Arsenite stress variably stimulates pro‐oxidant enzymes, anatomical deformities, photosynthetic pigment reduction, and antioxidants in arsenic‐tolerant and sensitive rice seedlings

Abstract

Contamination of arsenic (As) in rice (Oryza sativa L.) paddies and subsequent uptake by rice plants is a serious concern, because rice is a staple crop for millions of people. Identification of As toxicity and detoxification mechanisms in paddy rice cultivars would help to reduce As-associated risk. Arsenic tolerance and susceptibility mechanisms were investigated in 2 differential As-accumulating rice genotypes, Triguna and IET-4786, selected from initial screening of 52 rice cultivars as an As-tolerant and an As-sensitive cultivar, respectively, on the basis of root and shoot length during various arsenite (AsIII) exposures (0-50 μM). Indicators of oxidative stress, such as pro-oxidant enzymes (reduced nicotinamide adenine dinucleotide phosphate [NADPH] oxidase and ascorbate oxidase) and nitric oxide, were more numerous in the sensitive cultivar than in the tolerant cultivar. Arsenic-induced anatomical deformities were frequent in the sensitive cultivar, showing more distorted and flaccid root cells than the tolerant cultivar. Chlorophyll and carotenoid synthesis were inhibited in both cultivars, although the decline was more prominent in the sensitive cultivar at higher doses of As. Furthermore, the tolerant cultivar tolerated As stress by producing more antioxidants, such as proline, sustaining the ratio of ascorbate, dehydroascorbate, and glutathione peroxidase (GPX) activity as well as As detoxifying enzymes arsenate reductase, whereas these respective metabolic activities declined in sensitive cultivar, resulting in greater susceptibility to As toxicity.

Abiotic Stress Response to As and As+Si, Composite Reprogramming of Fruit Metabolites in Tomato Cultivars

“…This observation is in keeping with the MANOVA results ( Table 1 and Supplementary Table S1 ). One possible biological interpretation is that Arsenic toxicity, mainly in the form of oxidative stress, determined a chain of physiological and biochemical changes within ripening tomato fruit to produce a network of oxidizing/reducing mechanisms more complex than that observed in roots and shoots ( Tripathi et al, 2015 ; Pandey et al, 2016 ). In this context the alleviation of As-induced stress effected by Si was less clear cut than in roots and shoots ( Romero-Aranda et al, 2006 ; Gunes et al, 2007 ; Cao et al, 2015 ) and more effective on the long term.…”

Biochemical and molecular changes in rice seedlings (Oryza sativa L.) to cope with chromium stress

“…Tripathi et al . () reported that a tolerant rice cultivar produced more antioxidants, such as proline, dehydroascorbate and glutathione peroxidase, whereas these declined in a sensitive cultivar, resulting in greater susceptibility to arsenic. Apart from acting as an osmolyte, proline contributes to stabilising subcellular structures, scavenging free radicals and buffering cellular redox potential under stress conditions (Ashraf & Foolad ).…”

Characterisation of a putative glutamate 5‐kinase from Leishmania donovani

“…It is noteworthy that arsenic‐contaminated soil has a harmful effect on plant growth through perturbation of numerous metabolic pathways and other biological functions and antimony‐contaminated soil induces similar adverse effects on growth . Strikingly, plants exposed to either inorganic arsenic or antimony respond by increasing their intracellular proline content . In leishmania, no changes in expression of G5K, glutamate‐5‐semi‐aldehyde dehydrogenase or pyrroline‐5‐carboxylate reductase have been noted in whole‐genome sequencing, proteomics or gene expression studies comparing drug‐sensitive and drug‐resistant parasites .…”