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How Plant Roots Know to Grow—During Heat, Drought

Studies Break New Ground Amidst Climate Worries


According to ScienceDaily, two separate studies have broken ground—and altered previous concepts—about how plant roots know to grow deeper during heat and associated drought. Researchers hope their discoveries can assist plant breeders with efforts to help plants cope with rising global temperatures.

A team of scientists at the Sainsbury Laboratory Cambridge University (SLCU) in the UK has discovered a molecular signaling-pathway that is activated when leaves are exposed to low humidity. This causes plant roots to grow towards water.

Meanwhile, a team led by researchers from Martin Luther University Halle-Wittenberg (MLU) in Germany, succeeded in demonstrating that roots are equipped with a temperature sensing and response system of their own.


Exposed tree roots in dry terrain.  ©Pixabay
Exposed tree roots in dry terrain. ©Pixabay

The team’s study, published in The EMBO Journal, provides new information on how roots themselves both detect and react to higher temperatures.


As reported by ScienceDaily, Professor Marcel Quint from the Institute of Agricultural and Nutritional Sciences at MLU said, “Until now, it was assumed that the plant shoot controlled the process for the entire plant and acted as a long-distance transmitter that signaled to the root that it should alter its growth."

Prof. Quint and team discovered that root cells increased production of the growth hormone auxin, which was sent to root tips to stimulate cell division, enabling roots to grow deeper into the soil. "As heat and drought usually occur in tandem, it makes sense for the plants to tap into deeper and cooler soil layers that contain water," Quint explains in the ScienceDaily report.

The SLCU researchers, on the other hand, found that when the leaves of a plant are exposed to low humidity, they signal the plant's roots using the drought stress hormone abscisic acid (ABA) to direct them to continue growing. This was surprising because ABA is thought to be a growth inhibitor, rather than a growth promoter.

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