摘要The trace element selenium is essential for human nutrition but is distributed unevenly in soils worldwide with exten-sive selenium-deficient regions and selenium-enriched(seleniferous)areas.Neptunia amplexicaulis is one of the strongest selenium hyperaccumulator plants known and native to Australian seleniferous soils.Research in the genetic background of the selenium accumulation and tolerance mechanisms of this species lacks biotech-nological and molecular tools for functional genetics.Therefore,this study aimed to develop a de novo shoot regen-eration protocol for N.amplexicaulis and validate an selenium accumulation test system.Callus was induced on root and hypocotyl explants excised from 5-day old seedlings and cultured on an adjusted MS medium(SIM9)containing 4.5 μM Thidiazuron(TDZ)for two weeks in darkness.After this period,the TDZ concentration was reduced to 0.45 μM,and the explants were transferred to light conditions.In addition,seedlings of N.amplexicaulis,N.heliophila and Med-icago truncatula were placed on vertical MS agar plates containing 1.5 mM(standard)or 0.1 mM(low)magnesium sulphate with 0,30,90 μM sodium selenate.Initial shoot differentiation was observed 6 weeks after culture initia-tion.This regeneration response was successfully repeated in a second experiment.The outgrow of the shoot buds into complete shoots was not yet achieved but requires additional media optimization.Additionally,spontaneous shoot regeneration from a root was observed,highlighting potential for further studies.In vitro grown seedlings dem-onstrated efficient,selective selenium uptake in N.amplexicaulis and identified M.truncatula as a secondary selenium accumulator with selenium concentrations of＞300 μg Se g-1 DM.This project presents the first protocol for inducing early stages of development of indirect shoot organogenesis in N.amplexicaulis from hypocotyl and root explants as prerequisite for genetic transformation,though completing the regeneration cycle remains challenging.Neptunia amplexicaulis hyperaccumulates selenium also under in vitro conditions.