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The '''trifoliate orange''', '''''Citrus trifoliata''''' or '''''Poncirus trifoliata''''', is a member of the family [[Rutaceae]]. Whether the species should be considered to belong to its own genus, ''Poncirus'' or included in the genus ''Citrus'' is debated. The species is unusual among citrus for having [[deciduous]], [[compound leaf|compound leaves]] and pubescent (downy) fruit.<ref name=FOC1753>{{citation |chapter-url=http://www.efloras.org/florataxon.aspx?flora_id=2&taxon_id=107164 |chapter=''Citrus'' Linnaeus, Sp. Pl. 2: 782. 1753 |author1=Dianxiang Zhang |author2=David J. Mabberley |name-list-style=amp |title=Flora of China online |volume=11}}</ref><ref>{{citation|chapter-url=http://www.efloras.org/florataxon.aspx?flora_id=2&taxon_id=220002968 |chapter=''Citrus trifoliata'' Linnaeus, Sp. Pl., ed. 2. 2: 1101. 1763 |author1=Dianxiang Zhang |author2=David J. Mabberley |name-list-style=amp |title=Flora of China online |volume=11}}</ref>
The '''trifoliate orange''', '''''Citrus trifoliata''''' or '''''Poncirus trifoliata''''', is a member of the family [[Rutaceae]]. Whether the trifoliate oranges should be considered to belong to their own genus, ''Poncirus'', or be included in the genus ''Citrus'' is debated. The species is unusual among citrus for having [[deciduous]], [[compound leaf|compound leaves]] and pubescent (downy) fruit.<ref name=FOC1753>{{citation |chapter-url=http://www.efloras.org/florataxon.aspx?flora_id=2&taxon_id=107164 |chapter=''Citrus'' Linnaeus, Sp. Pl. 2: 782. 1753 |author1=Dianxiang Zhang |author2=David J. Mabberley |name-list-style=amp |title=Flora of China online |volume=11}}</ref><ref>{{citation|chapter-url=http://www.efloras.org/florataxon.aspx?flora_id=2&taxon_id=220002968 |chapter=''Citrus trifoliata'' Linnaeus, Sp. Pl., ed. 2. 2: 1101. 1763 |author1=Dianxiang Zhang |author2=David J. Mabberley |name-list-style=amp |title=Flora of China online |volume=11}}</ref>


It is native to northern [[China]] and [[Korea]], and is also known as the '''Japanese bitter-orange''',<ref name=BSBI07>{{BSBI 2007 |access-date=2014-10-17 }}</ref> '''hardy orange'''<ref>{{PLANTS|id=POTR4 |taxon=Poncirus trifoliata|access-date=31 January 2016}}</ref> or '''Chinese bitter orange'''.
It is native to northern [[China]] and [[Korea]], and is also known as the '''Japanese bitter-orange''',<ref name=BSBI07>{{BSBI 2007 |access-date=2014-10-17 }}</ref> '''hardy orange'''<ref>{{PLANTS|id=POTR4 |taxon=Poncirus trifoliata|access-date=31 January 2016}}</ref> or '''Chinese bitter orange'''.
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The fruits of the trifoliate orange are widely used in [[Traditional Asian medicine|medical traditions of East Asia]] as a treatment for allergic inflammation.<ref>{{citation |pmid=17662711 |author1=Zhou H.Y. |author2=Shin E.M. |author3=Guo L.Y. |author4=Zou L.B. |author5=Xu G.H. |author6=Lee S.-H. |author7=Ze K.R. |author8=Kim E.-K. |author9=Kang S.S. |author10=Kim Y.S. |title=Anti-inflammatory activity of 21(alpha, beta)-methylmelianodiols, novel compounds from ''Poncirus trifoliata'' Rafinesque |journal=European Journal of Pharmacology |volume=572 |issue=2–3 |pages=239–248 |year=2007 |doi=10.1016/j.ejphar.2007.07.005}}</ref>
The fruits of the trifoliate orange are widely used in [[Traditional Asian medicine|medical traditions of East Asia]] as a treatment for allergic inflammation.<ref>{{citation |pmid=17662711 |author1=Zhou H.Y. |author2=Shin E.M. |author3=Guo L.Y. |author4=Zou L.B. |author5=Xu G.H. |author6=Lee S.-H. |author7=Ze K.R. |author8=Kim E.-K. |author9=Kang S.S. |author10=Kim Y.S. |title=Anti-inflammatory activity of 21(alpha, beta)-methylmelianodiols, novel compounds from ''Poncirus trifoliata'' Rafinesque |journal=European Journal of Pharmacology |volume=572 |issue=2–3 |pages=239–248 |year=2007 |doi=10.1016/j.ejphar.2007.07.005}}</ref>


