Maize x Teosinte Hybrid Cobs Do Not Prevent Crop Gene Introgression

TLDR: It is expected that introgression of transgenes from maize into teosinte in Mexico should occur largely unimpeded by the hybrid cob, and test whether hybrid cobs hold their fruits as tightly as maize cobs found the force required to detach hybrid fruits was substantially and significantly less than that for maize.

Abstract: Maize x Teosinte Hybrid Cobs Do Not Prevent Crop Gene Introgression. Whether introgression from crops to wild relatives can occur is an important component of transgene risk assessment. In the case of maize, which co-occurs with its wild relative teosinte in Mexico, the possibility of introgression has been controversial. Maize is cross-compatible with teosinte, and spontaneous hybridization is known to occur. Some scientists have hypothesized that the maize x teosinte cob infructescence will prevent progeny dispersal, thus preventing introgression. Motivated by a prior study where we found maize x teosinte hybrid fruits naturally dispersed under field conditions, we tested whether hybrid cobs hold their fruits as tightly as maize cobs. We found the force required to detach hybrid fruits was substantially and significantly less than that for maize. Consequently, we expect that introgression of transgenes from maize into teosinte in Mexico should occur largely unimpeded by the hybrid cob.La mazorca o elote hibrido de maiz x teocintle no impide la introgresion de genes transgenicos provenientes del cultivo. La introgresion entre el maiz cultivado y el maiz silvestre, o teocintle, es un componente importante en la evaluacion ambiental relacionada con los riesgos de la introduccion de genes transgenicos. La posibilidad de introgresion entre el maiz domesticado y el teocintle ha sido un tema controversial, en particular en Mexico, donde maiz y teocintle coexisten. El maiz es compatible con el teocintle y la hibridizacion espontanea ocurre entre ellos. Algunos cientificos han planteado como hipotesis que al cruzar el maiz con teocintle, la estructura interna de la infrutescencia que sujeta los frutos conocida como la mazorca de maiz o el elote, impide la dispersion de la progenie evitando que la introgresion ocurra. Los resultados de un estudio previo evidencian la dispersion de los frutos hibridos del maiz x teocintle en condiciones naturales. Motivados por estos resultados, hemos decidido investigar si la mazorca o el elote de las infrutescencias del hibrido sujetan los frutos con una fuerza comparable o mayor a la del maiz. Nuestras mediciones implican que la fuerza necesaria para liberar los frutos hibridos son substancial y significativamente menores que aquellas necesarias para desprender los frutos del maiz. Como conclusion sugerimos que en Mexico, la mazorca o el elote no representan una barrera que impida la introgresion de los genes transgenicos del maiz al teocintle.