Two of the changes from teosinte to maize seem to represent reciprocal differences. When the solitary female spikelets of teosinte became binate (paired) in maize, simultaneously the paired spikes of teosinte became solitary in maize. In the origin of paired female spikelets in maize, the rudimentary pedicellate member of the pair was reactivated. In the reciprocal switch to solitary spikes (ears) in maize, the sessile member is usually suppressed. Since these differences involve secondary sex traits within teosinte and maize as well as between these species, there is usually instability in switching the phenotype. When one transfers solitary female spikelets to modern maize, the expression is usually unstable. Paired ears in modern maize usually occur at a low frequency (one in 500?) and their expression is unstable. The combination of solitary spikelets with paired ears in maize should be both stable and successful in novelty types such as the square sweet corn.
Walton C. Galinat
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