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Plants turned on by oxygen levels?

Maize tassel with anthers.
[Courtesy of Virginia Walbot]

Germ cells are the building blocks of reproductive cells, like sperm and eggs. And in humans, these germ cells are established during the early stages of development and then maintained until an individual is ready to have kids.

Plants, on the other hand, are able to develop germ cells much later in life—and they don't start making these cells until the plants are ready to reproduce. Until now, researchers didn't understand how plants accomplished this feat. But, Timothy Kelliher and Virginia Walbot have shown that plants actually take cues from oxygen levels in the air to start producing their germ cells.

The researchers studied sexual reproduction in the maize, or corn, plant and found that a low-oxygen environment could change any cell in the plant's anther into a germ cell.

Since maize anthers develop behind the plant's tightly closed leaves, which don't allow gases to sneak past, the researchers suggest that the oxygen levels behind the leaves must decrease toward the center of the anther. Cells that are closest to the center respond to the lack of oxygen by turning into germ cells, they say.