Researchers map advances in creating plants more resistant to the climate crisis

Plants that are more resistant to the climate crisis and that absorb nutrients efficiently are the new trend in the development of genetically modified organisms (GMOs). An article published on October 14 in the magazine Frontiers in Plant Science by researchers at the Climate Change Genomics Research Center (GCCRC) addresses the different techniques used to obtain new varieties and the trends for generating transgenics, especially genetically edited plants.

At work "maize ttransformation: from plant mmaterial to the release of genetically modified and edictated varieties (Corn transformation: from plant material to the release of genetically modified and edited varieties)” researchers review the genetic transformation of corn. From the first generation of transgenics to the CRISPR-Cas gene editing technique, the article provides a mapping of technical advances for the creation of agricultural varieties.

The GCCRC publication - an initiative by Embrapa and Unicamp, with support from the São Paulo State Research Support Foundation (Fapesp) - brings data of great interest to professionals in the biotechnology field, the scientific community and students.

In addition to describing advances in protocols, technologies and applications for corn transformation, in the review, researchers address current processes for developing new cultivars. They also map the characteristics of greatest interest sought by scientists, including the pipelines (a map of the process steps) that exist to produce genetically modified or edited plants, until they reach the market.

For the authors of the article, researchers and companies have currently faced a new challenge in relation to GMOs: the development of plants that tolerate adverse conditions resulting from the climate crisis, such as drought and high temperatures, for example, alongside efficiency in use of nutrients and productivity.

The manifestation of these characteristics in a substantial way, unlike the resistance to insects and more common herbicides, depends on the interaction between different genes and these with the environment. Such complexity has led companies and research institutions to invest in new gene discovery processes and large-scale evaluation programs. This is what researchers Juliana Yassitepe (Embrapa Informática Agropecuária/GCCRC), Viviane Heinzen (GCCRC/Center for Molecular Biology and Genetic Engineering[CBMEG]-Unicamp), José Hernandes-Lopes, Ricardo Dante, Isabel Gerhardt and Fernanda Rausch (Embrapa) point out. Agricultural Informatics/ GCCRC/CBMEG), Priscila Alves, Leticia Vieira, Vanessa Bonatti (GCCRC/CBMEG) and Paulo Arruda, coordinator of GCCRC and professor at CBMEG and the Institute of Biology at Unicamp.

Gene editing

The CRISPR-Cas system, which makes it possible to edit DNA more precisely, is the great promise of plant biotechnology, especially for developing countries like Brazil. The technique, released in 2012, won the 2020 Nobel Prize in Chemistry for researchers Emmanuelle Charpentier, from the Max Planck Institute, and Jennifer Doudna, from the University of Berkeley. It has been rapidly improved in recent years, stimulating research to obtain genetically edited agricultural cultivars.

The technique consists of editing the DNA sequence, that is, inserting, deleting or replacing nucleotides (the letters that make up the sequence) to produce a desirable characteristic, such as drought resistance. In addition to being a cheaper and more accessible technique, it favors the simplification of the regulatory process, considering that there would be no DNA from other species inserted into the genome of these varieties. “Each country follows its own legislation. Unlike the European Union, for example, Brazil has taken a more open position in relation to genome editing”, says José Hernandes, researcher at the GCCRC and one of the authors of the article. For him, the biggest challenge for regulating technology lies in the so-called mutations off-target, unforeseen changes that may arise from genomic editing; however, such changes are very rare in plants.

Although a gene discovery structure is still necessary to enable the development of an edited plant, trends point to increased access to technology. In some countries, there are already edited products commercially available, or in an advanced approval process (such as varieties of corn, soybeans, camellia and citrus), with improved nutrients and resistance to diseases. “Genome editing could contribute to increasing the number of laboratories capable of developing and commercializing new varieties. By simulating genetic changes that appear spontaneously in natural processes, some countries already consider some plants to be transgenic-free”, adds Viviane Heinzen, co-author of the publication.

GMOs represent 30% of the world's corn area

GMO plants have been part of agriculture for decades. Most have basically two advantages: resistance to herbicides and insects. Corn cultivation relies on widely used transgenic commercial varieties. This is the case of BT corn, which, upon receiving genes from the bacteria Bacillus thuringiensis, produces a protein capable of killing caterpillars that affect crops. These cultivars prevail on the market due to the relative ease of evaluating their characteristics during the development process. “These are qualitative characteristics; the effect of a gene is easier to measure, indicating whether the plant is resistant or not”, explains Juliana Yassitepe.

In recent years, advances in plant biotechnology have enabled the development of genetically modified corn varieties that have significantly impacted agricultural management and improved grain yields. The new GMOs incorporate characteristics such as herbicide, resistance to insects and diseases, tolerance to abiotic stress, high yield and better nutritional quality.

Adopted in 29 countries, GMO varieties cover 190 million hectares and, in the case of corn, represent around 30% of the cultivated areas on the planet. It is also the agricultural crop with the most GMO events approved by regulatory bodies: 148 in 35 different countries, the majority combining insect resistance and herbicide tolerance, according to a 2019 ISAAA (International Service for the Acquisition of Agrobiotechnology Applications) report.

If the first commercial corn GMOs were developed using the DNA bombardment technique, with less precise transformation control, today the use of bacteria prevails Agrobacterium tumefaciens to deliver the genes of interest in a more accurate way. This change in methodology helped to simplify the transgenic regulatory processes, considering the uncertainties of the bombardment technique, which could include fragments of the gene and pieces of the vector beyond what was planned, concludes Juliana Yassitepe.

Original article published on the Embrapa (Brazilian Agricultural Research Company) website.