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Biblioteca(s): | INIA Las Brujas.
Fecha corriente: | 13/11/2015
Fecha de la última actualización: | 13/11/2015
Autoria: | LADO, J.; CRONJE, P.; ALQUÉZAR, B.; PAGE, A.; MANZI, M.; GÓMEZ-CADENAS, A.; STEAD, A.D.; ZACARÍAS, L.; RODRIGO, M.J.
Afiliación: | JOANNA LADO LINDNER, INIA (Instituto Nacional de Investigación Agropecuaria), Uruguay.
Título: | Fruit shading enhances peel color, carotenes accumulation and chromoplast differentiation in red grapefruit.
Año de publicación: | 2015
Fuente/Imprenta: | Physiologia Plantarum, 2015, v.154, no. 4, p. 469-484.
Série: | 0031-9317
DOI: | 10.1111/ppl.12332
Idioma: | Inglés

Contenido:

ABSTRACT.

The distinctive color of red grapefruits is due to lycopene, an unusual carotene in citrus. It has been observed that red ?Star Ruby? (SR) grapefruits grown inside the tree canopy develop a more intense red coloration than those exposed to higher light intensities. To investigate the effect of light on SR peel pigmentation, fruit were bagged or exposed to normal photoperiodic conditions, and changes in carotenoids, expression of carotenoid biosynthetic genes and plastid ultrastructure in the peel were analyzed. Light avoidance accelerated chlorophyll breakdown and induced carotenoid accumulation, rendering fruits with an intense coloration. Remarkably, lycopene levels in the peel of shaded fruits were 49-fold higher than in light-exposed fruit while concentrations of downstream metabolites were notably reduced, suggesting a bottleneck at the lycopene cyclization in the biosynthetic pathway. Paradoxically, this increment in carotenoids in covered fruit was not mirrored by changes in mRNA levels of carotenogenic genes, which were mostly up-regulated by light. In addition, covered fruits experienced profound changes in chromoplast differentiation, and the relative expression of genes related to chromoplast
development was enhanced. Ultrastructural analysis of plastids revealed an acceleration of chloroplasts to chromoplast transition in the peel of covered fruits concomitantly with development of lycopene crystals and plastoglobuli. In this sense, an accelerated differentiation of chromoplasts may provide biosynthetic capacity and a sink for carotenoids without involving major changes in transcript levels of carotenogenic genes. Light signals seem to regulate carotenoid accumulation at the molecular and structural level by
influencing both biosynthetic capacity and sink strength. Abbreviations ? &#120573;CHX, &#120573;-carotene hydroxylase; &#120573;LCY, lycopene cyclase &#120573;; ABA, abscisic acid; C, covered; Chl, chlorophyll; DXS, 1-deoxy-D-xylulose-5-phosphate synthase; FIB, fibrillin; FW, fresh weight; GGPP, geranyl geranyl pyrophosphate; GGPPS, geranyl geranyl pyrophosphate synthase; HDR, hydroxymethylbutenyl diphosphate reductase; HPLC, high-performance liquid chromatography; MEP, methyl-D-erythritol-4-phosphate; NC, non-covered; PCR, polymerase chain reaction; PDS, phytoene desaturase; PSY, phytoene synthase; sHSP, small heat shock protein; SR, Star Ruby; ZDS, &#120577;-carotene desaturase.

Physiol. Plant.

Thesagro: | CITRUS; CITRUS PARADISI.
Categoría del tema: | --
Registro original: | INIA Las Brujas (LB)
Ejemplares: | LB - (100793-1) - PXI - AP - DD -  -  -  - DIS