Androgenesis, gynogenesis, significance of in vitro production of haploids

2.  The Significance of haploids in the field of genetics and plant breeding has been
realized for a long time.
 However their exploitation remained restricted because of low frequency with
which they occur in nature.
 Spontaneous production of haploids was attempted through distant hybridization,
delayed pollination, application of irradiated pollen hormone treatment and
temperature shock. However none of this Methods were dependable and
repeatable.
 Guha and Maheshwari (1964) introduced the first haploid embryos and plantlits
by culturing the excised anthers of Dutura innoxia in lab conditions. After this
experiment, several scientists worked in the direction of In vitro production of
haploids.

3.  Now much progress has been made in producing the haploids of several
economically important plants including wheat, rice, marge, etc.
 So far, the haploids have been produced from anther culture of more than 170
species, and in approximately so species, it is reported from the invitro female
gametophyte culture.
 Here we are going through the In vitro production of haploid production and its
Significance

4.  The production of haploids through anther or pollen culture is called
androgenesis.
 The principle is to halt the development of pollen cells in to a gamete and induce it
in a suitable environment to develop into a haploid plant.
 2 types;
1. Direct androgenesis : the formation of an embryo directly from pollen or
microscope without callus.
2. Indirect androgenesis : the formation of an embryo with an intermefiary callus
stage.
 The development of haploids through androgenesis depends on several factors
that include the genotype of donor plants, stage of microspore or pollrn,
physiological status of donor plants, and pre-treatments of anthers.

5. 1. ANTHER CULTURE
 In Vitro culture of anthers of suitable stage in a culture medium to produce
haploid plants.
 It is rather simple, quick and efficient.
Procedure
 Select flower buds of suitable stage from young plants grown under controlled
conditions of temperature, light and humidity.
 Surface sterilize the flower buds.
 Remove stamens- Dip in absolute alcohol and remove anthers under aseptic
conditions.
 Test the stage of pollen development using 1% Acetocarmine – uninucleate stage is
the most ideal stage anthers of the remaining stamens are detached and cultured
in a medium (Nitsch medium, M S medium).
 Anthers are placed horizontally on the medium 1 maintained in alternating
periods of light and darkness.(at 28 °C ). In responsive anthers, the wall tissues
gradually turn brown and undergo androgenesis.

6.  Anther culture has an advantage over microspore culture is being very quick for
practical purposes, and also sometimes the anther wall has an influence on the
development of microspores in it, acting as a conditioning factors.
2. MICROSPORE / POLLEN CULTURE
 In vitro culture of isolated pollen grains in a suitable culture medium to produce
haploid plants.
(E.g. In Datura, Petunia, Potato, Barley, wheat, rice, maize)
 Mainly done by nurse culture technique;
Isolated pollen grains are placed on a sterilised filter paper raft (8mmx8mm)
placed on cultured anthers – derive nutrition from the exudates diffusing through
the filter→→ haploids.
 Advantage of pollen culture over anther culture is, it can avoid the resultant
population of plants with various ploidy levels .

7. Other advantages are;
 Uncontrolled effects of the anther wall and other associated tissues are
eliminated and various factors governing androgenesis can be better regulated.
But disadvantageous where anther wall has a stimulatory effect.
 The sequence of androgenesis can be observed starting from a single cell.
 Microspores are ideal for uptake, transformation and mutagenic studies, as
microspores may be evenly exposed to chemicals or physical mutagens
 Higher yields of plants per anther could be obtained.

9.  The process of development of haploids through Ovary or ovule culture is known
as gynogenesis.
 It was first reported in Hordeum vulgare (Barley) by San Norm in 1976, and later
the technique was used for haploid production in wheat, maize, tobacco, sunflower
, sugar beet , and other economically important plants.
 This approach is used where androgenesis is not effective in producing haploids.
 To-date, haploids have been produced in about 19 species using the approach of
Gynogenesis.
 This method has a two-way approach, which includes direct embryogenesis and
indirect embryogenesis that goes through callus formation followed by plant
regeneration on another medium.

11. Haploids are organisms which have one set of
chromosomes.
When we use gametes of a single parent to produce a plant
that technique is known as haploid plant production.The
resultant plant body will have the same genetic sequence
and will be the same as a gamete.
The interest in haploids stems largely from their
considerable production of homozygous plants and in their
studies on the detection of mutations.

12. Haploid plants have been a useful resource for genetic
studies in identifying recessive mutations and plant
breeding programs.
Haploid production reduces the time required to produce
the improved cultivator of a specific plant.
Haploid plant production used in plant breeding to obtain
a pure homozygous line by using colchicine to double the
chromosome number,or by depending on spontaneous
mutations.

13. Its major importance is improvement of plant or crop
production.
Somaclonal variation leads to the creation of additional
genetic variability.
Traits for which somaclonal mutants can be improved by
using haploid plant production technique, during invitro
culture include resistance to disease, herbicides,high salt
concentration,mineral toxicity and tolerance to
environmental or chemical stress as well as for increased
production of secondary metabolites.

14. It is beneficial in developing genetically homozygous plant
which serve as parents in crossbreeding.
Homozygous plants can be raised by diploidization of
haploids by colchicine treatment.
In androgenic culture methods,anther culture has an
advantage over microscope culture in being very quick for
practical purposes,and also sometimes the anther wall has
an influence on the development of microspores in
it,acting as conditioning factor.

15.  Haploid plants , have been a useful resource for genetic studies
in identifying recessive mutations and plant breeding
programs.Haploids can be produced in vivo or in vitro.In Vivo
techniques includes androgenesis , gynogenesis, distant
hybridization, irradiation effects, chemical treatments.In vitro
technique includes androgenesis that involves anther culture
and microspore culture and gynogenesis.The major importance
of haploid plant production technique, during in vitro culture,
includes resistance to disease, herbicides,high salt
concentration,mineral toxicity and tolerance to environmental
or chemical stress,as well as for increased production of

16. Secondary metabolites.It is beneficial in developing
genetically homozygous plants which serve as parents in
cross breeding.

17. Thank you