NLP7 helps plants conserve water during drought

Scientists have found that disabling one plant protein allows leaves to close their pores more quickly in drought, reducing the amount of water plants lose.

The discovery connects growth signals with water-conserving behaviour, clarifying why plants supplied with ample nutrients may need more water just as drought begins.

A switch inside leaves

In controlled growth chambers in Santiago, Chile, researchers at Andrés Bello University (UNAB) subjected plants to high nitrogen levels to examine their response.

By observing which leaves wilted earliest, Dr José Miguel Álvarez at UNAB’s Plant Biotechnology Centre linked drought resistance to a single protein that acts like a switch.

A striking pattern repeatedly emerged: plants with plentiful nutrients remained in growth mode for longer, despite increasingly limited water.

For farmers, the very signal that increases yields can also discreetly increase water use, creating losses when rainfall fails.

Two signals collide

Nitrogen in the soil signals to plants that they should rapidly produce new tissue, a process that generally requires additional water.

When drought occurs, leaves defend themselves by narrowing their pores and reducing growth. This limits water loss, but also reduces energy production.

Operating both responses simultaneously would squander resources, meaning plants need to determine which group of genes takes priority.

A single control point able to detect both signals would enable a plant to change direction before damage occurs.

NLP7, the nitrogen and drought switch

Researchers commonly use Arabidopsis thaliana, a small flowering plant that serves as a laboratory model, to compare drought responses.

They identified the control point as NLP7, a gene regulator in leaves that reacts to nitrogen, and tracked its wider effects.

The findings showed that NLP7 functions as a transcription factor - a protein that switches genes on or off - and influenced 85% of the conflict.

“This shows that NLP7 not only promotes growth, but also defines when that growth should be slowed down to ensure survival under adverse conditions,” said Alvarez.

How leaves save water

Water leaves plants through stomata, tiny pores in leaves that exchange water for carbon dioxide throughout the day.

Under drought conditions, abscisic acid (ABA), the plant stress hormone, starts water-saving defences by causing guard cells to lose ions, which makes the tiny leaf pores constrict.

In plants that tolerate drought, ABA gained control earlier, allowing stomata to tighten before the leaves became dehydrated.

As closed pores slow photosynthesis, any crop modification must weigh water conservation against the need for growth.

Proof in dry tests

In pot experiments, plants lacking NLP7 retained water for longer, even as soil moisture fell to severe levels.

Following 14 days without water, the mutant lines remained greener, whereas plants modified to produce excess NLP7 wilted more quickly.

The survival figures highlighted the difference: 60% of wild plants survived the stress, compared with nearly 100% recovery among plants without NLP7.

The mutants retained their drought advantage even when both lines grew to a similar size using another nitrogen source.

What nitrogen really costs

Fertiliser can load fields with nitrogen, prompting plants to enlarge their leaves and draw more water from the soil.

Scientists also found that nitrate, a form of nitrogen absorbed by plants, attaches to NLP7 and makes it a sensor within cells.

When drought is approaching, a protein that reads nitrogen so effectively may continue promoting growth when restraint would be safer.

Decoupling nitrogen sensing from water loss could allow growers to nourish crops less intensively without driving plants into a panic response.

Drought reshapes gene control

During drought, NLP7 did more than simply diminish: it attached to different regions of genetic material in leaves.

Thousands of binding locations emerged exclusively in dry conditions, with many positioned near genes that control ABA responses.

By suppressing several of those gene switches, the protein kept ABA-related defences inactive while nitrogen encouraged growth.

This context-dependent activity suggests that crop breeders may need to assess alterations across different tissues, rather than only in seedlings.

Paths to tougher crops

Crop developers may be able to alter NLP7 activity to produce plants that continue growing in heat without unnecessarily losing water.

Modest changes may be preferable to fully disabling the protein, because certain nitrogen responses remain useful for producing proteins and seeds.

“This knowledge allows us to think about strategies that optimize nitrogen use without losing drought resistance, whether through genetic editing, selection of more resilient varieties, or adjustments to fertilization strategies,” said Alvarez.

Breeding for real conditions will still require patience, as drought can arrive in bursts and soil nitrogen levels may vary greatly from one season to the next.

Data meets plant stress

Rather than relying on a single experiment, the team initially reviewed findings from 37 earlier studies of drought and nitrogen.

Patterns in those datasets identified NLP7, after which greenhouse plants were used to examine what occurred when the switch stopped working.

At UNAB, Álvarez’s team then combined high nitrogen levels with drying soil and monitored changes in the timing of leaf water-saving responses.

Combining public datasets with practical biology can accelerate plant research, although field trials remain necessary for it to have an impact.

NLP7 now stands between fertiliser-led growth and drought defence, providing crop science with a clearer target for testing.

Any crop version will require precise adjustment, as slowing growth too soon can reduce yields even when water is available.