A radical new strategy for creating disease-resistant woody plants in a laboratory dish has met with preliminary success at the Department of Agriculture's Beltsville Agricultural Research Center.
Cells from the embryos in peach seeds were separated, put in a dish and exposed to a bacterial toxin, the cause of leaf spot disease, to see if any possessed natural resistance. Some did, and the lab's Freddi Hammerschlag used tissue culture techniques to coax the resistant cells to develop into whole plants.
The little peach trees proved immune to the disease in the laboratory and are now being grown in the field to see if mature trees retain the resistance.
The strategy is based on the theory that while the tree, or the embryo, as a whole, may be vulnerable, some of its cells may, through chance mutations, possess resistance. Under natural conditions the vulnerability of the other cells would doom the few resistant ones.
Although it is possible that the resistant cell might be the one to give rise to the whole seed, scientists might have to plant thousands of such seeds and wait years, in the case of woody plants, to see which ones resisted the disease.
By searching through many cells individually, as Hammerschlag has done, the process of developing naturally resistant varieties can be speeded greatly.