The fruit was found in the banks of the Kolyma River in Siberia, a top site for people looking for mammoth bones.
The Institute of Cell Biophysics team raised plants of Silene stenophylla - of the campion family - from the fruit.
Writing in Proceedings of the National Academy of Sciences (PNAS), they note this is the oldest plant material by far to have been brought to life.
Prior to this, the record lay with date palm seeds stored for 2,000 years at Masada in Israel.
The leader of the research team, Professor David Gilichinsky, died a few days before his paper was published.
In it, he and his colleagues describe finding about 70 squirrel hibernation burrows in the river bank.
"All burrows were found at depths of 20-40m from the present day surface and located in layers containing bones of large mammals such as mammoth, woolly rhinoceros, bison, horse, deer, and other representatives of fauna from the age of mammoths, as well as plant remains," they write.
"The presence of vertical ice wedges demonstrates that it has been continuously frozen and never thawed.
"Accordingly, the fossil burrows and their content have never been defrosted since burial and simultaneous freezing."
The squirrels appear to have stashed their store in the coldest part of their burrow, which subsequently froze permanently, presumably due to a cooling of the local climate.