Zea (plant)

{{Short description|Genus of flowering plants in the grass family Poaceae}} {{Redirect|Teosinte}} {{Automatic taxobox | image = Corncobs edit1.jpg | image_caption = ''Zea mays'' | display_parents = 4 | taxon = Zea (plant) | authority = L. | type_species = ''Zea mays'' | type_species_authority = L. | synonyms_ref = <ref name=y>[http://apps.kew.org/wcsp/synonomy.do?name_id=450340 Kew World Checklist of Selected Plant Families]{{dead link |date=January 2025}}</ref> | synonyms = * ''Euchlaena'' Schrad. * ''Mays'' Mill. * ''Mayzea'' Raf. * ''Reana'' Brign. * ''Thalysia'' Kuntze * × ''Euchlaezea'' Jan.Ammal ex Bor * ''Mais'' Adans. }}

'''''Zea''''' is a genus of flowering plants in the grass family. The best-known species is ''Z. mays'' (variously called maize, corn, or Indian corn), one of the most important crops for human societies throughout much of the world. The four wild species are commonly known as '''teosintes''' and are native to Mesoamerica.

==Etymology== ''Zea'' is derived from the Greek name ({{lang|el|ζειά}}) for another cereal grain (possibly spelt).<ref name="gledhill">Gledhill, David (2008). "The Names of Plants". Cambridge University Press (CUP). {{ISBN|9780521866453}} (hardback), {{ISBN|9780521685535}} (paperback). pp 411</ref>

==Recognized species== [[File:Maize-teosinte.jpg|thumb|teosinte (top), maize-teosinte hybrid (middle), maize (bottom)]] The five accepted species names in the genus are:<ref>{{Cite web|url=https://www.itis.gov/servlet/SingleRpt/SingleRpt?search_topic=TSN&search_value=42268#null|title = ITIS - Report: Zea}}</ref><ref name="Wu-et-al-2011" /> {| class="wikitable" |- ! Ear !! Plant !! Scientific name !! Common name !! Distribution |- | 120px || 120px || ''Zea diploperennis'' H.H.Iltis et al.|| diploperennial teosinte || Jalisco |- | 120px || || ''Zea luxurians'' (Durieu & Asch.) R.M.Bird || Maíz de Monte, Florida teosinte and Guatemalan teosinte || Chiapas, Guatemala, Honduras |- | 120px || 120px || ''Zea mays'' L. || Corn, Maize || southern Mexico, Guatemala; cultivated in many places |- | || || ''Zea nicaraguensis'' H.H.Iltis & B.F.Benz|| Nicaraguan teosinte || Nicaragua |- | || 120px || ''Zea perennis'' (Hitchc.) Reeves & Mangelsd.|| perennial teosinte || Jalisco |- |}

Maize (''Zea mays'') is further divided into four subspecies: ''Z. m. huehuetenangensis'', ''Z. m. mexicana'', ''Z. m. parviglumis'' (Balsas teosinte, the ancestor of maize), and ''Z. m. mays''.<ref name="Wu-et-al-2011"/> The first three subspecies are teosintes; the last is maize, or corn,<ref name="Wu-et-al-2011">{{cite journal |last1=Wu |first1=Chi-Chih |last2=Diggle |first2=Pamela K. |last3=Friedman |first3=William E. |title=Female gametophyte development and double fertilization in Balsas teosinte, ''Zea mays'' subsp. ''parviglumis'' (Poaceae) |journal=Sexual Plant Reproduction|date=September 2011 |volume=24 |issue=3 |pages=219–229 |doi=10.1007/s00497-011-0164-1 |pmid=21380710 |s2cid=8045294 }}</ref> the only domesticated taxon in the genus ''Zea''.{{Citation needed|date=January 2021}}

The genus is divided into two sections: ''Luxuriantes'', with ''Z. diploperennis'', ''Z. luxurians'', ''Z. nicaraguensis'', ''Z. perennis''; and ''Zea'' with ''Z. mays''. The former section is typified by dark-staining knobs made up of heterochromatin that are terminal on most chromosome arms, while most subspecies of section ''Zea'' may have none to three knobs between each chromosome end and the centromere and very few terminal knobs (except ''Z. m. huehuetenangensis'', which has many large terminal knobs).{{Citation needed|date=January 2021}}

==Description== thumb|Microscopic view of ''Zea'' seed

Both annual and perennial teosinte species occur. ''Z. diploperennis'' and ''Z. perennis'' are perennial, while all other species are annual. All species are diploid (n=10) with the exception of ''Z. perennis'', which is tetraploid (n=20). The different species and subspecies of teosinte can be readily distinguished based on morphological, cytogenetic, protein, and DNA differences and on geographic origin. The two perennials are sympatric and very similar and some consider them to be one species. What many consider to be the most puzzling teosinte is ''Z. m. huehuetenangensis'', which combines a morphology rather like ''Z. m. parviglumis'' with many terminal chromosome knobs and an isozyme position between the two sections. Considered to be phenotypically the most distinctive, as well as the most threatened, teosinte is ''Zea nicaraguensis''. This teosinte thrives in flooded conditions along 200 m of a coastal estuarine river in northwest Nicaragua.

