Reduced MdFLS Expression Decreases Flavonol Content in Apple Flesh.

Area of Science:

• Plant biochemistry
• Molecular biology
• Fruit science

Background:

• Flavonols are vital plant compounds for defense and human health.
• In apples (Malus domestica), flavonols are concentrated in skin, not flesh, limiting nutritional benefits.
• Understanding apple flavonol biosynthesis is key to enhancing flesh content.

Purpose of the Study:

• Investigate expression patterns of four apple flavonol synthase genes (MdFLS1-4).
• Determine the functional roles of MdFLS genes in flavonol accumulation.
• Explore factors influencing flavonol biosynthesis in apple fruit flesh.

Main Methods:

• Gene expression analysis of MdFLS1-4 in apple skin and flesh.
• Transient gene overexpression in apple fruit flesh.
• Stable gene overexpression in transgenic Arabidopsis and tomato.
• Assessing flavonol accumulation under different light conditions.

Main Results:

• MdFLS1, MdFLS2, and MdFLS3 showed higher expression in apple skin than flesh; MdFLS4 was unexpressed.
• All four MdFLS genes encode functional flavonol synthases, capable of increasing flavonol levels.
• Light exposure upregulated MdFLS1 and MdFLS2 expression and flavonol content in apple flesh.

Conclusions:

• MdFLS genes are functional regulators of flavonol biosynthesis in apples.
• Light is a critical factor influencing flavonol accumulation in apple fruit flesh.
• Findings provide insights for genetically improving apple nutritional value through enhanced flavonol content.