Effect of Salinity on Grape Embryo Growth and Physiology, The

The growth of grape somatic embryos can be affected by elements in their surrounding environment. Improving grapevine tolerance to salinity necessitates the optimization of protocols for screening response of various grapevine species and cultivars to salt stress under in vitro conditions. We germinated Thompson Seedless somatic embryos on MS medium containing 1.0 μM BAP and varying levels of sodium chloride. Salt treatments included MS medium containing: 1) no sodium chloride (control), 2) 5 mM NaCl, 3) 10 mM NaCl, 4) 25 mM NaCl, 5) 50 mM NaCl, 6) 100 mM NaCl and 7) 200 mM NaCl. Cultures were placed in a growth room. The plates were monitored regularly, photographed, and rated on a growth scale of one to four weekly over six weeks. Dry weights were collected, root samples were fixed in Histochoice, and embedded in paraffin to examine root tissue development. Increased NaCl led to decreased growth and development. Shoot and root structures were inhibited. Severe inhibition in shoot and root growth of germinated embryos was observed above 50 mM NaCL concentration. Frontenac grape embryos will be tested next. Once the concentration of NaCl that inhibits growth and development of somatic embryos is identified, this method will be used to screen genetically modified embryogenic cultures that carry genes inserted for salinity tolerance. Our in vitro screening technique should allow for rapid identification of embryo lines that exhibit salinity tolerance following genetic modification.