Rooting it out José Dinneny José Dinneny studies how plants grow under stress. What he learns could help to feed Earth’s growing population. José Dinneny wants us to see plants as strange. They have no brain and no nervous system. Yet they take in different kinds of information and can make good decisions. Plants also find water without sight or touch. They are everywhere in our lives: lawns, salads and pots on a sunny windowsill. They’re so familiar it’s easy to forget how odd they really are. “We’re out searching the solar system and the galaxy for extraterrestrial life,” says Dinneny. Yet, he argues, “We have aliens on our own planet.” Dinneny is a plant biologist at the Carnegie Institution for Science in Stanford, Calif. He says the thrill of discovering plants’ alien ways drives him to explore how roots search for water. His research group “runs on curiosity,” he says. He conducts projects just to discover how plants work. What he learns, though, could be useful in finding better ways to grow food. He started his career studying details of how plants develop their parts and shapes. With that background, he’s now interested in how the roots of plants hunt for water. These questions are important in “this huge crisis we face as a species,” says Jonathan Lynch. He is a root biologist at Pennsylvania State University, in University Park, and the University of Nottingham in England. The human population is growing — and fast. Whether farmers will be able to boost their crops and keep up is huge question. And Earth’s changing climate only makes this more complicated. BOX on About Prof José Dinneny Dinneny spent much of his childhood in California’s San Fernando Valley. “I was placed in classes that weren’t particularly challenging.” The school he went to had a high dropout rate. In 10th grade, though, he took an Advanced Placement biology class. Suddenly, things changed. He still remembers a pivotal moment when his teacher asked about a /chemical bond/ in DNA. “I was the only person who raised his hand.” The answer: a phosphodiester (FOS-foh-dy-ES-tur) bond. “Everyone looked around the room sort of wondering who could possibly have known that factoid,” he remembers. He even surprised himself. Dinneny began to realize he had a talent for understanding biology. He lobbied hard to transfer to advanced classes. He began to apply himself to studying. Dinneny didn’t come from an /academic/ family, but he had fine examples of working hard. That included his mother. She raised him as a single mom working as a government accountant. “Often we kind of cubbyhole ourselves into, ‘OK, I’m good at this,’ or ‘I’m not good at that.’ Or they’re doing well because they’re just /inherently/ better at doing this than I am,’” he says. “There is a magical relationship between effort and success.” Not every goal gets met, but “you’re going to do better than you ever thought.” By his final year of high school, Dinneny was a straight-A student, and he went to University of California, Berkeley. There, plant science captivated him. For his PhD, he went to the University of California, San Diego. He studied the genetics of plant development. Later, he studied plants trying to grow in difficult places. Now he’s focusing on ways to figure out what’s happening in roots. END OF BOX To study how plants grow those roots, biologists often start seedlings in petri dishes with a nutrient gel instead of soil. This lets researchers experiment with lots of plants in the lab. But this is very different from how plants grow in real life. For more realism, Dinneny and his colleagues created a system called GLO-Roots. It creates a special view of roots in soil. The technical name for the process is Fluorescence Activated Cell Sorting. It shows how genes get expressed (turned on or activated) depending on the water availability. In the GLO-roots system, plants grow their roots in slim sandwiches of soil held between two clear plates. The roots weave among air pockets, micro rivers and clots of dirt. It’s like mini versions of the conditions that roots find in the ground. But these roots are special: They glow when various genes turn on in this twinkling underground observatory. Computers analyze where that glow shows up. And that gives researchers clues to how roots are responding to their environment. The GLO-roots set-up allows researchers to visualize how the roots of a seedling explore the soil. The photo shows this by combining daily images of a growing root starting 11 days after sowing a seed. The closer the coloration gets to white, the more recently the little rootlets formed. We know that roots grow out side branches in their search for water. How do they decide in which direction to grow? How do they know that there is more water in a certain direction? In order to be able to sense this, root's tissues should be able to sense differences in the wetness of the surrounding soil. It turns out that the root tissues can sense differences at points that are only about 100 microns apart (0.1 mm apart). Dinneny and his colleagues learned this by analyzing /hormones/ in the root tissues. Dinneny calls this “hydropatterning.” Hydropatterning Hydropatterning may regulate nearly every aspect of root development. The contact of a root tip with water (or any liquid) or air determines the tissue growth. Changes in the liquid availability at the root tip can drastically change the way the root tissue develops. On one hand we may not find this strange. After all, we have learned from early classes that roots grow this way. But for the first time Dinneny asked the question, How do they do this? And he found the answer at the very fundamental genetic level. It allows the plant to grow its roots to optimise soil exploration. It automatically ensures that roots do not grow out into dry or hostile soil. The photo shows a cross section of a rice root. The root has formed a branch poking out to search for water. This is just one of the many tiny directional choices that will determine whether a plant can find what it needs to survive. Adapted from Science News for Children,