ARS | Publication request: Improved watermelon quality using bottle gourd rootstock expressing a Ca(2+)/H(+) antiporter

Submitted to: Molecular Breeding
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: April 6, 2009
Publication Date: April 21, 2009
Repository URL: http://www.springerlink.com/content/905n72653q922277
Citation: Han, J-S., Park, S., Shigaki T., Hirschi, K.D., Kim, C.K. 2009. Improved watermelon quality using bottle gourd rootstock expressing a Ca(2+)/H(+) antiporter. Molecular Breeding. 24(3):201-211.

Interpretive Summary: Grafting is a method of plant propagation where the tissues of one plant are encouraged to fuse with those of another. It is commonly used for the propagation of many melons grown commercially. In this study, we used genetically modified rootstocks for grafting of melons. The modified rootstocks produced larger, more robust melons than controls. Using the genetically engineered rootstocks could be a means of boosting plant productivity for many commercial crops that use grafting methods. This technique is particularly compelling in that the genetic modifications do not enter the food supply.

Technical Abstract: Bottle gourd ("Lagenaria siceraria" Standl.) has been commonly used as a source of rootstock for watermelon. To improve its performance as a rootstock without adverse effects on the scion, the bottle gourd was genetically engineered using a modified "Arabidopsis" Ca(2+)/H(+) exchanger sCAX2B. This transporter provides enhanced Ca(2+) substrate specificity and decreased Mn(2+) transport capability. Our previous work demonstrated that s"CAX2B" bottle gourds were more robust and nutrient dense than controls. Here, several cucurbit crops were test-grafted onto the transgenic bottle gourd to determine its effect on the scions. The grafted watermelons and melons onto the transgenic rootstocks appeared to show more robust growth than the controls 35 days after greenhouse transplanting. Watermelon fruits with the watermelon/transgenic bottle gourd (scion/rootstock) combination demonstrated higher osmotic pressure and more soluble solids than controls. These results suggest that s"CAX2B" expression in the bottle gourd rootstock facilitates improved watermelon quality through the translocation of nutrients and/or water toward enhancing the biomass of scion.