GYNOGENESIS

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SIJI SKARIAHM.Sc BOTANYST.THOMAS COLLEGEKOZHENCHERRY

INTRODUCTION The dominant life form of higher plants is

the free-living sporophyte.

The sporophyte is the resultant of fertilization of male and female gametes and contains a set of chromosomes from each parent which genomic constitution is 2n.

Cells of the gametophytes carry half the sporophytic set off of chromosomes [n]

In diploid plants, which contain two sets [2n] of chromosomes

Haploid plants are defined as sporophytes having only a single set of chromosomes (n;gametophytic number of chromosome).

Several strategies and methods have been worked for the production of haploid plants.

Two methods: Androgenic methods Gynogenic methods

Androgenic Methods: haploid production of plants

through anther or microspore culture has been referred to as androgenesis

Gynogenic methods: haploid production of plants

from ovary or ovule culture has been referred to as gynogenesis

GYNOGENESIS It is the formation of sporophyte from the female

gametophyte on artificial medium

“It is the process by which culturing of unfertilized ovaries to obtain haploid plants”

First report in Barley by San Noem in 1976

Later works done in Wheat, Rice, Maize, tobacco etc…….

In most cases,the optimum stage for ovary culture is the nearly mature embryo sac,but in rice ovaries at free nuclear embryo sac stage are the most responsive.

There are two methods for in vitro production of gynogenic haploids

They are : ovary culture ovule culture

in vitro gynogenesis is used as a alternate technique in species where anther/pollen culture is unsuccessful.

The gynogenic plants may arise through direct embryogenesis or the gametic cells may form a callus followed by plant regeneration.

Both ovary slice culture and ovule culture can be carried out simultaneously for achieving in vitro gynogenesis

TWO STAGES1.INDUCTION ovaries are located on a liquid medium(MS)

having low auxin content and kept in dark.2.REGENERATION ovaries are transferred into agar medium

with high auxin content and kept in light.

SOME WORKS…..

Gerbera jamesonii

Hordeum vulgare

Oryza sativa

Triticum aestivum

Allium cepa

Nicotiana tobacum

Brassica oleraceae

NAME OF PLANT

FAMILY Asteraceae

Poaceae

Poaceae

Poaceae

Lilliaceae

Solanaceae

Brassicaceae

TECHNIQUES The experimental plant is kept in controlled

condition for few days and a normal sized flower is taken for culture.

The flower is surface sterilized with 5% sodium hypochlorite for 10 minutes and then washed with sterile distilled water 3-4 times.

Using aseptic method,the pistil is kept on a petri dish after removing sepals,petals and stamens.In the petridish only fully grown mature pistil should be taken.

Then the excised ovary is inoculated on the basal medium aseptically.

The culture is incubated at 25 c for 16 hours photoperiod with 2000 lux light intensity.

o If the ovary is unpollinated,it will not grow on a simple medium containing mineral salts and sucrose.

o With the addition of B vitamins to the medium,normal healthy fruits can be obtained.

TRIGGERING FACTORS…Pretreatment:- cold/ heat shock treatments cold pretreatment of the

inflorescence/ flower enhances gynogenesis

eg: 24-28hr at 4 C in sunflower 24hr at 7 C in rice

Medium MS medium, N6, B5 etc. sucrose; 3-15% solid or liquid media phytohormones; auxin, cytokinin, 2,4-D

note: auxin can replace the pollination stimulus

growth regulators(GR); 0.125-0.5 mg/ml of MCPA( 2 methyl-4- chlorophenoxy acetic acid) induce somatic calli and somatic embryoids

DEVELOPMENTAL STAGES AT INOCULATION…

Late floweringEg:sugar beet, rice etc. Early floweringEg: mulberry, sunflower etc. Early maturing female gametophyte is

selected

IN VITRO MATURATION OF EMBRYO SAC …. The developmental pattern of the

female gametophyte in excised ovaries in vitro has been studied in onion,rice,barley etc

In an experiment with onion in which ovaries at different developmental stages were fixed at inoculation and then at 3 day intervels, in vitro maturation of the embryo sac was evident.

At day 12 in culture,only mature embryo sac were present

The maturation process is same as that of in situ maturation

Higher frequency than in situ maturation

ORGIN OF EMBRYO Embryo sac possess haploid egg cell,

but also other cells theoretically capable of forming a haploid embryo, such as synergids, antipodel cells or non fused polar nuclei.

Egg cells are predominant source of the haploid embryo(Beta vulgaris,Allium sepa etc)

An antipodel or synergid orgin of embryos has been proposed in Hordeum vulgare and Oryza sativa.

Embryos from synergids :- rice

Embryos from antipodal cells :- Allium cepa

USES The ability to produce haploid plants is a

tremendous benefit in genetics, plant breeding, plant physiology and embryology studies.

Study of genetic recombination in higher

plants. Haploids are use for mutation study

Heritability studies are simplified, due to haploid plant having only one set of chromosome hence recessive mutation are easily identified.

LIMITATIONS……… Successful in a relatively small number

of species.

Frequency of responding ovules is quite low

(1-5%)

Alisher Touraev, Brain P. Forster, S. Mohan Jain(Eds)(2009). Advances in Haploid Production in Higher plants. Springer, Heidelberg.

Sing B.D. Biotechnology. Kalyani pub.

Mahipal singh shekhawat,Vikrant,Plant Biotechnology, MJP Publishers

Google. co. in. Springer.com

REFERENCES……