Getting to the Root of Drought: Understanding the Transcriptomics of Maize Nodal Root Growth under Drought in the Field

Drought is the most important factor limiting crop production in the US and across the world. Therefore, understanding how crop plants can tolerate or avoid water deficit stress is critical. Studying drought in the context of cereal food crops such as maize is important as maize is one of the three most highly produced food crops in the world. Continually growing roots, even in very dry environments, is one way plants have developed to survive under drought conditions. In maize, the shoot-borne nodal roots form the framework of the mature root system, and have the ability to maintain growth at low water potentials that inhibit growth of other plant organs. However, the physiological and molecular bases of this survival mechanism are not well understood and are the focus of this work. We are exploring transcriptomic changes of the maize nodal root growth zone under controlled water stress conditions in both a lab (poster by McCubbin et al.) and field context. The project focuses on two inbred lines, FR697 and B73, which were selected for contrasting abilities to maintain nodal root growth under water stress. In the field, we use a “drought simulator” (rainout shelter) for precise imposition of the timing, intensity and duration of drought to grow and collect water-stressed and well-watered control samples for RNA-seq analyses. This approach allows us to determine the molecular changes during “real world” drought conditions, and to directly compare physiological and genomic characterizations of nodal root growth responses to water deficits in the lab and field environments. The results will provide a foundation for the goal of developing targeted approaches that will enhance the ability of plants to access greater amounts of limited water and increase yield under drought conditions. Supported by NSF Plant Genome Program grant no. 1444448.