Flower color is a defining trait of ornamental plants, shaping pollinator attraction, aesthetic value, and commercial appeal. While the biochemical pathways responsible for anthocyanin synthesis have been extensively studied, much less attention has been paid to what happens after pigments are produced. In blue flowers, anthocyanins often require precise intracellular transport and vacuolar storage to achieve stable coloration. However, the molecular identity of the transporters involved and their substrate preferences have remained unclear. Without efficient transport, even properly synthesized pigments may fail to accumulate. Based on these challenges, it is necessary to conduct in-depth research on the mechanisms governing vacuolar anthocyanin transport.
Researchers from Northwest A&F University reported (DOI: 10.1093/hr/uhaf270) in February 2026 in Horticulture Research that two vacuolar membrane transporters are essential for blue flower coloration in grape hyacinth (Muscari). Using genetic, cellular, and biochemical approaches, the team identified MaMATE11 and MaMATE14 as key components of the pigment transport machinery. Their results show that these transporters localize to the vacuolar membrane and actively mediate flavonoid sequestration, revealing that pigment transport—rather than biosynthesis alone—is a critical step in determining floral color outcomes.
The researchers first screened transporter genes associated with blue petals and found that MaMATE11 and MaMATE14 showed strong correlations with anthocyanin accumulation. Cellular localization experiments confirmed that both proteins reside on the vacuolar membrane, positioning them at the final checkpoint of pigment storage. Functional transport assays revealed that the two transporters share overlapping roles but differ in substrate preference. MaMATE11 displays broader activity toward common anthocyanin glucosides, while MaMATE14 shows stronger selectivity for malonylated anthocyanins and certain non-anthocyanin flavonoids.
Genetic evidence further supported their importance. Introducing MaMATE11 or MaMATE14 into an anthocyanin-transport-deficient Arabidopsis mutant restored purple pigmentation, demonstrating functional conservation across species. Conversely, silencing of MaMATE11 or MaMATE14 in grape hyacinth petals significantly reduced anthocyanin accumulation and resulted in visibly paler flowers.
The study also uncovered a coordinated regulatory mechanism in which anthocyanin-related MYB transcription factors directly activate MaMATE11 and MaMATE14, synchronizing pigment biosynthesis with transport. Together, these findings establish vacuolar transport as a decisive factor in blue flower coloration.
“Flower color is often treated as a question of pigment chemistry,” said the corresponding author. “Our work shows that transport is just as important as synthesis. Even the right pigments cannot produce a stable color unless they are efficiently delivered to the vacuole. By identifying MaMATE11 and MaMATE14 and clarifying how they are regulated, we provide a more complete picture of how blue coloration is achieved. This understanding opens new possibilities for precisely manipulating flower color in ornamental plants.”
The findings offer practical implications for ornamental plant breeding and biotechnology. Targeting pigment transporters provides a new strategy to fine-tune flower color intensity and stability, complementing traditional approaches that focus solely on biosynthetic enzymes. Manipulating transporter activity may allow breeders to enhance blue coloration or introduce it into species where it is naturally unstable or absent. Beyond ornamentals, the work advances understanding of flavonoid compartmentalization, a process linked to plant stress tolerance and metabolic regulation. By revealing how pigment logistics operate inside cells, this study broadens the toolkit for future applications in horticulture and plant metabolic engineering.
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References
DOI
10.1093/hr/uhaf270
Original Source URL
https://doi.org/10.1093/hr/uhaf270
Funding information
This study was supported by the National Natural Science Foundation of China (grant no. 32171863), Shaanxi Province Key Research and Development Program (grant no. 2024NC-YBXM-076), and the Fundamental Research Funds for the Central Universities (Z1090323181).
About Horticulture Research
Horticulture Research is an open access journal of Nanjing Agricultural University and ranked number one in the Horticulture category of the Journal Citation Reports ™ from Clarivate, 2023. The journal is committed to publishing original research articles, reviews, perspectives, comments, correspondence articles and letters to the editor related to all major horticultural plants and disciplines, including biotechnology, breeding, cellular and molecular biology, evolution, genetics, inter-species interactions, physiology, and the origination and domestication of crops.