Researchers at the Center for Genomics Applied to Climate Change (GCCRC), a partnership between Unicamp and the Brazilian Agricultural Research Corporation (Embrapa), managed to make an important advance with the aim of accelerating plant genome editing of corn for the tropical region. Tropical corn strains, in general, do not respond as efficiently to the genetic transformation process, necessary for genome editing experiments. O study, published in the magazine Frontiers in Genome Editing, brings the application of a genetic transformation protocol based on the use of “morphogenic regulators” for tropical corn lines.
The result was three times more efficient in such strains when compared to the model protocol, based on a temperate strain. The study used plants for proprietary and public use, which will facilitate the development of new research. Genome editing in agriculture is considered a powerful tool in the face of climate change as it enables, for example, the faster development of agricultural varieties that are more tolerant to drought and disease or more nutritious.
Currently, the four largest corn producers in the world are the United States, China, Brazil and Argentina. In 2023, Brazil has become the largest exporter of this product, supplanting the United States. The tropical region is responsible for 30% of global cereal production. However, corn productivity in tropical regions is significantly below that in temperate areas. According to the authors of the article, this disparity arises from factors such as low soil fertility, pest infestations and rain-dependent cultivation. The picture becomes even worse because genetic improvement in the region only started recently if the genetic improvement of temperate maize varieties is taken into account.
The corn lines used as a model for the study are mostly from temperate regions, whose performance in field tests carried out in Brazil proved to be unsatisfactory. “These plants are not adapted to the tropical climate and, therefore, do not perform as well in these regions”, explains José Hernandes, author of the study and who developed his research during a post-doctoral internship at the GCCRC.
Another barrier in corn editing processes is the low efficiency of traditional genetic transformation protocols. Transformation, a method by which external DNA – which, in this case, contains genes responsible for promoting genomic editing – is introduced into cells, allows the expression or alteration of specific genes.
In the research, the authors explored a new molecular biology strategy that is very promising in corn transformation: the use of genes that stimulate the regeneration process of transformed plants, the so-called morphogenic regulatory genes. “The protocol we used, developed by our collaborator Laurens Pauwels, from Belgium, was prepared for a temperate strain and worked very well for more than half of the tropical plants we tested”, reports Ricardo Dante, author of the study, member of Embrapa Agricultura Digital and researcher at GCCRC.
Three of the five tropical strains were successfully transformed using the morphogenic gene expression strategy, reaching efficiency rates three times higher than the average of protocols that do not use this strategy, reaching 6,63%.
“Now we have a study lineage that is more adapted to local field conditions”, points out Hernandes. This means obtaining lines with high susceptibility to transformation, a good capacity to generate healthy and agronomically suitable seedlings for studies under real production conditions in the country.
Brazilian public institutions at the forefront
Another concern of the group of researchers was carrying out the tests using Brazilian commercial strains and non-proprietary strains simultaneously. The latter came from the International Corn and Wheat Improvement Center (Cimmyt, in its Spanish acronym), an organization based in Mexico that conserves corn germplasm. The GCCRC became the national repository for some strains from the Cimmyt germplasm collection in Brazil. Any institution wishing to use this material can contact the GCCRC. “It is important to have public institutions leading this process, so that everyone can have access to the knowledge generated”, notes Juliana Yassitepe, author of the study, member of Embrapa Digital Agriculture and researcher at GCCRC.
According to the authors, the study increases the current availability of plants that can be successfully genetically edited, which will accelerate biotechnology research in the country. “Now that we are able to edit and transform tropical corn, we will test genes developed by the center more quickly and under field conditions”, explains Yassitepe. The GCCRC's main focus is the development of drought-tolerant corn lines.
The research, which was funded by the São Paulo Research Foundation (Fapesp), resulted from the GCCRC's partnership with VIB (Vlaams Instituut voor Biotechnologie), from Belgium, and with visiting researcher Sofya Gerasimova, from the Institute of Cytology and Genetics of the Russian Academy of Sciences and Novosibirsk State University (Russia). Gerasimova also received support from Fapesp.
About the GCCRC
O Center for Genomics Applied to Climate Change is part of the Center for Molecular Biology and Genetic Engineering at Unicamp. This is an initiative by Embrapa and Unicamp – within the scope of Fapesp's Engineering Research Centers (CPEs) program – for the development of plants adapted to the conditions imposed by global climate change. Its research platform involves bioinformatics tools, gene editing, transformation, microbiome, phenotyping, intellectual property and regulatory affairs.
