Angraecum sesquipedale,also known as Darwin’s orchid,possesses an exceptionally long nectar spur.Charles Darwin predicted the orchid to be pollinated by a hawkmoth with a correspondingly long proboscis,later identifi...Angraecum sesquipedale,also known as Darwin’s orchid,possesses an exceptionally long nectar spur.Charles Darwin predicted the orchid to be pollinated by a hawkmoth with a correspondingly long proboscis,later identified as Xanthopan praedicta.In this plant-pollinator interaction,the A.sesquipedale flower emits a complex blend of scent compounds dominated by diurnally regulated oximes(R_(1)R_(2)C=N-OH)to attract crepuscular and nocturnal pollinators.The molecular mechanism of oxime biosynthesis remains unclear in orchids.Here,we present the chromosome-level genome of A.sesquipedale.The haploid genome size is 2.10 Gb and represents 19 pseudochromosomes.Cytochrome P450 encoding genes of the CYP79 family known to be involved in oxime biosynthesis in seed plants are not present in the A.sesquipedale genome nor the genomes of other members of the orchid family.Metabolomic analysis of the A.sesquipedale flower revealed a substantial release of oximes at dusk during the blooming stage.By integrating metabolomic and transcriptomic correlation approaches,flavin-containing monooxygenases(FMOs)encoded by six tandem-repeat genes in the A.sesquipedale genome are identified as catalyzing the formation of oximes present.Further in vitro and in vivo assays confirm the function of FMOs in the oxime biosynthesis.We designate these FMOs as orchid oxime synthases 1-6.The evolutionary aspects related to the CYP79 gene losses and neofunctionalization of FMO-catalyzed biosynthesis of oximes in Darwin’s orchid provide new insights into the convergent evolution of biosynthetic pathways.展开更多
Oximes （R1R2C=NOH） are nitrogen-containing chemical constituents that are formed in species representing all kingdoms of life. In plants, oximes are positioned at important metabolic bifurcation points between gener...Oximes （R1R2C=NOH） are nitrogen-containing chemical constituents that are formed in species representing all kingdoms of life. In plants, oximes are positioned at important metabolic bifurcation points between general and specialized metabolism. The majority of plant oximes are amino acid-derived metabolites formed by the action of a cytochrome P450 from the CYP79 family. Auxin, cyanogenic glucosides, glucosinolates, and a number of other bioactive specialized metabolites including volatiles are produced from oximes. Oximes with the E configuration have high biological activity compared with Z-oximes. Oximes or their derivatives have been demonstrated or proposed to play roles in growth regulation, plant defense, pollinator attraction, and plant communication with the surrounding environment. In addition, oxime-derived products may serve as quenchers of reactive oxygen species and storage compounds for reduced nitrogen that may be released on demand by the activation of endogenous turnover pathways. As highly bioactive molecules, chemically synthesized oximes have found versatile uses in many sectors of society, especially in the agro- and medical sectors. This review provides an update on the structural diversity, occurrence, and biosynthesis of oximes in plants and discusses their role as key players in plant general and specialized metabolism.展开更多
基金supported by grants from the Shanghai Landscaping and City Appearance Administrative Bureau(G222406,G232408)Sino-Africa Joint Research Center,CAS(SAJC201607)+4 种基金the Science and Technology Commission of Shanghai Municipality(19390743600)the National Wild Plant Germplasm Resource Centre for Shanghai Chenshan Botanical Garden(ZWGX2102)to W.C.H.and K.J.,and by a Distinguished Investigator grant(NNF190CO05456)from the Novo Nordisk Foundation to B.L.M.E.H.J.N.acknowledges funding from the Novo Nordisk Foundation(0054890)the Independent Research Fund Denmark(1131-00002B and 1051-00083 B).
文摘Angraecum sesquipedale,also known as Darwin’s orchid,possesses an exceptionally long nectar spur.Charles Darwin predicted the orchid to be pollinated by a hawkmoth with a correspondingly long proboscis,later identified as Xanthopan praedicta.In this plant-pollinator interaction,the A.sesquipedale flower emits a complex blend of scent compounds dominated by diurnally regulated oximes(R_(1)R_(2)C=N-OH)to attract crepuscular and nocturnal pollinators.The molecular mechanism of oxime biosynthesis remains unclear in orchids.Here,we present the chromosome-level genome of A.sesquipedale.The haploid genome size is 2.10 Gb and represents 19 pseudochromosomes.Cytochrome P450 encoding genes of the CYP79 family known to be involved in oxime biosynthesis in seed plants are not present in the A.sesquipedale genome nor the genomes of other members of the orchid family.Metabolomic analysis of the A.sesquipedale flower revealed a substantial release of oximes at dusk during the blooming stage.By integrating metabolomic and transcriptomic correlation approaches,flavin-containing monooxygenases(FMOs)encoded by six tandem-repeat genes in the A.sesquipedale genome are identified as catalyzing the formation of oximes present.Further in vitro and in vivo assays confirm the function of FMOs in the oxime biosynthesis.We designate these FMOs as orchid oxime synthases 1-6.The evolutionary aspects related to the CYP79 gene losses and neofunctionalization of FMO-catalyzed biosynthesis of oximes in Darwin’s orchid provide new insights into the convergent evolution of biosynthetic pathways.
文摘Oximes （R1R2C=NOH） are nitrogen-containing chemical constituents that are formed in species representing all kingdoms of life. In plants, oximes are positioned at important metabolic bifurcation points between general and specialized metabolism. The majority of plant oximes are amino acid-derived metabolites formed by the action of a cytochrome P450 from the CYP79 family. Auxin, cyanogenic glucosides, glucosinolates, and a number of other bioactive specialized metabolites including volatiles are produced from oximes. Oximes with the E configuration have high biological activity compared with Z-oximes. Oximes or their derivatives have been demonstrated or proposed to play roles in growth regulation, plant defense, pollinator attraction, and plant communication with the surrounding environment. In addition, oxime-derived products may serve as quenchers of reactive oxygen species and storage compounds for reduced nitrogen that may be released on demand by the activation of endogenous turnover pathways. As highly bioactive molecules, chemically synthesized oximes have found versatile uses in many sectors of society, especially in the agro- and medical sectors. This review provides an update on the structural diversity, occurrence, and biosynthesis of oximes in plants and discusses their role as key players in plant general and specialized metabolism.
