The unit of Genetic and Biotechnology Resources of Brazil’s National Agricultural Research Company (Embrapa) located in the country’s capital, Brasília, has filed on June 7, 2016 a patent request for the new methodology of production of a resistant plant to the pests through the RNA interfering technology. The breakthrough is a result of a thesis of the PhD student of Nigeria bdulrazak Ibrahim at the Post-Graduation Program of the National University of Brasília. The thesis was developed at Applied Genetic Engineering Laboratory of Tropical Agriculture of the Unit under the orientation of the researcher Francisco Aragão.
They achieved to develop a lettuce plants resistant to the whitefly, one of the worst pests faced by the world agriculture that is capable of causing direct and indirect damage to the agricultural crops, since this is the vector of more than a hundred viruses reported in different parts of the world and also sucks the plants’ nutrients, deteriorating it.
The new methodology is based on the use of interfering RNA to silence vital genes to the survival of the insect. This technology, used by different countries on diverse areas like health, agriculture and industry, among others, allows the scientists to interfere at the genetic chain of individuals, modifying functions and silencing genes.
In order to understand this technique, it is necessary to better recognize the functioning of the regulation procedure of genetic expression. The plants, animals or human beings have their genes expressed for the RNA synthesis and proteins. The expression of these genes determine the genetic characteristics that form the individuals (height, color, productivity, appearance, etc). The synthesis of proteins occurs with the participation of RNA molecules like the RNA messenger, which is to transform the correct order of amino-acids to be synthesized later on proteins from its translation.
With the evolution of scientific knowledge, the researchers have learned that is possible to alter genetic characteristics of some organisms of small RNA regulators that act in the post-transcription stage. This technique, called interfering RNA, is the procedure in which the small RNAs can block the gene expressions.
In the case of this issue, as explains the researcher Francisco Aragão, small fragments of RNA were used to silence vital genes paw to whitefly. This insect is one of the worst pests and occurs in all countries like Brazil and Nigeria. In Brazil, it attacks almost all agricultural crops of economic importance, specially tomatoes, kidney beans and soybeans. The chemical control is becoming increasingly difficult throughout the years, the insect acquired resistance to agrochemicals used on the crop.
Genetic analysis developed at the laboratory of Embrapa Genetic Resources and Biotechnology has shown to researchers that small fragments of RNA of the whitefly were capable of silencing an indispensable gene to its survival. “It is a gene of the protein of the protons bomb that stays on cell membranes that is essential for energy production for the cell survival,” explains Francisco Aragão.
Using this knowledge, scientists have cloned these gene sequences and started to feed the flies with it. “The results were surprising. In four days, the population of flies was reduced to a quarter,” commemorates the researcher.
After in vitro tests in laboratory, the scientists decided then to transform genetically a lettuce plant, inserting genes for the production of fragments. The lettuce was chosen for being of easy transformation, so it is frequently used as a model and also because of the food preferences of the whitefly.
The results obtained with genetically-modified lettuce plants were even more significant, as explained Aragão. The flies fed themselves with conventional plants capable of putting 300 eggs per plant. The ones that fed themselves with genetically-modified lettuce had put just 20 eggs.
And this is better: the scientists have proven that the technology is capable of causing effects on future generations of the insect. “This means that of the 20 eggs, there will be no adult whitefly of second generation,” highlights.
The next step is to transfer these characteristics for soybean and tomato plants, which are the major victims of the whitefly on Brazilian crops. The investigations with tomatoes are already being started ans with soybeans would start soon.
The scientists intend to invest on deeper tests to evaluate if the genetic modification can cause damage to other insects and other living beings that feed with plants. The initial tests have proven negative, but it is necessary to amplify those tests. “The probability is to affect other living beings is very low because the RNA fragments were specifically excluded of the whitefly genome,” affirms the researcher.
Besides protecting the knowledge, the patent is important, in the view of Aragão, because it helps Embrapa to negotiate this technology with future partners.