Silicon tackles butachlor toxicity in rice seedlings by regulating anatomical characteristics, ascorbate-glutathione cycle, proline metabolism and levels of nutrients

Abstract

Reckless use of herbicides like butachlor (Buta) in the fields represents a serious threat to crop plants, and hence to their productivity. Silicon (Si) is well known for its implication in the alleviation of the effects of abiotic stresses; however, its role in mitigating Buta toxicity is not yet known. Therefore, this study was carried out to explore the role of Si (10 µM) in regulating Buta (4 µM) toxicity in rice seedlings. Buta reduced growth and photosynthesis, altered nitric oxide (NO) level and leaf and root anatomy, inhibited enzyme activities of the ascorbate-glutathione cycle (while transcripts of associated enzymes, increased except OsMDHAR ), as well as its metabolites (ascorbate and glutathione) and uptake of nutrients (Mg, P, K, S, Ca, Fe, etc. except Na), while addition of Si reversed Buta-induced alterations. Buta stimulated the expression of Si channel and efflux transporter genes- Lsi1 and Lsi2 while the addition of Si further greatly induced their expression under Buta toxicity. Buta increased free proline accumulation by inducing the activity of Δ 1 -pyrroline-5-carboxylate synthetase (P5CS) and decreasing proline dehydrogenase (PDH) activity, while Si reversed these effects caused by Buta. Our results suggest that Si-governed mitigation of Buta toxicity is linked with favorable modifications in energy flux parameters of photosynthesis and leaf and root anatomy, up-regulation of Si channel and transporter genes, ascorbate-glutathione cycle and nutrient uptake, and lowering in oxidative stress. We additionally demonstrate that NO might have a crucial role in these responses.

Silicon Improves the Redox Homeostasis to Alleviate Glyphosate Toxicity in Tomato Plants—Are Nanomaterials Relevant?

“…Thus, although several reports state that Si application can boost Pro levels to increase the antioxidant efficiency [ 82 ], the findings reported herein confirm the hypothetical role of Pro as a stress signal, rather than as a tolerance mechanism against herbicide exposure. Similarly, Tripathi et al [ 59 ], Spormann et al [ 11 ] and Sousa et al [ 83 ] found that pesticide- and Zn-mediated increases in Pro levels were efficiently counteracted by the application of Si, salicylic acid, and brassinosteroids (24-epibrassinolide), respectively. Thus, it appears that Si and nano-SiO 2 ’s ameliorative effects on ROS homeostasis and LP in shoots are not related to the action of Pro, but rather to other antioxidant components.…”

“…Not only did plants show a better growth potential at the macroscopic level, the results concerning biomass production and organ elongation further confirmed this trend. Curiously, the only available record exploring the ameliorative features of Si nutrition against herbicide toxicity was recently published [ 59 ]. In agreement with our data, Tripathi et al [ 59 ] also observed a positive effect of Si, provided as 10 µM sodium silicate, when 25-day-old rice plants were exposed to butachlor (4 µM).…”

“…Curiously, the only available record exploring the ameliorative features of Si nutrition against herbicide toxicity was recently published [ 59 ]. In agreement with our data, Tripathi et al [ 59 ] also observed a positive effect of Si, provided as 10 µM sodium silicate, when 25-day-old rice plants were exposed to butachlor (4 µM). Furthermore, Si-mediated alleviation of GLY phytotoxicity seems also to be related to a reduced herbicide bioaccumulation, since GLY levels decreased in roots of Si and nano-SiO 2 treated plants.…”

“…Positive effects of Si, along with nano-SiO 2 , on the prevention of ROS overproduction and membrane damage in stressed plants are quite common in the literature and strongly point towards the potential of this beneficial element for plant stress management [ 18 , 19 ]. Up to now, the potential of Si to overcome pesticide-induced toxicity is limited to a very recent work, conducted by Tripathi et al [ 59 ] in rice plants treated with butachlor. In that study, authors observed that Si’s ameliorative action was linked with an improvement in nutrient uptake, maintenance of the photosynthetic potential and prevention of oxidative damage, through an upregulation of the AsA-GSH cycle.…”

Highly sensitive and selective detection of butachlor based on the resonance light scattering of doped carbon quantum dots

“…3,4 Butachlor has a significant effect on weed control, but it can also decrease the amount of very-long-chain fatty acids in the plasma membrane of crop seedlings and lead to plant cell death. 5 For example, butachlor is highly toxic to algae which are beneficial to the growth of rice plants, such as the N 2 -fixing cyanobacterium Nostoc muscorum . 6,7 On the other hand, butachlor enters environmental water from the soil, and has a significant impact on the ecological environment and food safety.…”