==Taxonomy==
==Related cultivars==
The trifoliate orange was historically considered a member of the genus ''Citrus'' until Swingle moved it to its own novel [[genus]], ''[[Poncirus]]'', based on its deciduous trifoliate leaves differing from other ''Citrus'', as part of a larger reclassification that split the historical ''Citrus'' into seven genera. However, Mabberley and Zhang reunited all of Swingle's novel genera back into ''Citrus''.<ref name="citrus taxonomy">{{cite chapter |chapter=''Citrus'' taxonomy |last1=Ollitrault |first1=Patrick |last2=Curk |first2=Franck |last3=Krueger |first3=Robert |title=The Citrus Genus |editor-last1=Talon |editor-first1=Manuel |editor-last2=Caruso |editor-first2=Marco |editor-last3=Gmitter |editor-first3=Frederick G., Jr. |publisher=Elsevier |date=2020 |pages=57–81 |isbn=9780128121634 |chapter-url= https://books.google.com/books?id=2wo4swEACAAJ&pg=PA57 |doi=10.1016/B978-0-12-812163-4.00004-8}}</ref> Early phylogenetic analysis of trifoliate orange [[plastid]]s nested ''Poncirus'' within the citrus, consistent with a single genus,<ref name="Nicolosi 2000" /><ref>{{cite journal |doi=10.1078/1439-6092-00058 |title=What is Citrus? Taxonomic implications from a study of cp-DNA evolution in the tribe Citreae (Rutaceae subfamily Aurantioideae) |journal=Organisms Diversity & Evolution |last1=de Araújo |first1=Edson Freitas |last2=Queiroza |first2=Luciano Paganuccide |last3=Machado |first3=Marcos Antônio |date=2003 |volume= 1 |pages=55–62}}</ref><ref name="bayer">{{cite journal |last1=Bayer |first1=Randall J. |last2=Mabberly |first2=David J. |last3=Morton |first3=Cynthia |last4=Miller |first4=Cathy H. |last5=Sharma |first5=Ish K. |last6=Pfiel |first6=Bernard E. |last7=Rich |first7=Sarah |last8=Hitchcock |first8=Roberta |last9=Sykes |first9=Steve |date=2009 |title=A molecular phylogeny of the orange subfamily (Rutaceae: Aurantioideae) using nine cpDNA sequences |journal=American Journal of Botany |volume=96 |issue=3 |pages=668–685 |doi=10.3732/ajb.0800341 |pmid=21628223}}</ref><ref name="nuclear phylogenetic">{{cite journal |title=A nuclear phylogenetic analysis: SNPs, indels and SSRs deliver new insights into the relationships in the 'true citrus fruit trees' group (Citrinae, Rutaceae) and the origin of cultivated species |last1=Garcia-Lor |first1=Andres |last2=Curk |first2=Franck |last3=Snoussi-Trifa |first3=Hager |last4=Morillon |first4=Raphael |last5=Ancillo |first5=Gema |last6=Luro |first6=François |last7=Navarro |first7=Luis |last8=Ollitrault |first8=Patrick |journal=Annals of Botany |volume=111 |issue=1 |pages=1–19 |date=2011 |doi=10.1093/aob/mcs227 |pmid=23104641 |pmc=3523644}}</ref> but the sequencing of the nuclear genome by Wu, ''et al.'' showed its genome to be most divergent, different enough to justify retention of ''Poncirus'' as a separate genus.<ref name="Talon">{{cite journal |title=Genomics of the origin and evolution of ''Citrus'' |last1=Wu |first1=Guohong Albert |last2=Terol |first2=Javier |last3=Ibanez |first3=Victoria |last4=López-García |first4=Antonio |last5=Pérez-Román |first5=Estela |last6=Borredá |first6=Carles |last7=Domingo |first7=Concha |last8=Tadeo |first8=Francisco R |last9=Carbonell-Caballero |first9=Jose |last10=Alonso |first10=Roberto |last11=Curk |first11=Franck |last12=Du |first12=Dongliang |last13=Ollitrault |first13=Patrick |last14=Roose |first14=Mikeal L. |last15=Dopazo |first15=Joaquin |last16=Gmitter |first16=Frederick G., Jr. |last17=Rokhsar |first17=Daniel |last18=Talon |first18=Manuel |journal=Nature |date=2018 |volume=554 |issue=7692 |pages=311–316 |doi=10.1038/nature25447 |pmid=29414943 |bibcode=2018Natur.554..311W |doi-access=free}} and Supplement</ref> To explain the conflict between the plastid and nuclear genomic analysis, it was speculated that the trifoliate orange is likely either the progeny of an ancient hybridization between a core citrus and an unidentified more distant relative, or at some time in its history it acquired an [[introgression|introgressed]] cpDNA genome from another species.<ref name="origin citrus">{{cite chapter |chapter=The origin of citrus |last1=Talon |first1=Manuel |last2=Wu |first2=Guohong Albert |last3=Gmitter |first3=Frederick G. |last4=Rokhsar |first4=Daniel S |title=The Citrus Genus |editor-last1=Talon |editor-first1=Manuel |editor-last2=Caruso |editor-first2=Marco |editor-last3=Gmitter |editor-first3=Frederick G., Jr. |publisher=Elsevier |date=2020 |pages=9–31 |isbn=9780128121634|doi=10.1016/C2016-0-02375-6}}</ref> Ollitrault, Curk and Krueger indicate that the majority of data are consistent with the enlarged ''Citrus'' that includes the trifoliate orange, though they recognize that many botanists still follow Swingle.<ref name="citrus taxonomy" />
A second species in ''Poncirus'' native to [[Yunnan]] (China) has been reported and named ''P. polyandra''.<ref>{{cite journal |title=A nuclear phylogenetic analysis: SNPs, indels and SSRs deliver new insights into the relationships in the 'true citrus fruit trees' group (Citrinae, Rutaceae) and the origin of cultivated species |last1=Garcia-Lor |first1=Andres |last2=Curk |first2=Franck |last3=Snoussi-Trifa |first3=Hager |last4=Morillon |first4=Raphael |last5=Ancillo |first5=Gema |last6=Luro |first6=François |last7=Navarro |first7=Luis |last8=Ollitrault |first8=Patrick |journal=Annals of Botany |volume=111 |pages=1–19 |year=2011 |issue=1 |doi=10.1093/aob/mcs227|pmc=3523644 |pmid=23104641}}</ref> Were ''Poncirus'' to be subsumed into ''Citrus'', a renaming would be required since a ''C. polyandra'' is unavailable; ''Citrus polytrifolia'' has been suggested.<ref>{{cite web|title=''Citrus polytrifolia''|website=NCBI Taxonomy Browser|url=https://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi|access-date=2 February 2021}}</ref> Zhang and Mabberley concluded this Yunnan cultivar is likely a hybrid between the trifoliate orange and another ''Citrus'',<ref name=FOC1753 /> but recent genomic analysis of ''P. polyandra'' showed low levels of [[Zygosity#Heterozygous|heterozygosity]],<ref name=Ze>{{cite journal|title=A chromosome‐scale reference genome of trifoliate orange (Poncirus trifoliata) provides insights into disease resistance, cold tolerance and genome evolution in Citrus |first1=Ze |last1=Peng |first2=Jessen V. |last2=Bredeson |first3=Guohong A. |last3=Wu |first4=Shengqiang |last4=Shu |first5=Nidhi |last5=Rawat |first6=Dongliang |last6=Du |first7=Saroj |last7=Parajuli |first8=Qibin |last8=Yu |first9=Qian |last9=You |first10=Daniel S. |last10=Rokhsar |first11=Frederick G. Jr |last11=Gmitter |first12=Zhanao |last12=Deng |journal=The Plant Journal |volume=104 |pages=1215-1232 |year=2020 |doi=10.1111/tpj.14993|doi-access=free }}</ref> the opposite of what one would expect for a hybrid. This analysis dated its divergence from ''P. trifoliata'' about 2.82 million years ago.<ref name=Ze />

