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Khor, J.

Publications and source records attributed to Khor, J..

2 recordsLinked to original sources
bioRxiv2023

The Auxin Response Factor ARF27 is required for maize root morphogenesis

Crop root systems are central to nutrition acquisition and water usage. Root hairs and lateral roots contribute to fine-scale patterning of root systems and can offer many advantages for improving root function without drastically impacting overall system architecture. Key genetic regulators underpinning root hair morphogenesis have been well characterized in the model plant Arabidopsis but are less understood in maize. Here, we identify a novel determinant of root hair morphogenesis and auxin responses in maize, AUXIN RESPONSE FACTOR27 (ARF27), using both reverse and quantitative genetic approaches. ARF27 is enriched in maize primary root tissues at both the transcript and protein level. Loss of ARF27 leads to short primary roots and reduced root hair formation, while lateral root density is unaltered. In arf27 roots, auxin-responsive gene expression is dysregulated, which is consistent with the predicted function of this transcription factor. Moreover, a genome wide association study (GWAS) to uncover genetic determinants of auxin-dependent root traits identified ARF27 as a candidate gene. Furthermore, auxin hypersensitive maize genotypes exhibit altered crown root length and surface area in field-grown plants. A gene regulatory network (GRN) was reconstructed and an ARF27 subnetwork was integrated with DAP-seq and GWAS data to identify ARF27 target genes. The ARF27 GRN includes known maize root development genes, such as ROOTLESS CONCERNING CROWN ROOTS (RTCS), ROOTHAIRLESS 3 (RTH3) and RTH6. Altogether this work identifies a novel genetic driver of auxin-mediated root morphogenesis in maize that can inform agricultural strategies for improved crop performance.

plant biology↗
bioRxiv2023

ZmPILS6 is an auxin efflux carrier required for maize root morphogenesis

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, desirable traits during drought and low phosphate conditions. 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 co-expression analysis (WGNA) 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. Significance StatementCrop yield and stress resilience are significantly influenced by crown root architecture. A reverse genetic screen aimed at identifying novel regulators of maize root morphogenesis led to the discovery of ZmPILS6, an auxin efflux carrier. The loss of ZmPILS6 negatively impacts numerous root traits that are linked to plant physiology and function. Proteomic characterization of pils6-1 roots revealed that this evolutionarily conserved transporter is required for the proper expression of numerous phytohormone pathways, including abscisic acid, gibberellins, and jasmonic acid. Notably, ZmPILS6 appears to have a contrasting role in regulating root morphogenesis compared to its Arabidopsis ortholog, PILS6. This finding emphasizes the need for functional characterization of candidate genes directly within key crops of interest, which cannot always be correctly inferred from other model plants.

plant biology↗