Teosintes strongly resemble maize in many ways, notably their tassel (male inflorescence) morphology. Teosintes are distinguished from maize most obviously by their numerous branches each bearing bunches of distinctive, small female inflorescences. These spikes mature to form a two-ranked 'ear' of five to 10 triangular or trapezoidal, black or brown disarticulating segments, each with one seed. Each seed is enclosed by a very hard fruitcase, consisting of a cupule or depression in the rachis and a tough lower glume. This protects them from the digestive processes of ruminants that forage on teosinte and aid in seed distribution through their droppings. Teosinte seed exhibits some resistance to germination, but will quickly germinate if treated with a dilute solution of hydrogen peroxide.{{Cn|date=February 2025}}

==Origin of maize and interaction with teosintes==

Maize is a grass, related to sorghum and more distantly to rice and wheat. The genus ''Zea'' is closely related to ''Tripsacum'', gamagrass.<ref name="Gaut Le Thierry dEnnequin Peek Sawkins 2000">{{cite journal |last1=Gaut |first1=Brandon S. |last2=Le Thierry d'Ennequin |first2=Maud |last3=Peek |first3=Andrew S. |last4=Sawkins |first4=Mark C. |title=Maize as a model for the evolution of plant nuclear genomes |journal=Proceedings of the National Academy of Sciences |volume=97 |issue=13 |date=2000-06-20 |issn=0027-8424 |pmid=10860964 |pmc=34377 |doi=10.1073/pnas.97.13.7008 |pages=7008–7015|doi-access=free |bibcode=2000PNAS...97.7008G }}</ref>

{{clade| style=font-size:100%;line-height:100% |label1=(Part of Poaceae) |1={{clade |label1= BOP clade |1={{clade |1={{clade |1=various grasses e.g. fescue, ryegrass |2={{clade |1=''Hordeum'' (barley) |2=''Triticum'' (wheat) }} }} |2=''Oryza'' (rice) }} |label2= PACMAD clade |2={{clade |1=''Pennisetum'' (fountaingrasses, pearl millet) |2={{clade |1=''Sorghum'' (sorghum) |2={{clade |1=''Tripsacum'' (gamagrass) |label2=''Zea'' |2={{clade |1=''Zea mays'' (maize) |2=other ''Zea'' species ('''teosintes''') }} }} }} }} }} }}

Teosintes are critical components of maize domestication, but opinions vary about which taxa were involved. According to the most widely held evolutionary model, the crop was derived directly from ''Z. m. parviglumis'' by selection of key mutations;<ref name=Matsuoka2002>{{cite journal |last1=Matsuoka |first1=Y. |last2=Vigouroux |first2=Y. |last3=Goodman |first3=M. M. |last4=Sanchez G. |first4=J. |last5=Buckler |first5=E. |last6=Doebley |first6=J. |title=A single domestication for maize shown by multilocus microsatellite genotyping |journal=Proceedings of the National Academy of Sciences |date=30 April 2002 |volume=99 |issue=9 |pages=6080–6084 |doi=10.1073/pnas.052125199 |pmid=11983901 |pmc=122905 |bibcode=2002PNAS...99.6080M |doi-access=free }}</ref> but in some varieties up to 20% of its genetic material came from ''Z. m. mexicana'' through introgression.<ref>{{cite journal |last1=Hufford |first1=Matthew B. |last2=Lubinsky |first2=Pesach |last3=Pyhäjärvi |first3=Tanja |last4=Devengenzo |first4=Michael T. |last5=Ellstrand |first5=Norman C. |last6=Ross-Ibarra |first6=Jeffrey |title=The Genomic Signature of Crop-Wild Introgression in Maize |journal=PLOS Genetics|date=9 May 2013 |volume=9 |issue=5 |article-number=e1003477 |doi=10.1371/journal.pgen.1003477 |pmid=23671421 |pmc=3649989 |doi-access=free }}</ref>

All but the Nicaraguan species of teosinte may grow in or very near corn fields, providing opportunities for introgression between teosinte and maize. First, and later-generation hybrids are often found in the fields, but the rate of gene exchange is quite low. Some populations of ''Z. m. mexicana'' display Vavilovian mimicry within cultivated maize fields, having evolved a maize-like form as a result of the farmers' selective weeding pressure. In some areas of Mexico, teosintes are regarded by maize farmers as a noxious weed, while in a few areas, farmers regard it as a beneficial companion plant, and encourage its introgression into their maize.{{Cn|date=February 2025}}

===Early dispersal of maize in the Americas===

According to Matsuoka et al., the available early maize gene pool can be divided into three clusters: * An Andean group, that includes the hand-grenade-shaped ear types and some other Andean maize (35 plants); * All other South American and Mexican maize (80 plants); * U.S. maize (40 plants)

Also, some other intermediate genomes, or admixtures of these clusters occur.

