title: Selective defoliation affects plant growth, fruit transcriptional ripening program and flavonoid metabolism in grapevine.
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.
authors: Department of Fruit Tree and Woody Plant Science, University of Bologna, Viale Fanin, 46, 40126, Bologna, Italy.
authors: Chiara
authors: C
authors: Pastore
authors: Sara
authors: S
authors: Zenoni
authors: Marianna
authors: M
authors: Fasoli
authors: Mario
authors: M
authors: Pezzotti
authors: Giovanni Battista
authors: GB
authors: Tornielli
authors: Ilaria
authors: I
authors: Filippetti
mesh_terms: D005419:Flavonoids / Q000378:metabolism*; D005638:Fruit / Q000235:genetics*; D018506:Gene Expression Regulation, Plant; D018515:Plant Leaves / Q000235:genetics / Q000378:metabolism; D059467:Transcriptome / Q000235:genetics; D027843:Vitis / Q000235:genetics / Q000378:metabolism*
chemical_list: D005419:Flavonoids