Journal of Heredity Advance Access published online on March 30, 2007
Journal of Heredity, doi:10.1093/jhered/esm002
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Brief Communications |
Spontaneous Hybridization between Maize and Teosinte
From the Department of Botany and Plant Sciences, Center for Conservation Biology, and Biotechnology Impacts Center, University of California, Riverside, CA 92521-0124 (Ellstrand, Garner, Hegde, Guadagnuolo, and Blancas); the Horticulture and Crop Science Department, California Polytechnic State University, San Luis Obispo, CA 93407 (Garner); and the Laboratoire de Botanique Evolutive, Institut de Botanique, Université de Neuchâtel, rue Emile Argand 11, 2007, Neuchâtel, Switzerland (Guadagnuolo)
Address correspondence to N. C. Ellstrand at the address above, or e-mail: ellstrand{at}ucr.edu.
The closest wild relatives of maize, Zea mays ssp. mays are various Zea taxa known as "teosinte." Hybrids between maize and the teosinte taxon, Zea mays ssp. mexicana, often occur when the 2 are sympatric in Mexico. Measuring the spontaneous hybridization rate of the 2 taxa would shed light on the mechanisms contributing to the evolution and persistence of these hybrid swarms. We conducted a series of field experiments in Riverside, CA, to measure the natural hybridization rates between maize and 2 teosinte taxa, Z. m. ssp. mexicana and Zea mays ssp. parviglumis. We planted teosinte within and near maize plantations. Hybrids were identified by progeny testing for a maize-specific herbicide resistance allele and a teosinte-specific allozyme allele. Hybridity was confirmed by growing putative hybrid progeny to maturity to evaluate whether they had the characteristic morphology of maize x teosinte hybrids. We found that maize and Z. m. ssp. mexicana naturally hybridize at a low rate (<1%), whereas Z. m. ssp. parviglumis hybridizes with the crop at a high rate (>>50%).
Corresponding Editor: John Burke
Received October 9, 2006
Accepted November 29, 2006