How a Specific Protein Affects Astringency and Compound Buildup in Persimmons

Jim Crocker
23rd August, 2024

How a Specific Protein Affects Astringency and Compound Buildup in Persimmons

Image Source: Natural Science News, 2024

Key Findings

  • The study by Huazhong Agricultural University found that the DkDTX1/MATE1 transporter protein regulates PA composition in persimmons, affecting their astringency
  • Overexpression of DkDTX1/MATE1 in persimmon leaves and fruit discs increased PA levels and upregulated PA biosynthesis genes
  • DkDTX1/MATE1 preferentially transports key PA precursors, influencing the overall PA composition and taste of persimmons
Proanthocyanidins (PAs) are polyphenolic compounds found in many plants, known for their astringent properties that deter herbivores and influence fruit taste. A recent study by Huazhong Agricultural University[1] has explored how the DkDTX1/MATE1 transporter protein regulates PA composition in persimmons, a fruit known for its significant variation in astringency between different types. The study focused on the astringent (A)-type and nonastringent (NA)-type persimmons, which differ in their PA content. Using fluorescence microscopy, researchers observed that the green fluorescence of DkDTX1/MATE1 overlapped with the blue light emitted by PAs, indicating a close association between the transporter and PA accumulation. Overexpression of DkDTX1/MATE1 in persimmon leaves resulted in a significant increase in PA concentrations and upregulated the expression of genes involved in the PA biosynthesis pathway. Further experiments involving overexpression in persimmon fruit discs and stable genetic transformation confirmed these findings, showing a consistent increase in PA levels. Molecular docking and transporter assays revealed that DkDTX1/MATE1 preferentially transports catechin, epicatechin gallate, and epigallocatechin gallate—key PA precursors. The protein mainly binds to these precursors via a serine residue at position 68, suggesting a specific mechanism for PA precursor transport. This study builds on earlier research that identified key genes and enzymes involved in PA biosynthesis. For instance, previous studies have shown that the anthocyanin and proanthocyanidin (PA) biosynthetic pathways share common intermediates until leucocyanidin[2]. Another study highlighted the importance of flavonoid 3'5' hydroxylase (F3'5'H) and anthocyanidin reductase (ANR) in PA accumulation in persimmon fruits[3]. Furthermore, DkMyb4 was identified as a regulator of PA biosynthesis, directly binding to the promoters of PA pathway genes[4]. The current study ties these findings together by demonstrating that DkDTX1/MATE1 not only transports PA precursors but also influences the expression of PA biosynthesis genes, thereby affecting the overall PA composition and astringency of persimmon fruits. This provides a theoretical basis for using metabolic engineering to regulate PA composition in persimmons, potentially leading to the development of new fruit varieties with desired taste profiles. In summary, the research conducted by Huazhong Agricultural University has identified DkDTX1/MATE1 as a key player in the regulation of PA composition in persimmons. By preferentially transporting specific PA precursors and upregulating biosynthesis pathway genes, DkDTX1/MATE1 significantly impacts the astringency of the fruit. This study not only advances our understanding of PA biosynthesis but also opens up new avenues for improving fruit quality through metabolic engineering.

FruitsBiochemPlant Science

References

Main Study

1) DkDTX1/MATE1 mediates the accumulation of proanthocyanidin and affects astringency in persimmon.

Published 22nd August, 2024

https://doi.org/10.1111/pce.15092

Related Studies

2) The Arabidopsis TDS4 gene encodes leucoanthocyanidin dioxygenase (LDOX) and is essential for proanthocyanidin synthesis and vacuole development.

Journal: The Plant journal : for cell and molecular biology, Issue: Vol 35, Issue 5, Sep 2003

3) Expression balances of structural genes in shikimate and flavonoid biosynthesis cause a difference in proanthocyanidin accumulation in persimmon (Diospyros kaki Thunb.) fruit.

https://doi.org/10.1007/s00425-009-0991-6

4) DkMyb4 is a Myb transcription factor involved in proanthocyanidin biosynthesis in persimmon fruit.

https://doi.org/10.1104/pp.109.146985


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