Contrasting grapevines grafted into naturalized rootstock suggest scion-driven transcriptomic changes in response to water deficit

Abstract

Viticulture is facing water deficit problems related to climate change, new extremes in heat and precipitation regimes and drought events. Rootstocks use was assessed as strategy for enhancing performance of Cabernet Sauvignon (CS) and Syrah (Sy) under water deficit. Vines were grafted onto naturalized grapevines selected from hyper-arid Chile, and compared to own-grafted and commercial Ruggeri 140. Plants were submitted to optimal (100 % ETc) and deficit (30 % ETc) irrigation throughout two seasons at field conditions. Functional traits along both seasons were determined. Water deficit reduced all growth and physiological traits especially in CS. R32 rootstock induced significantly higher values for most traits irrespective of cv and seasons associated to higher root growth. Transcriptomic analysis was further performed in both cultivars grafted over R32 rootstock by RNA-Seq, determining that gene up-regulation extent was higher in Sy. More stable transcriptional landscape was determined in CS than Sy, which might be linked to its hydric strategy. Unexpectedly, major differences in transcriptional behaviour were detected in R32 rootstock, revealing major transcriptional changes occurring at root level, suggesting scion-driven transcriptional regulation in response to stress. Finally, R32 rootstock can be considered for both near iso and anisohydric grapevines as adaptive strategy for climate constrains.