Genetic and Epigenetic Responses of Autochthonous Grapevine Cultivars from the ‘Epirus’ Region of Greece upon Consecutive Drought Stress

Abstract

Within the framework of preserving and valorizing the rich grapevine germplasm of the Epirus region of Greece, indigenous grapevine (Vitis vinifera L.) cultivars were characterized and assessed for their resilience to abiotic stresses in the context of climate change. The cultivars ‘Debina’ and ‘Dichali’ displayed significant differences in their response to drought stress as judged by morpho-physiological analysis, indicating higher drought tolerance for Dichali. Hence, they were selected for further study aiming to identify genetic and epigenetic mechanisms possibly regulating drought adaptability. Specifically, self-rooted and heterografted on ‘Richter 110’ rootstock plants were subjected to two phases of drought with a recovery period in between. Gene expression analysis was performed for two stress-related miRNAs and their target genes: (a) miRNA159 and putative targets, VvMYB101, VvGATA-26-like, VvTOPLESS-4-like and (b) miRNA156 and putative target gene VvCONSTANS-5. Overall, grafted plants exhibited a higher drought tolerance than self-rooted plants, suggesting beneficial rootstock–scion interactions. Comparative analysis revealed differential gene expression under repetitive drought stresses between the two cultivars as well as between the self-rooted and grafted plants. ‘Dichali’ exhibited an up-regulation of most of the genes examined, which may be associated with increased tolerance. Nevertheless, the profound down-regulation of VvTOPLESS-4-like (a transcriptional co-repressor of transcription factors) upon drought and the concomitant up-regulation of miRNA159 highlights the importance of this ‘miRNA-target’ module in drought responsiveness. DNA methylation profiling using MSAP analysis revealed differential methylation patterns between the two genotypes in response to drought. Further investigations of gene expression and DNA methylation will contribute to our understanding of the epigenetic mechanisms underlying grapevine tolerance to drought stress.

Crop Landraces and Indigenous Varieties: A Valuable Source of Genes for Plant Breeding

“…These genes code for proteins related to defense mechanisms against biotic stresses and include receptor signal transduction kinases, pathogen effectors, a leucine-rich repeat receptor-like serine/threonine-protein kinase, an ethylene-responsive factor, and a zinc finger RNA-binding protein. Importantly, upon pathogen infection, these genes displayed marked upregulation in resistant Vitis accessions as compared to susceptible ones, indicating a functional role in successful response and resistance to white rot [ 197 ]. Identifying abiotic stress tolerance- and disease-resistant-associated genes in indigenous genotypes could be exploited in breeding programs aiming to confer resilience to commercial varieties or develop rootstocks with enhanced stress resilience properties [ 180 , 181 ].…”

“…In a recent study on the indigenous grapevine varieties from the Epirus region of Greece, an indigenous local variety named ‘Dichali’ was found to display tolerance to consecutive drought stress. Moreover, enhanced resilience to water deficit was accompanied by altered expression patterns of two microRNAs (miR157 and miR159) and genes encoding transcription factors (TFs) of the MYB and TPR families, suggesting epigenetic responses as well as the implication of potential miRNA/TF regulatory networks in dehydration tolerance [ 197 ]. A deeper understanding of the molecular mechanisms underlying key responses to environmental stressors would provide useful information for grapevine improvement and contribute to climate-smart viticulture.…”