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Previous investigations had found that the nucleus and cytosol (fluid inside cells) play some role in helping plants to beat the heat. This new plant genome research found a gene called bZIP28 that's important for heat tolerance.
The protein product of the gene is anchored to an organelle known as the endoplasmic reticulum (ER). This is the first time that the ER has been implicated in the mechanics of heat tolerance.
According to the researchers, when a plant is stressed by heat, one end of the protein (which has been tethered to the ER) falls away and migrates to the nucleus. Here it turns on genes that are involved in heat tolerance. Basically it's a genetic switch that controls a plant's response.
Plants that had the bZIP28 gene inactivated soon died when temperatures reached certain levels.