Soil compaction represents a major challenge for modern agriculture. Compaction is intuitively thought to reduce root growth by limiting the ability of roots to penetrate harder soils. A new article just published in the journal Science reports that root growth in compacted soil is instead actively suppressed by the volatile plant hormone ethylene.
An international collaboration of researchers, including The University of Adelaide’s Professor Dabing Zhang, found that mutant Arabidopsis and rice roots that were insensitive to ethylene penetrated compacted soil more effectively than did wild-type roots.
The group found that ethylene will diffuse through aerated soil, but compacted soil reduces such diffusion, increasing the concentration of ethylene near root tissues. The cellular signaling cascades triggered by too much ethylene stop root growth, with gaseous diffusion therefore serving as a readout of soil compaction for plant roots growing in search of productive nutrition.
Their results indicate that soil compaction lowers gas diffusion through a reduction in air-filled pores, thereby causing ethylene to accumulate in root tissues and trigger hormone responses that restrict growth.
Given that ethylene appears to act as an early warning signal for roots to avoid compacted soils, this study is likely to prove highly relevant to research into the breeding of crops resilient to soil compaction.
The full article can be viewed at https://science.sciencemag.org/content/371/6526/276.full