A second species of trifoliate orange native to [[Yunnan]] (China) has been reported and named ''Poncirus polyandra''.<ref>{{cite journal |title=A nuclear phylogenetic analysis: SNPs, indels and SSRs deliver new insights into the relationships in the 'true citrus fruit trees' group (Citrinae, Rutaceae) and the origin of cultivated species |last1=Garcia-Lor |first1=Andres |last2=Curk |first2=Franck |last3=Snoussi-Trifa |first3=Hager |last4=Morillon |first4=Raphael |last5=Ancillo |first5=Gema |last6=Luro |first6=François |last7=Navarro |first7=Luis |last8=Ollitrault |first8=Patrick |journal=Annals of Botany |volume=111 |pages=1–19 |year=2011 |issue=1 |doi=10.1093/aob/mcs227|pmc=3523644 |pmid=23104641}}</ref> Were ''Poncirus'' to be subsumed into ''Citrus'', where ''C. polyandra'' is unavailable, the name ''Citrus polytrifolia'' has been suggested.<ref>{{cite web|title=''Citrus polytrifolia''|website=NCBI Taxonomy Browser|url=https://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi|access-date=2 February 2021}}</ref> Zhang and Mabberley concluded this Yunnan cultivar is likely a hybrid between the trifoliate orange and another ''Citrus'',<ref name=FOC1753 /> but recent genomic analysis of ''P. polyandra'' showed low levels of [[Zygosity#Heterozygous|heterozygosity]],<ref name=Ze>{{cite journal|title=A chromosome‐scale reference genome of trifoliate orange (Poncirus trifoliata) provides insights into disease resistance, cold tolerance and genome evolution in Citrus |first1=Ze |last1=Peng |first2=Jessen V. |last2=Bredeson |first3=Guohong A. |last3=Wu |first4=Shengqiang |last4=Shu |first5=Nidhi |last5=Rawat |first6=Dongliang |last6=Du |first7=Saroj |last7=Parajuli |first8=Qibin |last8=Yu |first9=Qian |last9=You |first10=Daniel S. |last10=Rokhsar |first11=Frederick G. Jr |last11=Gmitter |first12=Zhanao |last12=Deng |journal=The Plant Journal |volume=104 |pages=1215-1232 |year=2020 |doi=10.1111/tpj.14993|doi-access=free }}</ref> the opposite of what one would expect for a hybrid. This analysis dated its divergence from ''P. trifoliata'' about 2.82 million years ago.<ref name=Ze />


