Metabolic and transcriptional changes associated with the use of Ascophyllum nodosum extracts as tools to improve the quality of wine grapes (Vitis vinifera cv. Sangiovese) and their tolerance to biotic stress

Abstract

BACKGROUND Recent studies report that Ascophyllum nodosum extracts, once applied on the canopy of different crops, deliver positive effects, increasing yield, inducing tolerance to biotic stress, and improving the quality of products. However, the mechanisms of action are still unclear. In this research, vines subjected to multiple foliar applications of an A. nodosum extract (ANE) at label doses were compared with untreated vines (NTV) in accordance with a comparative approach. The investigation coupled a field experiment with a second trial conducted under semi‐controlled conditions, to clarify the mechanisms of action involved. RESULTS The biostimulant did not affect soluble solids or the acidity of grapes; instead, it improved their anthocyanin and phenolic concentrations and the respective profiles. At the time of harvest, anthocyanin, and phenolic concentration were increased by 10.4% and 14.5%, respectively, when compared to the NTV. These effects correlated with a specific modulation of genes involved in the flavonoid metabolic pathways. Moreover, grapes from ANE vines witnessed a significant reduction in the spreading of gray mold when they were either assessed in field conditions or in vitro, compared to the grapes of NTV vines. This was related to a significant upregulation of the defense‐related genes of the plant. CONCLUSIONS Overall, the results showed that A. nodosum extracts can be valuable tools in viticulture considering the emergence of challenging environmental conditions; hence, the regulation of specific metabolic pathways is the mechanism of action that leads to an increased tolerance of biotic stress and of changes in the content of grape metabolites. © 2019 Society of Chemical Industry

Phenolic composition of Tempranillo Blanco (Vitis vinifera L.) grapes and wines after biostimulation via a foliar seaweed application

“…reported that seaweed application to grapevines improved skin anthocyanins accumulation and total phenolic content in grape berries. Frioni et al . reported that increases in anthocyanins and phenolic concentrations in grapes after seaweed applications are related to specific modulation of genes involved in the flavonoid metabolic pathways.…”

“…Frioni et al 20 and Salvi et al 23 reported that seaweed application to grapevines improved skin anthocyanins accumulation and total phenolic content in grape berries. Frioni et al 58 reported that increases in anthocyanins and phenolic concentrations in grapes after seaweed applications are related to specific modulation of genes involved in the flavonoid metabolic pathways. Additionally, it was shown that grapevines treated with an A. nodosum fertilizer were less affected by gray mold compared to untreated grapevines.…”

Effects on must and wine volatile composition after biostimulation with a brown alga to Tempranillo grapevines in two seasons

“…These results are similar to those exposed by certain authors, who showed scarce effects on must and wine physico-chemical parameters after the application of seaweeds to the grapevines. 14,15,[17][18][19][20]26 Volatile acidity was higher in the wines produced in 2018 than in 2017, probably due to the duration of the MLF. According to the multifactorial analysis (MFA), treatment affected probable alcohol and pH in musts and wines.…”

“…9,39 To our knowledge, there is little information available in the literature about the effects of seaweed applications to grapevines and how they affect systematic responses of plants. Frioni et al 15 reported that the increase in the content of certain phenolic compounds in grapes after seaweed applications are related to specific modulation of genes involved in the flavonoid metabolic pathways. However, gene-specific modulation in grapes after seaweed elicitation has not yet been reported in the literature.…”

“…13 Different reports showed that Ascophyllum nodosum extracts applied to the grapevines increased the content of skins anthocyanins and the total phenolics content in grapes. [14][15][16] Taskos et al 17 showed that A. nodosum foliar applications to Merlot grapevines allowed to increase yield, number of berries, anthocyanin extraction capacity from berry skins and seed tannins, and decreased the total polyphenol index of grapes. In addition, it was reported that seaweed foliar applications to Tempranillo Blanco grapevines increased the content of catechin and flavonols, independently of climatic conditions of the seasons and the content of several amino acids in a dry season.…”