Gossypium () 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, making it the largest genus in the tribe Gossypieae, and new species continue to be discovered.

Cotton is the primary natural fibre used by humans today, amounting to about 80% of world natural fibre production. 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. 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. 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.

Species

55 species are accepted.

  • Gossypium thurberi <small>Tod.</small> – Arizona wild cotton (Arizona and northern Mexico)
  • Gossypium timorense
  • Gossypium tomentosum <small>Nutt. ex Seem</small> – Maʻo or Hawaiian cotton (Hawaii)
  • Gossypium trifurcatum
  • Gossypium trilobum
  • Gossypium triphyllum
  • Gossypium turneri
  • Gossypium vollesenii }

Formerly placed in genus Gossypium

  • Gossypioides brevilanatum <small>(Hochr.) J.B.Hutch.</small> (as G. brevilanatum <small>Hochr.</small>)
  • Gossypioides kirkii <small>(Mast.) J.B.Hutch.</small> (as Gossypium kirkii <small>Mast.</small>)
  • Kokia drynarioides <small>(Seem.) Lewton</small> (as G. drynarioides <small>Seem.</small>) 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. 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. raimondiis. 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. 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

250px|thumb|Cotton field in [[Sukhumi Botanical Garden, photo circa 1912]]

250px|thumb|Cotton field in [[Greece]]

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>

Cotton plant flower G. hirsutum.JPG|A Gossypium hirsutum flower, lateral view, growing in Barcelona

Càpsula obrint-se.JPG|The same G. hirsutum plant with the opening capsule

Cotton pollination 5892.JPG|G. hirsutum flower with bumblebee pollinator, Hemingway, South Carolina

Hawn Cotton.jpg|G. tomentosum boll

IPMtrap4854.JPG|Integrated pest management bollworm trap at a cotton field in Manning, South Carolina

Organic-agriculture biocontrol-cotton polistes-wasp.JPG|Natural biocontrol: predatory Polistes wasp looking for bollworms or other caterpillars on cotton plant in Hemingway, South Carolina

Cotton boll nearly ready for harvest.jpg|Cotton boll ready for harvest, South Carolina

Gossypium Sp. Brun MHNT.BOT.2018.28.8.jpg|Gossypium Sp. Brun - MHNT

</gallery>

See also

  • Vegetable Lamb of Tartary, a European legendary plant remotely based on cotton.

References

  • Central Institute for Cotton Research – located in India.