Getting a little salt tolerance
Like I mentioned last week I like it when plants find a way against all odds. It is not just the perseverance and adaption. But also, that we can learn something from how those pioneering plants manage to survive against all odds.
Take for example plants growing in saline conditions. Plants, like all organisms, don’t like to much salt. But if the seed you germinated from was dropped on salty soil, you better learn to deal with it. This is what Spanish and French researchers show in a newly published article “Parallel evolution of salinity tolerance in Arabidopsis thaliana accessions from Cape Verde Islands”.
They set out with the question what strategies do Arabidopsis plants (tale cress) growing on the salty soils of the Cape Verde Islands use. They specifically looked at how the metabolites the Cape Verde Islands plants accumulated differ from those in the standard lab variety of Arabidopsis.
A metabolite for salt tolerance
One unknown metabolite stood out. The researchers named it U2746. And after further characterising it, the researchers concluded that U2746 is most likely an ether-linked glucuronyl-mannose. Arabidopsis plants from the Cape Verde Islands accumulated more of it.
The question was if more U2746 results in a better tolerance to salty soils. To test this, researchers grew Cape Verde Islands Arabidopsis and lab standard Arabidopsis under normal and salty conditions. Under normal conditions the researchers observed no difference in growth between the two Arabidopsis lines.
Growing in salty conditions, not only did the Cape Verde Islands Arabidopsis line germinate better than the lab line, they also had longer roots and where healthier. In other words, the Cape Verde Island Arabidopsis did better under salty conditions that the lab line.
Turned up twice
For breeders to make use of this trait they need to know which gene is responsible. After analysis this turned out to be GH38cv, an α-mannosidase. Plants with a defect GH38cv gene accumulated more U2746.
Zooming in on GH38cv in The Cape Verde Islands Arabidopsis plants the researchers found that there were three versions of GH38cv. One with an active gene. And two versions with an inactive gene, each developed on its own island. Evolution thus came up twice with this handy trick for salt tolerance.
How exactly more U2746 results in salt tolerance the researchers don’t know. Although they have some theories. The first one is that U2746 like other sugary metabolites functions as an osmolyte, thereby increasing the ability of the plant to take up water, and protecting its membranes against damage.
The second option is that because the accumulation of U2746 comes at a cost of less glucuronic acid, a cell wall component, it results in an altered cell wall which might affect salt tolerance. A third option is that U2746 functions as a signalling molecule. But there are no clear indicators for which of the three options are the cause of the salt tolerance. So as always more research is needed.
Literature
Félix J. Martínez Rivas et al., Parallel evolution of salinity tolerance in Arabidopsis thaliana accessions from Cape Verde Islands.Sci. Adv.11,eadq8210(2025). https://www.science.org/doi/10.1126/sciadv.adq8210
Plant en Zo 