Auxins play an important role in stem initiation and
elongation which involves in different features of
growth and developments in higher plants. The auxins 2, 4-D are strong promoters of callus induction and growth
of cell suspensions. There are only a few examples of
the shoot and root induction by phenoxy auxins in tree
tissue cultures (Zaerr and Mapes, 1982). For shoot
induction generally requires the combination of auxin
and cytokinin. However, auxin should be used carefully
since too much auxin favors callus growth. Moreover, for shoot initiation in some explants, the production of
endogenous auxin is sufficient for induction of shoots in
larix decidue (Bondga and Von-Aderkas, 1992). The
number of shoots induced on MS medium (Murashige
and Skoog, 1962). The auxin signal is predictable by
plant cells and rapidly converted to a wide variety of
responses in the growth and development of plant
organs. These comprise alters in the direction of growth,
shoot and root branching, and vascular differentiation
(Leyser, 2001).
The plant cell division and growth of tissue, cells
cultured in vitro require an external source of auxin
(Petrasek et al., 2002). The proportion of external to
internal auxin concentrations is essential for regulation
of the different stages of the standard growth cycle. The
type of auxin used in the medium influences culture
morphology (Hofmann, et al., 2004). Most of the plants
naturally contain cytokinins such as 6-furfuryl- aminopurine, Ribosyl zeatin, Zeatin Isopentenyl adenine and Dihydro zeatin. These endogenous cytokinins
interact with exogenous auxin 2, 4-D may lead to
shoot induction. Auxin pulse produced a clear effect
improving regeneration (Pascual and Marin et al., 2005). Indeed, auxins obviously involved in
morphological changes since it regulates plant cell
division, elongation, and differentiation (Chen, 2001). The effect of a liquid 2, 4-dichlorophenoxyacetic acid
(2, 4-D) influence on the adventitious regeneration of
both shoots and roots in the regeneration medium
containing 2, 4-D concentration (Pascual and Marin et
al., 2005). Numerous alterations occur in plant
morphology by lighting conditions and altering
hormone composition in the regeneration medium
(Gentile et al., 2002).
Orthosiphon stamineus is a medicinal plant belongs to
Lamiaceae which is distributed mainly in South East
Asian countries. This plant was reported to have
secondary metabolites with biological activity
properties; therefore, it has a great potential value for
the development of this plant through in vitro
propagation. This may help to develop an alternative
documentary repository protocol for this plant. In the
past, few micro propagation protocols have been
developed using MS medium with an auxin-cytokinin
combination of different concentrations for this plant;
alternatively, this protocol may influence the ability to
develop whole plants. The aim of this study was to
develop a new protocol for the development of whole
plantlets with more number of nodes in a single shoot
using MS medium with different concentrations of
auxins such as 2, 4-D, NAA and IBA (0.5 – 3.0 mg/l)
on nodal explants of O. stamineus.
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