Effects of lanthanum on POD expression and DNA methylation of purple pepper under salt stress

Pepper seedlings were hydroponically cultivated in 0–20 mg/L extraneous lanthanum chloride (La3+) for different numbers of days to investigate its regulating effects under salt stress. The results showed that, depending on the salt stress of 0.75 g/L, a lower concentration of La3+ (1.0 mg/L) might result in the lowest death rate, increase POD activity and change the band type of the stem and root on the 8th day. Furthermore, a methylation analysis by the methylation-sensitive amplified polymorphism (MSAP) technique indicated that a lower concentration of La3+ (1.0 mg/L) triggered the lowest methylation level of 26.1%, of which the hypermethylation events were the primary type of methylation. In addition, the sequencing of 14 differentially expressed polymorphic fragments and the subsequent blast search revealed that La3+ could induce methylation events in salt-tolerance sequences.