Transcriptome and metabolome analyses reveal the promoting effects of arbuscular mycorrhizal fungi on selenium uptake in grapevines

To improve the selenium (Se) uptake in grapes, the effects of arbuscular mycorrhizal fungi (AMF) on the Se accumulation in grapevines were studied under a soil Se concentration of 5 mg/kg, and the transcriptome and metabolome sequencing were used to elucidate the regulatory mechanism of AMF on Se accumulation. AMF initially decreased the biomass of grapevines, but later increased the biomass. Moreover, AMF enhanced the activities of Se metabolism enzymes (adenosine triphosphate sulfurylase, adenosine 5'-phosphosulfate reductase, serine acetyltransferase, and cysteine methyltransferase) and the Se concentration in grapevines. Compared to Se treatment alone, AMF resulted in a 20% increase in root Se concentration and a 21% increase in shoot Se concentration 60 days after treatment. Transcriptome and metabolome analyses revealed that AMF up-regulated the expression levels of inorganic phosphate transporter proteins 1-11 and down-regulated the expression levels of ABC transporter family members, water channel proteins, and sulfur transporter proteins in grapevines. In addition, AMF elevated the levels of hesperidin, naringenin, apigenin, neohesperidin, pine sapogenin, and rutin in grapevines. Therefore, AMF can enhance Se accumulation in grapes by modulating the phosphate transport pathway and the biosynthesis of secondary metabolites involved in the phenylpropane biosynthesis pathway, flavonoid biosynthesis pathway, and flavonoid and flavonol biosynthesis pathway.