Changes in carotenoids and ABA content in Citrus leaves in response to girdling

The effect of girdling on abscisic acid, carotenoids content, xanthophylls cycle and non-photoquemical quenching was studied in leaves from different shoot types of containerized two-year-old ‘Loretina’ mandarin during spring flush period. Girdling increased abscisic acid in young leaves and decreased it in mature leaves. These changes were accompanied by a significant increase in leaf carotenoids, carotenoids:chlorophylls ratio, xanthophylls and xanthophylls cycle pool size and its de-epoxidation state in vegetative and multiflowered young leafy shoots. However, changes in de-epoxidation state did not correlate with the energy-dependent non-photochemical quenching. The role of carotenoids and abscisic acid as photoprotecting agents during the oxidative stress caused by girdling is discussed. In conclusion, this study provides evidence linking carotenoids-based photoprotecting mechanisms in the response to the stress induced by girdling in Citrus trees.

Research highlights▶ Article provides evidence that Girdling triggers stress response in Citrus. ▶ Article provides novel information about changes in carotenoids-based photoprotecting mechanism in different Citrus leaves. ▶ Changes in de-epoxidation state of the Xanthophyll cycle is not correlated with non-photochemical quenching. ▶ Changes in ABA content in different Citrus leaves as response to girdling.