Fascinated by plant disease

The call went out this April from the UN body's central office in Rome to its North American headquarters in Washington: "Get Hiruki."

Officials were sent scrambling and soon the phone was ringing in Professor Chuji Hiruki's office in the Agriculture and Forestry Centre at the University of Alberta. Hiruki's mission — should he choose to accept it — was to confront a menace striking at the heart of China: a virulence ravaging vast stands of timber critical to the economy of China's heartland.

Within weeks of being contacted by the UN's Food and Agriculture Organization, Hiruki was in China to observe first-hand the damage resulting from the remorseless spread of the "witch's broom" disease that is devastating the one variety of tree upon which Chinese agro-forestry is based.

In July, having just returned from a month in China, Hiruki was able to provide some background to the problem confronting that nation. About one third of China — the land from the middle part to the coast — has very fertile soil; however, it is extremely susceptible to wind erosion. "Because of that, the first thing the Communist Party did when it took over was to plant trees — as many as possible," explains Hiruki. Besides protecting the soil, the trees were to be a source of lumber.

To date, some 1.3 billion trees have been planted, and most are of one variety. The Paulownia was favored for two reasons: crops can be grown right up to its base, and it is fast-growing, producing a popular hardwood (the wood of choice for coffins in some Asian countries).

Unfortunately, China's massive initiative in wedding agriculture and forestry is now threatened by the witch's broom disease that stunts tree growth and damages the wood. Desperate for help, the Chinese turned to the FAO. Because it was known that the disease-causing agent was a form of mycoplasma (a genus of tiny organisms much smaller than bacteria and lacking a cell wall), Hiruki's name quickly surfaced, for the U of A plant virologist is considered the world's foremost authority on mycoplasma diseases in plants.

Soon Chinese scientists will be arriving to work in his laboratory, and a plan of attack will be formulated. "The final goal will likely be the development of resistance," predicts Hiruki, whose international stature as an authority on mycoplasma disease is only one of the reasons that he won a 1993 Kaplan Research Prize at the University. Also cited were his work proving that fungi can act as a transmission vector for viruses; his involvement in the development of methods and techniques for a virus-free seed potato scheme (now applied in nations as distant as Poland); and his role in defining a new virus family, the dianthovirus group, officially recognized in 1981.

The eldest son of a Japanese farmer, Hiruki recalls spending "more time in the field than in my studies as a youngster," and becoming fascinated by plant disease. As a BSc student at Kyushi University he became eager to specialize in the study of plant viruses after reading an article written on the subject by one of his professors. The young Hiruki approached the professor hoping to begin study in this area, but was told that it was too soon for him to specialize. "Work hard at studying English," advised the teacher — there were then no Japanese texts on virus disease in plants.

Three times Hiruki returned to the professor only to meet with the same advice, but the professor eventually relented. "Finally I was permitted to do virus research in my third year," recalls Hiruki. "I spent my third and fourth years doing research on the tobacco mosaic virus, and as a result of this independent project I was able to produce a 200-page thesis for my BSc."

Following graduation Hiruki was promptly hired by the Hatano Tobacco Experimental Station, where he worked closely with farmers for 11 years.

Although a Fulbright Research Scholarship that took him to the U.S. to study biochemistry pointed him to an academic career, he has never forgotten the importance of applied research and the lessons he learned working with farmers.

After completing his PhD at Kyushi I Universitv, Hiruki returned to the United ' States, spending a year as a visiting plant pathologist at the University of Califor- 14w0 nia and another as an honorary fellow at Wisconsin. In 1966 he accepted an invitation from the University of Alberta to fill a virologist's position in plant science and to start a graduate program.

For the lecture that he delivered as part of the Kaplan Research Prize ceremonies, Hiruki focused on a single aspect of the work he has done in his distinguished career at the U of A: his work with the sweet clover necrotic mosaic virus.

In 1979 Hiruki, who was completing a survey of alfalfa, was about to return to his motel room in Athabasca, Alberta when he spotted a diseased seed clover.

"Without thinking I took a sample, and the next day when I tested it I got a very strange result," recalls Hiruki. The disease didn't match the data for any virus previously described. Intrigued, he studied the new virus further and found that it contained two pieces of RNA, one long , and one short, and both had to be present i to cause infectivity. Later, through interchanging RNA strands, Hiruki was able to show that the virus infecting his clover sample was of the same family as two other viruses that were not before suspected to be related — one that affected i carnations in England, another found in red clover in Czechoslovakia.

This work not only resulted in the identification of the dianthovirus group, it introduced the use of genetic information as a basis for virus classification. Now, Hiruki hopes to take this work one step further, to See if the virus's genetic material could be manipulated to make it a carrier of useful genes.

Despite the varied demands resulting from the world-wide interest in his work, Hiruki remains an enthusiastic teacher, and his laboratory attracts students from around the world. His students remember not only his lucid and well-organized lectures but his concern for their welfare. "He consistently tries to challenge his students dents and research fellows and teaches them how to become independent learners and to apply their knowledge in problem-solving situations," wrote one former student in support of Hiruki's Kaplan nomination.

For Hiruki's part, he continues to find his work rewarding. "My job is my hobby. I really enjoy my work," he says.

Published Autumn 1993.