Total RNA were extracted from roots using Trizol reagent (Invitrogen, United States), and genomic DNA contamination in RNA samples were digested by DNase (Promega, United States). Then, about 500 ng of total RNA was reversely transcribed into first-strand cDNA using a PrimeScript® RT Reagent kit (TaKaRa, Japan) following the manufacturer’s instructions. qRT-PCR reactions were performed in a ABI 7500 real-time PCR machine. Each reaction contained 10 μl of 2 × SYBR Green Master Mix reagents, 1 μl of cDNA samples, and 0.5 μl of 10 μM primers in a final volume of 20 μl. The reaction conditions were as follows: 95°C for 30 s, followed by 40 cycles of 95°C for 15 s, 60°C for 30 s, and 72°C for 30 s. The GAPDH gene was used as an internal control to normalize target gene expression. Each experiment was conducted in three biological replicates. Each biological replicate was run with three independent cDNA samples. Gene specific primers for IRT1, FRO2, FRD3, NHX1, NHX2, NHX5, AHA2, ZEP1, YSL1, YSL2, SAUR21, NAS1, and GAPDH were listed in Supplementary Table S1.