Cytogenetics of maize in Mexico as a field of transnational exchange: The case of Takeo Ángel Kato Yamakake

Societal Impact Statement Maize is one of the most consumed grains worldwide. Its production and international trade are expected to continue increasing because of its use as animal fodder and direct human food. Although maize's history spans millennia, in the last century it underwent significant changes due to genetic engineering, particularly during the Green Revolution. Due to maize's importance for current food security and energy production, it is fundamental to understand this engineering process to assess the implications of current styles of maize production for local and global landscapes, scientific institutions, and transnational networks of agricultural science. Summary This article aims to explain how Mexican agricultural expertise contributed to the development of cytogenetics as a specialized field in the study of the diversity of maize within the framework of the Green Revolution. To this end, the article follows the work of Mexican agronomist Takeo Ángel Kato Yamakake within the activities of the Inter‐American Maize Improvement Program (IMIP), formally established in 1960. By reconstructing the debate on the genetic implications of chromosomal structure and function, this study contributes to the historiography devoted to the role played by local experts in the classification, experimentation, and conservation of maize. The article is based on sources from Mexico and the United States, an interview with Kato, and the consultation of the database “Rockefeller Fellows. Individual Mobility Awards at Rockefeller‐endowed Organizations, 1914‐1970.” Kato's trajectory provides an overview of agronomy in Mexico and shows the relevance of transnational exchange in the establishment of plant cytogenetics. Kato's academic activity features collaborations with key figures such as Edwin Wellhausen, Albert Longley, Barbara McClintock, W. Gallinat, Czeslawa Prywer, and Almiro Blumenschein. A Green Revolution era quest to unravel the origin of maize as a way of perfecting its genetic manipulation fueled the interest in establishing cytogenetics in Mexico. However, the irruption of the molecular approach made the study of the position of chromosomal knobs less of a priority. Despite this, classical cytogenetics, under Kato's leadership, remains a field that contributed to the knowledge of the vegetal genome, even when the IMIP disappeared and the logic of the Green Revolution lost its centrality.