Chromoplast Differentiation: Current Status and Perspectives

Abstract

Chromoplasts are carotenoid-accumulating plastids conferring color to many fl owers and fruits as well as to some tubers and roots. Chromoplast differentiation proceeds from preexisting plastids, most often chloroplasts. One of the most prominent changes is remodeling of the internal membrane system associated with the formation of carotenoidaccumulating structures. During the differentiation process the plastid genome is essentially stable and transcriptional activity is restricted. The buildup of the chromoplast for specifi c metabolic characteristics is essentially dependent upon the transcriptional activity of the nucleus. Important progress has been made in terms of mediation of the chloroplast-to-chromoplast transition with the discovery of the crucial role of the Or gene. In this article we review recent developments in the structural, biochemical and molecular aspects of chromoplast differentiation and also consider the reverse differentiation of chromoplasts into chloroplast-like structures during the regreening process occurring in some fruit. Future perspectives toward a full understanding of chromoplast differentiation include in-depth knowledge of the changes occurring in the plastidial proteome during chromoplastogenesis, elucidation of the role of hormones and the search for signals that govern the dialog between the nuclear and the chromoplastic genome. Keywords: Carotenoids synthesisAbbreviations : ABA , abscisic acid ; ARC5 , accumulation and replication of chloroplasts5 ; ARF4 , auxin response factor ; CHRC , plastoglobulin carotenoid-associated protein ; DDB1 , UV-damaged DNA-binding protein 1 ; DET1 , deetiolated 1 ; GFP , green fl uorescent protein ; MFP1 , thylakoid-associated DNA-binding protein ; ORFs , open reading frames ; PVD1 , plastid division1 ; PVD2 , plastid division 2 ; ROS , reactive oxygen species.

A Comprehensive Analysis of Chromoplast Differentiation Reveals Complex Protein Changes Associated with Plastoglobule Biogenesis and Remodeling of Protein Systems in Sweet Orange Flesh

“…Chromoplasts exhibit various morphologies, such as crystalline, globular, tubular, and membranous structures (Egea et al, 2010). The relationship between the architecture and carotenoid composition has been well stated in diverse pepper (Capsicum annuum) and tomato (Solanum lycopersicum) fruits (Kilcrease et al, 2013;Nogueira et al, 2013).…”

“…Carotenoid composition has been reported to be regulated by the expression of carotenogenic genes in the flesh of various citrus fruits differing in their internal colors (Fanciullino et al, 2006(Fanciullino et al, , 2008. Chromoplasts are frequently derived from fully developed chloroplasts, as seen during fruit ripening from green to red or yellow fruits in tomato and pepper (Egea et al, 2010). In some cases, chromoplasts also arise from nonphotosynthetic plastids, such as colorless proplastids, leucoplasts, or amyloplasts (Knoth et al, 1986;Schweiggert et al, 2011).…”

“…In some cases, chromoplasts also arise from nonphotosynthetic plastids, such as colorless proplastids, leucoplasts, or amyloplasts (Knoth et al, 1986;Schweiggert et al, 2011). To date, most studies on chromoplast differentiation have been focused on the synthesis of carotenoids by combining biochemical and molecular analyses (Cazzonelli and Pogson, 2010;Egea et al, 2010;Bian et al, 2011;Li and Yuan, 2013), and little is known about the molecular mechanisms underlying chromoplast biogenesis .…”

“…Additionally, citrus fruits exhibit a unique anatomical fruit structure consisting of two major sections, the pericarp and the edible flesh. Considerable progress has been made in the understanding of chromoplast differentiation in the pericarp of citrus fruits (Eilati et al, 1969;Iglesias et al, 2007), which is a process similar to that of tomato and pepper (Egea et al, 2010). However, little is known about the molecular basis of chromoplast differentiation in the edible flesh, even though there is increasing evidence suggesting an essential role of carotenoid synthesis in inducing chromoplast differentiation (Egea et al, 2010;Bian et al, 2011;Li and Yuan, 2013).…”

Proteomic Analysis of Chloroplast-to-Chromoplast Transition in Tomato Reveals Metabolic Shifts Coupled with Disrupted Thylakoid Biogenesis Machinery and Elevated Energy-Production Components

“…However, although highly specialized, chromoplasts carry out a variety of functions, many of them persisting from the chloroplast (Bouvier and Camara, 2007;Egea et al, 2010). The biochemical and structural events during chromoplast differentiation have been reviewed in a number of articles over the last decades (Thomson and Whatley, 1980;Ljubesić et al, 1991;Marano et al, 1993;Camara et al, 1995;Waters and Pyke, 2004;Lopez-Juez, 2007;Egea et al, 2010;Bian et al, 2011).…”