Salt tolerance of wild grapevine seeds during the germination phase

Wild grapevine [Vitis vinifera L. subsp. sylvestris (Gmelin) Hegi], belonging to the Vitaceae family, is the ancestor of cultivated grapevine varieties (Vitis vinifera L. subsp. vinifera) and is considered an important Crop Wild Relative (CWR). The response to different levels of saline stress (0, 125, 250, 500 mM NaCl) during the seed germination phase of five populations was evaluated, as well as the potential ability of seeds to recover their germination after the salt exposure. The maximum level of salt in which seeds were able to germinate was 250 mM NaCl, except for the population of Sylv3, which did not germinate at more than 125 mM NaCl. Great inter-populational variability was detected among the other four population ns that germinated at up to 250 mM NaCl, and each of them showed a preferential temperature in this pattern. The ability of seeds to recover their germination after the salt stress greatly varied among populations and as a function of the salinity concentration to which seeds were exposed in the previous phase. No more than ca. 30% of wild grapevine seeds recovered after being sown at 500 mM NaCl, but up to 95% had the ability to recover after 250 mM, showing that seeds of this taxon could tolerate moderate salinity levels in the soil and have successful recovery after rainfalls. Our findings could help in understanding the actual distribution and ecophysiology of the wild grapevine in the Mediterranean area and could be useful in the selection of populations with more salt-tolerant plants that could be used as rootstock for the cultivation of grapevines in areas near to the coastline or salinized soils, where salinity is an important limiting factor.