Introduction
Plant tissue culture technology is being
widely used for large scale plant
multiplication.

Apart from their use as a tool
of research, plant tissue culture techniques
have in recent years, become of major
industrial importance in the area of plant
propagation, disease elimination, plant
improvement and production of secondary
metabolites.

Small pieces of tissue (named
explants) can be used to produce hundreds
and thousands of plants in a continuous
process

. A single explant can be multiplied
into several thousand plants in relatively
short time period and space under controlled

In addition, plant tissue culture is considered
to be the most efficient technology for crop
improvement by the production of
Somaclonal and Gametoclonal variants. The
micro propagation technology has a vast
potential to produce plants of superior
quality, isolation of useful variants in well-
adapted high yielding genotypes with better
disease resistance and stress tolerance
capacities (Brown et al., 1995). Certain type
of callus cultures give rise to clones that have
inheritable characteristics different from
those of parent plants due to the possibility of
occurrence of Somaclonal variability (George
et al., 1993), which leads to the development
of commercially important improved
varieties. Commercial production of Recent
Advances in Plant in vitro Culture plants
through micropropagation techniques has
several advantages over the traditional
methods of propagation through seed, cutting,
grafting and air-layering etc. It is rapid
propagation processes that can lead to the
production of plants virus free (Garcia-
Gonzales R et al., 2010). Meristem tip culture
of banana plants devoid from banana bunchy
top virus (BBTV) and brome mosaic virus
(BMV) were produced (El-Dougdoug et al.,
2011). Higher yields have been obtained by
culturing pathogen free germplasm in vitro.
Increase in yield up to 150% of virus-free
potatoes was obtained in controlled
conditions (Singh et al., 1992).
In plant cell culture, plant tissues and organs
are grown in vitro on artificial media, under
aseptic and controlled environment. The
technique depends mainly on the concept of
totipotency of plant cells, which refers to the
ability of a single cell to express the full
genome by cell division. Along with the
totipotent potential of plant cell, the capacity
of cells to alter their metabolism, growth and
development is also equally important and
crucial to regenerate the entire plant (Thorpe
T, 2007).
Basic requirement for plant tissue culture
There are some important aspects of tissue
culture. These are: (A) Aseptic condition (B)
Aeration (C) Equipment‟s and (D) Nutrient
medium.
Tissue culture is the method of „in vitro’
culture of plant or animal cells, tissue or
organ on nutrient medium under aseptic
conditions usually in a glass container. Tissue
culture is sometimes referred to as „sterile
culture‟ or „in vitro‟ culture.
(a) Aseptic condition
Tissue culture should be done in completely
aseptic condition. Dry heat is used to sterilise
equipment‟s in an incubator. Wet heat
sterilization is done in an autoclave at 120°C
at 15 lb pressure for 15 minutes. Liquid
media, which are unstable at high
temperature are sterilised by ultrafiltration.
Chemicals, such as alcohol is used to sterilise
working area and instruments. The tissue to
be cultured is surface sterilised chemically
some of the commonly used sterilising agents
are:
(I) 9-10% calcium hypochlorite, (I) 2%
sodium hypochlorite solution, (III) 10-12%
hydrogen peroxide, (IV) 1-2% bromine
water. Some other sterilising agents are: 1%
chlorine water, mercuric chloride, silver
nitrate, antibiotics etc.

(b) Aeration
Proper aeration of the tissue in the culture
medium is essential. Those tissues, which are
cultured on semi-solid medium do not require
any special method for aeration. But those
tissues, which are cultured in liquid medium
require special device for aeration.
(c) Equipment
Glassware used for tissue culture should be of
borosilicate glass (Pyrex glass), because soda
glass may hamper the growth of the tissue.
(d) Nutrient media
Plant tissue culture medium contains all the
nutrients required for the normal growth and
development of plants. It is mainly composed
of macronutrients, micronutrients, vitamins,
other organic components, plant growth
regulators, carbon source and some gelling
agents in case of solid medium (Murashige
and Skoog, 1962). Murashige and Skoog
medium (MS medium) is most extensively
used for the vegetative propagation of many
plant species in vitro. The pH of the media is
also important that affects both the growth of
plants and activity of plant growth regulators.
It is adjusted to the value between 5.4 – 5.8.
Both the solid and liquid medium can be used
for culturing. The composition of the
medium, particularly the plant hormones and
the nitrogen source has profound effects on
the response of the initial explant.
Methods of plant tissue culture
1. Micropropagation: which is a form of
tissue culture, increases the amount of
planting material to facilitate distribution and
large-scale planting. In this way, thousands of
copies of a plant can be produced in a short
time. Micropropagated plants are observed to
establish more quickly, grow more
vigorously and are taller, have a shorter and
more uniform production cycle, and produce
higher yields than conventional propagules.
Stage 0: Preparation of donor plant- To
enhance the probability of success, the
mother plant should be ex vitro cultivated
under optimal conditions to minimize
contamination in the in vitro culture (Cassells
and Doyle, 2005).

