Particle-based model shows complex rearrangement of tissue mechanical properties are needed for roots to grow in hard soil

Author summaryThe lack of suitable approaches for studying how plant roots adapt to mechanical resistance from soils is limiting our ability to adapt cropping system to climate change. Drought resistance for example is enhanced both by deep rooting and the ability to grow through dry layers of soil. In this study, we overcome experimental limitations to measure tissue mechanics in-situ with a computational model able to solve simultaneously the physical process of growth macroscopically and the behavior of individual cells in the meristem. The study reveals that complex rearrangement of tissues mechanical properties may occurs in response to increased mechanical resistance from the soil. Results show the potential of particle-based models to compute the growth of an entire organ at cellular resolution and such models could significantly advance the studies of plant morphogenesis. When exposed to increased mechanical resistance from the soil, plant roots display non-linear growth responses that cannot be solely explained by mechanical principles. Here, we aim to investigate how changes in tissue mechanical properties are biologically regulated in response to soil strength. A particle-based model was developed to solve root-soil mechanical interactions at the cellular scale, and a detailed numerical study explored factors that affect root responses to soil resistance. Results showed how softening of root tissues at the tip may contribute to root responses to soil impedance, a mechanism likely linked to soil cavity expansion. The model also predicted the shortening and decreased anisotropy of the zone where growth occurs, which may improve the mechanical stability of the root against axial forces. The study demonstrates the potential of advanced modeling tools to help identify traits that confer plant resistance to abiotic stress.

Automated summary

This study successfully measured the mechanical properties of plant roots using a computational model, revealing the complex adaptability of roots to soil resistance. The results show that particle-based models can compute the growth of an entire organ at cellular resolution, which could significantly advance the studies of plant morphogenesis.