A study led by research groups of Prof. FU Qiaomei from the Institute of Vertebrate Paleontology and Paleoanthropology (IVPP) of the Chinese Academy of Sciences and Prof. ZHANG Hucai from Yunnan University covers the largest temporal transect of population dynamics in East Asia so far and offers a clearer picture of the deep population history of northern East Asia.

The study was published in Cell on May 27.

Northern East Asia falls within a similar latitude range as central and southern Europe, where human population movements and size were influenced by Ice Age climatic fluctuations. Did these climatic fluctuations have an impact on the population history of northern East Asia?

Stories uncovered by ancient DNA in East Asia remain relatively underexplored. The population dynamics between 40,000 years ago (40 ka) and 9.5 ka still remain mysterious.

To answer questions related to the deep population history of East Asia, the researchers obtained genome-wide genotype data from 25 ancient humans ranging from 33 to 3.4 ka from the Songnen Plain (Heilongjiang Province, northeastern China) in the Amur Region. This period covers the Last Glacial Maximum (LGM), which is crucial to understanding what happened to northern East Asians before, during and after the LGM.

The bacterium, which they named Candidatus Phytoplasma dypsidis was found to cause a fatal wilt disease. This new discovery was reported in the International Journal of Systematic and Evolutionary Microbiology.

In 2016, several ornamental palms within a conservatory in the Cairns Botanic Gardens, Queensland, died mysteriously. A sample was taken from one of the diseased plants and investigated by Dr Richard Davis and colleagues from the Australian Government Department of Agriculture, Water and the Environment, and state and local government. They compared the characteristics and genome of the bacterium identified as the cause of the disease and found the bacterium was similar to other species of Candidatus Phytoplasma, many of which are responsible for disease epidemics in palms elsewhere but was different enough to be an independent species. “When the laboratory testing indicated it was something close to, but not the same as, devastating palm pathogens overseas, we were very surprised,” said Dr Davis.

“At first we thought it was most likely an unrelated fungal disease. Almost as an afterthought, I suggested we screen for phytoplasma because there are some very bad phytoplasma diseases of palms moving around the world, including in neighbouring Papua New Guinea,” he explained.

So far, infection with Candidatus Phytoplasma dypsidis has been found to cause disease in 12 different species of palms, including Cocos nucifera, which produces coconuts. “Although palms are not grown as a cash crop in Australia, they are important ornamental garden and amenity plants. Coconuts and other palms are an economically significant component of Australia’s tourism industry in the tropics,” said Dr Davis.