Transcriptome analysis of differentially expressed genes in lily leaves under selenite application

Selenium (Se), an essential trace element for human health, is acquired primarily through the consumption of Se-enriched foods. Lily (Lilium lancifolium Thunb.) is a traditional Chinese medicinal plant that efficiently assimilates selenite through foliar uptake. This investigation elucidates the phytophysiological responses and molecular regulatory networks underlying selenite metabolism in lilies through comprehensive transcriptomic characterization. The experimental treatments consisted of graded selenite concentrations (0-8.0 mmol/L), revealing 2.0 mmol/L as the optimal concentration for enhancing biomass production and osmoprotectant accumulation. High-throughput RNA sequencing generated 59.38 Gb of clean data, yielding 76,814 functionally annotated unigenes. GO analysis revealed that the unigenes were involved mainly in cell, binding and cellular processes. Through KEGG pathway enrichment analysis, differentially expressed genes were shown to be involved mainly in translation and carbohydrate metabolism predominant pathways. Validation through RT-qPCR confirmed that pivotal enzymatic regulators including sulfite reductase, serine acetyltransferase, sterol methyltransferase, cystathionine beta-lyase, mitochondrial translation, and methionone s-methyltransferase, are important enzyme-encoding genes involved in the metabolic pathway of selenite in lily. Moderate Se exposure upregulated the expression of carbohydrate metabolism pathway genes, including SUS, SPS, and Inv genes, which was correlated with increased growth parameters. In contrast, supraoptimal concentrations induced a reactive oxygen species burst. Moreover, the expression levels of antioxidant genes such as superoxide dismutase, catalase, ascorbate peroxidase, glutathione peroxidase, and glutathione reductase decreased, ultimately leading to Se toxicity in lily plants. These results delineate the regulatory network of Se accumulation and biosynthesis in lily, which helps to elucidate the physiological and molecular mechanisms of lily growth under Se accumulation.