Seed priming with nitric oxide and/or spermine mitigate the chromium toxicity in rice (

Abstract

Chromium (Cr) is a serious environmental contaminant that drastically limited the crop yields. Nitric oxide (NO) and spermine (Spm) portrayal significance in improving the plant tolerance against abiotic stresses. Therefore, we investigate the protective efficacy of seed priming with NO (100 μM) and/or Spm (0.01 mM) in minimising the Cr-induced toxic effects in rice (Oryza sativa L.) plants. Our outcomes revealed that Cr alone treatments (100 μM) notably reduced the seed germination rate, plant growth, photosynthetic apparatus, nutrients uptake and antioxidant defence system, but extra generation of reactive oxygen species (ROS). Interestingly, the combine applications of NO and Spm significantly reversed the Cr-induced toxic effects by reducing the Cr-accumulation, maintaining the nutrient balance, improving the germination indices, levels of photosynthetic pigments (chl a by 24.6%, chl b by 36.3%, chl (a + b) by 57.2% and carotenoids by 79.4%), PSII, photosynthesis gas exchange parameters and total soluble sugar (74.9%) by improving antioxidative enzyme activities. As a result, NO + Spm lowered the accumulation of oxidative markers (H2O2 by 93.9/70.4%, O2˙− by 86.3/69.9% and MDA by 97.2/73.7% in leaves/roots), electrolyte leakage (71.4% in leaves) and improved the plant growth traits. Based on these findings, it can be concluded that NO triggers Spm to minimise the Cr-accumulation and its adverse effects on rice plants. Additionally, combined treatments (NO + Spm) were more effective in minimising the Cr-induced toxic effects in comparison to NO and Spm alone treatments. Thus, co-exposure of NO and Spm may be utilised to boost rice tolerance under Cr stress conditions.

Calcium Oxide Nanoparticles Have the Role of Alleviating Arsenic Toxicity of Barley

“…In general, plant roots have a higher tolerance to heavy metals than shoots. Hence, less translocation of toxic metals accumulated in roots to shoots is a trait associated with higher tolerance ( Cui et al, 2018 ; Tian et al, 2019 ; Basit et al, 2022 ). In this study, we quantified As translocation of roots to shoots in the two barley genotypes and the effect of CaO NPs on As translocation ( Figure 6C ).…”

Screening of rice cultivars for Cr-stress response by using the parameters of seed germination, morpho-physiological and antioxidant analysis

“…The plants roots were inhibited under Cr toxicity, especially in the HV10 cultivar ( Table 3 , Table 4 ). It might have happened because the roots are the primary source that comes in contact with the heavy metal contamination ( Ganesh et al, 2008 ; Basit et al, 2022 ). First, plants uptake Cr contents through the nutrient solution, it accumulates inside roots, and it may decrease the polysaccharide inside the roots cell wall which further causes cellular elongation restriction and later-stage plant growth and development damage ( Alam et al, 2021 , Terzi and Yıldız, 2021 , Ao et al, 2022 ).…”

“…Most probably, it built a Cr-detoxification mechanism, which reduced oxidative stress and ultimately improved the photosynthetic capabilities. It further lowered the electrolyte leakage and provided membrane stability, and production by reducing the ROS extra-generation, and accumulation ( Adhikari et al, 2020 , Devi and Kumar, 2020 , Basit et al, 2022 ). Earlier investigations also supported the outcomes obtained from a recent study that plants build some mechanism to uphold the cellular metabolism by lowering the generation of free radicals that eventually reduce the ROS, and MDA levels as well as electrolyte leakage.…”

“…Cr cause severe phytotoxic effects on plants growth, and biomass by decreasing the photosynthetic rate, disturbing mineral uptake balance, and increasing Cr uptake ( Singh et al, 2021 ). It is noticed that Cr stress cause reduction in seed germination rate, and disturb the antioxidative defense mechanism as well ( Basit et al, 2021a , Basit et al, 2021c , Basit et al, 2022 ). It is revealed that Cr uptake, and translocation minimize the germination, and growth ratio, negatively effects on chlorophyll pigments production, and PSII system, and increase electrolyte leakage by stimulating the ROS generation ( Wakeel et al, 2020 ), and ultimately crop yield is compromised.…”

“…In addition, Cr accumulation cause cellular structure damage which further increase the cellular oxidative damage by triggering the ROS over-production such as MDA, H 2 O 2, and EL ( Patra et al, 2019 ). Higher ROS accumulation cause membrane peroxidation of lipids, interruption of membrane organization and function, beside the oxidation of cellular macromolecules such DNA and proteins ( Farid et al, 2017 , Wakeel et al, 2019 , Basit et al, 2022 ). To overcome the adverse effects of ROS production, and accumulation, plants develop a specific mechanism named as antioxidative defense system that includes both enzymatic and non-enzymatic ( Zaheer et al, 2020 , Kharbech et al, 2022 ).…”