New protocol can be three times more efficient in tropical corn varieties A paper published in the Frontiers in Genome Editing in early December presents the application of a gene transformation protocol based on the use of “morphogenic regulators” for corn lineages that are suited to tropical conditions. The new protocol, which is considered an important advance to accelerate corn gene editing for tropical regions, was developed by researchers at the Center for Genomics Applied to Climate Change (GCCRC), an initiative by Embrapa and the State University of Campinas (Unicamp) funded by the São Paulo State Research Support Foundation (Fapesp). Generally speaking, tropical corn lineages do not offer very efficient responses to the genetic transformation process required for gene editing experiments. The result of the new study was three times more efficient in such lineages in comparison with the model protocol, which is based on lineages that were developed for temperate climate conditions. Gene editing in agriculture is considered a powerful tool against climate change as it allows, for instance, the faster development of crop varieties that are more tolerant to drought or diseases, or are more nutritious. The GCCRC study was carried out with plants both of proprietary use and in public domain, which will facilitate access to new research. Currently, the top four corn producing countries in the world are the United States, China, Brazil and Argentina. In 2023, Brazil became the largest exporter, supplanting the United States. The tropics are responsible for 30% of the global production of the cereal. However, corn productivity in tropical regions is significantly lower than in temperate areas. According to the paper's authors, this disparity stems from challenges such as low soil fertility, pest infestations and rain-dependent cultivation, which can be worsened by a history of genetic improvement that is very recent as opposed to temperate corn varieties. The corn lineages used as study models are mostly from temperate regions, whose performance in field tests in Brazil is not satisfactory. “Those plants are not adapted to the tropical climate, and thus do not perform so well in these regions”, explains José Hernandes, one of the study's authors who conducted the research during his post-doctoral internship at GCCRC. Another barrier in corn editing processes is the low efficiency of traditional genetic transformation protocols. Transformation is a method through which external DNA - which, in this case, contains genes that promote gene editing - is introduced into cells, allowing the expression or modification of specific genes. In the study, the authors explored a new molecular biology strategy that has shown great promise in corn transformation: the use of genes that stimulate regeneration in the transformed plants, which are named morphogenic regulators. “The protocol we used, developed by our collaborator Laurens Pauwels, in Belgium, was prepared for a temperate lineage and worked very well for over half of the tropical lines that we tested”, reports Ricardo Dante, a researcher at Embrapa Digital Agriculture and co-author of the study. Three of the five tropical lines were successfully transformed using the morphogenic gene expression strategy, with efficiency rates that were three times higher than the average in protocols that do not use this strategy, reaching 6.63%. “Now we have a study lineage that is more adapted to local field conditions,” Hernandes points out. This means lineages that are highly amenable to transformation and able to generate healthy plantlets that are agronomically suited for studies in Brazil's actual production conditions. Cutting-edge public institutions in Brazil Another concern of the research group was to perform the tests using both Brazilian commercial lines and non-proprietary lineages. The latter came from the International Maize and Wheat Improvement Center (CIMMYT), a Mexico-based organization that conserves corn germplasm. The GCCRC became the national repository of some lineages from the Mexican center's gene bank in Brazil. Any institution that wishes to use this material can contact the GCCRC. “It is important that we have public institutions leading this process, so that everyone can have access to the knowledge that is being generated”, observes Embrapa Digital Agriculture researcher Juliana Yassitepe, another co-author of the study. According to the authors, the study findings expand the current availability of plants that can be successfully gene-edited, which will accelerate biotechnology research in Brazil. “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”, Yassitepe explains. The GCCRC's main focus is the development of drought-tolerant corn lineages. The study, which was funded by Fapesp, is the result of GCCRC's partnership with VIB (Vlaams Instituut voor Biotechnologie) in Belgium, and with visiting researcher Sofya Gerasimova, from the Institute of Cytology and Genetics of the Siberian Branch of the Russian Academy of Sciences (ICiG/SB-RAS) and Novosibirsk State University, Russia, who was also funded by Fapesp. Read to learn more: Hernandes-Lopes J, Pinto MS, Vieira LR, Monteiro PB, Gerasimova SV, Nonato JVA, Bruno MHF, Vikhorev A, Rausch-Fernandes F, Gerhardt IR, Pauwels L, Arruda P, Dante RA and Yassitepe JEdCT (2023) Enabling genome editing in tropical maize lines through an improved, morphogenic regulator-assisted transformation protocol. Front. Genome Ed. 5:1241035. doi: 10.3389/fgeed.2023.1241035 .