Analysis of Maize (Zea mays L.) Seedling Roots with a New High-Throughput Tool to Connect Seedling Roots to Adult Roots

The maize root system is crucial for plant establishment as well as water and nutrient uptake. There is substantial genetic and phenotypic variation for root architecture, which gives opportunity for selection. Root traits, however, have not been used as selection criterion mainly due to the difficulty in measuring them, as well as their quantitative mode of inheritance. Seedling root traits offer an opportunity to study multiple individuals and to enable repeated measurements per year as compared to adult root phenotyping. Currently no strong relationships between seedling and adult root traits have been established with the traits and tools available so far. Our new tool is based on graphs, is fully automated, and is extendable to 3D tomography imagining data. It will enable capture of various traits from a single image of seedling roots. In order to evaluate this tool, a subset of the 384 inbred lines from the Ames panel, for which extensive genotype by sequencing data is available, was investigated. GWAS was applied to this panel for 27 traits captured from seedling root images using 135,311 SNP markers. This new software will enables capture of a large number of morphological root traits simultaneously, which may help to establish relationships between developmental stages between seedling and adult traits in the future.