Developments to Watch
HUNTING DOWN GENES THAT SAY `NO' TO DISEASE
Scientists have tried in vain to pinpoint the genes in crops that resist disease. If they could insert them in plants, it could help increase yields and curb pesticide use.
For the first time, researchers at Cornell University have cloned such a gene in tomatoes. Resistance in plants occurs most often when a gene in an invading bacterium triggers a specific resistance gene in the plant. The Cornell researchers used the Pseudomonas syringae, which causes bacterial speck disease in tomatoes, to activate the so-called Pto resistance gene. They adapted map-based cloning, a technique used to find human genes by mapping their location on chromosomes, to pinpoint the Pto gene in tomatoes. They then inserted it into tomato plants, which became resistant to the disease. The researchers have thus laid a foundation for other scientists to use gene-mapping to find critical plant genes faster and with less knowledge of the molecular biology of the gene than is possible with other methods.EDITED BY EMILY T. SMITH