Auxinic herbicides, mechanisms of action, and weed resistance: A look into recent plant science advances

Todd Gaines,Pedro Jacob Christoffoleti,Marcelo Rodrigues Alves De Figueiredo,Scott Nissen,Lázaro Eustáquio Pereira Peres

doi:10.1590/0103-9016-2014-0360

Todd Gaines, Pedro Jacob Christoffoleti + Show 3 more

Open Access

https://doi.org/10.1590/0103-9016-2014-0360

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Abstract

Auxin governs dynamic cellular processes involved at several stages of plant growth and development. In this review, we discuss the mechanisms employed by auxin in light of recent scientific advances, with a focus on synthetic auxins as herbicides and synthetic auxin resistance mechanisms. Two auxin receptors were reported. The plasma membrane receptor ABP1 (Auxin Binding Protein 1) alters the structure and arrangement of actin filaments and microtubules, leading to plant epinasty and reducing peroxisomes and mitochondria mobility in the cell environment. The second auxin receptor is the gene transcription pathway regulated by the SCFTir/AFB ubiquitination complex, which destroys transcription repressor proteins that interrupt Auxin Response Factor (ARF) activation. As a result mRNA related with Abscisic Acid (ABA) and ethylene are transcribed, producing high quantities of theses hormones. Their associated action leads to high production of Reactive Oxygen Species (ROS), leading to tissue and plant death. Recently, another ubiquitination pathway which is described as a new auxin signaling route is the F-box protein S-Phase Kinase-Associated Protein 2A (SKP2A). It is active in cell division regulation and there is evidence that auxin herbicides can deregulate the SKP2A pathway, which leads to severe defects in plant development. In this discussion, we propose that SFCSKP2A auxin binding site alteration could be a new auxinic herbicide resistance mechanism, a concept which may contribute to the current progress in plant biology in its quest to clarify the many questions that still surround auxin herbicide mechanisms of action and the mechanisms of weed resistance.

Highlights

Auxin herbicides are similar to the natural auxin indole-3-acetic acid (IAA), as most are organic acids containing an aromatic ring and a carboxyl group and characterized by their low molecular weight (George, 1963)
It is active in cell division regulation and there is evidence that auxin herbicides can deregulate the S-Phase Kinase-Associated Protein 2A (SKP2A) pathway, which leads to severe defects in plant development
We propose that SFCSKP2A auxin binding site alteration could be a new auxinic herbicide resistance mechanism, a concept which may contribute to the current progress in plant biology in its quest to clarify the many questions that still surround auxin herbicide mechanisms of action and the mechanisms of weed resistance

Summary

Introduction

Auxin herbicides are similar to the natural auxin indole-3-acetic acid (IAA), as most are organic acids containing an aromatic ring and a carboxyl group and characterized by their low molecular weight (George, 1963). Auxin induced signal transduction The cell responses to auxin at the plasma membrane are characterized by fast metabolic reactions due to the existence of a chemical receptor called Auxin Binding Protein 1 (ABP1). This receptor was first identified by Hertel et al (1972) in maize (Zea mays) coleoptile membranes. Degradation of the repressor protein activates the ARFs and transcription of genes related to auxin responses (Badescu and Napier, 2006; Tan et al, 2007; Sauer et al, 2013). Because peroxisomes are antioxidant organelles, their most important function is to remove

Auxinic herbicides and weed resistance

Final Remarks