A spore from downey mildew lands on a New York grape. The fungus digs in, sprouts a microscopic tree full of spores that are whisked away by the wind to find more grapes, where they will grow into fuzzy mildew that will eventually kill the fruit.

This scene is repeated hundreds if not thousands of times each day with a variety of fruits and vegetables on any farm in any state.

But, there is hope. Cornell genetics researcher Terrence P. Delaney is one of the scientific soldiers in the war against plant pathogens like downy mildew. The biological grail for which Delaney searches is something called systemic acquired resistance in plants. Essentially, through genetics, Delaney wants to enable plants to fend for themselves against fungi, bacteria and viruses.

"We don't know why we have resistant plants, or if a particular gene is responsible," says Delaney, professor of plant pathology. "We don't know all the genes responsible for the response."

Soon, agricultural scientists will finish mapping the genes in Arabidopsis. Through this plant, scientists hope to understand which are regulatory genes and which genes stave off disease. Arabidopsis, which belongs to the mustard family, likely will be the first plant genus to have its genetic code fully sequenced, making it the foundation for plant genome investigation.

In the past three years, Delaney's laboratory has examined 300,000 Arabidopsis plants. The researchers use salicylic acid, benzo-thiadiazole or dichloroisonicotinic acid to kick-start the plantÔs own immune system. Within a few days, the chemical is inducing the plant's natural protection functions. The plant is then infected with a disease-causing organism. Ideally, the plant will protect itself from the invading spore. Delaney is looking for those plants that lack disease protection and that are normal rather than mutant plants.

The lab has found six plants lacking immune response. All possessed a mutant gene -- nim1 -- which Delaney says is the master regulatory gene controlling systemic acquired resistance.

"By understanding nim1, we can control the systemic acquired resistance in a plant, and if we understand this plant, we can understand others in the process for all of agriculture," he says.

Plant breeders have selected plants for disease resistance and raised those cultivars, explains Delaney. "We're approaching disease resistance from the other point of view, which is to study the plant at the molecular level and learn its disease response system. There is a lot of room for synergy between the disciplines," he says.

One positive side effect of this research, he notes, is a reduction in the reliance on pesticides. Says Delaney: "We're finding and bolstering the plant's natural immune system -- what the plant already had."