Somatic Embryogenesis in a Mistletoe — Dendrophthoe falcata (L.f.) Ettingsh

Abstract

Dendrophthoe falcata (Loranthaceae) commonly grows as a semiparasite on the branches of a wide range of trees (Singh 1954), especially Ficus religiosa and Ehretia laevis. It flowers and fruits during January to April. The tubular/ companulate flowers are orange to red in color. Several embryo sacs develop simultaneously in the same ovary and their tips which enclose the egg apparatus extend up to two-thirds the length of the style (Singh 1952). Usually, several zygotes elongate appreciably and divide vertically. This is followed by transverse divisions resulting in biseriate proembryos comprising a terminal embryonal tier and the remaining suspensor tiers. Further transverse divisions of the embryonal and suspensor tiers and elongation of the latter push the proembryos through the style into the lower part of the embryo sac (situated in the ovary) containing a four-seriate cellular endosperm. After reaching the saucer-shaped hypostase, the embryonal tier gives rise to the globular, heart-shaped, and dicot stages. In a mature embryo, the cotyledons (except in the region of the plumule) become closely appressed against each other, giving a pseudomonocotyledonous appearance. The mature embryo is peg-shaped and the cotyledonary portion remains buried in the endosperm.