Bacteria found on the skin of a tropical frog could offer growers a sustainable treatment against a costly disease that causes havoc in fruit and vegetable crops around the world.
Caused by a fungal pathogen called Botrytis cinerea, grey mould disease infects over 250 plants including tomatoes, cucumbers, strawberries and peppers.
As well as damaging leaves and flowers in the field, the disease causes particular damage during harvest, post-harvest and storage, leading to major losses across the supply chain.
While synthetic fungicides have typically been used to treat the mould, concerns over their safety and efficacy have lead to research into alternative, more sustainable, control methods.
In recent years scientists have identified a number of bacteria that prompt plants to fire up their own in-built defense systems against pathogens. However, while some bacteria are already being used on farms, concerns about b. cinerea’s growing resistance to them means researchers are looking to more unusual solutions — hop up, a tiny frog typically at home in Colombia’s forests.
Natural defence systems
Having previously found that a type of bacteria from the species Acinetobacter can inhibit the growth of B. cinerea, scientists in Mexico and Argentina decided to look at the impact of three Acinetobacter bacteria found on the Fitzinger’s robber frog (Craugastor fitzinger).
As well as investigating the bacteria’s ability to inhibit growth and development of B. cinerea, the researchers also wanted to look at their involvement in prompting plant’s natural defense systems, enabling them to fend off grey mould naturally.
In trials on thale cress (Arabidopsis thaliana) and tomato (Solanum lycopersicum), the research team found two of the bacteria impacted the growth of the fungus significantly.
This was due to the bacteria prompting the plants to produce defence hormones including salicylic acid, jasmonic acid and ethylene.
Meanwhile blueberries treated with the bacteria — after they had been infected with the fungus — saw a slowing in mould growth. In untreated trials, 95% of fruits developed the disease, while fruits treated with bacteria saw incidence drop by almost 70%.
Writing in Frontiers in Plant Science, the researchers said until now there had been little research into the use of bacteria from animals as a potential fungicide.
“[However these bacteria] present an efficient and feasible method to prevent fruit diseases by inhibiting
pathogen development and contributing to plant defense through immune system induction.
“Based on these findings, we propose that the bacteria from amphibian skin have the potential to serve as promising biological control agents against plant pathogens.”
