conference schedule and program with abstracts - Horticulture ...

O-37
Differential expressed genes in berries of cv. Sangiovese (Vitis Vinifera L.) during ripening
following cluster thinning at véraison
C. Pastore* 1 , I. Filippetti 1 , S. Zenoni 2 , M. Fasoli 2 , A. Ferrarini 3 , M. Pezzotti 2 , C. Intrieri 1
1 Department of Fruit Tree and Woody Plant Science, University of Bologna, Bologna, Italy;
2 Department of Sciences, Technologies and Grapevine and Wine Markets, University of Verona,
San Floriano, Verona, Italy; 3 Department of Biotechnology, University of Verona, Verona, Italy
*Corresponding author: cpastore@agrsci.unibo.it
Yield reduction and quality improvement are not always strictly related, cluster thinning is
considered a technique which, involving an increase in source-sink ratio, could lead to
improvement in grape berry sugar and anthocyanin concentration. In this research an integrated
agronomical, biochemical and molecular approach aims to understand which mechanisms are
involved, during ripening, in determining final berry composition in cv Sangiovese vines
submitted to thinning at véraison (CT, 50% of total clusters removed at véraison). The yield
reduction observed in CT vines implied a significant increase in leaf area/crop weight ratio,
which caused an acceleration in berry ripening rate immediately after the treatment and higher
values of soluble sugars at harvest compared to control vines (C). Anthocyanin amount was
strongly affected by the treatment, as their accumulation increases in parallel with soluble sugars
content, reaching higher values than C at harvest. Microarray analyses, carried out with a
NimbleGen array assembled on the basis of the 12X Vitis vinifera genome sequence, allowed to
discriminate between CT and C at the end of véraison (14% of 29550 genes analyzed were
differentially expressed between CT and C at this stage). Genes involved in carbohydrate
metabolism, response to stress and flavonoid accumulation were analyzed in depth. As a result,
CT transcriptional profile was characterized by the increase in expression of genes involved in
sugars storage which usually follows sugar utilization as energy source, and by a decrease in
genes induced in response to oxidative stress, corresponding to the final ripening phase.
Source/sink ratio increase, positively influenced anthocyanin structural and transcriptional
regulatory genes and in particular those involved in anthocyanin transport, which were strongly
up-regulated in CT compared to C. The results of this research confirm the key role of
source/sink ratio in conditioning sugars metabolism and reveals that carbohydrates availability is
a crucial issue in triggering expression of genes involved in anthocyanin biosynthesis in field
condition too.
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