Formation and Change of Chloroplast-Located Plant Metabolites in Response to Light Conditions

Abstract

Photosynthesis is the central energy conversion process for plant metabolism and occurs within mature chloroplasts. Chloroplasts are also the site of various metabolic reactions involving amino acids, lipids, starch, and sulfur, as well as where the production of some hormones takes place. Light is one of the most important environmental factors, acting as an essential energy source for plants, but also as an external signal influencing their growth and development. Plants experience large fluctuations in the intensity and spectral quality of light, and many attempts have been made to improve or modify plant metabolites by treating them with different light qualities (artificial lighting) or intensities. In this review, we discuss how changes in light intensity and wavelength affect the formation of chloroplast-located metabolites in plants.

Keywords: biosynthesis; chloroplast; light intensity; light wavelength; metabolite; photosynthesis.

Figure 1

Schematic representation of biosynthetic pathways for the main metabolites in chloroplasts. (This figure is summarized based on review by Gontero et al., 2014 [39]; Joyard et al., 2010 [66]; Lancien et al., 2007 [53]; Kelly et al., 1976 [43]). Different regions represent different metabolite pathways, (A) Carbohydrates; (B) Amino acids; (C) Fatty acids; (D) Vitamins; (E) Hormones. The enzymes are indicated by number surrounded by a full circle, and orange circle represent sensitive to light-regulation (1, 3, 6, 9 and 12). All the enzymes of these overlapping metabolic pathways are listed in the Table 1. Abbreviations: 2PGA, 2-phosphoglycerate; 3PGA, 3-phosphoglycerate; ACP, acyl-carrier protein; ADP, adenosine diphosphate; ADP-Glu, adenosine diphosphate glucose; ATP, adenosine triphosphate; BPGA: 1,3-bisphosphoglycerate; DHAP: dihydroxyacetone phosphate; E4P: erythrose-4-phosphate; ent-CDP, ent-copalyl diphosphate; F6P, fructose-6-phosphate; FBP: fructose-1,6-bisphosphate; GA, gibberellin; GAP: glyceraldehyde-3-phosphate; GGDP, geranylgeranyl diphosphate; Glu-1-P, glucose-1-phosphate; HPP, p-hydroxyphenylpyruvate; IPP, isopentenylpyrophosphate; KIY, α-ketoisovalerate; NADH, nicotinamide adenine dinucleotide; MPBQ, methyl-6-phytyl-1,4-benzoquinone; NADPH, nicotinamide adenine dinucleotide phosphate; PEP, phosphoenolpyruvate; phytyl-DP, phytyl-diphosphate; Ru5P: ribulose-5-phosphate; RuBP: ribulose-1,5-bisphosphate; S7P: sedoheptulose-7-phosphate; SBP: sedoheptulose-1,7-bisphosphate; Triose-P, triose-phosphate; Xu5P: xylulose-5-phosphate.