Chromium Toxicity in Plants: Signaling, Mitigation, and Future Perspectives

Abstract

Plants are very often confronted by different heavy metal (HM) stressors that adversely impair their growth and productivity. Among HMs, chromium (Cr) is one of the most prevalent toxic trace metals found in agricultural soils because of anthropogenic activities, lack of efficient treatment, and unregulated disposal. It has a huge detrimental impact on the physiological, biochemical, and molecular traits of crops, in addition to being carcinogenic to humans. In soil, Cr exists in different forms, including Cr (III) “trivalent” and Cr (VI) “hexavalent”, but the most pervasive and severely hazardous form to the biota is Cr (VI). Despite extensive research on the effects of Cr stress, the exact molecular mechanisms of Cr sensing, uptake, translocation, phytotoxicity, transcript processing, translation, post-translational protein modifications, as well as plant defensive responses are still largely unknown. Even though plants lack a Cr transporter system, it is efficiently accumulated and transported by other essential ion transporters, hence posing a serious challenge to the development of Cr-tolerant cultivars. In this review, we discuss Cr toxicity in plants, signaling perception, and transduction. Further, we highlight various mitigation processes for Cr toxicity in plants, such as microbial, chemical, and nano-based priming. We also discuss the biotechnological advancements in mitigating Cr toxicity in plants using plant and microbiome engineering approaches. Additionally, we also highlight the role of molecular breeding in mitigating Cr toxicity in sustainable agriculture. Finally, some conclusions are drawn along with potential directions for future research in order to better comprehend Cr signaling pathways and its mitigation in sustainable agriculture.

Current Status of Biotechnological Approaches to Enhance the Phytoremediation of Heavy Metals in India—A Review

“…Studies that assessed the molecular alterations brought about by Cr(III) and Cr(VI) on the germination of kiwifruit pollen came to the conclusion that none of the Cr species had genotoxic consequences. Both caused a sharp fall in the amounts of ATP and a substantial reduction in the proteins associated with mitochondrial oxidative phosphorylation [50].…”

Estimation and photocatalytic reduction of toxic chromium metal ions from environmental samples by zinc-based nanocomposite

“…Chromium is a dangerous heavy metal that can be discharged into the environment through a variety of industrial processes including electroplating, mining, printing, and dyeing. 1,2 In aqueous solutions, chromium exists primarily in two stable oxidation states: trivalent Cr( iii ) and hexavalent Cr( vi ). 3 Chromium output and application have increased over the last few decades, reaching 41 million metric tonnes globally.…”

“…It is crucial to remember, however, that the quantities of hexavalent chromium and other pollutants in tobacco products might vary depending on the product. 1,2 However, the amounts of hexavalent chromium and other pollutants in tobacco products might vary depending on factors such as the geographical region where the tobacco is cultivated, cultivation practices, and processing procedures.…”

Metal-Resistant PGPR Strain Azospirillum brasilense EMCC1454 Enhances Growth and Chromium Stress Tolerance of Chickpea (Cicer arietinum L.) by Modulating Redox Potential, Osmolytes, Antioxidants, and Stress-Related Gene Expression

“…Heavy metals can be accumulated in plant tissues and organs, causing adverse impacts on the performance and yields of crops [1][2][3]. One of the major heavy metals being toxic to plants is chromium (Cr), which can be found in soil and water [4], and can enter the soil initially from natural sources such as chromite.…”

“…One of the major heavy metals being toxic to plants is chromium (Cr), which can be found in soil and water [4], and can enter the soil initially from natural sources such as chromite. Excess Cr found in soil and water is due to several human activities, including tanning, mining, and other activities that produce Cr-containing effluents and atmospheric depositions [3,5,6]. Like other heavy metals, Cr can have detrimental impacts on plant growth, morphology, performance, and gene expression [3,[7][8][9].…”