The trifoliate orange does not naturally interbreed with core ''Citrus'' taxa due to different flowering times,<ref name="Froelicher">{{cite journal |title=New universal mitochondrial PCR markers reveal new information on maternal citrus phylogeny |doi=10.1007/s11295-010-0314-x |volume=7 |journal=Tree Genetics & Genomes |pages=49–61 |year=2011 |last1=Froelicher |first1=Yann |last2=Mouhaya |first2=Wafa |last3=Bassene |first3=Jean-Baptiste |last4=Costantino |first4=Gilles |last5=Kamiri |first5=Mourad |last6=Luro |first6=Francois |last7=Morillo |first7=Raphael |last8=Ollitrault |first8=Patrick|s2cid=32371305 |url=http://agritrop.cirad.fr/558353/}}</ref> but hybrids have been produced artificially between the trifoliate orange and other citrus. In the Swingle system, where the trifoliate orange is placed in ''Poncirus'', a hybrid genus name has been coined for these intra-generic crosses, "×&nbsp;''Citroncirus''". The most notable of these are the [[citrange]], a cross between the trifoliate and [[sweet orange]]s, and the [[citrumelo]], a hybrid of trifoliate orange and 'Duncan' [[grapefruit]]. Placing the trifoliate orange in ''Citrus'' would mean these hybrids would no longer be intergeneric, but instead hybrids within ''Citrus''. Genomic analysis of a number of these hybrids showed them all to derive from ''P. trifoliata'' and not ''P. polyandra''.<ref name=Ze />
The trifoliate orange does not naturally interbreed with core ''Citrus'' taxa due to different flowering times,<ref name="Froelicher">{{cite journal |title=New universal mitochondrial PCR markers reveal new information on maternal citrus phylogeny |doi=10.1007/s11295-010-0314-x |volume=7 |journal=Tree Genetics & Genomes |pages=49–61 |year=2011 |last1=Froelicher |first1=Yann |last2=Mouhaya |first2=Wafa |last3=Bassene |first3=Jean-Baptiste |last4=Costantino |first4=Gilles |last5=Kamiri |first5=Mourad |last6=Luro |first6=Francois |last7=Morillo |first7=Raphael |last8=Ollitrault |first8=Patrick|s2cid=32371305 |url=http://agritrop.cirad.fr/558353/}}</ref> but hybrids have been produced artificially between the trifoliate orange and other citrus. In the Swingle system, where the trifoliate orange is placed in ''Poncirus'', a hybrid genus name has been coined for these intra-generic crosses, "×&nbsp;''Citroncirus''". The most notable of these are the [[citrange]], a cross between the trifoliate and [[sweet orange]]s, and the [[citrumelo]], a hybrid of trifoliate orange and 'Duncan' [[grapefruit]]. Placing the trifoliate orange in ''Citrus'' would mean these hybrids would no longer be intergeneric, but instead hybrids within ''Citrus''. Genomic analysis of a number of these hybrids showed them all to derive from ''P. trifoliata'' and not ''P. polyandra''.<ref name=Ze />

