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Results for “Chalcone synthase”

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PubMed2026

Pangenome-wide identification and expression analysis of the chalcone synthase (CHS) gene family in five yellowhorn spp.

Chalcone synthase (CHS) is a pivotal enzyme in flavonoid biosynthesis involved in plant development, defense, and secondary metabolism. Xanthoceras sorbifolium (yellowhorn) is a medicinal and ornamental species with high resistance to environmental stresses, but its CHS gene family remains uncharacterized. We performed a pangenome-wide identification of CHS genes across five yellowhorn genomes (Xzs4, Xwf8, Xjg, Xg11, and Xzg2). Across the five yellowhorn genomes, 27 CHS genes were identified and classified into four core pangenes, present in all five genomes, and two dispensable genes, present only in a subset of genomes. Phylogenetic analysis grouped these genes into three major clades, and chromosomal mapping and duplication analyses identified four tandemly duplicated gene pairs under purifying selection. The analyses of conserved structural features, including protein motifs and exon-intron organization, together with promoter cis-regulatory elements and gene ontology annotation, further indicated the potential involvement of CHS genes in flavonoid biosynthesis and stress-responsive mechanisms. Gene expression profiling identified significant upregulation of Xg11_CHS1 and Xg11_CHS3 under cold and drought stress, with tissue-specific expression patterns. These findings provide valuable insights into the evolution, functional diversification, and stress-responsive roles of the CHS gene family, identifying candidate genes for future studies targeting stress tolerance and flavonoid biosynthesis in yellowhorn.

Acyltransferases↗
PubMed2026

Suppressor activity against cosuppression conferred by the petunia vein clearing virus genome.

The petunia genome contains an endogenous pararetrovirus, petunia vein clearing virus (PVCV). Previous analyses indicate that PVCV has suppressor activity against RNA silencing, but the suppressor protein has not been identified. Here we tested whether an open reading frame (ORF) of PVCV confers the activity that can suppress cosuppression of the CHS-A genes encoding chalcone synthase, which has a high rate of RNA turnover in the petal tissues of petunia. Petunia transformants that express PVCV ORF under the control of cauliflower mosaic virus 35S promoter were produced. The transgenic plants were crossed with those that have CHS-A cosuppression to produce plants that contain both the PVCV ORF transgene and CHS-A transgene. The coexistence of these transgenes resulted in phenotypic changes: pigmentation of various extents occurred on the originally white petals of CHS-A cosuppression phenotype. The generation of pigmented portions in flower petals coincided with higher transcript levels of CHS-A and PVCV ORF and less CHS-A short interfering RNA. These results indicate that the PVCV ORF can suppress CHS-A cosuppression and change the flower color phenotype when it is expressed as a transgene.

Petunia↗
PubMed2026

Progressive salinity drives flavonoid branch reprogramming in Anoectochilus roxburghii.

Flavonoids play critical roles in plant adaptation to abiotic stress; however, how salt stress modulates metabolic flux distribution within flavonoid branches remains poorly understood, particularly in non-model medicinal plants. Here, we integrated targeted metabolomics, transcriptomics, and proteomics to examine flavonoid regulation in Anoectochilus roxburghii under 0, 50, 100, and 200 mmol·L- 1 NaCl. Metabolite profiling showed that salinity reshaped flavonoid composition rather than uniformly increasing flavonoid abundance. A metabolite-derived branch bias index (MI), representing the balance between reductive branch metabolites and flavonol products, increased under salt treatment, peaked at 100 mmol·L- 1 NaCl, and declined at 200 mmol·L- 1, indicating maximal branch bias under moderate stress followed by partial rebalancing under severe stress. Transcriptomic analysis showed induction of upstream phenylpropanoid and flavonoid entry genes, including PAL, 4CL, and CHS, whereas F3H was suppressed and FLS showed no induction. Furthermore, several short-chain dehydrogenase/reductase homologs (IFR-like SDR homologs) were upregulated, and the transcript-derived reductive branch index (EI) increased progressively across the salt gradient. EI was positively associated with MI, although the relationship was not strictly proportional under severe stress (200 mmol·L- 1 NaCl). Proteomic profiling further provided supportive evidence for sustained activation of upstream flavonoid biosynthesis, such as salt-induced accumulation of chalcone synthase (CHS) protein, complementing the transcriptomic and metabolomic datasets. Together, these results indicate that salt stress reorganizes flavonoid metabolism in A. roxburghii through persistent upstream activation and branch-specific regulation, favoring the reductive branch under moderate salinity.

