New Phytol. http://doi.org/bj2g (2016)

The architecture of a plant has a large influence on its value as a commercial crop. Ancestral cotton (Gossypium hirsutum) is a tall shrub that flowers on its upper branches, triggered by shortening days — but domestication has created squat bushes producing copious flowers and fruits independent of day length. Roisin McGarry at the University of North Texas, USA and colleagues show that this structural change is controlled by the relative amounts of two antagonistic gene products, SINGLE FLOWER TRUSS (GhSFT) and SELF-PRUNING (GhSP).

The role of SFT and SP in determining architecture has already been explored in tomato, and the two genes are orthologues of genes known to control meristem identity in Arabidopsis. The researchers identified the cotton genes through sequence similarity with their equivalents in tomato, and showed that they were differently expressed in ancestral and domesticated varieties. They then proceeded to specifically manipulate the expression of GhSFT and GhSP in cotton, both silencing and overexpressing the genes.

GhSFT stimulates a bushy growth pattern with flowers arising from multiple side branches. However, it could not override the influence of GhSP to produce monopodial, unbranching growth. In addition, GhSFT and GhSP are active in growth of all shoots, not just apical and axillary meristems. For example, GhSP is needed for cambium initiation and maintenance, and is thus an important determinant in wood production.