Revision as of 17:36, 15 September 2021

Trifoliate orange
Citrus trifoliata or Poncirus trifoliata (syn.)
A fruiting tree in Jardin des Plantes, Paris
Scientific classification
Kingdom:
(unranked):
(unranked):
(unranked):
Order:
Family:
Subfamily:
Tribe:
Genus:
Species:
C. trifoliata
Binomial name
Citrus trifoliata
Synonyms[1]
  • Aegle sepiaria DC.
  • Bilacus trifoliata (L.) Kuntze
  • Citrus trifolia Thunb.
  • Citrus triptera Desf.
  • Pseudaegle sepiaria (DC.) Miq.
  • Poncirus trifoliata (L.) Raf

The trifoliate orange, Citrus trifoliata or Poncirus trifoliata, is a member of the family Rutaceae. Whether the trifoliate oranges should be considered to belong to their own genus, Poncirus, or be included in the genus Citrus is debated. The species is unusual among citrus for having deciduous, compound leaves and pubescent (downy) fruit.[2][3]

It is native to northern China and Korea, and is also known as the Japanese bitter-orange,[4] hardy orange[5] or Chinese bitter orange.

The plant is a fairly cold-hardy citrus (USDA zone 6) and will tolerate moderate frost and snow, making a large shrub or small tree 4–8 m (13–26 ft) tall. Because of its relative hardiness, citrus grafted onto Citrus trifoliata are usually hardier than when grown on their own roots.[6]

Description

The trifoliate orange is recognizable by the large 3–5 cm (1.2–2.0 in) thorns on the shoots, and its deciduous leaves with three (or rarely, five) leaflets, typically with the middle leaflet 3–5 cm (1.2–2.0 in) long, and the two side leaflets 2–3 cm (0.79–1.18 in) long. The flowers are white, with pink stamens, 3–5 cm (1.2–2.0 in) in diameter, larger than those of true citrus but otherwise closely resembling them, except that the scent is much less pronounced than with true citrus. As with true citrus, the leaves give off a spicy smell when crushed.

