Artificial culture of phytoplasma – a pathogenic microorganism that causes a wide variety of symptoms in plants ranging from dwarfing and yellowing to withering – may have become a reality.
It has been said that phytoplasmas cannot be grown in axenic culture. But in late April, plant pathologist Kunihei Kishi, 90, presented in the meeting of the Phytopathological Society of Japan that he has succeeded in culturing the microbe in vitro.
If the genetic sequence analysis proves the presence of phytoplasmas in the culture fluid, it will be the world’s first successful culture of the organism.
Kishi extracted from mulberry trees microorganisms which appear to have caused a phytoplasma-associated disease, and cultured them in a petri dish containing a growth medium.
After preserving the culture medium in a tube for two and a half years, he inoculated the culture solution into a healthy mulberry tree and found typical symptoms of mulberry dwarf disease, a disease caused by phytoplasma.
Kishi also inoculated the solution into hydrangea, chrysanthemum and paulownia trees and detected symptoms of a phytoplasma-induced disease.
The solution samples are expected to be sent to the National Agriculture and Food Research Organization’s Institute of Agrobiological Sciences to verify the presence of phytoplasmas through genetic sequencing analysis.
“If artificial culture of phytoplasmas becomes possible, it will lead to a substantial progress in the research on prevention of phytoplasma-induced diseases,” Kishi said.
Phytoplasmas are plant pathogenic microbes associated with diseases in over a thousand plant species. Spread by leafhoppers, the bacteria infects plant leaves, stems and roots, inhibiting translocation of nutrients and causing yellowing and withering. If one rice plant for example gets infected, it can easily spread through the whole crop. There is a case in which phytoplasma caused devastating damage to mulberries in China.