Synchrotron seedlings. Researchers have used high-energy X-rays to peer inside 20-day-old pine-tree seedlings and study their developing tissues in microscopic detail. They placed living seedlings in a synchrotron and imaged cross sections of their stems to show what happens inside the plant when it is deprived of water. The images show how the different tissues change over about 24 hours. Unexpectedly, the seedling seems to dry up from outside in — as time goes on, dark air pockets appear in the outer tissues (bottom row), while the central core containing the xylem, the plant’s vascular tissue, remains hydrated. “I was completely shocked,” said Dan Johnson at the University of Georgia, who led the work. “The way we thought these seedlings were going to fail, hydraulically, as they dried out, was not at all how they failed.”
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