A comprehensive analysis of chromoplast differentiation reveals complex protein changes associated with plastoglobule biogenesis and remodelling of protein systems in orange flesh.

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TitleA comprehensive analysis of chromoplast differentiation reveals complex protein changes associated with plastoglobule biogenesis and remodelling of protein systems in orange flesh.
Publication TypeJournal Article
Year of Publication2015
AuthorsZeng, Y, Du, J, Wang, L, Pan, Z, Xu, Q, Xiao, S, Deng, X
JournalPlant Physiol
Date Published2015 Jun 8
ISSN1532-2548
Abstract<p>Globular and crystalloid chromoplasts were observed to be region-specifically formed in orange flesh (Citrus sinensis Osbeck) and converted from amyloplasts during fruit maturation, which was associated with the composition of specific carotenoids and expression of carotenogenic genes. Subsequent iTRAQ-based quantitative proteomic analyses of purified plastids from the flesh during chromoplast differentiation and senescence identified 1,386 putative plastid-localized proteins, 1,016 of which were quantified by spectral counting. The iTRAQ values reflecting the expression abundance of three identified proteins were validated by immunoblotting. Based on iTRAQ data, chromoplastogenesis appeared to be associated with three major protein expression patterns (1) marked decrease in abundance of the proteins participating in the translation machinery through ribosome assembly; (2) increase in abundance of the proteins involved in terpenoid biosynthesis (including carotenoids), stress-responses (redox, ascorbate, and glutathione) and development; and (3) maintenance of the proteins for signalling and DNA&RNA. Interestingly, strong increase in abundance of several plastoglobule-localized proteins coincided with the formation of plastoglobules in the chromoplast. The proteomic data also showed that stable functioning of protein import, suppression of ribosome assembly and accumulation of chromoplast proteases are correlated with amylo-to-chromoplast transition and thus these processes may play a collective role in chromoplast biogenesis and differentiation. By contrast, chromoplast senescence process was inferred to be associated with a significant increase in stress response and energy supply. In conclusion, this comprehensive proteomic study identified many potentially new plastid-localized proteins and provides insights into the potential developmental and molecular mechanisms underlying chromoplast biogenesis, differentiation and senescence in orange flesh.</p>
DOI10.1104/pp.15.00645
Alternate JournalPlant Physiol.
PubMed ID26056088