Craig L. Cowling, Arielle L. Homayouni, Jodi B. Callwood, Maxwell R. McReynolds, Jasper Khor, Haiyan Ke, Melissa A. Draves, Katayoon Dehesh, Justin W. Walley, Lucia C. Strader, and Dior R. Kelley

PNAS May 28, 2024, vol. 121 no. 22

Figure: The molecular and hormonal pathways of CR and BR development in maize. Arrows indicate positive regulation, and lines with a flat head represent negative regulation (Singh et al. 2022).

Significance

Roots are a key organ for water and nutrient uptake in plants. Changes in root architecture can impact yield and resilience to stress in crops. To find factors that contribute to root development in corn, a genetic screen was performed. Herein, we identify a hormone transporter that influences numerous root traits of agronomic significance. This work has implications for translational approaches aimed at improving cereal crops.

Abstract

Plant root systems play a pivotal role in plant physiology and exhibit diverse phenotypic traits. Understanding the genetic mechanisms governing root growth and development in model plants like maize is crucial for enhancing crop resilience to drought and nutrient limitations. This study focused on identifying and characterizing ZmPILS6, an annotated auxin efflux carrier, as a key regulator of various crown root traits in maize. ZmPILS6-modified roots displayed reduced network area and suppressed lateral root formation, which are desirable traits for the “steep, cheap, and deep” ideotype. The research revealed that ZmPILS6 localizes to the endoplasmic reticulum and plays a vital role in controlling the spatial distribution of indole-3-acetic acid (IAA or “auxin”) in primary roots. The study also demonstrated that ZmPILS6 can actively efflux IAA when expressed in yeast. Furthermore, the loss of ZmPILS6 resulted in significant proteome remodeling in maize roots, particularly affecting hormone signaling pathways. To identify potential interacting partners of ZmPILS6, a weighted gene coexpression analysis was performed. Altogether, this research contributes to the growing knowledge of essential genetic determinants governing maize root morphogenesis, which is crucial for guiding agricultural improvement strategies.

See https://www.pnas.org/doi/10.1073/pnas.2313216121