Nikolai Ivanovich Vavilov

The great Russian plant geneticist Nikolai Ivanovich Vavilov, who collected 200,000 different varieties of plants from literally every part of the world, collected a particular sunflower variety in West Texas in 1932. (Unfortunately, the Linnaean name is garbled in the article where I read this.) Forty years later, a hybrid descendant of this variety, now much richer in oil production, was reintroduced into West Texas by sunflower-oil producers, an early and sterling example of U.S.-U.S.S.R. cooperation.

During the German siege of Leningrad (9/41 to 1/44), which caused a famine in the city, either nine or fourteen of Vavilov's staff (accounts vary) died at their desks of starvation rather than allow any of the collection's tons of irreplaceable genetic stocks to be touched. "Patriotism is not enough." -- Edith Cavell

Vavilov himself wasn't there. He had openly defied the powerful pseudo-scientist Trofim Lysenko, who had Stalin's full support for his "Marxist genetics", and had been thrown into prison. He died there in 1943.