Authors:
Dr. Akanksha Pareek | University of Missouri - Columbia | United States
Hallie J. Thompson | University of Missouri - Columbia | United States
Amelia E. Griffith | University of Missouri - Columbia
Dr. Priyamvada Voothuluru | University of Missouri - Columbia
Prof. Melvin J. Oliver | University of Missouri - Columbia
Prof. Robert E. Sharp | University of Missouri - Columbia
Prof. Felix B. Fritschi | University of Missouri - Columbia
Drought significantly hampers global crop production, particularly impacting maize yields. The relative maintenance of root growth is one of the prominent plant adaptations to water deficits, enabling access to water in deeper soil profiles. In maize, nodal roots emerge from the stem base and can penetrate dry and hard soils, yet the underlying mechanisms that facilitate root growth maintenance under water deficits remain unclear. In this study, we examined the physiological and metabolic responses of nodal roots in maize inbred lines B73 and FR697 under irrigated and dry conditions in the field. At low soil water potentials, FR697 maintained elongation rates within the nodal root growth zone that correlated with their higher root tip water potential (-0.8 MPa) compared to B73 (-0.96 MPa). Metabolite profiling and pathway analysis performed with the apical and basal regions of the nodal root growth zone revealed alterations in proline and glutathione metabolism both in B73 and FR697 as common stress responses. The significance of these pathways in water stress responses is well established, and their cooccurrence in nodal roots in the field demonstrates the congruence of results from lab and field studies. Other interesting metabolites that accumulated differentially in FR697 and B73 include glycerophospholipids and phenylpropanoids that could be involved in membrane and cell wall remodeling in response to water stress. To further understand nodal root growth maintenance mechanisms in FR697 under water deficits, we performed lab-based physiological and transcriptomic analyses. This study observed an increase in the abundance of transcripts related to suberin and lignin, hydrophobic polymers that act as a physical barrier to water loss. Further studies are ongoing to demonstrate that the accumulation of these compounds is causally related to maintaining nodal root growth under water deficits.