LIBRO-CONGRESO-CITRUS

S05
the regulation of carotenogenesis, due to its theoretically identical genetic background to other plant tissues. Light
regulates the carotenoids synthesis. White light hampered the carotenoids biosynthesis in callus of ‘Red Marsh’
grapefruit (Citrus paradisi), while boosted it in ‘Tarocco’ blood orange (C. sinensis); the synthesis of carotenes
seemed more sensitive to light than xanthophylls; PSY transcription was up-regulated in callus of two sweet
oranges, while was down-regulated in ‘Murcott’ tangor (C. reticulata × C. sinensis); PSY was emphasized as a ratelimiting
gene; however, in the callus of ‘Red Marsh’, PDS and ZDS might be the rate-limiting genes with an inhibited
transcription. Sucrose supply affects carotenoids production. Sucrose starvation induced decreased carotenoid
production in callus of ‘Red Marsh’. Microarray analysis declared more than 1600 up- and down-regulated genes
with 4-fold change. Among them, the expression of most carotenogenesis genes was boosted. Interestingly, the
expression of transcription factors, such as AP2, was largely altered. The network began with sucrose starvation
to the carotenoid decrease; the senescence signalling and the regulation of transcription factors will be discussed.
S05O04
Terpene downregulation triggers innate immunity and resistance to fungal pathogens in orange
fruits
Rodríguez A. 1 , Shimada T. 2 , Cervera M. 1 , Alquézar B. 1 , Gadea J. 3 , Gómez-Cadenas A. 4 , de Ollas C. 4 , Rodrigo M.J. 5 , Zacarías
L. 5 , and Peña L. 1
1 Instituto Valenciano de Investigaciones Agrarias (IVIA), Centro de Protección Vegetal y Biotecnología, Spain; 2 National Institute of
Fruit Tree Science. National Agricultural Research Organization, Okitsu Citrus Research Station, Japan; 3 Instituto de Biología Molecular
y Celular de Plantas. CSIC-Universidad Politécnica de Valencia. (IBMCP), Spain; 4 Escuela Superior Ciencias Experimentales y Tecnología.
Universidad Jaume I de Castellón, Departamento de Ciencias Agrarias y del Medio Natural, Spain; and 5 Instituto de Agroquímica y
Tecnología de Alimentos-CSIC (IATA), Departamento de Ciencia de los Alimentos, Spain. arodrig@ivia.es
Volatile organic compounds, most of them being terpenes, are signals emitted by plants for communication
with the environment. Orange fruit accumulates mainly terpenes in mature peel oil glands, D-limonene
accounting for approximately 97% of terpene content. We have generated transgenic orange plants carrying a
D-limonene synthase gene in antisense (AS) configuration. Transgenic expression caused a dramatic decrease
in the accumulation of D-limonene in fruit peels, being about 80-100 times lower in AS samples than in empty
vector (EV) transgenic ones. This affected the interaction of fruits with their biotic environment because
they resulted to be resistant to different specialized pathogens. A gene expression analysis of these fruits
linked the decrease of D-limonene to the upregulation of genes involved in the innate immunity response.
Additionally, it caused an increase in the accumulation of jasmonates in AS orange peels, explaining their
resistance to different fungi. Furthermore, this indicates for the first time an inverse correlation between
volatile terpene accumulation upon fruit development and depletion of JA-mediated defense responses, thus
stressing the importance of D-limonene for specialized pathogens to establish infections in mature orange
peels. High D-limonene content in mature orange peels may be a signal for attractiveness of microorganisms
which might be likely involved in facilitating the access to the pulp of seed dispersal frugivores.
S05O05
Improving in vivo antioxidant properties of orange fruits through increased β-carotene content
Pons E. 1 , Alquézar B. 1 , Rodríguez A. 1 , Martorell P. 2 , Genovés S. 2 , Llopis S. 2 , González N. 2 , Ramón D. 2 , Rodrigo M.J. 3 ,
Zacarías L. 3 , and Peña L. 1
1 Instituto Valenciano de Investigaciones Agrarias (IVIA), Centro de Protección Vegetal y Biotecnología, Spain; 2 Biópolis SL, Cell Biology
Laboratory, Food Biotechnology Department, Spain; and 3 Instituto de Agroquímica y Tecnología de Alimentos-CSIC (IATA), Departamento
de Ciencia de los Alimentos, Spain. elponba@ivia.es
β-Carotene is one of the most efficient carotenoid singlet oxygen quenchers and may interfere in free radical
oxidation, typical of many degenerative diseases. Besides its activity as protective agent against oxidative
stress, β-carotene also plays a nutritional role as precursor of vitamin A with twice the efficiency of any
other pro-vitamin A carotenoid. Orange fruit is an excellent natural dietary source of carotenoids, as well as
other nutrients and health-promoting compounds such as vitamin C, flavonoids and folic acid. However, the
most abundant carotenoids present in the pulp of mature oranges are β-β-xanthophylls, while β-carotene is
hardly detectable. In response to a growing public interest in healthy plant products, this work was aimed
to strengthen the health benefits of orange fruits by increasing its β-carotene content through metabolic
76 - VALENCIA CONFERENCE CENTER, 18th-23rd NOVEMBER 2012