Sensing temperature
When heat strikes plants can not just find a place in the shade. Instead they initiate their heat protocol. Now German and French researchers report in Nature that they found one of the switches of this protocol.
One of the things that the heat stress protocol regulates is making sure that not to much water evaporates. For this the hormone ABA is responsible. One of the things that ABA regulates like a manager is the opening and closing of stomata. This enables plants to keep water in. This clear reaction to heat makes it a great tool for screening for heat tolerance.
To find the switch of the heat stress protocol, the researchers went searching for plants that reacted differently to heat. They noticed one mutant, that did not made any TWA1, that was much more susceptible to heat stress than other plants. Plants with an ABA-receptor that lights up in the presence of ABA, lighted up more when there was more TWA1 present. But it did this only at temperatures above 25°C. Plants growing at 20°C did not light up at all.
Plants with extra TWA1 deal better with heat stress
To study TWA1 in more detail the researchers replaced a part of TWA1 with that of a part of TWA1 coming from plants that were growing at higher or lower temperatures. When the part was coming from plants growing at lower temperatures then the ABA-reporter also lighted up at a lower temperature. But was the TWA1 part coming from a plant growing at higher temperatures, then the ABA-receptor lighted up at higher temperatures.
Subsequently the researchers analysed with which other proteins TWA1 interacts. They noticed that the interaction of TWA1 with the gene regulator JAM2 only occurs during during heat stress. TWA1 appears to unfold itself more and more by increasing temperatures. Giving JAM2 access to its binding place on TWA1. In addition they researchers noticed that TWA1 interacts with gen regulator TLP.
Lastly the researchers studied if they could make plants more heat tolerant using TWA1. One approach was to give plants more TWA1. These plants grew just as well under stress free circumstances. But the appeared to do better during heat stress. Closer study indicated that these plants had a higher activation of their heat stress protocol.
The temperature sensor TWA1 appears to be the ideal candidate to make plants more heat tolerant. Without the cost that comes from activating the heat stress protocol at stress free temperatures.
Literature
Bohn, L., Huang, J., Weidig, S. et al. The temperature sensor TWA1 is required for thermotolerance in Arabidopsis. Nature (2024). https://doi.org/10.1038/s41586-024-07424-x
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