Hybridization and phenology of hybrids obtained between teosinte introduced in Spain and cycloxydim tolerant maize

Abstract

The term teosinte applies to a group of species and subspecies of the genus Zea, including the wild ancestor of maize. In 2014, its presence was reported in corn fields in Aragon and Catalonia, where it can cause significant reductions in the harvest. Different control measures have been put in place to contain its advance, including the exceptional authorization of the cultivation of corn tolerant to the herbicide cycloxydim (acetyl CoA carboxylase enzyme inhibitor) in infested areas. The relationship between maize and teosinte allows hybridization and the possibility of gene flow from maize to the wild plant. Introgression of herbicide resistance genes from maize to teosinte has recently been reported in France where cycloxydim-tolerant maize is authorized for cultivation. In this study, the hybridization rate between a cycloxydim tolerant maize cultivar and teosinte introduced in Spain was determined during three years and the phenology during the vegetative and reproductive phase of hybrids and parents was monitored. For this purpose, free-flowering crosses between teosinte as female parent and maize as male parent were carried out under outside uncontrolled environmental conditions. Hybrid identification was carried out by spraying with cycloxydim (200 g. m.a. ha-1). Despite the flowering overlap between teosinte and maize, hybrids were obtained in only one of the three years at a rate of 3.4%.