Chromium Induces Toxicity at Different Phenotypic, Physiological, Biochemical, and Ultrastructural Levels in Sweet Potato (Ipomoea batatas L.) Plants

Abstract

Crop productivity is enormously exposed to different environmental stresses, among which chromium (Cr) stress raises considerable concerns and causes a serious threat to plant growth. This study explored the toxic effect of Cr on sweet potato plants. Plants were hydroponically grown, and treatments of 0, 25, 50, 100, and 200 µM Cr were applied for seven days. This study exhibited that a low level of Cr treatment (25 µM) enhanced the growth, biomass, photosynthesis, osmolytes, antioxidants, and enzyme activities. However, significant deleterious effects in growth, biomass, photosynthetic attributes, antioxidants, and enzymes were observed at higher levels of Cr treatment. The remarkable reduction in plant growth traits was associated with the over-accumulation of H2O2 and MDA contents (410% and 577%, respectively) under the highest rate of Cr (200 µM). Under 200 µM Cr, the uptake in the roots were 27.4 mg kg−1 DW, while in shoots were 11 mg kg−1 DW with the highest translocation rate from root to shoot was 0.40. The results showed that the higher accumulation of Cr negatively correlated with the phenotypic and physiological parameters. It may be proposed that Cr toxicity causes oxidative damage as sustained by augmented lipid peroxidation, reactive oxygen species, and reduced photosynthetic rate, chlorophyll, and stomatal traits. The chloroplastic ultrastructure was damaged, and more apparent damage and size reduction were observed at higher Cr levels. Furthermore, aggregated Cr concentration positively correlates with the increase of osmolytes and superoxide dismutase (SOD) activity in the leaves of sweet potato. Moreover, improved osmolytes and SOD do not help protect sweet potato against high Cr stress. Overall, these findings will improve the understanding of the defense mechanisms of sweet potato to Cr stress.

Effect of Chromium ions on the biochemical parameters of cotton plant, Gossypium hirsutum (L.)

“…Heavy metals treatment causes serious effect to the plants due to their respirational toxicity. Kumar et al (2022) reported the mechanism of chromium stress in the plants as low concentrations (25µM) showed enhanced growth rate, photosynthetic pigments and enzyme activities while increased concentrations showed remarkable stunned growth in Ipomoea batatas (L.) plants. Accumulation of Cr ions developed a stress in plant cell which resulted in the increased proline levels in the cytoplasm.…”

Vanadium Stress Alters Sweet Potato (Ipomoea batatas L.) Growth, ROS Accumulation, Antioxidant Defense System, Stomatal Traits, and Vanadium Uptake

“…V toxicity mediates stomatal abnormalities, such as a reduction in the stomatal length, width, pore length, and width of guard cells ( Figure 9 and Table 4 ). A study reported that the reduction in the stomata size is linked with more distorted stomata under an elevated level of heavy metals in the leaves [ 30 , 55 ]. Photosynthesis, transpiration, and gas exchange can be adversely affected by reductions in stomatal size and closure frequency.…”

“…To observe the stomatal morphology, we used a published protocol [ 30 ]. To remove any debris, leaves were acetylated in 80% ethanol for two to three min.…”

“…In addition, sweet potato leaves are rich in protein, iron, calcium, fiber, carotenoids, vitamins, and total polyphenols and possess medicinal properties [ 28 , 29 ]. Sweet potato can severely affect productivity and quality under heavy metal stresses [ 23 , 30 ]. Several studies found that trace amounts of certain elements may stimulate the growth and production of horticultural crops [ 11 , 31 ].…”

Calorific Value of Zea mays Biomass Derived from Soil Contaminated with Chromium (VI) Disrupting the Soil’s Biochemical Properties

“…Because Cr(VI) does not undergo biodegradation in soil, it is far more toxic than Cr(III) towards all living organisms, including plants [35]. Chromium induces changes in plants on the phenotypic, physiological, biochemical, and ultrastructural levels [36]. Admittedly, the response of plants to exposure to Cr is manifested by growth inhibition and decreased biomass, chlorosis, and deformation of the structure of chloroplasts through the peroxidation of fatty acids and lipids in their membranes induced by an increase in lipoxygenase [37,38].…”