Call them the martyrs for biodiversity.

During the terrible winter of 1941-42, while Hitler's armies were blockading Leningrad and thousands were starving to death, a small band of Soviet scientists accepted the same fate, even as they guarded tons of rice, wheat, corn, beans and potatoes in a huge seed bank.

Nine botanists perished in the midst of plenty, thus preserving the seeds for science -- and for future generations, including Americans, many of whose crops today are the result of cross-breeding with varieties the scientists saved from destruction.

The researchers were on the staff of the Vavilov Institute of Plant Industry, and their ordeal helped maintain their institute as one of the world's largest repositories of the genetic diversity of food crops.

Their story, little known in the West, was recently told in the journal Diversity by two institute officials, S.M. Alexanyan and V.I. Krivchenko.

When World War II came to Leningrad, now called St. Petersburg, the Vavilov Institute had accumulated seeds from 187,000 varieties of plants, of which about 40,000 were food crops. By maintaining the stock, which requires periodically replanting and harvesting fresh seed, various qualities such as resistance to particular pests or adaptability to various climates are available to be bred into existing crops.

In the fall of 1941, Nazi forces tried to take Leningrad but were held off by the Red Army. The stalemate became a siege with frequent shelling and skirmishing that would last 880 days.

"It became increasingly difficult to work in the institute," Alexanyan and Krivchenko wrote. "The building was unheated, as there was neither firewood nor coal. Because of unrelenting firing on the city's center, the building's windows were broken and had to be boarded up. The institute was cold, damp and dark."

As the winter wore on and temperatures plummeted to 40 below, the potato collection was at special risk of freezing. It, like much of the collection, also was vulnerable to plunder by hungry townspeople.

Institute workers "burned everything to get heat," the authors wrote -- "boxes, paper, cardboard and debris from destroyed buildings. To guard and care for the collection they established 24-hour vigils for the scientific workers at a special outpost near the potato storage area."

Working secretly, the scientists prepared a sample of the collection to be smuggled out of Leningrad. The collection was transported over a frozen lake to a storage site in the Ural mountains. Other parts of the collection were divided into smaller lots and also smuggled out of Leningrad.

As the weeks passed, even the rats became hungrier and bolder.

Famine in the city reached major proportions, killing tens of thousands.

In January 1942, Alexander Stchukin, a peanut specialist, died at his writing table. Georgi Kriyer, who was in charge of medicinal plants, and Dmitri Ivanov, head of the rice collection, also succumbed.

"After Ivanov's death," the authors wrote, "workers found several thousand packs of rice in his collection that he had preserved while dying of starvation."

The siege of Leningrad would continue until January 1944. Through it all, the Vavilov collection was largely preserved. In the postwar years the institute grew and prospered as one of the world's premier sites for the collection and preservation of plant genetic diversity.

Since the collapse of the Soviet Union, however, the Vavilov has again fallen on hard times. Sources of money have become uncertain and, according to Jose Esquinas-Alcazar of the U.N. Food and Agriculture Organization, "the Vavilov doesn't even have money to pay its electricity bills. It would be a terrible shame if the world lost that institution."