Fig. 5

Relative expression levels of genes (a. SKOR, b. AKT2) related to K absorption and transport in tobacco with two K supply conditions. The tobacco graft combinations included the nongrafted tobacco W (Wufeng No.2) and Y (Yunyan 87) and grafted tobacco Y/W (Y grafted onto W) and W/Y (W grafted onto Y). Different uppercase letters denote significant differences (P < 0.05) under normal K levels (5 mmol L^− 1), and lowercase letters indicate significant differences (P < 0.05) under K starvation (0.5 mmol L^− 1)