Abstract
(1) Background: Eragrostis plana Ness is a invasive C4 perennial grass in South America and very adaptable to environmental stresses. Our hypothesis is that there is a transgenerational cross-talk between environmental stresses and weed response to herbicides. This study’s objectives were to: (1) evaluate if E. plana primed by drought stress (DRY), a sub-lethal dose of quizalofop-p-ethyl (QPE), or a combination of both drought and herbicide stresses (DRY × QPE), produce a progeny with decreased sensitivity to quizalofop and (2) investigate the potential mechanisms involved in this adaptation; (2) Methods: A population of E. plana was isolatedly submitted to treatments for drought, quizalofop or drought plus quizalofop for two generations. The progenies were analyzed for sensitivity to the herbicide quizalofop and performed biochemical, chromatographic and molecular analyses.; (3) Results: In the G2 generation, the quizalofop-treated CHK population had reduced stomatal conductance and increased hydrogen peroxide and lipid peroxidation. On the other hand, there was no change in stomatal conductance, hydrogen peroxide level, and lipid peroxidation in the quizalofop-treated DRY population. In addition, this population had increased antioxidant enzyme activity and upregulated CYP72A31 and CYP81A12 expression, which was accompanied by reduced quizalofop-p-ethyl concentrations; (4) Conclusions: E. plana demonstrated a capacity for transgenerational adaptation to abiotic stresses, with the population exposed to drought stress (DRY) becoming less sensitive to quizalofop-p-ethyl treatment.
Highlights
South African lovegrass (Eragrostis plana Ness) is a perennial C4-grass species native to southern African savannas [1]
The main tolerance mechanisms induced by herbicides include antioxidant enzymatic complexes such as superoxide dismutase (SOD), catalase (CAT), and ascorbate peroxidase (APX) enzymes [9,10], as well as a complex of enzymes that metabolize xenobiotics, such as cytochrome P450 monooxygenases (CYP450), glutathione-S-transferase (GST), and glycosyltransferases (GT) [11]
4 mL supernatant was collected from falcon tubes, 600 mg MgSO4, 200 mg primary-secondary amine (PSA), and 20 mg graphitized carbon black (GCB) was added and tubes were vortexed for 1 min and centrifuged for 10 min at 5000 rpm
Summary
South African lovegrass (Eragrostis plana Ness) is a perennial C4-grass species native to southern African savannas [1]. It was introduced in Southern Brazil as a forage species and became a rapidly invasive weed species in grassland within a few years after its introduction [2]. Inhibition of ACCase enzyme in grasses causes a drastic reduction in phospholipids synthesis, disrupting membrane biosynthesis, especially in meristematic regions [14]. It is possible that abiotic stresses, which can stimulate antioxidant enzyme machinery, may allow E. plana progeny to be more tolerant to ACCase-inhibiting herbicides than its parents. Mechanisms of resistance of Echinochloa crus-galli to quizalofop, for example, are related to the increased activity of GST enzymes and antioxidants [9]. We are assessing whether the antioxidant enzyme machinery and the mechanisms of herbicide resistance could be involved in this process
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