Plant & zo
The science of plants and more
Keeping the balance when submerged
Plants, just like animals and humans need oxygen to survive. Normally this is no problem. As a by-product of photosynthesis, oxygen is freely available. But by flooding a plant is under water, no photosynthesis can take place resulting in a lack of oxygen. To survive such a submergence, plants switch to oxygen-free use of energy. Less efficient. Plants are therefore keeping an eye out for their energy reserves. Now a group of European researchers found out how plants use this information to regulate the speed of oxygen-free energy use.
The important regulators of the switch from an aerobic to an anaerobic metabolism are ERF-VIIs. This are gene on/off switches. When there is lots of oxygen, then ERF-VIIs are turned off. ERF-VIIs are only allowed by absence of oxygen, like during a flood, to do their job.
To investigate how ERF-VII react to a shortage of energy, the researchers starved plants before submerging them. This they did by placing them for longer than normal in the dark. The researchers noticed that in non-starved, submerged plants ERF-VIIs do their job, switching on genes for the anaerobic metabolism. But this did happen less in starved plants.
TOR is need to let ERF-VIIs know how much energy there is
The question was why. To answer this, the researchers focused on the energy sensor TOR. They analysed TORs activity in submerged starved and non-starved plants. In starved plants TOR appeared not to do much. In contrast, in non-starved plants TOR was very active. But this was short lived, the longer the submergence, the less active TOR got.
To make sure that TOR is actually the cause that the ERF-VIIs were less active in starved plants, the researchers directly studied the effect of TOR on ERF-VIIs. Doing this, the researchers noticed that in plants without TOR the ERF-VIIs did not do their job.
TOR is needed to let the ERF-VIIs know that there is enough energy to keep the anaerobic metabolism going. The longer the plant is submerged the slower TOR does its job. To save energy to survive.
Literature
Alicja B. Kunkowska, Fabrizia Fontana, Federico Betti, Raphael Soeur, Gerold J. M. Beckers, Christian Meyer, Geert De Jaeger, Daan A. Weits, Elena Loreti, Pierdomenico Perata (2023) Target of rapamycin signaling couples energy to oxygen sensing to modulate hypoxic gene expression in Arabidopsis. PNAS Vol. 120 e2212474120 https://doi.org/10.1073/pnas.2212474120
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