Root responses at the proteomic and metabolomic level to drought in two grapevine rootstocks with different susceptibility

INTRODUCTION. The selection of new rootstocks represents a crucial factor for the development of future sustainable agricultural models. In this view, the identification of biomarkers for abiotic stresses that will reinforce the choices and streamline the process of genotype selection represents a crucial aspect in the assisted selection protocols. The use of high-throughput proteomic and metabolomic approaches is a very powerful tool to deepen the knowledge on the mechanisms as well as to select putative biomarkers. M4, a new putative rootstock, previously characterized at the biochemical and physiological point of view, showed a greater tolerance to WS. This capacity resulted strictly related to root integrity/functionality, so confirming that these aspects have to be considered in the further selection programs. This work focused on both the proteomic and the metabolimic changes in the root organ evoked by drought stress, comparing the susceptible commercial rootstock 101.14 with the newselected genotype M4. MATERIALS AND METHODS. The two genotypes were grown in pots and were exposed to a severe stress, obtained by a progressive reduction of the water availability to the 30% of field capacity during a period of 10 days. The SDS-PAGE was used to fractionate the proteins. Large portions of the gel were then analysed by nLC-nESI-Q-TOF mass spectrometry. The metabolomic analyses were conducted by means of the Gas Chromatography–Mass Spectrometry technique (GC-MS) on the trimethylsylyl-derivatized metabolites of the polar fraction. The generated dataset was analyzed through multivariate statistical techniques. RESULTS AND DISCUSSION. This study allowed the characterization of about one-thousand of proteins for each genotype, providing the first proteomic set of root organ in Vitis. The drought stress significantly affected the levels of about 15% of the proteins, especially those linked to energy and amino acid metabolism, protein turn-over and (a)biotic stress responses, highlighting interesting differences between the two rootstocks. Metabolomic analysis permitted the identification of around 120 metabolites. The generated dataset, evaluated through multivariate statistical techniques, showed that for the tolerant genotype M4 the response to the water stress was more marked and involved many compounds known to play a role in the osmotic component of the tolerance to the water stress. A good convergence was found between proteomic and metabolomic results. CONCLUSIONS.Taken together, these results permitted the identification of some putative biomarkers for abiotic stresses that will reinforce the choices and streamline the process of genotype selection. Acknowledgments: Work was supported by SERRES-AGER project, grant n°2010-2105.