According to these authors, "The maize of the Andes Mountains with its distinctive hand grenade-shaped ears was derived from the maize of lowland South America, which in turn came from maize of the lowlands of Guatemala and southern Mexico."<ref name=Matsuoka2002 />

==Ecology== ''Zea'' species are used as food plants by the larvae (caterpillars) of some Lepidopteran species including (in the Americas) the fall armyworm (''Spodoptera frugiperda''), the corn earworm (''Helicoverpa zea''), and the stem borers ''Diatraea'' and ''Chilo''; in the Old World, it is attacked by the double-striped pug, the cutworms heart and club and heart and dart, ''Hypercompe indecisa'', the rustic shoulder-knot, the setaceous Hebrew character and turnip moths, and the European corn borer (''Ostrinia nubilalis''), among many others.

Virtually all populations of teosintes are either threatened or endangered: ''Z. diploperennis'' exists in an area of only a few square miles; ''Z. nicaraguensis'' survives as about 6000 plants in an area of 200 × 150 m. The Mexican and Nicaraguan governments have taken action in recent years to protect wild teosinte populations, using both ''in situ'' and ''ex situ'' conservation methods. Currently, a large amount of scientific interest exists in conferring beneficial teosinte traits, such as nitrogen fixation,<ref name="PLOS_NitroFix">{{cite journal |last1=Van Deynze |first1=Allen |last2=Zamora |first2=Pablo |last3=Delaux |first3=Pierre-Marc |last4=Heitmann |first4=Cristobal |last5=Jayaraman |first5=Dhileepkumar |last6=Rajasekar |first6=Shanmugam |last7=Graham |first7=Danielle |last8=Maeda |first8=Junko |last9=Gibson |first9=Donald |last10=Schwartz |first10=Kevin D. |last11=Berry |first11=Alison M. |last12=Bhatnagar |first12=Srijak |last13=Jospin |first13=Guillaume |last14=Darling |first14=Aaron |last15=Jeannotte |first15=Richard |last16=Lopez |first16=Javier |last17=Weimer |first17=Bart C. |last18=Eisen |first18=Jonathan A. |last19=Shapiro |first19=Howard-Yana |last20=Ané |first20=Jean-Michel |last21=Bennett |first21=Alan B. |title=Nitrogen fixation in a landrace of maize is supported by a mucilage-associated diazotrophic microbiota |journal=PLOS Biology|date=7 August 2018 |volume=16 |issue=8 |article-number=e2006352 |doi=10.1371/journal.pbio.2006352 |pmid=30086128 |pmc=6080747 |doi-access=free }}</ref> insect resistance, perennialism, and flood tolerance, to cultivated maize lines, although this is very difficult due to linked deleterious teosinte traits.{{Cn|date=February 2025}}

==Genomics== Gene flow from genetically modified maize to teosinte weeds has only been observed to produce a GM teosinte with the same trait but this may not always be the outcome.<ref name="Risk-Assessment"/> Teosinte with a different insertion of the transgene may result and functionally different outcomes may be produced.<ref name="Risk-Assessment"> :{{Cite journal|issue=1|year=2020|publisher=Springer Science and Business Media LLC|volume=32|last1=Bauer-Panskus|first1=Andreas|last2=Miyazaki|first2=Juliana|last3=Kawall|first3=Katharina|last4=Then|first4=Christoph|journal=Environmental Sciences Europe|issn=2190-4707|s2cid=211540730|doi=10.1186/s12302-020-00301-0|title=Risk assessment of genetically engineered plants that can persist and propagate in the environment|doi-access=free}} : :This review cites this research. : {{Cite journal |year=2018 |publisher=Elsevier BV |pages=19–27 |last1=Devos |first1=Yann |last2=Ortiz-García |first2=Sol |last3=Hokanson |first3=Karen E. |last4=Raybould |first4=Alan |volume=259 |journal=Agriculture, Ecosystems & Environment |issn=0167-8809 |s2cid=90341111 |doi=10.1016/j.agee.2018.02.032 |title=Teosinte and maize × teosinte hybrid plants in Europe−Environmental risk assessment and management implications for genetically modified maize}} </ref>

==References== {{Reflist}}

==External links== {{Commons category|Zea| Zea (genus)}} * {{cite news |last1=Carroll |first1=Sean B. |title=Tracking the Ancestry of Corn Back 9,000 Years |url=https://www.nytimes.com/2010/05/25/science/25creature.html |work=The New York Times |date=24 May 2010 }}

Category:Zea (plant) Category:Grasses of North America Category:Grasses of South America Category:Agriculture in Mesoamerica Category:Crops originating from North America Category:Crops originating from South America Category:Crops originating from Pre-Columbian North America Zea Category:Botanical taxa named by Carl Linnaeus Category:Andropogoneae