Harnessing the role of selenium in soil-plant-microbe ecosystem: ecophysiological mechanisms and future prospects

Selenium (Se) is the critical element that is required by various organisms for biological functions. There are numerous beneficial aspects of Se in plants such as reduced cell viability, regulation of membrane structures, chloroplast and plastid membrane stability, activation of membranous enzyme and transport of different solutes and metabolites within cell organelles. Moreover, they have also been observed to enhance photosynthesis, delayed senescence and induced plant yield in plants with decreased oxidative stress. Se uptake by different organisms occur in various inorganic forms namely, selenate, elemental Se, selenite and selenide. These are further converted into organic forms through biological pathways as selenoamino acid, selenomethionine and selenocysteine respectively. The biological processes of living cells convert these amino acids into Se-comprising proteins by replacing methionine with SeMet. SeCys is the crucial component of active sites of enzymes. Therefore, Se-biofortification in plants have been considered as pioneer approach in agriculture. Moreover, microbes undergo reductive transformation of Se that also governs its bioavailability as well as mobility within the environment. Along with its beneficial aspects, it is also considered as contaminant due to its bioaccumulation within the environment. In regard to its contaminating nature, enormous strategies have been developed so far for its treatment as well as bioremediation. Besides, there are plethora of challenges associated such as establishment of stringent discharge concentration, fate within environment along with its long-term stability. The present review mainly focuses on factors linked with Se nature and distribution in ecosystem along with its sources, speciation, toxicity, biogeochemical cycle, bioavailability, resistance and detoxification mechanisms in plants as well as microbes. By this review, we have offered the substantial insights to develop effective regulation methods for Se within the ecosystem. We have also summarised the prospects of Se-biofortification in improving agricultural practices as well as coping deficiencies within the living cells.

Automated summary

This article mainly discusses factors related to the nature and distribution of selenium in ecosystems, including its sources, speciation, toxicity, biogeochemical cycle, bioavailability, resistance, and detoxification mechanisms in plants and microbes. Through this review, we have provided significant insights for the development of effective regulatory methods for selenium within ecosystems and summarized the prospects of selenium biofortification in improving agricultural practices and coping with selenium deficiencies in living cells.