How long can I store extracted RNA? If I extract RNA from a (leaf tissue) sample using a one-step phenol:chloroform extraction, how long can those samples be stored at -80°C? And how many times can I defrost and refreeze them before they will become degraded?

I've found that extracted RNA using commercial kits has stayed stable for many years at -80 C. I would certainly aliquot it before freezing however as RNA is particularly sensitive to freeze-thaw cleavage.