(or native varieites) - as per my answer to your other q.

Las razas criollas son maíces mejorados y mantenidos desde hace siglos por campesinos que los han seleccionado para que se den bien en ciertas condiciones ambientales y respondan a los gustos culinarios de su localidad. En consecuencia, estas razas suelen poseer características únicas que son portadas y transmitidas en sus genes. Dado el gran número de razas criollas que existen en el mundo —pero especialmente en América Latina— es enorme la diversidad de estas características y genes.
http://www.cimmyt.org/english/wps/transg/s_Iwanaga_051202.ht...

... materiales como variedades, razas criollas y parientes silvestres del maíz),
y por medio del mantenimiento de esa diversidad en ambientes naturales. ...
www.cimmyt.org/english/wps/transg/transgenico.htm

Maize Landraces:
Always Evolving

A widely held misconception about maize landraces is that they do not change. In fact, the landraces found even in remote areas of Mexico today are not the same as the maize found in the same location hundreds of years ago. Maize is an open-pollinating species. Individual maize plants readily exchange genes with other maize plants growing nearby, a characteristic that farmers recognized long ago as a way to adapt varieties to their own needs. Today's farmers in Oaxaca, Mexico, for example, readily notice when their maize has been inbred over too many generations and lost vigor. Some will say the maize "gets tired" ("se cansa" ) and will seek other varieties to mix with it.
http://www.cimmyt.org/whatiscimmyt/recent_ar/D_Sustain/mexic...

... resources of landraces (native varieties) and wild relatives of maize, ... The CaMV 35S sequence was detected in four of the six landrace samples, ...
www.colostate.edu/programs/lifesciences/TransgenicCrops/hot...