A plant hormone that speeds root growth could be a new agricultural tool

plant roots
Credit: CC0 Public Domain

A molecule sold as a food additive has an underground role, too: helping roots grow faster.

When added to , the molecule, called beta-cyclocitral, speeds growth in and tomato , scientists report May 8, 2019, in the journal Proceedings of the National Academy of Sciences. It also makes rice plants resistant to salty soil, which usually turns plants sickly and stunted. The molecule, a hormone found naturally in plants, could be a useful tool for farmers seeking healthier and more drought-resistant crops.

For centuries, plants have been bred for vigorous foliage and other easily visible traits. Because roots are hidden underground, "they've been largely ignored," says developmental biologist Philip Benfey, a Howard Hughes Medical Institute investigator at Duke University.

And yet, roots make up half the plant, points out coauthor Jazz Dickinson, also at Duke. She and Benfey wanted to find plant hormones that affected root development. Their previous research had hinted that some molecule chemically related to carotenoids – the pigments that give carrots their vibrant orange hue – might be important. But the researchers weren't sure exactly which one, Dickinson says.

These racing roots show the effects of beta-cyclocitrical, a plant hormone that boosts root growth. The rice plants on the left are growing in a gel that contains the hormone, but the ones on the right aren’t getting any help. Credit: Benfey Lab/Duke University/Howard Hughes Medical Institute

Many of these carotenoid relatives have been repurposed and are available commercially as food additives or dietary supplements. Dickinson rounded up about 20 and tested their effects on a common lab plant, Arabidopsis. She added each compound to the clear agar gel in which the plants were growing – a setup that let her easily see the roots – and monitored what happened over 10 days.

"Beta-cyclocitral stood out," she says. It made the roots grow faster and also branch out more. And it had the same effect in rice and , follow-up tests showed.

In rice plants, the team noticed an even more striking effect: the plants could also withstand salty soil. Irrigation of farm fields can make soil saltier, especially near the top. The team mimicked those conditions in the lab, and then watched how rice plants grew. "Untreated rice plants were very unhappy with that level of salt," Benfey says. But with beta-cyclocitral added, the plants didn't seem perturbed.

It's possible that the compound helped the roots push down through the salty topsoil to reach the deeper, less-salty soil more quickly, Dickinson proposes.

The researchers hope that beta-cyclocitral will be useful agriculturally, either added to soil or sprayed onto crops. And since the molecule worked in both rice and tomatoes – two very different plants – it may boost root growth in crops more broadly.


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More information: Alexandra J. Dickinson et al. β-Cyclocitral is a conserved root growth regulator, Proceedings of the National Academy of Sciences (2019). DOI: 10.1073/pnas.1821445116
Citation: A plant hormone that speeds root growth could be a new agricultural tool (2019, May 10) retrieved 15 July 2019 from https://phys.org/news/2019-05-hormone-root-growth-agricultural-tool.html
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May 10, 2019
Beta-cyclocitral

β-Cyclocitral, a small molecule derived from β-carotene
β-Cyclocitral promotes root stem cell divisions to enhance root growth and branching

Is this extracted from crushed carrots mixed in the soil by the roots?
https://www.pnas....21445116
Well apparently it comes in liquid form
https://www.india...448.html
A mite expensive, especially if crushed carrots mixed in the soil works
there is one simple way of finding out
as of late most plants grown in pots are suffering a root growing problem
where repotted in the soil the roots are not growing from side where the pot was into the soil
with the result that the plant after months in the soil
just falls out the soil with the root still in a pot shape
resulting in the plant not taking root in the soil
they look as though there growing then they shrivel up and depart from the soil
It is as though the roots stop growing out the pot!

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