What is the carotenoid pathway?

The carotenoid biosynthetic pathway serves manifold roles in plants related to photosynthesis, photoprotection, development, stress hormones, and various volatiles and signalling apocarotenoids.

Are carotenoids enzymes?

The core of the carotenoid biosynthetic pathway consists of around 10 enzymes. In plants, the enzymatic formation of carotenoids occurs on plastid membranes and is mediated by nuclear-encoded enzymes (DellaPenna and Pogson 2006; Cuttriss et al. 2011).

Which is the direct carotenoids precursor?

Both α- and β-carotenes are yellow pigments; β-carotene is more commonly marketed, being one of the most important commercial carotenoids. As mentioned earlier, β-carotene is a direct precursor of vitamin A (Figure 2).

What do carotenoids do in photosynthesis?

Carotenoids are essential in oxygenic photosynthesis: they stabilize the pigment–protein complexes, are active in harvesting sunlight and in photoprotection. In plants, they are present as carotenes and their oxygenated derivatives, xanthophylls.

What is the main function of the carotenoids?

Carotenoids have been shown to have two major functions in photosynthesis. They act as photoprotective agents, preventing the harmful photodynamic reaction, and as accessory light-harvesting pigments, extending the spectral range over which light drives photosynthesis.

Where are carotenoids synthesized?

In higher plants, carotenoids are synthesized and accumulated through multiple catalytic steps in plastids7,8. These plastids are classified on their structure as proplastids, etioplasts, chloroplasts, chromoplasts, and amyloplasts9.

Are carotenoids secondary metabolites?

Carotenoids are lipophilic secondary metabolites derived from the isoprenoid pathway and are accumulated in most plant organs [1]. They contribute to the red, yellow and orange colors of many fruits and flowers, and are a factor in attracting pollinators to flowers.

Which skeleton is present in carotenoids?

Most carotenoids have 40-carbon skeleton (C40 carotenoid). Some carotenoids have a 45- or 50-carbon skeleton, which are called higher carotenoids.

Is chlorophyll A carotenoid?

The key difference between chlorophyll and carotenoids is that the chlorophyll is a family of green colour pigments primarily used for photosynthesis in photosynthetic organisms while the carotenoids are a group of yellow to red colour pigments including carotenes and xanthophylls that are accessory pigments.

What is total carotenoid?

Carotenoids are a class of more than 750 naturally occurring pigments synthesized by plants, algae, and photosynthetic bacteria (1). These richly colored molecules are the sources of the yellow, orange, and red colors of many plants. Fruit and vegetables provide most of the 40 to 50 carotenoids found in the human diet.

What is role of carotenoids in plants?

Carotenoids are essential pigments in photosynthetic organs along with chlorophylls. Carotenoids also act as photo-protectors, antioxidants, color attractants, and precursors of plant hormones in non-photosynthetic organs of plants.

What determines the activity of carotenoid biosynthetic enzymes?

A major determinant of the activity of carotenoid biosynthetic enzymes is membrane association. As described in the Biosynthesis section, many of the pathway enzymes (including PSY) need to be in a membrane context for activity.

What is the first step in plant carotenoid biosynthesis?

The first committed step in plant carotenoid biosynthesis is the synthesis of phytoene from GGPP (Figure 1). This reaction is catalyzed by PSY, which is probably the best studied enzyme of the plant carotenoid family.

What is the carotenoid metabolic pathway?

The carotenoid metabolic pathway is highly conserved and ubiquitous in photosynthetic organisms. (reviewed in [ 6 ]). Carotenoids are essential pigments in photosynthetic organisms (plants and some micro-organisms) and are involved in a number of physiological and developmental processes.

Is there a chromoplast-specific carotenoid biosynthesis pathway?

A chromoplast-specific carotenoid biosynthesis pathway is revealed by cloning of the tomato white-flower locus. Plant Cell. 2006;18:1947–1960.