conditions, irrespective of the season and
weather on a year-round basis (Akin-Idowu
PE et al., 2009). Endangered, threatened and
rare species have successfully been grown
and conserved by micro propagation because
of high coefficient of multiplication and
small demands on number of initial plants
and space.

Stage I: Initiation stage: In this stage an
explant is surface sterilized and transferred
into nutrient medium. Generally, the
combined application of bactericide and
fungicide products is suggested. The
selection of products depends on the type of
explant to be introduced. The surface
sterilization of explant in chemical solutions
is an important step to remove contaminants
with minimal damage to plant cells (Hussain
and Anis, 2009). The most commonly used
disinfectants are sodium hypochlorite (Tilak
et al., 2009), calcium hypochlorite (Garcia
et al., 1999), ethanol and mercuric chloride
(Hussain and Anis, 2009). The cultures are
incubated in growth chamber either under
light or dark conditions according to the
method of propagation.
Stage II: Multiplication stage: This phase
is to increase the number of propagules
under which the number of propagules is
multiplied by repeated subcultures until the
desired number of plants is attained (Saini
and Jaiwal, 2002).
Stage III: Rooting stage: The rooting stage
may occur simultaneously in the same
culture media used for multiplication of the
explants. However, in some cases it is
necessary to change media, including
nutritional modification and growth
regulator composition to induce rooting and
the development of strong root growth.
Stage IV: Acclimatization stage: At this
stage, the in vitro plants are weaned and
hardened. Hardening is done gradually from
high to low humidity and from low light
intensity to high light intensity. The plants
are then transferred to an appropriate
substrate (sand, peat, compost etc.) and
gradually hardened under greenhouse.
Somatic embryogenesis: It is an in vitro
method of plant regeneration widely used as
an important biotechnological tool for
sustained clonal propagation (Park et al.,
1998). It is a process by which somatic cells
or tissues develop into differentiated
embryos. These somatic embryos can
develop into whole plants without
undergoing the process of sexual
fertilization as done by zygotic embryos.
The somatic embryogenesis can be initiated
directly from the explants or indirectly by
the establishment of mass of unorganized
cells named callus (Suman and Kumar,
2016). Plant regeneration via somatic
embryogenesis occurs by the induction of
embryogenic cultures from zygotic seed,
leaf or stem segment and further
multiplication of embryos. Mature embryos
are then cultured for germination and
plantlet development, and finally transferred
to soil. Somatic embryogenesis has been
reported in many plants including trees and
ornamental plants of different families.
There are various factors that affect the
induction and development of somatic
embryos in cultured cells. A highly efficient
protocol has been reported for somatic
embryogenesis on grapevine (Jayasankar et
al., 1999) that showed higher plant
regeneration sufficiently when the tissues
were cultured in liquid medium. Plant
growth regulators play an important role in
the regeneration and proliferation of somatic
embryos. Highest efficiency of embryonic
c(Bouquet and Terregosa, 2003) and to
introduce the genes by genetic
transformation (Maynard et al., 2003). A
successful protocol has been developed by
using this tool for regeneration of cotton
cultivars with resistance to Fusarium and
Verticillium wilts (Han et al., 2009).
Organogenesis: It refers to the production
of plant organs i.e. roots, shoots and leaves
that may arise directly from the meristem or
indirectly from the undifferentiated cell
masses (callus). Plant regeneration via
organogenesis involves the callus production
and differentiation of adventitious meristems
into organs by altering the concentration of
plant growth hormones in nutrient medium.
(Skoog and Miller, 1957) were the first who
demonstrated that high ratio of cytokinin to
auxin stimulated the formation of shoots in
tobacco callus while high auxin to cytokinin
ratio induced root regeneration.
Embryo culture: It is a type of plant tissue
culture that is used to grow embryos from
seeds and ovules in a nutrient medium. In
embryo culture, the plant develops directly
from the embryo or indirectly through the
formation of callus and then subsequent
formation of shoots and roots. The technique
has been developed to break seed dormancy,
test the vitality of seeds, production of rare
species and haploid plants (Holeman, 2009).
It is an effective technique that is employed
to shorten the breeding cycle of plants by
growing excised embryos and results in the
reduction of long dormancy period of seeds.
Intra-varietal hybrids of an economically
important energy plant “Jatropha” have been
produced successfully with the specific
objective of mass multiplication (Mohan et
