Quantitative Genetic Analysis of Root System Architecture in Rice

Plant health and survival is dependent on the root system architecture (RSA), the spatial configuration of different types and ages of roots on a single plant. Root systems are highly plastic, allowing for soil exploration in diverse conditions. Modification of RSA could contribute to improvements of desirable agronomic traits such as drought tolerance and resistance to nutrient deficiencies. Although roots are central to plant fitness, knowledge regarding the genes underlying RSA is limited, in part due to the inaccessibility of root systems. We have developed a non-destructive gel-based imaging and analysis system for automated phenotyping of root system architecture in two and three dimensions. Here, we use this system for QTL analysis of rice root architecture. We imaged and automatically phenotyped 16 traits in the root systems of 180 recombinant inbred lines of rice under nutrient replete conditions across three days. We find multiple QTL on each day, several of which correspond to those previously identified using sand or soil-based systems. In addition, we explore the effects of different abiotic stresses on the root system. This work forms the foundation for fine-mapping and cloning the genes responsible for root system architecture in a variety of environmental conditions.