Induction of somatic embryos in cultures of Asparagus racemosus Willd: an endangered medicinally important plant

Abstract

BackgroundSomatic embryogenesis is one of the most popular in vitro regeneration methods for mass micropropagation. In the present study, somatic embryogenesis via zygotic embryos was studied in Asparagus racemosus Willd. Since the callus quality plays an important role in plantlet development, therefore, compact embryogenic callus was selected for further embryogenesis.ResultsSomatic embryos were induced by zygotic embryos germinating on callus induction medium (MS media with 1.54 mg L−1 2,4-D and 0.43 mg L−1 kinetin) in dark. Thereafter, the compact embryogenic callus differentiated up on MS media with 0.1 mg L−1 NAA and 0.5 mg L−1 kinetin supplemented with various concentrations of ancymidol. An addition of 0.75 mg L−1 ancymidol resulted in significant enhancement of somatic embryo formation and no malformed embryos were observed. Scanning electron micrographs and thin sections confirmed the structures as somatic embryos. Furthermore, these embryos were transferred to the same medium supplemented with glutamine, casein hydrolysate, and 3% sucrose for conversion into green shoots. These shoots could be multiplied in vitro using BAP-supplemented medium.ConclusionsAn effective method for conservation of an overexploited threatened medicinally important species Asparagus racemosus has been developed. This is the first report of the formation of somatic embryos from zygotic embryos in A. racemosus. Ancymidol in combination with kinetin and NAA was found to be most efficient for somatic embryo maturation and germination. The established protocol would certainly advance the efficient somatic embryo induction, maturation, and germination which could be utilized for large-scale propagation of Asparagus species.