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Title: Identification of chalcone isomerase in the basal land plants reveals an ancient evolution of enzymatic cyclization activity for synthesis of flavonoids

Flavonoids ubiquitously distribute to the terrestrial plants and chalcone isomerase (CHI)- catalyzed intramolecular and stereospecific cyclization of chalcones is a committed step in the production of flavonoids. However, so far the bona fide CHIs are found only in vascular plants, and their origin and evolution remains elusive. We conducted transcriptomic and/or genomic sequence search, subsequent phylogenetic analysis, and detailed biochemical and genetic characterization to explore the potential existence of CHI proteins in the basal bryophyte liverwort species and the lycophyte Selaginella moellendorffii. We found that both liverwort and Selaginella species possess canonical CHI-fold proteins that cluster with their corresponding higher plant counterparts. Among them, some members exhibited bona fide CHI activity, which catalyze stereospecific cyclization of both 60- hydroxychalcone and 60-deoxychalcone, yielding corresponding 5-hydroxy and 5- deoxyflavanones, resembling the typical type II CHIs currently known to be ‘specific’ for legume plants. Expressing those primitive bona fide CHIs in the Arabidopsis chi mutant restores the seed coat transparent testa phenotype and the accumulation of flavonoids. These findings, in contrast to our current understanding of the evolution of enzymatic CHIs, suggest that emergence of the bona fide type II CHIs is an ancient evolution event that occurred before the divergence of liverwortmore » lineages.« less
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  1. Shandong Univ., Jinan (China). Key Lab. of Chemical Biology of Natural Products, Ministry of Education, School of Pharmaceutical Sciences
  2. Brookhaven National Lab. (BNL), Upton, NY (United States). Biology Dept.
Publication Date:
Report Number(s):
Journal ID: ISSN 0028-646X
Grant/Contract Number:
SC0012704; MCB-1051675
Accepted Manuscript
Journal Name:
New Phytologist
Additional Journal Information:
Journal Volume: 217; Journal Issue: 2; Journal ID: ISSN 0028-646X
Research Org:
Brookhaven National Laboratory (BNL), Upton, NY (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
59 BASIC BIOLOGICAL SCIENCES; Flavonoids; Chalcone isomerase; Evolution; Liverwort; Selaginella moellendorffii (Spikemoss)
OSTI Identifier:
Alternate Identifier(s):
OSTI ID: 1405542