First Discovery of the Female Hormone Progesterone in a Plant

Scientists have discovered the female sex hormone progesterone in a walnut tree, shaking up what's known about the different between plants and animals.

Until now, scientists thought that only animals could make progesterone. A steroid hormone secreted by the ovaries, progesterone prepares the uterus for pregnancy and maintains pregnancy. A synthetic version, progestin, is used in birth control pills and other medications.

"The significance of the unequivocal identification of progesterone cannot be overstated," write Guido F. Pauli and colleagues in the American Chemical Society's Journal of Natural Products. "While the biological role of progesterone has been extensively studied in mammals, the reason for its presence in plants is less apparent."

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