Abstract
Use of antibiotic-contaminated manure in crop production poses a severe threat to soil and plant health. However, few studies have studied the mechanism by which plant development is affected by antibiotics. Here, we used microscopy, flow cytometry, gene expression analysis and fluorescent dyes to study the effects of oxytetracycline (OTC), a widely used antibiotic in agriculture, on root meristem activity and the accumulation of hydrogen peroxide (H2O2) and nitric oxide (NO) in the root tips of tomato seedlings. We found that OTC caused cell cycle arrest, decreased the size of root meristem and inhibited root growth. Interestingly, the inhibition of root growth by OTC was associated with a decline in H2O2 levels but an increase in NO levels in the root tips. Diphenyliodonium (DPI), an inhibitor of H2O2 production, showed similar effects on root growth as those of OTC. However, exogenous H2O2 partially reversed the effects on the cell cycle, meristem size and root growth. Importantly, cPTIO (the NO scavenger) and tungstate (an inhibitor of nitrate reductase) significantly increased H2O2 levels in the root tips and reversed the inhibition of root growth by OTC. Out results suggest that OTC-induced NO production inhibits H2O2 accumulation in the root tips, thus leading to cell cycle arrest and suppression of root growth.
Highlights
Which play critical roles in transforming chlortetracycline into less toxic glutathione conjugates[11]
Our results indicate that OTC has detrimental effects on the cell cycle in the root meristem and on root growth, whereas OTC-induced nitric oxide (NO) plays a role in inhibiting root meristem activity by inhibiting H2O2 accumulation
Flow cytometry indicated that the number of S-phase cells, which underwent DNA replication, was significantly inhibited by 63% in the root tips after OTC treatment, whereas the number of G1-phase cells was not affected (Fig. 1c)
Summary
Which play critical roles in transforming chlortetracycline into less toxic glutathione conjugates[11]. It has been demonstrated that cucurbit crops exposed to active pharmaceutical ingredients exhibit growth retardation due to disturbed nutrient and hormone homeostasis[12] These studies have revealed plant responses to high concentrations of antibiotics, studies demonstrating plant developmental responses at both the cellular and molecular levels to lower concentrations of antibiotics are still scarce. We analyzed the effects of oxytetracycline (OTC), a widely used antibiotic in agriculture, on root growth during the early development of tomato seedlings, with a focus on cell division status and the expression of cell-cycle genes in the root tips. Our results indicate that OTC has detrimental effects on the cell cycle in the root meristem and on root growth, whereas OTC-induced NO plays a role in inhibiting root meristem activity by inhibiting H2O2 accumulation
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