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Ethanol is known to accumulate in various plant organs under various environmental conditions. However, there is very little data on the detection of ethanol by the plants themselves. The team of researchers from the Genomics and Biotechnology of Fruit unit described in a recent Plant Science article that ethanol accumulates when the tomato seeds soak up water, especially when the seeds are stacked together on the others. The stacked seeds germinate less than the spread seeds, suggesting that ethanol inhibits germination.

Taking seeds and adding exogenous ethanol to them, the researchers note the same phenomenon of inhibition. However, the effects of the added ethanol were not related to differences in ethylene production by the soaked seeds. They observe that exogenous ethanol at low concentration regulates the expression of certain ethylene receptors. In addition, the triple response induced by ethylene in tomato plants was partially attenuated by ethanol. These results show that there are interactions between the detection of ethylene and ethanol in plants. Similar observations have been made on Arabidopsis thaliana seeds and seedlings.
But what about the detection of ethylene?

New ethylene receptor revealed by tomato genome sequencing

Ethylene is perceived by a family of well-known ethylene receptors (ETRs). However, a complete understanding of the ETR function is complicated by the functional redundancy between proteins of different forms of this receptor. In the second article that interests us, published in the journal Horticulture Research, the same researchers characterize a new ETR, called SlETR7, which was revealed by the sequencing of the tomato genome. They show that this receptor specifically binds to ethylene.

The expression of SlETR7 in the tomato pericarp increases when the fruit ripens and its expression is synchronized with the expression of other receptors. The authors of the article also discovered an error in the SlETR7 sequence documented in previous versions of the tomato genome, so they were able to correct it ("ITAG 4" version of the tomato genome).

Overall, these results show that SlETR7 is a functional ethylene receptor. Research remains to be carried out to better understand its specific roles linked to the six other tomato REEs.
Beyond the issue of ethylene in tomatoes, certain ethylene perception genes are found in many taxa, so this research tells us about signaling mechanisms that could be widely distributed.