Molecular docking and differential rbcl gene expression reveal variation in glyphosate herbicide tolerance of sugarcane varieties.

Abstract

Background: Glyphosate is an extensively employed herbicide in agriculture, specifically for sugarcane cultivation. The situation is different with the extensive physiological and genetic effects exerted by this herbicide on a range of plant species, including sugarcane, whose model basis is still poorly characterized, although its primary mode of action, which acts on the EPSPS enzyme in the shikimic acid pathway, is completely elucidated. The current study was aimed at investigating the stability of glyphosate formulation, molecular interactions of glyphosate formulation with rbcL enzyme associated with chlorophyll metabolism, and its effects on varieties of sugarcane.

Methods and results: The stability of a ground-up glyphosate formulation was assessed under accelerated storage conditions. Molecular docking was performed to analyze interactions between glyphosate derivatives and rbcL. Two sugarcane varieties (G84-47 and GT54-9) were treated with increasing glyphosate concentrations (0.2, 0.4, and 0.8 mg L^-1) to evaluate effects on chlorophyll content, plant height, herbicide tolerance, and rbcL expression. The formulation showed good stability with minor degradation (47.55-47.14%). N-Nitrosoglyphosate and 2-(phosphonomethylamino)acetic acid exhibited favorable binding affinities with rbcL. Glyphosate treatment reduced chlorophyll content and plant height dose-dependently, with G84-47 showing higher sensitivity. GT54-9 demonstrated higher herbicide tolerance in survival analysis. rbcL expression remained stable in G84-47 but was significantly upregulated in GT54-9 under high herbicide stress.

Conclusions: This study reveals genetic variability in sugarcane responses to glyphosate, with variety-specific mechanisms underlying stress adaptation. The inducible rbcL expression in tolerant varieties provides insights into herbicide resistance mechanisms. These findings can inform marker-assisted breeding and improve agronomic practices for enhanced sugarcane cultivation resilience and sustainability.