Abstract:
Selenium (Se) is an essential trace element for humans and animals, and adequate Se nutrition heavily relies on sufficient Se in plants. Plants acquire Se predominantly through root uptake from soil, however, large areas in the world are deficient in Se. To increase the Se absorption and accumulation of Se in plants, selenate and selenite have traditionally been applied. Nevertheless, these chemicals are highly soluble and prone to loss via runoff and leaching, posing risks of secondary soil and water cocontamination and exhibiting low utilization efficiency by plants.Various novel Se biofortification techniques are emerging to address these challenges. This study summarized the progress in the researches of current Se biofortification technologies within soil-plant systems. Distinguished by the approaches to enhancing selenium (Se) uptake and accumulation in plants, novel Se biofortification technologies encompass several strategies. These include utilizing genetic engineering to enhance plants' capacity for Se uptake, utilization, and accumulation; employing nanotechnology to produce highly efficient nano-selenium formulations (fertilizers); leveraging functional microorganisms to activate Se in the soil, thereby synergizing Se uptake; and producing organic fertilizers with high Se content from the by-products of industrial and agricultural activities in Se-rich regions. Genetic engineering techniques primarily aim to modify the inherent genetic traits of plants, enabling them to possess greater Se absorption and accumulation capabilities and to stably transmit Se-enriched traits to subsequent generations. Nano-selenium biofortification mainly harnesses nanotechnology to improve Se bioavailability and reduce its toxicity, featuring a relatively short synthesis cycle and a broad safe dosage range, thus holding the potential to replace traditional inorganic Se fertilizers. Microbial-assisted biofortification exploits microorganisms' ability to transform Se, increasing the available Se forms in the soil-plant system and facilitating Se uptake by plants, thereby elevating Se content. The slow-release Se fertilizers derived from Se-rich organic materials fully utilize Se-rich plants and their by-products grown in Se-rich or Se-contaminated areas to produce slow-release Se fertilizers, which not only enhance crop Se content but also improve resource recycling and utilization efficiency. To expedite the practical application of these novel Se-enrichment technologies, future research should focus on the following areas: 1) investigating the genetic mechanisms underlying Se uptake and transformation in crops and breeding Se-rich crop varieties; 2) optimizing the preparation methods of nano-selenium biofertilizers to enhance their stability and bioactivity; 3) screening and identifying microorganisms capable of Se transformation and exploring their transformation mechanisms; 4) developing and applying Se-rich slow-release organic fertilizers, as well as determining how to regulate Se release rates to align with the demands of plant growth cycles.