USDA- Sponsored Workshop at the last leg of their program. Visits UCD
The participants to the USDA-workshop spent their last working day at the University of California at Davis. They were taken to meet Professor Eduardo Blumwald at the Department of Pomology who, in collaboration with Dr. Zhang Hong-Xia of Botany Department at the University of Toronto bioengineered a salt tolerant tomato line by inserting and overexpressing a vacuolar Na+/H+ antiport gene that was shown to improve salt tolerance in Arabidopsis. In the picture at the top the fruit size of the salt tolerant line is shown to be slightly smaller compared to the two fruits of the control. The genetically modified transgenic tomato plants were able to grow, flower and produce fruits in the presence of 200 mM NaCl. While the transgenic leaves accumulated Na+ to almost 1% of their dry weight, the fruits displayed only a marginal increase in Na+ content and a 25% increase in K+ content. The results of their experiments show clearly that transgenic tomato plants can utilize salty water for growth.
Professor Blumwald explained that the strategy followed so long by breeders was to exclude sodium but in their approach they are allowing Na+ into the cell, compartmentalizing it in the vacuole.
Since the Na+ was sequestered inside the vacuole, it did not have any toxicity on the other cell components. Since arabidopsis plants are not as sensitive to salinity as their tomato counterparts, overexpression of an Arabidopsis vacuolar Na/H antiport gene in tomato genome worked very well to exclude the transport of Na salts into tomato fruits. This strategy may prove helpful to breed salt tolerant lines of other crops.
