Title : Iron oxide nanoparticles confer cross-tolerance to arsenate-induced stress in rice roots by engaging nitric oxide
Abstract:
Plants exhibit sensitivity and can face significant risks from a range of stressors and environmental pollutants. The term "cross tolerance" is employed because exposure to one stressor enhances the plant's ability to withstand a different stressor. Understanding cross-tolerance in plants is crucial for developing strategies to enhance their resilience and adaptability to a changing environment, ultimately improving crop productivity and plant health.Top of form soil pollution caused by heavy metals as an abiotic stress has emerged as a significant concern and has the capacity to impede plant growth, diminish crop yield and present a potential hazard by infiltrating the food chain, thereby endangering human health. It becomes apparent that FeO NPs can have toxic effects at higher concentrations, but when combined with HMs, they act as cross tolerating agent that promotes plant growth against HMs. Given this perspective, it's intriguing to investigate the potential of FeO NPs as agents that promote cross-tolerance against the phytotoxic effects of HMs in plants. Additionally, among various types of NPs, the dose-dependent effects and cross tolerating role of FeO NPs are noticeable. However, their potential in mitigating heavy metal-induced stress, such as arsenic contamination, remains poorly understood. Arsenic (As) pollution in soil represents a notable menace to the developmental patterns of agricultural crops, acting as a major obstacle to crop productivity. Recent literature indicates that FeO NPs possess excellent adsorption properties, capable of adsorbing metals at their surfaces due to their magnetic and electrical properties. Hence experiment was conducted to explore the role of FeO NPs in alleviating arsenic As(V) toxicity in rice seedlings.
FeO NPs at a concentration of 500 μM was able to contribute in developing cross tolerance against arsenic As(V)-triggered toxicity in rice. As(V) significantly changed growth characteristics, photosynthetic efficiency, nutrient levels and biochemical factors. FeO NPs was noted to negatively impact the growth of rice seedlings when used independently. However, these nanoparticles counteracted the adverse effects of As(V) by limiting its entry, potentially through the contribution of NO in rice roots. Additionally, the study revealed that As(V) toxicity greatly inhibited gene expression related to NO (OsNoA1 and OsNIA1) and proline metabolism. Yet, FeO NPs counteracted As(V) toxicity by enhancing proline metabolism and prompting NO-mediated enhancement of antioxidant enzymes, specifically glutathione-S-transferase. These mechanisms might explain the decrease in As(V) toxicity within rice roots. In summary, FeO NPs seem to function as a shield against As(V), limiting its absorption by roots and providing cross tolerance by regulating diverse morphological, biochemical, and molecular traits. This study underscores the need for further scientific inquiry to comprehensively understand how these nanoparticles may alleviate stress on plants over extended periods in the soil, which is important for making informed decisions in the realm of agriculture sustainability. The analysis of transcriptomics and proteomics could offer insights into the signaling pathways involved under NPs exposure.
