Molecule used in human health controls pests that attack citrus
An antioxidant molecule called N-acetylcysteine (NAC), used in human health as a mucolytic syrup to clear the airways, has resulted in the development of products that have been shown to be effective in controlling citrus-attacking pests such as citrus variegated chlorosis (CVC) - popularly known as "yellow" -, citrus canker and greening (HLB).
In field trials, plants with CVC and healthy treated with NAC products showed higher fruit numbers and larger diameter than those that did not receive the same treatment, said Simone Picchi, founder of
CiaCamp - a São Paulo startup that developed the Products with the support of the Small Business Innovation Research Program (PIPE) of FAPESP.
"The first field trials were conducted by the researcher Helvécio Della Coletta Filho, from the 'Sylvio Moreira' Citrus Center, with plants that were extremely sick with CVC during a drought in São Paulo, and the results were very positive," Said Picchi during a lecture at the event "From basic to applied: FAPESP's support in citrus research," held in November at the Fundação auditorium.
"We estimate that similar results may be obtained in other states, such as Sergipe, where, unlike São Paulo, CVC is not yet a controlled disease," he said.
The researcher had the idea of developing the products after completing a postdoctoral fellowship in the area of bacterial biofilms in 2010 at the National Institute of Science and Technology of Citrus Genomics (INCT Citros) - one of the INCTs financed by FAPESP and the National Development Council Scientific and Technological Institute (CNPq) in the State of São Paulo -, based at the "Sylvio Moreira" Citriculture Center of the Agronomic Institute (IAC), in Cordeirópolis, in the interior of São Paulo, under the supervision of researcher Alessandra Alves de Souza.
At the time, Souza studied the NAC as a possible alternative for the control of the yellow.
Through complete sequencing of the Xylela fastidiosa bacterium genome in 1999 - funded by the Genome Program - the Center's researchers had already discovered that after infecting the plant, Xylela forms a biofilm for invasive microorganisms to Adhere to the xylem, thereby clogging these water-conducting vessels and mineral salts of the plant.
Based on this finding, Souza decided to test if the NAC could break this biofilm at the beginning of its formation, combating the disease and unclogging the plant xylem to enable the flow of water and minerals.
The results were very positive and encouraged Picchi to test the use of NAC also in the fight against the bacterium Xanthomonas citri subsp. Citri, a cause of citrus canker, during her postdoctoral fellowship at the Center.
"We observed that NAC also works to reduce citrus canker," she said.
The researcher decided to license the patent application of the molecule for the control of agricultural pests of the Center and founded the company.
Through the PIPE program of FAPESP, it began to carry out research to use the molecule in products that could be used as sustainable alternatives in the management of phytopathogenic (bacterial) diseases that affect citriculture.
The researches resulted in two NAC-based products, one to be sprayed and the other to be applied as a fertilizer at the root of the plants.
"NAC has some advantages: it is a small molecule, easily absorbed, that can be combined with other molecules to potentiate its action, and does not cause bacteria resistance. In addition, it is easily degraded, not causing environmental impacts, "he said.
Field Tests
According to Picchi, the sprayable product, called NAC Solution, was applied in field trials in plants with citrus canker and HLB, with the support of researcher Coletta Filho. Fertilizer, called NACagri, was tested in plants with CVC and citrus canker.
"CVC plants treated with fertilizer produced 14 kilos more fruits compared to those infected with the disease and did not receive treatment," Picchi said.
Plants with citrus canker that received the powdered product showed a regression of the disease comparable to that treated with copper alone.
"We do not yet have the results of the application of the product in a complete harvest, but we have already observed that the use of it for a few months presents a performance comparable to that of copper, which shows that it can be an alternative to this product that causes environmental impacts" , Said Picchi.
The researchers are conducting tests to control citrus canker disease in symptomatic and asymptomatic plants and to evaluate NAC as an antioxidant agent for biotic stress - usually caused by living beings - and abiotic stress (as environmental factors) in healthy plants.
"As we have seen that the product also has an effect on healthy plants it may still contribute to the reduction of stress and, with that, help the plant to have greater resistance," said Picchi. According to her, the next steps will be to continue the field research during two complete crops to evaluate the ideal dosage and number of applications of the products to start commercialization in 2018. In addition, they intend to evaluate the effects of NAC on 10 other phytopathogenic bacteria Disease in crops such as coffee, soybeans and tomatoes.