thrips tabaci and Frankliniella schultzei

Diseases

Alternaria leaf spot, caused by Alternaria macrospora and Alternaria alternata
Anthracnose boll rot, caused by Colletotrichum gossypii
Black root rot, caused by the fungus Thielaviopsis basicola
Blight caused by Xanthomonas campestris pv. malvacearum
Fusarium boll rot caused by Fusarium spp.
Phytophthora boll rot, caused by Phytophthora nicotianae var. parasitica
Sclerotinia boll rot, caused by the fungus Sclerotinia sclerotiorum
Stigmatomycosis, caused by the fungi Ashbya gossypii, Eremothecium coryli, (Nematospora coryli) and Aureobasidium pullulans

Gallery

A Gossypium hirsutum flower, lateral view, growing in Barcelona
The same G. hirsutum plant with the opening capsule
G. hirsutum flower with bumblebee pollinator, Hemingway, South Carolina
G. tomentosum boll
Integrated pest management bollworm trap at a cotton field in Manning, South Carolina
Natural biocontrol: predatory Polistes wasp looking for bollworms or other caterpillars on cotton plant in Hemingway, South Carolina
Cotton boll ready for harvest, South Carolina
Gossypium Sp. Brun - MHNT

References

^ ^a ^b "Genus: Gossypium L". Germplasm Resources Information Network. United States Department of Agriculture. 2007-03-12. Archived from the original on 2011-07-17. Retrieved 2011-09-08.
^ "Gossypium". Merriam-Webster.com Dictionary. Merriam-Webster. Retrieved 2020-05-19.
^ ^a ^b ^c Wendel JF, Brubaker C, Alvarez I, et al. (2009). "Evolution and Natural History of the Cotton Genus". In Andrew H. Paterson (ed.). Plant Genetics and Genomics: Crops and Models. Vol. 3. pp. 3–22. doi:10.1007/978-0-387-70810-2_1. ISBN 978-0-387-70809-6.
^ Gledhill, D. (2008). The Names of Plants (4 ed.). Cambridge University Press. p. 182. ISBN 978-0-521-86645-3.
^ Townsend, Terry (2020). "1B - World natural fibre production and employment". Handbook of Natural Fibres. Vol. 1 (2 ed.). Woodhead Publishing. pp. 15–36. doi:10.1016/B978-0-12-818398-4.00002-5. ISBN 9780128183984. S2CID 212822506.
^ ^a ^b Senchina DS, Alvarez I, Cronn RC, et al. (2003). "Rate variation among nuclear genes and the age of polyploidy in Gossypium". Mol. Biol. Evol. 20 (4): 633–643. doi:10.1093/molbev/msg065. PMID 12679546.
^ Chaudhry, M. R. (2010). "10 - Cotton Production and Processing". Industrial Applications of Natural Fibres. John Wiley & Sons, Ltd. pp. 219–234. doi:10.1002/9780470660324.ch10. ISBN 9780470660324.
^ "Gossypium". Integrated Taxonomic Information System. Retrieved 2011-09-08.
^ ^a ^b "GRIN Species Records of Gossypium". Germplasm Resources Information Network. United States Department of Agriculture. Archived from the original on 2015-09-24. Retrieved 2011-09-08.
^ Chen ZJ, Scheffler BE, Dennis E, et al. (Dec 2007). "Toward sequencing cotton (Gossypium) genomes". Plant Physiol. 145 (4): 1303–10. doi:10.1104/pp.107.107672. PMC 2151711. PMID 18056866.
^ APPDMZ\gyoung. "Monsanto and Illumina Reach Key Milestone in Cotton Genome Sequencing". www.monsanto.com. Archived from the original on 2016-02-01. Retrieved 2016-01-31.