An improved method of proliferation of proembryogenic calli of Mangifera indica L. var. Amrapali for scale-up of somatic embryo production

Abstract

Rapid enhancement of proliferation of PECs (proembryogenic calli), obtained from the excised nucellus tissue of var. Amrapali, with high efficiency somatic embryo production has been achieved by manipulating the medium with different growth regulators. Among the growth regulators tested, 1. 0 mg/l 2,4-D (2,4-dichlorophenoxy acetic acid) and 1.0 mg/l NAA (α-naphthalene acetic acid), either alone or with 1.0 mg/l Kn (kinetin), stimulated proliferation of the PEC in both the liquid and solid medium; although, it was more profuse (<5 times) in the liquid medium. Depending upon the physical state and growth regulator(s) supplemented to the medium, the PECs appeared in three morphotypes. Type-III PEC, which was in the form of fine suspensions of dispersible and highly proliferating single cells and small cell aggregates, showed greater potentially for differentiation of somatic embryos in both states of the medium; however, in liquid medium the globular somatic embryos dedifferentiated and callused soon after their differentiation. In contrast, on the semi-solid medium these globular somatic embryos successfully developed into cotyledonary-stage. Type-III PEC (10 mg) had the capacity to produce up to 350 somatic embryos on semi-solid medium. Such somatic embryos matured and grew into plantlets. The method offers a possibility of rapid multiplication in the mango var. Amrapali.