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Research in maize‐Tripsacum hybridization is extensive and encompasses a period of more than 60 years of collective research. A vast amount of literature exists on various facets of this type of hybridization ranging from agronomy, plant disease, cytogenetics, breeding, and genetic analysis. Consequently, no single article can cover all the research relevant to this topic. This report will not address all the various issues, but focus primarily on specific research and experiments which would perhaps be of value to a student interested in this topic. The interested student is encouraged to review the references below and follow the additional references cited by the various authors to obtain more information on this topic.

Interspecific hybrids, or hybrids generated between species, are utilized by plant breeders to discover and transfer genes from one plant to another plant of a related species which cannot be found in the particular species of interest. One of the most interesting instances of interspecific hybridization is that between maize (Zea mays L.) and its most distant relative gamagrass (Tripsacum spp.). Tripsacum L. is a perennial, warm season bunch grass found throughout most of the subtropical and tropical regions of the Western Hemisphere (de Wet et al. 1981, 1982) (Figure B6.1).

Figure B6.1 A stand of Tripsacum dactyloides (eastern gamagrass) in Woodward, County, OK, USA. Individual standing in the gamagrass is Dr. Victor Sokolov, Institute of Cytology and Genetics, Novosibirsk, Russia.

Approximately 16 species have been classified taxonomically in Tripsacum. The most common species is Tripsacum dactyloides L. that can be found growing in much of the USA, Mexico, Central America, and South America (de Wet et al. 1981, 1982). The most commonly studied maize‐Tripsacum interspecific hybrids are those generated between diploid maize (2n = 2x = 20) and tetraploid Tripsacum dactyloides (2n = 4x = 72). Regardless of their complete difference in chromosome number, plant phenotype, and environmental niche, hybrids are relatively easy to generate.

In 1939, Mangelsdorf and Reeves published their historical monograph “The Origin of Indian Corn and Its Relatives,” in which they discussed their research and views on the relationship of cultivated Zea mays to its distant cousins, teosinte (the closest relative of maize) and Tripsacum spp. (Mangelsdorf and Reeves 1939). Though these early views regarding the origins of maize and its relationship to teosinte and Tripsacum are controversial and are open to discussion and further investigations, the procedures for generating such interspecific hybridizations remains relatively unchanged.