Densely planted maize communicates with neighboring plants to defend against pests

A careful experiment by Dongsheng Guo and colleagues reveals that maize in a densely planted plot can communicate with neighboring plants through the release of the volatile gas linalool, triggering the roots of its neighbors to release compounds that can change the bacterial composition of the soil. This plant-soil communication helps the plants defend against the increased risk of pests and predation found in high-density plantings, Guo et al. conclude. The findings could aid agricultural researchers looking for ways to sustainably optimize crop yield through different planting patterns and possibly through targeting linalool production. Across several experimental plots of maize planted at different densities in China, Guo et al. noted that when concentrations of linalool in the air reach a certain plant density-dependent threshold, linalool triggers the production of jasmonate and other plant hormones in the roots of plants, which in turn leads to the release of compounds called benzoxazinoids into the soil. The benzoxazinoids alter the composition of the microbiome in surrounding soil, which helps protect the plants against pests but also leads to smaller growth. As Niklas Schandry and Claude Becker note in a related Perspective, one of the most surprising findings of the study is the speed at which this plant-soil communication happens—after only three days of maize growth at high density.