Orchidaceae↗
PubMed2026

The R2R3-MYB transcription factor ScMYB20 negatively regulates drought and salt tolerance through a dual-repression of ScCHALCONE SYNTHASE-1 (ScCHS1)-mediated flavonoid biosynthesis in the desert moss Syntrichia caninervis.

The desert moss Syntrichia caninervis is one of the most desiccation-tolerant land plants known and provides a powerful system for dissecting the molecular foundations of extreme stress adaptation in early-diverging land lineages. The MYB transcription factor superfamily orchestrates secondary metabolism and stress signaling across plants, yet its lineage-specific evolution and mechanistic deployment in bryophytes remain poorly understood. Here, we identified 65 ScMYB genes in the S. caninervis genome and showed that the family expanded predominantly through dispersed duplication, with no detectable synteny to vascular-plant MYBs, indicating bryophyte-specific neo-functionalization. Integrating phylogenetic clustering, cis-element architecture and stress-responsive expression profiling, we pinpointed ScMYB20, a nuclear-localized, S13-subgroup R2R3-MYB that is rapidly and strongly induced by dehydration and salinity. Heterologous overexpression in Arabidopsis, together with overexpression and RNAi in S. caninervis, demonstrated that ScMYB20 negatively regulates drought and salt tolerance by suppressing antioxidant capacity, osmotic adjustment and photosynthetic performance, while concomitantly elevating ROS and MDA accumulation. Mechanistically, ScMYB20 directly binds a TAACCA motif in the ScCHS1 promoter to repress its transcription, and simultaneously sequesters the WD40 protein ScTTG1, a positive transcriptional activator of ScCHS1, thereby antagonising ScTTG1-mediated activation. Transient ScCHS1 overexpression restored flavonoid accumulation, antioxidant capacity and stress tolerance. Together, our findings define a dual-repression module (ScMYB20-ScTTG1-ScCHS1) that fine-tunes flavonoid flux under abiotic stress, and provide evolutionary and mechanistic insights into how R2R3-MYB repressors evolved to balance metabolic investment and stress survival in land plants.

Syntrichia caninervis↗
PubMed1978

The occurrence of enzymes involved in phenylpropanoid metabolism in the tapetum fraction of anthers.

The contents of another loculus were separated in a pollen and tapetum fraction. The following enzymes involved in phenylpropanoid metabolism were present in the tapetum fraction: shikimate dehydrogenase; phenylalanine ammonialyase; cinnamic acid 4-hydroxylase; SAM (S-adenosylmethionine): caffeate 3-O-methyltransferase; hydroxycinnamate: CoA ligase; "flavanone synthase"; chalcone-flavanone isomerase; SAM: 3',4'-dihydroxyflavonoid 3'-O-methyltransferase; O-glucosyltransferase. It is postulated, that these enzymes derived from the tapetum catalyze the different steps of phenylpropanoid metabolism at or in cavities of the exine after their transfer into the loculus.

Acyltransferases↗
PubMed1975

Enzymic synthesis of an aromatic ring from acetate units. Partial purification and some properties of flavanone synthase from cell-suspension cultures of Petroselinum hortense.

Flavanone synthase was isolated and purified about 300-fold from fermenter-grown, light-induced cell suspension cultures of Petroselinum hortense. The enzyme catalyzed the formation of the flavanone naringenin from p-coumaroyl-CoA and malonyl-CoA. Trapping experiments with an enzyme preparation, which was free of chalcone isomerase activity, revealed that in fact the flavanone and not the isomeric chalcone was the immediate product of the synthase reaction. Thus the enzyme is not a chalcone synthase as previously assumed. No coafactors were required for flavanone synthase activity. The enzyme was strongly inhibited by the two reaction products naringenin and CoASH, by the antibiotic cerulenin, by acetyl-CoA, and by several compounds reacting with sulfhydryl groups. Optimal enzyme activity was found at pH 8.0, at 30 degrees C, and at an ionic strength of 0.1--0.3 M potassium phosphate. EDTA, Mg2+, Ca2+, or Fe2+ at concentrations of about 0.7 muM did not affect the enzyme activity. Apparent molecular weights of approx. 120 000, 50 000, and 70 000, respectively, were determined for flavanone synthase and two metabolically related enzymes, chalcone isomerase and malonyl-CoA: flavonoid glycoside malonyl transferase. The partially purified flavanone synthase efficiently catalyzed the formation of malonyl pantetheine from malonyl-CoA and pantetheine. This malonyl transferase activity, and a general similarity with the condensation steps involved in the mechanisms of fatty acid and 6-methylsalicylic acid synthesis from "acetate units", are the basis for a hypothetical scheme which is proposed for the sequence of reactions catalyzed by the multifunctional flavanone synthase.

Acetyl Coenzyme A↗