Sexual transmutation consistent with the cupule reduction mode of maize's origin

--Walton C. Galinat

Most of the oldest Tehuacan and all of the oldest Bat Cave cobs are like most modern corn in having well-developed cupules and elongated female rachillae. The pronounced cupules are female secondary sex traits of teosinte and the elongate rachillae are female baggage from the tunicate allele carried by Chapalote maize. They are not part of the complex of male secondary sex traits from teosinte which includes reduced cupules, short rachillae, paired spikelets, and foliaceous glumes. Since the entire male secondary sex baggage is not transported into the female rachis of these particular archaeological cobs, the origin of maize from teosinte in these cases, representing the parviglumis-Northern Flint pathway by rachilla elongation, is not consistent with the expectations of the CSTT theory of Iltis (Science 22:886-894, 1983).

But cupule reduction and short rachillae do occur in a different grouping of maize races, the pathway that I have termed Chalco-Southern Dent (Galinat, Agronomy 18:1-31, 1988). Furthermore, ts2 (tassel seed 2) derivatives of both teosinte and Tripsacum have paired female spikelets with foliaceous glumes, reduced cupules and short rachillae in their "tassels" that are similar to certain Tehuacan specimens. Thus, contrary to what I have stated previously, there is some evidence that Iltis might correctly interpret as consistent with his CSTT. I should add that the string-cob trait of Confite Morocho involves cupule reduction and short rachillae controlled by the Sg1 and Sg2 genes without any transmutation of the tassel. Confite Morocho appears to be an ancient isolate of the Tehuacan maize that drifted to Peru at an early time.


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