Abstract
Glyphosate is a systemic, nonselective and most widely used herbicide in the world. The introduction of glyphosate-resistant crops in the mid-1990s resulted in a dramatic increase in the use of glyphosate herbicide making it most widely used herbicide in the world. The average maize yield loss in the field caused by pests is around 20 % but in many regions it is much higher. It is now clear that glyphosate causes broader range of physiological alterations than previously assumed and some plants gain higher level of resistance to glyphosate without the need to use genetic engineering methods. To understand the mechanisms of such heightened resistance we must first know the processes mediating the plants’ death in response to glyphosate treatment. Here, we show that 12 miRNAs, belonging to miR167, miR396, miR159, miR156, miR169, miR444 and miR827 families, are significantly upregulated, and one, miR166, downregulated following glyphosate treatment. These miRNAs have been previously shown to be involved in abiotic stress responses and implicated in senescence. Strikingly, two of the induced miRNAs, miR444 and miR827, have been shown to regulate phosphate transport pathways, which seem to be common for Pi and glyphosate uptake.
Highlights
Glyphosate, a glycine derivative (N-(phosphonomethyl)glycine), is a broad-spectrum, post-emergence herbicide
An active system operates at low concentrations of herbicide and may presumably involve a phosphate transporter since it has been shown that the glyphosate uptake is inhibited by sodium phosphate and phosphonoformic acid, competitive inhibitors of phosphate assimilation in plant cells
The holistic understanding of RoundupÒ mechanism of action is of great importance since it has been shown that glyphosate affects the growth of plants by inhibiting enolpyruvylshikimate-3-phosphate synthase (EPSPS) and through altering several crucial plant physiological processes
Summary
Glyphosate, a glycine derivative (N-(phosphonomethyl)glycine), is a broad-spectrum, post-emergence herbicide. Glyphosate is active as a salt and effective only when it comes into contact with green, growing parts of plants (Duke and Powles 2008) after which it becomes distributed throughout the organism. There appear to be at least two mechanisms of glyphosate uptake (active and passive) in plants; they are not well understood to date. An active system operates at low concentrations of herbicide and may presumably involve a phosphate transporter since it has been shown that the glyphosate uptake is inhibited by sodium phosphate and phosphonoformic acid, competitive inhibitors of phosphate assimilation in plant cells Large-scale expression profiling experiments indicate the existence of cross-talk between developmental senescence and responses to abiotic stresses (Allu et al 2014; Buchanan-Wollaston et al 2005)
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