Kids Web Japan

Welcome to the Plant Hospital!

Here people can have plants examined and treated at the University of Tokyo Faculty of Agriculture, where some of the world's top plant researchers are making cutting-edge discoveries. It's the world's first "plant general hospital." Whether it's an ordinary problem that you just couldn't get help for or a complex physiological disorder, the Plant Hospital's specialists are there to help. From families to companies, anyone can bring a plant to be checked up. Wouldn't it be great if clinics like this spread all over the world?

Phytoplasma: Solving One of the Mysteries of How Plant Diseases Spread

Plant diseases can be caused by all sorts of things-viruses, weeds, insects, and the wrong fertilizer, to name but a few. Phytoplasmas are a particular focus of attention.

Phytoplasmas are microbes that live as parasites in the cells of plants and insects. When an insect sucks the sap of an infected plant, phytoplasmas can infect the body of the insect, too. Then the insect becomes a "carrier" and spreads the disease to other plants.

Because phytoplasmas live directly off a plant's rich nutrients, they can get by with a very small genome (the genes containing all of an organism's genetic information). In addition, the arrangement or sequence of genes can vary, helping the phytoplasma to adapt to different environments. Professor Namba Shigetou of the University of Tokyo is discovering more and more about this group of organisms, which is still quite new to science. He notes that phytoplasmas have been divided into 36 types according to the most recent data, each adapted to its respective host insect. Scientists have discovered the mechanism by which phytoplasmas infect only certain insects, and if preventive drugs are developed based on this discovery it may be possible to prevent the spread of diseases without killing insects.

Plants get sick, too.

Phytoplasmas cause certain characteristic diseases. Sometimes it is hard to tell that the plant is sick, such as when hydrangea flowers become infected and turn into leafy structures, a process called phyllody (left). Such plants are sometimes even bought and sold for high prices because they are rare.

Tomato yellow leaf curl, caused by a virus, leads to curled up leaves and small tomatoes.

Plant diseases can result in bad harvests and make it harder to get food that is safe to eat.

How much do you know about plants?

Plant diseases include illnesses caused by microbes, pests, and parasitic weeds, as well as physiological disorders caused by poor growing conditions. The field of clinical plant science is developing new approaches to diagnosing, treating, and preventing these diseases. As Professor Namba explains, plants, which are rooted in the ground, can hardly come for help when they're sick, so it's important to observe them carefully in the field and take preventive steps to protect them from the spread of disease.

(Updated in January 2009)