At New York’s Cornell University, scientists have developed a new material called AquaDust that could measure a plant’s water intake from the leaves without harming the plant.
Leaves contain vein-like channels called xylem, which carry water up from a plant’s roots. That water is subsequently distributed into a spongy leaf material between the xylem, known as the mesophyll. It is precisely in this area where a lack of water is likely to cause the most stress and where most of the plant’s photosynthesis occurs. With this in mind, the scientists are confident that signals produced by the mesophyll are mainly responsible for controlling the plant’s water uptake and distribution.
Previously, measuring the materials’ water potential involved altering how leaves functioned or removing them for analysis. However, these techniques are labor-intensive, and besides, stressing the plant can distort the data.
AquaDust, on the other hand, is an easier and more accurate alternative. It’s made from nanoparticles of a soft, synthetic hydrogel dye, which are injected into a live leaf’s mesophyll. Those particles end up nestled in the interstitial spaces between the mesophyll cells, where they absorb water. The more they absorb water, the larger they grow, and the smaller the spaces between them become.
A fiber optic probe is then used to illuminate the mesophyll, causing the hydrogel dye molecules to respond by fluorescing. The wavelength at which they fluoresce differs depending on how close they are to one another. Measuring that wavelength allows one to know how swollen the gel particles have become and how much water content is within the mesophyll.
The novel material has already been used to measure water gradients in several locations along the length of meters-long maize leaves. The team hopes that once AquaDust is commercialized, it could be used by farmers and crop researchers. The findings were published on June 8 in the journal Proceedings of the National Academy of Sciences.
