Root proteome responses to drought in two grapevine rootstocks with different susceptibility

This work represents one of the biochemical sections of the project SERRES and adopted the same experimental plan described in the dedicate posters. This work was focused on the study of proteomic changes in the root organ evoked by drought stress, comparing the susceptible commercial rootstock 101.14 with the new selected genotype M4. The two genotyes were grown in pots and were exposed to a sevre stress, obtained by a progressive reduction of the water availability to the 30% of field capacity during a period of 10 days. The biological samples, consisting in lignified root organs of one-year-old plants grown in soil, posed technical challenges related to the paucity of biochemical active tissue as well as to the high content of phenolic substances. In order to overcome these aspects, we used the SDS-PAGE as a tool not only to fractionate the proteins but also to remove interfering compounds. Large portions of the gel (0.8x1x0.1 cm) were then analysed by nLC-nESI-Q-TOF mass spectrometry. The MS/MS experiments were optimized to quantify and compare the identified proteins in the different samples. This approach showed high reproducibility , high dynamic range but no limits of protein hydrophobicity and pI. On the whole, this study allowed to analyze the responses of about ne-thousand of roteins for each genotype, providing the first proteomic characterization of root organ in Vitis. On the other hand, the work showed as the drought stress significantly affected the levels of about the 15% of the proteome, especially linked to energy and redox metabolism, protein turn-over and (a)biotic stress responses, highlighting interesting differences between the two rootstocks. Acknowledgments: work was supported by SERRES-AGER project, grant n°2010-2105.