Linking ascorbic acid production in Ribes nigrum with fruit development and changes in sources and sinks

Area of Science:

• Plant Physiology
• Nutrient Metabolism
• Fruit Development

Background:

• Ascorbic acid (l-AsA) synthesis in green tissues is well-studied, but its production and accumulation in fruit remain less understood.
• Investigating the source-sink relationship for l-AsA between leaves and fruits is crucial for understanding its accumulation in berries.

Purpose of the Study:

• To elucidate the role of leaf tissue in ascorbic acid (l-AsA) production and its subsequent accumulation in fruit.
• To determine if manipulating leaf number and assimilate availability impacts fruit l-AsA concentration and yield.
• To explore potential strategies for enhancing fruit l-AsA content through organ-specific manipulation.

Main Methods:

• Field experiments using Ribes nigrum (blackcurrant) to manipulate source-sink relationships.
• Methods included raceme removal (reducing reproductive capacity) and leaf/phloem removal (altering assimilate availability).
• Observed natural variation in fruit growth and abscission to inform experimental design and data interpretation.

Main Results:

• Fruit l-AsA concentration remained conserved despite manipulations.
• Total plant l-AsA yield was influenced by innate factors, particularly raceme attributes.
• Leaf and phloem removal reduced fruit weight and overall yield, with leaves contributing significantly to assimilate supply for fruit growth.

Conclusions:

• Fruit l-AsA concentration was not directly coupled to assimilate supply, challenging the hypothesis of leaf-driven synthesis and transfer.
• No evidence supported predominant l-AsA production in green leaf tissue for subsequent fruit accumulation.
• Ascorbic acid (l-AsA) production is concluded to occur predominantly within the fruit of Ribes nigrum.