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Open Access Research article

Selective defoliation affects plant growth, fruit transcriptional ripening program and flavonoid metabolism in grapevine

Chiara Pastore1, Sara Zenoni2, Marianna Fasoli2, Mario Pezzotti2, Giovanni Battista Tornielli2* and Ilaria Filippetti1

Author affiliations

1 Department of Fruit Tree and Woody Plant Science, University of Bologna, Viale Fanin, 46, 40126, Bologna, Italy

2 Department of Biotechnology, University of Verona, Strada Le Grazie 15, 37134, Verona, Italy

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Citation and License

BMC Plant Biology 2013, 13:30  doi:10.1186/1471-2229-13-30

Published: 22 February 2013

Abstract

Background

The selective removal of grapevine leaves around berry clusters can improve the quality of ripening fruits by influencing parameters such as the berry sugar and anthocyanin content at harvest. The outcome depends strongly on the timing of defoliation, which influences the source–sink balance and the modified microclimate surrounding the berries. We removed the basal leaves from Vitis vinifera L. cv Sangiovese shoots at the pre-bloom and veraison stages, and investigated responses such as shoot growth, fruit morphology and composition compared to untreated controls. Moreover, we performed a genome-wide expression analysis to explore the impact of these defoliation treatments on berry transcriptome.

Results

We found that pre-bloom defoliation improved berry quality traits such as sugar and anthocyanin content, whereas defoliation at veraison had a detrimental effect, e.g. less anthocyanin and higher incidence of sunburn damage. Genome-wide expression analysis during berry ripening revealed that defoliation at either stage resulted in major transcriptome reprogramming, which slightly delayed the onset of ripening. However, a closer investigation of individual gene expression profiles identified genes that were specifically modulated by defoliation at each stage, reflecting the uncoupling of metabolic processes such as flavonoid biosynthesis, cell wall and stress metabolism, from the general ripening program.

Conclusions

The specific transcriptional modifications we observed following defoliation at different time points allow the identification of the developmental or metabolic processes affected in berries thus deepening the knowledge of the mechanisms by which these agronomical practices impact the final berry ripening traits.

Keywords:
Vitis vinifera; Defoliation; Berry ripening; Transcriptome; Flavonoid; Source-sink balance