Carotenoid responses to environmental stimuli: integrating redox and carbon controls into a fruit model

Abstract

Carotenoids play an important role in plant adaptation to fluctuating environments as well as in the human diet by contributing to the prevention of chronic diseases. Insights have been gained recently into the way individual factors, genetic, environmental or developmental, control the carotenoid biosynthetic pathway at the molecular level. The identification of the rate-limiting steps of carotenogenesis has paved the way for programmes of breeding, and metabolic engineering, aimed at increasing the concentration of carotenoids in different crop species. However, the complexity that arises from the interactions between the different factors as well as from the coordination between organs remains poorly understood.This review focuses on recent advances in carotenoid responses to environmental stimuli and discusses how the interactions between the modulation factors and between organs affect carotenoid build-up. We develop the idea that reactive oxygen species/redox status and sugars/carbon status can be considered as integrated factors that account for most effects of the major environmental factors influencing carotenoid biosynthesis. The discussion highlights the concept of carotenoids or carotenoid-derivatives as stress signals that may be involved in feedback controls. We propose a conceptual model of the effects of environmental and developmental factors on carotenoid build-up in fruits.

The common transcriptional subnetworks of the grape berry skin in the late stages of ripening

“…The ripening berry is a sink organ for photosynthate, losing its photosynthetic capacity with time and changing color as chloroplasts are degraded or converted to other plastids with changing carotenoid production [46, 69]. In tomato, chloroplasts are converted to chromoplasts, which are the source of the red pigments.…”

Breadfruit (Artocarpus altilis and hybrids): A traditional crop with the potential to prevent hunger and mitigate diabetes in Oceania

“…Carotenoids are produced by plants in the chloroplast in order to protect the photosynthetic apparatus from reactive oxygen species (ROS), consequently they are natural antioxidants (Fanciullino et al, 2014). Upon consumption, some carotenoids (provitamin A carotenoids, pVACs) are converted by the enzyme beta-carotine 15,150-monooxygenase to form vitamin A (Bai et al, 2011).…”

Reactive Oxygen Species and Photosynthesis

“…Besides the function of CARs as antenna molecules, in capturing light in the blue light region (450À570 nm) and transferring photons energy to the Chl, the main crucial role of CARs is its ROS detoxifying function in chloroplasts (Cazzonelli, 2011). Regarding antioxidant properties, CARs can protect photosystems (i) via interacting with lipid radicals and breaking chain reactions, (ii) by scavenging 1 O 2 , (iii) by reacting with 1 Chl à or 3 Chl à to impair generation of 1 O 2 , or (iv) by dissipating EEE through the xanthophyll cycle (Blokhina et al, 2003;Fanciullino et al, 2013). The major role of β-carotene in green tissues is quenching of 3 Chl à , thus providing inhibition of 1 O 2 production and damage.…”