Glyphosate hormesis stimulates tomato (Solanum lycopersicum L.) plant growth and enhances tolerance against environmental abiotic stress by triggering nonphotochemical quenching

Abstract

BackgroundGlyphosate is the most widely applied herbicide in the world. Hormesis caused by low glyphosate doses has been widely documented in many plant species. However, the specific adaptative mechanism of plants responding to glyphosate hormesis stimulation remains unclear. This study focused on the biphasic relationship between glyphosate dose and tomato plant growth and how glyphosate hormesis stimulates plant growth and enhances tolerance to environmental stress.ResultsWe constructed a hormesis model to describe the biphasic relationship with a maximal stimulation (MAX) of 162% above control by glyphosate at 0.063 g ha−1. Low‐dose glyphosate increased photosynthetic pigment contents and improve photosynthetic efficiency, leading to plant growth stimulation. We also found that glyphosate hormesis enhanced plant tolerance to diuron (DCMU; a representative photosynthesis inhibitor) by triggering the non‐photochemical chlorophyll fluorescence quenching (NPQ) reaction to dissipate excess energy stress from photosystem II (PSII). Transcriptomic analysis and quantitative real‐time PCR results revealed that the photosynthesis–antenna proteins pathway was the most sensitive to glyphosate hormesis, and PsbS (encoding photosystem II subunit S), ZEP (encoding zeaxanthin epoxidase), and VDE (encoding violaxanthin de‐epoxidase) involved in NPQ played crucial roles in the plant response to glyphosate hormesis.ConclusionThese results provide novel insights into the mechanisms of plant hormesis and is meaningful to the application of glyphosate hormesis in agriculture.This article is protected by copyright. All rights reserved.

Mechanistic Insights on Salicylic Acid-Induced Enhancement of Photosystem II Function in Basil Plants under Non-Stress or Mild Drought Stress

“…Overall, the beneficial role of SA under various abiotic stress conditions is associated with its ability to counteract oxidative damage triggered by these stressors [ 62 , 63 , 92 ], serving as an antioxidant [ 50 , 62 , 79 ] and playing a regulatory role in photosynthetic reactions [ 93 ]. The most sensitive component of the photosynthetic machinery to various abiotic stresses has been demonstrated to be PSII [ 21 , 26 , 27 , 94 ]. The effectiveness of chlorophyll fluorescence analysis for exploring PSII functionality under MiDS has been extensively documented [ 2 , 3 , 4 , 81 , 88 , 95 ].…”

“…NPQ, which reveals heat dissipation of excitation energy, decreased after SA treatment in tomato plants at LL, while at HL, remained equal to control plants [ 50 ]. Activation of the NPQ mechanism to dissipate excess PSII energy in tomato plants, by the herbicide glyphosate, conferred tolerance to environmental abiotic stress [ 94 ].…”