Grass architecture: genetic and environmental control of branching.

Variation in grass architecture profoundly affects light capture, competition, and reproductive success, and is responsive to environmental factors such as crowding and nutrient limitation. Recent work in both model and crop systems has uncovered many aspects of the genetic control of branching, including conservation of the MONOCULM1 and MORE AXILLARY BRANCHING/DECREASED APICAL DOMINANCE/RAMOSUS (MAX/DAD/RMS) genetic pathways among the grasses and the model dicot systems of tomato, Arabidopsis, Petunia and pea. Parallel studies on the effect of environment on branching have also begun to uncover links between environmental sensing through phytochrome pathways, and resultant changes in TEOSINTE BRANCHED1 expression, and meristem inhibition. Future work promises to integrate knowledge of phenotypic responses to environment with our understanding of the genetic and hormonal changes that underlie phenotypic change.