Selenium species transforming along soil–plant continuum and their beneficial roles for horticultural crops
Qingxue Guo1 , Jianhui Ye2 , Jianming Zeng3 , Liang Chen3 , Helena Korpelainen4 and Chunyang Li,2,
1College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou 311121, China 2College of Agriculture and Biotechnology, Zhejiang University, Hangzhou 310058, China 3Tea Research Institute, Chinese Academy of Agricultural Sciences, Hangzhou 310008, China 4Department of Agricultural Sciences, Viikki Plant Science Centre, University of Helsinki, P.O. Box 27, FI-00014, Finland *Corresponding author. E-mail: email@example.com
Received: 30 Aug 2022 Accepted: 01 Dec 2022 Published online: 02 Dec 2022
Selenium (Se) acquirement from daily diet can help reduce the risk of many diseases. The edible parts of crop plants are the main source of dietary Se, while the Se content in crops is determined by Se bioavailability in soil. We summarize recent research on the biogeochemical cycle of Se driven by specific microorganisms and emphasize the oxidizing process in the Se cycle. Moreover, we discuss how plant root exudates and rhizosphere microorganisms affect soil Se availability. Finally, we cover beneficial microorganisms, including endophytes, that promote crop quality and improve crop tolerance to environmental stresses. Se availability to plants depends on the balance between adsorption and desorption, reduction, methylation and oxidation, which are determined by interactions among soil properties, microbial communities and plants. Reduction and methylation processes governed by bacteria or fungi lead to declined Se availability, while Se oxidation regulated by Se-oxidizing microorganisms increases Se availability to plants. Despite a much lower rate of Se oxidization compared to reduction and methylation, the potential roles of microbial communities in increasing Se bioavailability are probably largely underestimated. Enhancing Se oxidation and Se desorption are crucial for the promotion of Se bioavailability and uptake, particularly in Se-deficient soils. Beneficial roles of Se are reported in terms of improved crop growth and quality, and enhanced protection against fungal diseases and abiotic stress through improved photosynthetic traits, increased sugar and amino acid contents, and promoted defense systems. Understanding Se transformation along the plant–soil continuum is crucial for agricultural production and even for human health.