Identification of auxin response factor
ARF27
as a regulator of maize root morphogenesis
Linkan Dash, Melissa A. Draves, Rajdeep S. Khangura, Maxwell R. McReynolds, Rebekah L. Muench, Craig L. Cowling, Gaoyuan Song, Brian P. Dilkes, Justin W. Walley, Dior R. Kelley Summary
Auxin is a central phytohormone that mediates root development. This study investigated the genetic basis of auxin‐mediated primary root growth in
Zea mays
(maize) seedlings, which is not well‐understood in this key cereal crop.
To address this knowledge gap, 618 accessions from the Wisconsin Diversity panel were leveraged for a genome wide association study (GWAS) followed by reverse genetics and
in silico
gene regulatory network reconstruction (GRN).
The GWAS identified several candidate genes associated with variation in root growth responses, including
RAMOSA2
and multiple members of the AUXIN RESPONSE FACTOR (ARF) gene family. Maize
AUXIN RESPONSE FACTOR27
(
ZmARF27
), an ortholog of Arabidopsis
ARF7
and
ARF19
, was prioritized for functional characterization. A reduction in
ZmARF27
levels led to short primary roots, insensitivity to exogenous auxin, and altered transcriptional responses. Reconstruction of an ZmARF27 GRN included known maize classical root development genes, such as
ROOTLESS CONCERNING CROWN ROOTS
, numerous auxin pathway genes, and genes associated with cell wall biogenesis.
Altogether, this study identifies
ZmARF27
as a novel genetic driver of auxin‐mediated root growth and gene expression in maize.