The fruits are green, ripening to yellow, and 3–4 cm (1.2–1.6 in) in diameter similar in size to a lime and resembling a small orange, but with a finely downy surface and having a fuzzy texture similar to a peach. The fruits also have distinctive smell from other citrus varieties and often contain a high concentration of seeds.

Uses

Cultivation

The cultivar 'Flying Dragon' is dwarfed in size and has highly twisted, contorted stems. It makes an excellent barrier hedge due to its density and strong curved thorns. Such hedges have been grown for over 50 years at Oklahoma State University in Stillwater, and are highly student-proof.[7] The plant is also highly deer-resistant.[8] In central London, mature specimens of the trifoliate orange can be seen in the gardens of St Paul's Cathedral.

Trifoliate orange and various hybrids of this plant are widely used as citrus rootstock.

Recent studies have revealed that the trifoliate orange contains auraptene at a high concentration, which is one of the functional components having immunity against citrus tristeza virus (CTV).[9]

As food

The fruits are very bitter, due in part to their poncirin content. Most people consider them inedible fresh, but they can be made into marmalade.[8] When dried and powdered, they can be used as a condiment.

Medicine

Traditional medicine

The fruits of the trifoliate orange are widely used in medical traditions of East Asia as a treatment for allergic inflammation.[10]

Taxonomy

The trifoliate orange was historically considered a member of the genus Citrus until Swingle moved it to its own novel genus, Poncirus, based on its deciduous trifoliate leaves differing from other Citrus, as part of a larger reclassification that split the historical Citrus into seven genera. However, Mabberley and Zhang reunited all of Swingle's novel genera back into Citrus.[11] Early phylogenetic analysis of trifoliate orange plastids nested Poncirus within the citrus, consistent with a single genus,[12][13][14][15] but the sequencing of the nuclear genome by Wu, et al. showed its genome to be most divergent, different enough to justify retention of Poncirus as a separate genus.[16] To explain the conflict between the plastid and nuclear genomic analysis, it was speculated that the trifoliate orange is likely either the progeny of an ancient hybridization between a core citrus and an unidentified more distant relative, or at some time in its history it acquired an introgressed cpDNA genome from another species.[17] Ollitrault, Curk and Krueger indicate that the majority of data are consistent with the enlarged Citrus that includes the trifoliate orange, though they recognize that many botanists still follow Swingle.[11]

A second species of trifoliate orange native to Yunnan (China) has been reported and named Poncirus polyandra.[18] Were Poncirus to be subsumed into Citrus, where C. polyandra is unavailable, the name Citrus polytrifolia has been suggested.[19] Zhang and Mabberley concluded this Yunnan cultivar is likely a hybrid between the trifoliate orange and another Citrus,[2] but recent genomic analysis of P. polyandra showed low levels of heterozygosity,[20] the opposite of what one would expect for a hybrid. This analysis dated its divergence from P. trifoliata about 2.82 million years ago.[20]

The trifoliate orange does not naturally interbreed with core Citrus taxa due to different flowering times,[21] but hybrids have been produced artificially between the trifoliate orange and other citrus. In the Swingle system, where the trifoliate orange is placed in Poncirus, a hybrid genus name has been coined for these intra-generic crosses, "× Citroncirus". The most notable of these are the citrange, a cross between the trifoliate and sweet oranges, and the citrumelo, a hybrid of trifoliate orange and 'Duncan' grapefruit. Placing the trifoliate orange in Citrus would mean these hybrids would no longer be intergeneric, but instead hybrids within Citrus. Genomic analysis of a number of these hybrids showed them all to derive from P. trifoliata and not P. polyandra.[20]

