Researchers from the University of Pennsylvania, supported by the NSF, German Research Foundation and National Institute for General Medical Sciences, have identified proteins that can be targeted in order to grow hardy plants that can withstand drought or low-nutrient conditions.

By targeting these two proteins, researchers can regulate whether a cell in plant roots forms a hair cell, which increases surface area for absorption, or a non-hair cell. They found that even when deprived of phosphorus, a key nutrient, plans thrived if they overexpressed one of these regulator proteins.

“Normally plants respond to phosphorous deprivation by becoming smaller, which means less biomass, less food production and less seed production,” said Brian Gregory, associate professor in the department of biology and senior author on the paper. “The intriguing thing is, by overexpressing one of these proteins we identified, GRP8, we were able to produce plants that don’t show this kind of dwarfing nearly as significantly as normal plants under phosphorous starvation. That’s the exact phenotype we want.”

These plants could outlast others under conditions predicted to be more prevalent under climate change, particularly in widespread droughts.

The initial goal of the study was to determine the difference in RNA between two very similar populations of hair and non-hair cells in the roots of the plant species Arabidopsis thaliana. Using an approach called PIP-seq, which obtains a complete catalog of the interactions between RNA and RNA-binding proteins, the team also was able to examine the secondary structure, or folding, of all of the cells’ RNA transcripts.

“We were able to see that there were distinct differences in RNA secondary structure as well as differences in protein binding between root hair and non-hair cells,” said Shawn W. Foley, a recent PhD recipient in Penn’s cell and molecular biology program in the Biomedical Graduate Studies group.

Next, they identified some of the RNA binding proteins that displayed distinct binding profiles between the cell populations. Two were significant: SERRATE and GRP8. When they interrogated mutant plant lines with reduced SERRATE levels, they found that plants had more, longer hair cells, while plants that the researchers engineered to overexpress GRP8 had an increased number of root-hair cells. In addition, GRP8-overexpressing plants in phosphorous-depleted soil were able to turn on genes that increase the ability to take up and transport phosphate compared to normal plants. The result was larger plants.

The next step is testing to see whether these findings extend to other plant species, specifically in crop plants. Crop plants requiring less phosphate could lessen the negative environmental impact of fertilizers on aquatic systems.