al., 2011). Somatic embryogenesis and plant
regeneration have been carried out in
embryo cultures of Jucara Palm for rapid
cloning and improvement of selected
individuals (Guerra and Handro, 1988). In
addition, conservation of endangered species
can also be attained by practicing embryo
culture technique. A successful protocol has
been developed for the in vitro propagation
of Khaya grandifoliola, a plant of high
economic value for timber wood and for
medicinal purposes as well, by excising
embryos culture from mature seeds (Okere
and Adegey, 2011). Plant tissue culture
technology has an important application in
forestry by offering a mean of propagation
of elite individuals where the selection and
improvement of natural population is not
feasible and viable too.
Anther culture: Anther culture has become
the most popular method for production of
homozygous lines for rice cultivars
worldwide. Haploids can be produced by
culturing anthers or haploid plant explants.
Induction of haploidy was first reported in
Datura Innoxia by Guha and Maheshwari
(1964). Research on pea (Pisum sativum L.)
haploidy began in the 1960–1980s. Calli,
roots, shoots and embryos were produced in
anther culture (Gupta et al., 1972; Gupta
1975). More recently haploid plant recovery
from culture of isolated anthers and
microspores is attempted. Calli, embryo-like
structures, regenerated shoots and plants
were produced in anther culture (Sidhu and
Davies 2005).
Haploid production: By use of the tissue
culture techniques it is possible to produce
homozygous plants in relatively short time
period through the protoplast, anther and
microspore cultures instead of conventional
breeding (Morrison and Evans, 1998).
Haploids are sterile plants having single set
of chromosomes which are converted into
homozygous diploids by spontaneous or
induced chromosome doubling. The
doubling of chromosomes restores the
fure breeding new cultivars (Basu et al.,
2011). The term androgenesis refers to the
production of haploid plants from young
pollen cells without undergoing fertilization.
(Sudherson et al., 2008) reported haploid
plant production of sturt‟s desert pea by
using pollen grains as primary explants via
tissue culture. Now a day the haploidy
technology has become an integral part of
crop improvement programmes through
plant breeding by speeding up the
production of inbred lines (Bajaj, 1990) and
overcoming the constraints of seed
dormancy and embryo non-viability (Yeung
et al., 1981). The technique has a
remarkable use in genetic transformation by
the production of haploid plants with
induced resistance to various biotic and
abiotic stresses. Introduction of genes with
desired trait at haploid state followed by
chromosome doubling led to the production
of double haploids inbred wheat and drought
tolerant plants were attained successfully
(Chauhan and Khurana, 2011)ertility of plants resulting in production of
double haploids with potential to becomeallus was induced by culturing nodal stem
segments of rose hybrids on medium
supplemented with various PGRs alone or in
combination (Xiangqian et al., 2002). The
embryonic callus showed high germination
rate of somatic embryos when grown on
abscisic acid (ABA) alone. Somatic
embryogenesis is not only a process of
regenerating the plants for mass propagation
but also regarded as a valuable tool for
genetic manipulation. The process can also
be used to develop the plants that are
resistant to various kinds of stresses

food, fuel and space for habitation. Hence indiscriminate deforestation by man for his own interest i.e. for agriculture, construction and habitation purposesForest checks flood, drought and soil erosion. But the increasing world population re­quires more ultimately reduces the forest covered area on earth.

It is feared that in the coming decades, there is going to be an acute shortage of forest products and the ecological balance will be lost. So deforestation should be stopped. One method of avoiding this situation is afforestation with superior genotype and the conservation of forest by adopting some scien­tific and technical measures. The most common traditional measure is the rapid propagation and plantation of forest trees. Many forest trees are propagated vegetatively by cuttings, grafting, layering’s etc.

These methods produce the plant geneti­cally alike to the parent plants, but there are some difficulties. Only a small number of plants can be produced by this way and it takes years to build up enough stock for planting in fields or forests. Sometimes the method proves to be im­possible.

The long life cycle of trees also makes development of superior varieties a very lengthy and tedious process. Traditional methods of tree breeding and improvement, particularly in the area of genotype evolution with respect to grow­th rates, cold hardiness, disease resistance, tol­erance to draught or chemicals may take many years to produce a desired hybrid and sometimes it is not easy to raise such improved tree hybrid.