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Background <p>The invasive weed <i>Ageratina adenophora</i> poses significant ecological threats, necessitating novel control strategies. This study investigated the phytotoxic potential of methyl indole-3-acetate (MEIAA) through foliar application. As a methylated derivative of IAA, MEIAA exists in plants at extremely low concentrations and exhibits herbicidal properties distinct from conventional auxin mimics such as 2,4-D. Additionally, we integrated histochemical staining, transmission electron microscopy (TEM), and multi-omics analyses to reveal MEIAA mediated structural changes in <i>A. adenophora</i>.</p> Results <p>At 20 mM (optimized concentration), MEIAA induced dose-dependent stem curvature (1d post-treatment) and apical meristem necrosis (3d). Mechanistic analyses revealed three combined effects: (1) Structural compromise: MEIAA reduced lignin (20–73%), cellulose (9–29%), hemicellulose (4–11%), and pectin (6–36%) in stems, impairing mechanical integrity. Transmission electron microscopy (TEM) further demonstrated severe ultra-structural aberrations, including plasmolysis, organelle disintegration, and cell wall fragmentation. (2) Vascular collapse: Histological staining revealed disorganized vascular bundles and lignin-depleted xylem vessels, disrupting water/nutrient transport. (3) Metabolic-transcriptional dysregulation: Multi-omics integration identified MEIAA-induced perturbations in carbohydrate metabolism (e.g., elevated D-mannose, D-galactose; altered starch/sucrose pathways) and phenylpropanoid biosynthesis (suppressed lignin precursors: coniferaldehyde, sinapaldehyde). Concurrently, MEIAA bi-directionally regulated 26 phytohormone signaling genes (e.g., AUX/IAA, ARF, PYR/PYL), diverting metabolic flux from growth to stress responses. Crucially, qRT-PCR validated RNA-seq reliability, highlighting MEIAA’s unique regulatory divergence from both natural auxin (IAA) and synthetic analogs like 2,4-D.</p> Conclusion <p>These findings position MEIAA as a potent and distinctive auxin-mimic herbicide, disrupting physiological homeostasis via multi-target inhibition. Our results provide a mechanistic foundation for developing MEIAA as an eco-friendly herbicide specifically for controlling invasive <i>A. adenophora</i>.</p>

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Methyl Indole-3-Acetate (MEIAA) mediated stem curvature and apical meristem necrosis in Ageratina adenophora: impacts on cell wall components, vascular system integrity, and key metabolic pathways

  • 期刊论文

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  • 发表日期：

    2025年8月23日

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  • Yanan Ruan,
  • Xi Gao,
  • Mehboob Hussain,
  • Xiaoping Qin,
  • Jingyi Ning,
  • Dewei Yang,
  • Tao Zhu,
  • Deqiang Qin,
  • Min Ye,
  • Guoxing Wu

摘要

Background

The invasive weed Ageratina adenophora poses significant ecological threats, necessitating novel control strategies. This study investigated the phytotoxic potential of methyl indole-3-acetate (MEIAA) through foliar application. As a methylated derivative of IAA, MEIAA exists in plants at extremely low concentrations and exhibits herbicidal properties distinct from conventional auxin mimics such as 2,4-D. Additionally, we integrated histochemical staining, transmission electron microscopy (TEM), and multi-omics analyses to reveal MEIAA mediated structural changes in A. adenophora.

Results

At 20 mM (optimized concentration), MEIAA induced dose-dependent stem curvature (1d post-treatment) and apical meristem necrosis (3d). Mechanistic analyses revealed three combined effects: (1) Structural compromise: MEIAA reduced lignin (20–73%), cellulose (9–29%), hemicellulose (4–11%), and pectin (6–36%) in stems, impairing mechanical integrity. Transmission electron microscopy (TEM) further demonstrated severe ultra-structural aberrations, including plasmolysis, organelle disintegration, and cell wall fragmentation. (2) Vascular collapse: Histological staining revealed disorganized vascular bundles and lignin-depleted xylem vessels, disrupting water/nutrient transport. (3) Metabolic-transcriptional dysregulation: Multi-omics integration identified MEIAA-induced perturbations in carbohydrate metabolism (e.g., elevated D-mannose, D-galactose; altered starch/sucrose pathways) and phenylpropanoid biosynthesis (suppressed lignin precursors: coniferaldehyde, sinapaldehyde). Concurrently, MEIAA bi-directionally regulated 26 phytohormone signaling genes (e.g., AUX/IAA, ARF, PYR/PYL), diverting metabolic flux from growth to stress responses. Crucially, qRT-PCR validated RNA-seq reliability, highlighting MEIAA’s unique regulatory divergence from both natural auxin (IAA) and synthetic analogs like 2,4-D.

Conclusion

These findings position MEIAA as a potent and distinctive auxin-mimic herbicide, disrupting physiological homeostasis via multi-target inhibition. Our results provide a mechanistic foundation for developing MEIAA as an eco-friendly herbicide specifically for controlling invasive A. adenophora.