Grasses suppress shoot-borne roots to conserve water during drought
Sebastian, Jose | Yee, Muh-Ching | Viana, Willian Goudinho | Rellán-Álvarez, Rubén | Feldman, Max | Priest, Henry, D. | Trontin, Charlotte | Lee, Tak | Jiang, Hui | Baxter, Ivan | Mockler, Todd, C. | Hochholdinger, Frank | Brutnell, Thomas, P. | Dinneny, José, R.
Many important crops are members of the Poaceae family, and develop fibrous root systems characterized by a high-degree of root initiation from the basal nodes of the shoot, termed the crown. While this post-embryonic shoot-borne root system represents the major conduit for water uptake, little is known regarding what effect water availability has on its development. Here we demonstrate that in the model C4 grass 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 soil-grown root systems revealed a shift in root growth from crown to primary-root derived branches, suggesting that tap-root-like 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.Show more [+] Less [-]