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John Doebley studies the genetics of changes in plant form, especially the domestication of maize from teosinte. His own research profile describes quantitative genetics as a principal approach.^[ref]

In 1997, Doebley and colleagues identified teosinte branched1 as a regulator associated with the stronger apical dominance of maize. Higher expression in maize connected altered gene regulation to reduced lateral branching. This work made a major crop difference experimentally approachable as a change in a developmental programme rather than an inexplicable difference between two plant forms.^[ref]

A PNAS biographical profile includes a labelled photograph taken in 2003.

Teosinte branched1, conventionally written tb1 for the gene, encodes a transcription factor that suppresses outgrowth of lateral buds in maize. It is a major component of the difference in apical dominance between cultivated maize and its wild teosinte relatives.

John Doebley and colleagues connected tb1 expression and mutant morphology to suppression of axillary growth. Cultivated maize showed increased tb1 expression in the relevant comparison, linking altered regulation of a developmental gene to a conspicuous domestication trait.^[ref]

This illustrates why regulatory change matters: a large difference in branching need not require inventing an entirely new protein. Changing where or how strongly an existing regulator acts can reshape the plant.