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Citrus PH4–Noemi regulatory complex is involved in proanthocyanidin biosynthesis via a positive feedback loop
- Source :
- Journal of Experimental Botany
- Publication Year :
- 2019
- Publisher :
- Oxford University Press (OUP), 2019.
-
Abstract
- In citrus, PH4–Noemi, a regulatory complex, controls proanthocyanidin accumulation by activating the transcription of proanthocyanidin biosynthetic genes, and also regulates expression of Noemi, promoting proanthocyanidin accumulation by positive feedback.<br />Proanthocyanidins (PAs; or condensed tannins) are a major class of flavonoids that contribute to citrus fruit quality. However, the molecular mechanism responsible for PA biosynthesis and accumulation in citrus remains unclear. Here, we identify a PH4–Noemi regulatory complex that regulates proanthocyanidin biosynthesis in citrus. Overexpression of PH4 or Noemi in citrus calli activated the expression of PA biosynthetic genes and significantly increased the PA content. Interestingly, Noemi was also shown to be up-regulated in CsPH4-overexpressing lines compared with wild-type calli. Simultaneously, CsPH4 partially complemented the PA-deficient phenotype of the Arabidopsis tt2 mutant and promoted PA accumulation in the wild-type. Further analysis revealed that CsPH4 interacted with Noemi, and together these proteins synergistically activated the expression of PA biosynthetic genes by directly binding to the MYB-recognizing elements (MRE) of the promoters of these genes. Moreover, CsPH4 could directly bind to the promoter of Noemi and up-regulate the expression of this gene. These findings explain how the CsPH4–Noemi regulatory complex contributes to the activation of PA biosynthetic genes via a positive feedback loop and provide new insights into the molecular mechanisms underlying PA biosynthesis, which can be effectively employed for metabolic engineering to improve citrus fruit quality.
- Subjects :
- 0106 biological sciences
0301 basic medicine
Citrus
Physiology
Mutant
Arabidopsis
Plant Science
01 natural sciences
Feedback
Metabolic engineering
03 medical and health sciences
chemistry.chemical_compound
Biosynthesis
Gene Expression Regulation, Plant
regulatory complex
Transcriptional regulation
transcriptional regulation
Proanthocyanidins
Gene
Plant Proteins
biology
Chemistry
positive feedback
food and beverages
proanthocyanidin biosynthesis
Promoter
biology.organism_classification
Research Papers
Phenotype
Cell biology
030104 developmental biology
Crop Molecular Genetics
010606 plant biology & botany
Subjects
Details
- ISSN :
- 14602431 and 00220957
- Volume :
- 71
- Database :
- OpenAIRE
- Journal :
- Journal of Experimental Botany
- Accession number :
- edsair.doi.dedup.....3417309cf257a860cfe97d83dae791f9