The NPR7-TGA6-MYB1 module promotes anthocyanin biosynthesis and integrates salicylic acid and strigolactone signaling in apple.
Zhao L, Li ZY, Ai D, Li MY, Jiang YJ
Plant Signaling
Red color of apples isn't just cosmetic — anthocyanins are the antioxidants that make apples healthy to eat, and understanding what controls their production could help growers breed redder, more nutritious apples with less reliance on chemical treatments.
Inside apple trees, a natural defense chemical called salicylic acid acts like a starting pistol that sets off a relay race between three proteins, ending with the tree making more red pigment. The study figured out exactly how each protein passes the baton to the next. They also discovered that another plant chemical — one that normally controls root branching — can interfere with this relay by pulling the protein team apart, essentially putting the brakes on red pigment production.
Key Findings
A three-protein module (NPR7 → TGA6 → MYB1) forms the core salicylic acid signaling chain that directly switches on anthocyanin-making genes in apple.
When salicylic acid is absent, an enzyme called RHA2a tags the NPR7 protein for destruction via ubiquitination, effectively shutting the pathway off until defense signals return.
The strigolactone pathway antagonizes anthocyanin production by physically dismantling the NPR7-TGA6 and NPR7-MYB1 protein complexes through the repressor protein SMXL8.
chevron_right Technical Summary
Scientists discovered how a plant defense hormone called salicylic acid triggers the production of red pigments (anthocyanins) in apple fruit, mapping a three-protein chain that acts like a molecular switch. They also found that a second hormone, strigolactone, can dial this process back by breaking up the protein team.
Abstract Preview
The salicylic acid (SA) signal transduction pathway and its association with anthocyanin biosynthesis have been reported, but the molecular mechanisms underlying SA-mediated anthocyanin biosynthesi...
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An apple is the round, edible fruit of an apple tree. Fruit trees of the orchard or domestic apple, the most widely grown in the genus, are cultivated worldwide. The tree originated in Central Asia, where its wild ancestor, Malus sieversii, is still found. Apples have been grown for thousands of ...