Good news for giant pandas: scientists from Kunming in Yunnan province believe they have identified a genetic trigger for bamboo flowering. Photo: Xinhua

Gene may help solve great botanical mystery - the flowering and mass die-off bamboo

Gene may explain why bamboo mysteriously flowers en masse - then dies

Good news for giant pandas: scientists from Kunming in Yunnan province believe they have identified a genetic trigger for bamboo flowering.

The barely understood cycles of mass flowering, then death, of bamboo are a problem for animals and humans as forests, sometimes covering hundreds of square kilometres, can be wiped out in one go, depriving the pandas of their food source.

Such an incident in the early 1980s wiped out 40 per cent of the panda population.

The Kunming scientists have found an important part of the puzzle - a small ribonucleic acid molecule dubbed dla-miR18 that they believe may help understand what makes bamboo flower. They have identified more than 200 "suspect genes" related to the flowering process and believe dla-miR18 could play a central role in coordinating their functions.

"The performance of dla-miR18 is very eye-catching. After flowering, its level can increase to 100 times its pre-flowering level," said professor Guo Zhenhua, a researcher at the Chinese Academy of Sciences' Kunming Institute of Botany and the lead scientist of the study.

The scientists' findings were published in late last year.

After more than a century's research, bamboo flowering is still one of the greatest mysteries in botanical science.

Many species of bamboo - the largest member of the grass family - exhibit mass flowering, in which all plants of a particular type flower at about the same time. Yet even today, scientists are still unable to say exactly how this happens.

"The biggest difficulty is time," Guo said.

Many bamboo species take decades to flower, some more than 60 years, leaving researchers a long wait to collect samples from the plants' various growth periods.

This meant that the hunt for dla-miR18 had been a "long and painful marathon", Guo said.

Her team has been sampling Yunnan's bamboo species and waiting for them to flower since 2007. Some earlier samples were passed down from retired researchers, obtained in the 1980s.

But discovering the gene was "only the first step".

"We are not quite clear about the functioning mechanism of dla-miR18," Guo said. "We have made some guesses, but they need to be verified by more experiments."

Professor Xu Yingwu, a biologist at the Zhejiang Agriculture and Forestry University who has studied bamboo flowering but was not involved in the research, said enormous challenges remained.

For example, it could take years to find a way to control the level of a particular gene.

"We still know little about bamboo," he said.

"It is not a model plant, such as rice, whose genetic map is well understood with many tools to manipulate their genes."

Finding the secret to bamboo flowering would not only be good news for pandas, but farmers whose livelihoods depend on it.

But the long time frame involved meant researchers often struggled to find funding for their work.

"Some funding authorities expect us to come up with results in two or three years, or the funding can be cancelled," Guo said.

"This is deeply troubling because some bamboos we monitor may take two or three decades to flower."


This article appeared in the South China Morning Post print edition as: Saving the panda's favourite but fickle food