Biology

Dr. Jose Sebastian
Carnegie Institution for Science, Stanford University, USA

Many important cereal crops such as rice, wheat are members of the Poaceae family, which develop root systems characterized by a high-degree of root initiation from the belowground basal nodes of the shoot, termed the crown. While this post-embryonic shoot-borne root system (crown roots) represents the major conduit for water uptake, little is known regarding what effect water availability has on its development. In this talk, I will demonstrate that in the newly developed cereal crop model plant Setaria viridis, the crown locally senses water availability and suppresses post-emergence crown root growth under water deficit. This response was observed in field and growth room environments and in all grass species tested. Luminescence-based imaging of root systems grown in soil revealed a shift in root growth from crown to primary-root derived branches, suggesting that primary-root-dominated architecture can be induced in S. viridis under certain stress conditions. Crown roots of Zea mays (maize) and Setaria italica, domesticated relatives of teosinte and S. viridis, respectively, show reduced sensitivity to water deficit, suggesting that this response may have been influenced by human selection. Enhanced water status of maize mutants lacking crown roots suggests that, under water deficit, stronger suppression of crown roots may actually benefit crop productivity. I will also highlight future directions that may enable us to breed new resilient cereal crop cultivars.