Flooding responses on grapevine: A physiological, transcriptional and molecular perspective

Abstract

According to IPCC, in 2001-2010 floods have been the most frequent extreme event. Root exposure to prolonged hypoxic conditions produced by temporary flooding of the soil, may induce the synthesis of stress hormones, the production of reactive oxygen species and undergo metabolic re-programming. The aim of the research was to study the physiological and transcriptional responses in Vitis vinifera L. cv Sauvignon blanc grafted on K5BB. Potted vines were flooded before bud-break and primary roots were sampled at 2 (T1), 8, 16 and 21 days and one week later upon recovery (T5). While initial phenological development was significantly affected due to flooding, upon recovery, higher and earlier stem internode elongation and leaf extension rates were observed compared to control. Expression analyses of three hypoxia markers (Vv_ACO1, Vv_Susy and Vv_ADH1) were performed by qRT-PCR on all samples, pointing out a marked up-regulation at T1, followed by a general down-regulation and a full normalization at recovery. An RNAseq profiling of the root transcriptome at T1 allowed to identify 850 and 1365 up- and down- regulated genes, respectively. Enrichment analyses highlighted extensive changes of the root physiology, especially concerning the response to stress, oxygen transport, response to phytosteroids, and flavonoids/(di)terpenoids metabolism. At T5 (Recovery), only few differentially expressed genes (15 down and 2 up) were pointed out, confirming a full recovery of the plant to flooding, at least at the transcriptional level. The present dataset will enable the development of a model of the responses dynamics in grapevine to hypoxia.