“With the increase in mechanized planting, expansion of planting areas, and the use of poor-quality seedlings, “pineapple rot” has become more present in sugarcane fields.”
Juliana Velasco de Castro Oliveira is a researcher at the Brazilian Biorenewables National Laboratory. She graduated in Biological Sciences and has a PhD in Biotechnology from the University of São Paulo. Velasco coordinates a study that discovered bacteria of the Pseudomonas genus capable of inhibiting growth and causing death of the fungus responsible for “pineapple rot”, disease that affects sugarcane fields.
Juliana Velasco, researcher at the Brazilian Biorenewables National Laboratory
AgriBrasilis – What are the main diseases caused by fungi that affect sugarcane?
Juliana Velasco – Incidence of diseases depends a lot on the region, planting season, sugarcane varieties used, soil management, among others, but, in general, we can say that the main diseases are: “pineapple rot”, “charcoal”, “rust” and “red rot”.
AgriBrasilis – What is “pineapple rot” and what are its causes? What is the relationship with the sugarcane yield?
Juliana Velasco – The disease is caused by the fungus Thielaviopsis ethacetica and until recently it was not considered important. With the increase in mechanized planting, expansion of planting areas, and use of poor-quality seedlings, it has become more present in sugarcane fields.
The fungus penetrates through natural openings or wounds that can be caused by the mechanization process in the billet, for example. One can observe excessive moisture on the stem and a decrease of up to 50% in germination, as well as the death of new seedlings. When sugarcane manages to develop, its content may be compromised, which acquires a reddish color to darker tones due to the proliferation of the fungus and production of spores in the vascular bundles.
It is very common for infected plants to give off an odor similar to pineapple essence, which gave the disease its name. In general, the disease can decrease yields between 30 and 40%.
AgriBrasilis – What is the mechanism of action of the growth-inhibiting bacteria of the “pineapple rot” fungus?
Juliana Velasco – As it is a new area of study, there is still much to be discovered. However, we found that after treatment with the bacteria, the fungus ceases to express genes essential for its growth, such as those for carbon metabolism. In addition, we verified that the compounds, directly or indirectly, cause damage to the microorganism’s DNA, as well as its death. For these findings, we used molecular biology, microscopy and spectroscopy techniques.
AgriBrasilis – What stage is the research at and what impacts are expected from this work?
Juliana Velasco – It is important to emphasize that this is the first work with this type of molecules inhibiting this sugarcane phytopathogen, resulting from the work of PhD student Carla Freitas, who dedicated more than 4 years to this research.
Looking at how these molecules behave, the range of possibilities we can explore is enormous. Although interesting results have been observed in the laboratory, for this to become a reality, many other studies are needed to prove the effectiveness of the bacteria in the field and its safety for humans, animals and the environment.
Although the bacteria have been isolated from the soil of sugarcane fields, these studies are essential.
Another alternative would be the application of the most promising biomolecules and, again, further research would be necessary to develop a microorganism that produces them in large quantities. In general, it is expected that the use of the microorganism and/or the molecules will be less aggressive than the chemicals that exist today, and, as it is of biological origin, it may present better biodegradability. Finally, it could represent a biological alternative developed in the country, capable of reducing our dependence on imports of agrochemicals, which burdens the sector and represents a weakness in our agribusiness.