Investigation of Rice Root Tip Circumnutation Functions in Heterogeneous Environments

Circumnutation is the pattern of oscillatory growth widespread among plants. Little is known about the function of circumnutation, particularly in root-heterogeneity interactions. Traits that allow for exploration may be advantageous, as roots can encounter heterogeneities in their environment that prevent productive growth. In this work we used a clear gel-based media to create a growth environment of two gel layers with varying stiffness, which can model soil horizons with varying compaction. A high-throughput automatic imaging system acquired images to visualize the root growth. Roots were grown in either a soft gel upper layer to a stiffer gel bottom layer, or the opposite. Our results show interesting differences in the ability of wild-type and non-circumnutating roots to penetrate the lower gel layer. These differences provide insights into the function of circumnutation.