L-Ascorbic acid metabolism and regulation in fruit crops

Area of Science:

• Plant Physiology
• Biochemistry
• Horticultural Science

Background:

• L-Ascorbic acid (AsA), or vitamin C, is a vital antioxidant regulating plant growth, stress resistance, and senescence.
• AsA content exhibits significant variation across fruit crops, with differences up to 1,800-fold.
• Recent research has elucidated AsA accumulation mechanisms over the past two decades.

Purpose of the Study:

• To review the advancements in understanding L-Ascorbic acid (AsA) accumulation in fruit crops.
• To identify key genes involved in AsA synthesis, degradation, and regeneration pathways.
• To highlight current knowledge gaps and future research directions in AsA metabolism.

Main Methods:

• Identification of rate-limiting genes in the L-galactose (GMP, GME, GGP, GPP) and D-galacturonic acid (GalUR) synthesis pathways.
• Characterization of key genes in AsA degradation and regeneration (APX, MDHAR, DHAR).
• Investigation of gene regulation by environmental factors (e.g., GGP induction by light).

Main Results:

• Critical rate-limiting genes for AsA synthesis pathways in fruit crops have been identified.
• Key genes involved in AsA degradation and regeneration pathways are recognized.
• Strategies like editing upstream open reading frames (uORF) and multi-gene vectors show potential for enhancing AsA content.

Conclusions:

• The metabolism of AsA in fruit crops is now well-understood.
• Further research is needed on AsA transport mechanisms and the synergistic improvement of AsA with other desirable traits.