Field and Lab-Based Phenotyping Approaches to Crop Root Growth Dynamics

Effective root foraging is at a premium in drought-prone, nutrient poor, and other sub-optimal environments, and thus the architecture of the root system becomes greatly important. We describe here our efforts to accelerate genetic and mechanistic understanding of crop root architecture and growth dynamics using non-destructive, controlled-environment imaging techniques such as optical (OPT), X-ray (XRT), and positron emission tomography (PET), and to corroborate these findings with field data. In one study, we conducted a multivariate QTL analysis in rice using optical 3D reconstructions to discover new regions of the genome controlling root traits. A similar approach was used to characterize a maize root ideotype for enhanced Nitrogen uptake in the Illinois Selection Lines, and is facilitating genetic mapping in high-resolution IPSRI lines. These data are being compared to field-excavated root systems of the same genotypes using image-based phenotyping to discover features that are robust across environments. Using XRT, we have begun to explore GxE effects of soil-type on root growth in maize and rice, and are developing a large-format platform to capture both shoot and root 3D architecture over time. On the scale of minutes, we have combined optical and PET imaging to correlate root growth with ¹¹Carbon flow, where dynamic responses of genotypes with known agronomic qualities can be tested under various stress scenarios.