Plants that are more resistant to the climate crisis and with an efficient absorption of nutrients are the new trend in the development of genetically modified organisms (GMOs). An article published on October 14 in the journal Frontiers in Plant Science, written by researchers at the Genomics for Climate Change Research Center (GCCRC), covers the different techniques used to develop new varieties and the trends to generate transgenics, especially of genetically modified plants.
The article Maize Transformation: From Plant Material to the Release of Genetically Modified and Edited Varieties presents a review about the advances in the genetic modification of corn. From the first generation of transgenics to the CRISPR-Cas genome editing technique, the paper maps the technical advances for the development of agricultural varieties.
The article published by GCCRC – an initiative by Embrapa and the University of Campinas (Unicamp), with support from the São Paulo Research Foundation (FAPESP) – provides information of significant interest, especially for professionals in the field of biotechnology, students, and the scientific community.
Besides presenting significant advances made in the protocols, technologies, and applications for corn processing, the review gathers the latest processes for the development of new cultivars and also maps the traits of greatest interest to scientists, including pipelines (type of map showing the steps of the process) to produce genetically modified or edited plants and to introduce them to the market.
According to the authors, currently, researchers and companies have sought a new challenge in relation to GMOs: the development of plants with more complex characteristics and a greater tolerance to the adverse conditions caused by the climate crisis, such as drought and high temperatures, and that also show efficiency in nutrient use and yield.
The manifestation of these characteristics – differently from those related to resistance to insects and herbicides, which are more common–, depends simultaneously on the interaction between different genes and the environment. This complexity has led companies and research institutions to invest in new techniques, gene discovery processes, and large-scale assessment programs.
This is the conclusion of the researchers: Juliana Erika de Carvalho Teixeira Yassitepe, from Embrapa Digital Agriculture and GCCRC; Viviane Cristina Heinzen da Silva, from GCCRC and the Molecular Biology and Genetic Engineering Center (CBMEG) at the State University of Campinas (Unicamp); José Hernandes-Lopes, Ricardo Augusto Dante, Isabel Rodrigues Gerhardt, and Fernanda Rausch Fernandes from Embrapa Digital Agriculture, GCCRC, and CBMEG; Priscila Alves da Silva, Leticia Rios Vieira, and Vanessa Bonatti from GCCRC and CBMEG; and Paulo Arruda, coordinator of GCCRC and professor at Unicamp’s CBMEG and Institute of Biology.
Gene editing through the CRISPR-Cas system, which allows editing DNA with higher precision, is the great promise of plant biotechnology, especially for developing countries such as Brazil. The technique released in 2012 – for which the 2020 Nobel Prize in Chemistry was awarded to researchers Emmanuelle Charpentier of Max Planck Institute and Jennifer A. Doudna of University of California, Berkeley – has been rapidly improved in recent years and has stimulated investments in research aiming to obtain genetically edited cultivars.
This technique consists in literally editing the DNA sequence, i.e., inserting, deleting, or replacing nucleotides – the letters that make up the DNA sequence – to obtain a desirable trait, such as drought resistance, for example. Besides being a cheaper and more accessible genetic modification technique, trends for its regulation aim towards a simplification of the process, since there would be no DNA of other species within the genome of these varieties.
“Each country follows its own legislation, with certain peculiarities. Unlike the European Union, for example, Brazil has taken a more open position in relation to genomic editing”, says José Hernandes, a researcher at GCCRC and one of the authors of the article. According to Hernandes, the greatest challenge for the regulation of the technology lies in the so-called off-target mutations, in which unforeseen alterations can be made in a genome through genomic editing; however, these changes are very rare in plants.
Although a gene discovery structure is still needed for the development of an edited plant, the current trends point towards an increase in access to technology. Edited products are already commercially available in some countries or almost approved for the market, including varieties of corn, soybean, camellia, and citrus that present characteristics ranging from improved nutrients to resistance to diseases.
“Genome editing may contribute to the increase in the number of laboratories that are capable of developing and marketing new varieties. Because it simulates genetic changes that also occur spontaneously through natural processes, a few countries already consider some plants as being transgenic free”, adds Viviane Heinzen, coauthor of the publication.
GMOs represent 30% of the world’s corn area
Although plants that are GMO have been part of agriculture for a few decades, most of them basically present two advantages: resistance to herbicides and to insects. Corn is one of the crops with widely used transgenic commercial varieties. This is the case of Bt Maize that, after receiving genes from the bacterium Bacillus thuringiensis (Bt), expresses a protein capable of killing caterpillars that affect crops.
These cultivars are prevalent in the market because they present characteristics that are relatively easy to evaluate during their development process. “They are qualitative characteristics; the effect of a gene is easier to measure, indicating whether the plant is resistant or not”, explains Juliana Yassitepe.
The advances in plant biotechnology in recent years allowed the development of genetically modified corn varieties that have significantly impacted agricultural management and improved grain yield. The new GMOs incorporate characteristics such as herbicide action, resistance to insects and diseases, tolerance to abiotic stress, high yield, and a better nutritional quality.
Adopted in 29 countries, the GMO varieties cover 190 million hectares and, in the case of corn, represent about 30% of the cultivated areas around the globe. This crop also has more GMO events approved by regulatory agencies: 148 within 35 different countries, most of which combine insect resistance and herbicide tolerance according to a report prepared in 2019 by International Service for the Acquisition of Agri-biotech Applications (ISAAA).
The first commercial GM corn varieties were developed using the DNA bombardment technique, which has a more imprecise control over transformation, leading to the current and prevailing use of the bacterium Agrobacterium tumefaciens for a more accurate delivery of genes of interest. This change in methodology has helped to simplify the processes for the regulation of transgenics considering the uncertainties of the bombardment technique, which could include fragments of the gene and pieces of the vector beyond planned, explains Juliana Yassitepe, a researcher of Embrapa.
Originally published in Embrapa website.