Abstract
Chromoplasts are nonphotosynthetic plastids that accumulate carotenoids. They derive from other plastid forms, mostly chloroplasts. The biochemical events responsible for the interconversion of one plastid form into another are poorly documented. However, thanks to transcriptomics and proteomics approaches, novel information is now available. Data of proteomic and biochemical analysis revealed the importance of lipid metabolism and carotenoids biosynthetic activities. The loss of photosynthetic activity was associated with the absence of the chlorophyll biosynthesis branch and the presence of proteins involved in chlorophyll degradation. Surprisingly, the entire set of Calvin cycle and of the oxidative pentose phosphate pathway persisted after the transition from chloroplast to chromoplast. The role of plastoglobules in the formation and organisation of carotenoid-containing structures and that of theOrgene in the control of chromoplastogenesis are reviewed. Finally, using transcriptomic data, an overview is given the expression pattern of a number of genes encoding plastid-located proteins during tomato fruit ripening.
Highlights
Chromoplasts are nonphotosynthetic plastids that accumulate carotenoids and give a bright colour to plant organs such as fruit, flowers, roots, and tubers
The loss of photosynthetic activity was associated with the absence of the chlorophyll biosynthesis branch and the presence of proteins involved in chlorophyll degradation
Proteomic analysis have demonstrated that an almost complete set of proteins involved in the oxidative pentose phosphate pathway (OxPPP) are present in isolated tomato fruit chromoplasts (Figure 2)
Summary
Chromoplasts are nonphotosynthetic plastids that accumulate carotenoids and give a bright colour to plant organs such as fruit, flowers, roots, and tubers. Details of the early steps of tomato chromoplast biogenesis from chloroplasts are provided at the cellular level that show the formation of intermediate plastids containing both carotenoids and chlorophylls. The comparison of data arising from proteomics of the chloroplast [33] and of the chromoplast [16] as well as biochemical analysis of enzyme activities suggest that several pathways are conserved during the transition from chloroplast to chromoplast Such is the case for (i) the Calvin cycle which generates sugars from CO2, (ii) the oxidative pentose phosphate pathway (OxPPP) which utilizes the 6 carbons of glucose to generate 5 carbon sugars and reducing equivalents, and (iii) many aspects of lipid metabolism (Figure 2). Proteomic analysis have demonstrated that an almost complete set of proteins involved in the OxPPP are present in isolated tomato fruit chromoplasts (Figure 2). New membranes are synthesized such as those participating in the formation of
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