References

  1. ^ The Plant List: A Working List of All Plant Species, retrieved 26 March 2016
  2. ^ a b Dianxiang Zhang & David J. Mabberley, "Citrus Linnaeus, Sp. Pl. 2: 782. 1753", Flora of China online, vol. 11
  3. ^ Dianxiang Zhang & David J. Mabberley, "Citrus trifoliata Linnaeus, Sp. Pl., ed. 2. 2: 1101. 1763", Flora of China online, vol. 11
  4. ^ BSBI List 2007 (xls). Botanical Society of Britain and Ireland. Archived from the original (xls) on 2015-06-26. Retrieved 2014-10-17.
  5. ^ USDA, NRCS (n.d.). "Poncirus trifoliata". The PLANTS Database (plants.usda.gov). Greensboro, North Carolina: National Plant Data Team. Retrieved 31 January 2016.
  6. ^ "Notice to Fruit Growers and Nurseymen Related to the Naming and Release of the US-942 Citrus Rootstock" (PDF). Agricultural Research Service, USDA. 22 October 2010. pp. 1–2. Retrieved 23 October 2017.
  7. ^ Gerald Klingaman. "Plant of the Week. Hardy Orange or Trifoliate Orange. Latin: Poncirus trifoliat". University of Arkansas. Division of Agriculture.
  8. ^ a b Green Deane Hardy. "Hardy Orange".
  9. ^ Ohta, Satoshi; Endo, Tomoko; Shimada, Takehiko; Fujii, Hiroshi (2011). "Karatachi no kankitsu torisuteza wīrusu teikōsei to rensa suru DNA mākā" [PCR Primers for Marker Assisted Backcrossing to Introduce a CTV Resistance Gene from Poncirus trifoliata (L.) Raf. into Citrus]. Shimizu, Tokuro; Kuniga, Takeshi; Yoshioka, Terutaka; Nesumi, Hirohisa; Yoshida, Toshio; Omura, Mitsuo (University of Shizuoka). Japanese Society for Horticultural Science. pp. 295–307. Retrieved 23 October 2017.
  10. ^ Zhou H.Y.; Shin E.M.; Guo L.Y.; Zou L.B.; Xu G.H.; Lee S.-H.; Ze K.R.; Kim E.-K.; Kang S.S.; Kim Y.S. (2007), "Anti-inflammatory activity of 21(alpha, beta)-methylmelianodiols, novel compounds from Poncirus trifoliata Rafinesque", European Journal of Pharmacology, 572 (2–3): 239–248, doi:10.1016/j.ejphar.2007.07.005, PMID 17662711
  11. ^ a b Ollitrault, Patrick; Curk, Franck; Krueger, Robert (2020). "Citrus taxonomy". In Talon, Manuel; Caruso, Marco; Gmitter, Frederick G., Jr. (eds.). The Citrus Genus. Elsevier. pp. 57–81. doi:10.1016/B978-0-12-812163-4.00004-8. ISBN 9780128121634.{{cite book}}: CS1 maint: multiple names: editors list (link)
  12. ^ Cite error: The named reference Nicolosi 2000 was invoked but never defined (see the help page).
  13. ^ de Araújo, Edson Freitas; Queiroza, Luciano Paganuccide; Machado, Marcos Antônio (2003). "What is Citrus? Taxonomic implications from a study of cp-DNA evolution in the tribe Citreae (Rutaceae subfamily Aurantioideae)". Organisms Diversity & Evolution. 1: 55–62. doi:10.1078/1439-6092-00058.
  14. ^ Bayer, Randall J.; Mabberly, David J.; Morton, Cynthia; Miller, Cathy H.; Sharma, Ish K.; Pfiel, Bernard E.; Rich, Sarah; Hitchcock, Roberta; Sykes, Steve (2009). "A molecular phylogeny of the orange subfamily (Rutaceae: Aurantioideae) using nine cpDNA sequences". American Journal of Botany. 96 (3): 668–685. doi:10.3732/ajb.0800341. PMID 21628223.
  15. ^ Garcia-Lor, Andres; Curk, Franck; Snoussi-Trifa, Hager; Morillon, Raphael; Ancillo, Gema; Luro, François; Navarro, Luis; Ollitrault, Patrick (2011). "A nuclear phylogenetic analysis: SNPs, indels and SSRs deliver new insights into the relationships in the 'true citrus fruit trees' group (Citrinae, Rutaceae) and the origin of cultivated species". Annals of Botany. 111 (1): 1–19. doi:10.1093/aob/mcs227. PMC 3523644. PMID 23104641.
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