Abstract:
Identification of the structures 'Proembryo' and 'Embryo' is important in studies on
somatic embryogenesis. Therefore, characteristic features of these two structures
should be identified and clarified in such a study.
The main objective of this study was to identify and characterize the meristematic
globules developed from in vitro proliferating buds of Musa, ABB, cv. Bluggoe.
Initially a critical review was done on zygotic and somatic embryogenesis in plants
related to Musa.
The uppermost part of in vitro grown buds of Musa, ABB, cv. Bluggoe was the
explant. The explants, cultured on basic Murashige and Skoog, 1962 (MS) medium
supplemented with 2,4-D (10"6 M) and BAP (10"6 M) with 3% sugar, produced
globules from about 2 weeks after inoculation. Histological studies were carried out
on these globules and also at various stages of their development.
It was found that globules with a diameter of about 2 mm or less, had only non
differentiated and differentiating cells. Thus they were termed as 'meristematic
globules'. They showed the characteristic features of a proembryo (e.g. absence of
an epidermis and vascular strands in the structures and, dense cytoplasm, a large
nucleus, a prominent nucleolus and small number of vacuoles in the individual cells.
Upon transfer to two successive liquid media, each meristematic globule developed
into an embryo (a structure with a shoot and a root apex connected by procambial
strands). The meristematic globules were confirmed as 'proembryos' as they finally
developed into embryos
