Potassium uptake function of LbKT1 and LbSKOR from Lycium barbarum and their influence on the arbuscular mycorrhizal symbiosis.

Potassium participates in a variety of plant physiological processes and has great impact on plant growth and stress adaptation. The absorption of potassium by Plant is mediated by potassium channels and transporters, and the Shaker potassium channel gene family plays an important role in potassium uptake. Arbuscular mycorrhizal (AM) fungi form ubiquitous symbioses with plants and increase plants' potassium uptake. However, few studies have focused on the interaction of plant potassium channels from the Shaker gene family with AM fungi. In this study, the potassium uptake function of LbKT1 and LbSKOR (homologs of AKT1 and SKOR in Arabidopsis) from the Shaker gene family in Lycium barbarum was verified by the complementary assay using a yeast potassium uptake mutant. LbKT1 and LbSKOR were also overexpressed in tobacco to assess their influence on AM fungi under low and normal potassium conditions in a pot experiment. LbKT1 could rescue the phenotype of the yeast mutant, while LbSKOR could not. Overexpression of LbKT1 increased tobacco plant growth and potassium uptake and promoted the colonization of AM fungi. Meanwhile, overexpression of LbSKOR promoted potassium translocation from root to shoot and showed no obvious influence on the colonization of AM fungi. Our results suggested that the AM fungi could promote tobacco growth and potassium uptake, while the plant potassium status and the AM fungal colonization may form positive feedback in promoting tobacco potassium uptake and growth.