Study reveals key gene protecting plants from harmful metals in soil

Amazing stuff! Could be very useful!

"The negative impact of human activity on Earth doesn’t just affect our planet’s atmosphere—it goes much deeper, into its soils. For instance, excessive application of manure or sewage sludge can increase heavy metal concentrations in agricultural land where vital crops are grown. One of these heavy metals is zinc, a micronutrient necessary for plant and animal health. In excess, however, zinc can be extremely damaging to sensitive plant species. ...
The findings ... reveal that plants tolerate high levels of zinc by trapping it in their root cell walls, a process facilitated by a gene called trichome birefringence or TBR. Scientists and farmers can now use this information to develop and grow crops that are more resilient to soil contamination. ...
A cell wall’s capacity to store zinc is largely dependent on a process called pectin methylesterification—a process that alters the structure of the spongy pectin molecules inside cell walls so that they can absorb more zinc. To better understand this, the researchers performed a genome-wide association study to identify plant genes associated with increased pectin methylesterification. ...
“We found that TBR allele variants influence changes in pectin methylesterification and help determine a plant’s ability to tolerate higher zinc levels,” ..."

From the abstract:

"Zinc (Zn) is an essential micronutrient but can be cytotoxic when present in excess. Plants have evolved mechanisms to tolerate Zn toxicity. To identify genetic loci responsible for natural variation of plant tolerance to Zn toxicity, we conduct genome-wide association studies for root growth responses to high Zn and identify 21 significant associated loci. Among these loci, we identify Trichome Birefringence (TBR) allelic variation determining root growth variation in high Zn conditions. Natural alleles of TBR determine TBR transcript and protein levels which affect pectin methylesterification in root cell walls. Together with previously published data showing that pectin methylesterification increase goes along with decreased Zn binding to cell walls in TBR mutants, our findings lead to a model in which TBR allelic variation enables Zn tolerance through modulating root cell wall pectin methylesterification. The role of TBR in Zn tolerance is conserved across dicot and monocot plant species."

Study reveals key gene protecting plants from harmful metals in soil - Salk Institute for Biological Studies "... scientists find a gene to enhance plants’ zinc tolerance, an important step for producing crops resilient to heavy metals"

Natural variation of TBR confers plant zinc toxicity tolerance through root cell wall pectin methylesterification (open access)

Lotus japonicus sprouts, wildtype (left) and TBR homolog (right), in normal zinc levels (top) and high zinc levels (bottom).

Fig. 2: Natural allelic variation of TBR is associated with root growth responses to high Zn levels.