To expand the drought-tolerant gene resources of peanut, we conducted in vitro mutagenesis with pingyangmycinum (PYM) as the mutagen and directed screening with medium containing Hydroxyproline (HYP).After embryonic leaflets from mature peanut seed were cultured on somatic embryogenesis-induction medium containing 3-4 mg/L PYM for 4 weeks, the somatic embryos were sequentially transferred to a germination medium containing 4 and then 8 g/LHYP.