03233naa a2200301 a 450000100080000000500110000800800410001902400350006010000130009524501440010826000090025250002770026152021470053865000170268565000110270265000160271365000170272965300160274665300170276265300170277965300190279670000180281570000150283370000130284870000140286170000180287577300380289310538602019-10-15       2015    bl uuuu     u00u1 u    #d7 a10.1007/s00425-015-2370-92DOI1 aLADO, J.  aExploring the diversity in Citrus fruit colouration to decipher the relationship between plastid ultrastructure and carotenoid composition.  c2015  aArticle history: Received: 13 March 2015 / Accepted: 9 July 2015 / Published online: 23 July 2015. Electronic supplementary material The online version of this article (doi:10.1007/s00425-015-2370-9) contains supplementary material, which is available to authorized users.  aABSTRACT.  Main conclusion: Differentiation of new and characteristic plastid ultrastructures during ripening of citrus fruits in both peel and pulp appears to be strongly correlated with the content and complement of carotenoids.  Most of the species of the Citrus genus display a wide range in fruit colouration due to differences in car- otenoids; however, how this diversity is related and may contribute to  plastid differentiation and ultrastructure  is currently unknown. To that end, carotenoid profile and plastid ultrastructure were compared in peel and pulp of three sweet oranges: the ordinary orange-coloured Navel, rich in b,b-xanthophylls, the yellow Pinalate mutant with an elevated content of colourless carotenes and reduced b,b-xanthophylls, and the red-fleshed Cara Cara with high concentration of colourless carotenes and lycopene in the pulp; and two grapefruits: the white Marsh, with low carotenoid content, and the red Star Ruby, accumulating upstream carotenes and lycopene. The most remarkable differences in plastid ultrastructure among varieties were detected in the pulp at full colour, coinciding with major differences in carotenoid composition. Accumulation of lycopene in Cara Cara and Star Ruby pulp was associated with the presence of needle-like crystals in the plastids, while high content of upstream carotenes in Pinalate pulp was related to the development of a novel plastid type with numerous even and round vesicles. The presence of plastoglobuli was linked to phytoene and xanthophyll accumulation, suggesting these structures as the main sites for the accumulation of these pigments. Peel chromoplasts were richer in membranes compared to pulp chromoplasts, reflecting their different biogenesis. In summary, differences in carotenoid composition and accumulation of unusual carotenoids are mirrored by the development of diverse and novel chromoplast types, revealing the plasticity of these organelles to rearrange carotenoids inside different structures to allow massive accumulation and thus contributing to the chemical stability of the carotenoids.  @ Springer-Verlag Berlin Heidelberg 2015  aCAROTENOIDES  aCITRUS  aCLOROPLASTO  aMADURAMIENTO  aCAROTENOIDS  aCHLOROPLASTS  aCHROMOPLASTS  aFRUIT RIPENING1 aZACARÍAS, L.1 aGURREA, A.1 aPAGE, A.1 aSTEAD, A.1 aRODRIGO, M.J.  tPlanta, 2015gv. 242, p. 645-661.