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Article: Convergent recruitment of 5´-hydroxylase activities by CYP75B flavonoid B-ring hydroxylases for tricin biosynthesis in Medicago legumes

TitleConvergent recruitment of 5´-hydroxylase activities by CYP75B flavonoid B-ring hydroxylases for tricin biosynthesis in Medicago legumes
Authors
KeywordsAlfalfa (Medicago sativa)
dicot legume
Medicago truncatula
pathway evolution
Issue Date2020
PublisherWiley-Blackwell Publishing Ltd. The Journal's web site is located at https://nph-onlinelibrary-wiley-com.eproxy.lib.hku.hk/journal/14698137
Citation
New Phytologist, 2020, Epub 2020-02-21 How to Cite?
AbstractTricin (3´,5´‐dimethoxylated flavone) is a predominant flavonoid amongst monocots but occurs only in isolated and unrelated dicot lineages. Although tricin biosynthesis has been intensively studied in monocots, it remained largely elusive in tricin‐accumulating dicots. We investigated a subgroup of cytochrome P450 (CYP) 75B subfamily flavonoid B‐ring hydroxylases (FBHs) from two tricin‐accumulating legumes, Medicago truncatula and alfalfa (M. sativa), by phylogenetic, molecular, biochemical and mutant analyses. Five Medicago cytochrome P450 CYP75B FBHs are phylogenetically distant from other legume CYP75B members. Among them, MtFBH‐4, MsFBH‐4 and MsFBH‐10 were expressed in tricin‐accumulating vegetative tissues. In vitro and in planta analyses demonstrated that these proteins catalyze 3´‐ and 5´‐hydroxylations critical to tricin biosynthesis. A key amino acid polymorphism, T492G, at their Substrate Recognition Site 6 domain is required for the novel 5´‐hydroxylation activities. M. truncatula mtfbh‐4 mutants were tricin‐deficient, indicating that MtFBH‐4 is indispensable for tricin biosynthesis. Our results revealed that these Medicago legumes had acquired the tricin pathway through molecular evolution of CYP75B FBHs subsequent to speciation from other non‐tricin‐accumulating legumes. Moreover, their evolution is independent from that of grass‐specific CYP75B apigenin 3´‐hydroxylases/chrysoeriol 5´‐hydroxylases dedicated to tricin production and Asteraceae CYP75B flavonoid 3´,5´‐hydroxylases catalyzing the production of delphinidin‐based pigments.
DescriptionLink to Free access
Persistent Identifierhttp://hdl.handle.net/10722/280932
ISSN
2017 Impact Factor: 7.433
2015 SCImago Journal Rankings: 3.603

 

DC FieldValueLanguage
dc.contributor.authorLUI, ACW-
dc.contributor.authorLAM, PY-
dc.contributor.authorChan, KH-
dc.contributor.authorWANG, L-
dc.contributor.authorTobimatsu, Y-
dc.contributor.authorLo, C-
dc.date.accessioned2020-02-25T07:42:55Z-
dc.date.available2020-02-25T07:42:55Z-
dc.date.issued2020-
dc.identifier.citationNew Phytologist, 2020, Epub 2020-02-21-
dc.identifier.issn0028-646X-
dc.identifier.urihttp://hdl.handle.net/10722/280932-
dc.descriptionLink to Free access-
dc.description.abstractTricin (3´,5´‐dimethoxylated flavone) is a predominant flavonoid amongst monocots but occurs only in isolated and unrelated dicot lineages. Although tricin biosynthesis has been intensively studied in monocots, it remained largely elusive in tricin‐accumulating dicots. We investigated a subgroup of cytochrome P450 (CYP) 75B subfamily flavonoid B‐ring hydroxylases (FBHs) from two tricin‐accumulating legumes, Medicago truncatula and alfalfa (M. sativa), by phylogenetic, molecular, biochemical and mutant analyses. Five Medicago cytochrome P450 CYP75B FBHs are phylogenetically distant from other legume CYP75B members. Among them, MtFBH‐4, MsFBH‐4 and MsFBH‐10 were expressed in tricin‐accumulating vegetative tissues. In vitro and in planta analyses demonstrated that these proteins catalyze 3´‐ and 5´‐hydroxylations critical to tricin biosynthesis. A key amino acid polymorphism, T492G, at their Substrate Recognition Site 6 domain is required for the novel 5´‐hydroxylation activities. M. truncatula mtfbh‐4 mutants were tricin‐deficient, indicating that MtFBH‐4 is indispensable for tricin biosynthesis. Our results revealed that these Medicago legumes had acquired the tricin pathway through molecular evolution of CYP75B FBHs subsequent to speciation from other non‐tricin‐accumulating legumes. Moreover, their evolution is independent from that of grass‐specific CYP75B apigenin 3´‐hydroxylases/chrysoeriol 5´‐hydroxylases dedicated to tricin production and Asteraceae CYP75B flavonoid 3´,5´‐hydroxylases catalyzing the production of delphinidin‐based pigments.-
dc.languageeng-
dc.publisherWiley-Blackwell Publishing Ltd. The Journal's web site is located at https://nph-onlinelibrary-wiley-com.eproxy.lib.hku.hk/journal/14698137-
dc.relation.ispartofNew Phytologist-
dc.rightsPreprint This is the pre-peer reviewed version of the following article: [FULL CITE], which has been published in final form at [Link to final article using the DOI]. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions. Postprint This is the peer reviewed version of the following article: [FULL CITE], which has been published in final form at [Link to final article using the DOI]. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions.-
dc.subjectAlfalfa (Medicago sativa)-
dc.subjectdicot legume-
dc.subjectMedicago truncatula-
dc.subjectpathway evolution-
dc.titleConvergent recruitment of 5´-hydroxylase activities by CYP75B flavonoid B-ring hydroxylases for tricin biosynthesis in Medicago legumes-
dc.typeArticle-
dc.identifier.emailLo, C: clivelo@hku.hk-
dc.identifier.authorityLo, C=rp00751-
dc.description.naturelink_to_subscribed_fulltext-
dc.identifier.doi10.1111/nph.16498-
dc.identifier.hkuros309223-
dc.identifier.volumeEpub 2020-02-21-
dc.publisher.placeUnited Kingdom-

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