1. KENYATTA UNIVERSITY
SCHOOL OF PURE & APPLIED SCIENCES
DEPARTMENT OF BIOTECHNOLOGY
UNIT NAME : PLANT & TISSUE CULTURE
UNIT CODE : SBC 322
TASK: EMBRYO CULTURE & ITS APPLICATIONS IN PLANT BREEDING
LECTURER: MRS. MARY MWANGI
DATE: 6TH
DECEMBER, 2011
MEMBERS :
1. RICHARD MWANGANGI I28/0660/2009
2. EDWIN MUTWIRI I28s/7239/2009
3. WAWERU DUNCAN I28/0588/2009
4. JULIAN SITEMBA I28/1934/2009
5. OPIYO JOHN I28/0605/2009

2. INTRODUCTION
Embryo culture is the sterile isolation and growth of an immature or mature embryo in vitro,
with the goal of obtaining a viableplant. The first attempt to grow the embryos of angioaperms
was made by hanning in 1904, who obtained viable plants from in vitro isolated embryos of two
crucifers Cochleria and Raphanus. Dietrich grew embryos of different plant species and
established that mature embryos grew normally but those excised from immature seeds failed to
achieve the organization of a mature embryo.
A picture of embryo culture
APPLICATIONS
Embryo culture is an important aspect in
plant breeding. Many developments in
this technique have come up and most of
them being positive in shortening the
breeding cycle of plants and improving
plant reproduction. The technique is
thus involved in a variety of applications in plants and these include:
Prevention of embryo abortion in wide crosses. Successful interspecific hybrids have been seen
in cotton, barley, tomato, rice and legumes. Well known intergeneric hybrids include wheat x
barley, wheat x rye, barley x rye, maize x Tripsacum. Distant hybrids have also been obtained
via embryo recue in Carica and Citrus species. Embryo rescue technique has been successfully
used for raising hybrid embryos between Actidinia deliciosa x A. eriantha and A. deliciosa x A.
arguata. Embryo culture is also used in crosses between diploids and tetraploids.
Production of haploids. Embryo culture can be utilized in the production of haploids or
monoploids. Kasha and Kao (1970) have developed a technique to produce barley monoploids.
Interspecific crosses are made with Hordeum bulbosum as the pollen parent, and the resulting
hybrid embryos are cultured, but they exhibit H. bulbosum chromosome elimination resulting in
the monoploids of the female parent H. vulgare.
Overcoming seed dormancy. Embryo culture technique is applied to break seed dormancy that
can be caused by numerous factors including endogenous inhibitors, specific light requirements,
low temperature, dry storage requirements and embryo immaturity. These factors can be
circumvented by embryo excision and culture. Seed dormancy in Iris is due to the presence of a
stable chemical inhibitor in the endosperm. American basswood seed is borne within a tough
indehiscent pericarp where the resistance is mechanical. Thus there’s difficulty in germinating
seeds of these species. By excising embryos, germination occurred without delay at all stages of
seed maturity. A potential use of this technique is in the production of seedlings from seed of

3. naturally vegetatively propagated plants such as bananas whose seed do not germinate in nature,
probably due to recalcitrant dormancy. Embryo culture techniques are thus able to produce
viable seedlings in these species.
Shortening of breeding cycle. There are many species that exhibit seed dormancy that is often
localized in the seed coat and/or in the endosperm. By removing these inhibitions, seeds
germinate immediately. Seeds sometimes take up water and oxygen gas very slowly or not at all.
E.g. Brussel sprouts, rose, apple, oil palm and iris. Hollies (llex) are important plants for
Christmas decorations. llex embryos remain in the mature heart-shaped stage though the fruits
have reached maturity. Under proper germination conditions, three years are required for seeds
of I. opaca from mature berries to complete their embryonic development and to begin
germination. The excised embryo goes through all the developmental sequences in vitro and
plants can be obtained in 2-3 weeks time. Rosa normally takes a whole year to come to flowering
and through embryo culture, it has been possible to produce two generations in a year.
Prevention of embryo abortion with early ripening stone fruits. Some species produce sterile
seeds that will not germinate under appropriate conditions and will eventually decay in soil, e.g.
early ripening varieties of peach, cherry, apricot, plum. Seed sterility may be due to incomplete
embryo development, which results in the death of the germinating embryo. In crosses of early
ripening stone fruits, the transport of water and nutrients to the yet immature embryo is
sometimes cut off too soon resulting in abortion of the embryo. Macapuno coconuts are priced
for their characteristic soft endosperm which fills the whole nut. These nuts always fail to
germinate because the endosperm invariably rots before germinating embryo comes out of the
shell. Embryo culture has been practiced as a general method in horticultural crops including
avocado, peach, nectarine and plum.
Embryos are excellent materials for in vitro clonal propagation. This is especially true for
conifers and members of Gramineae family.
Germination of seeds of obligatory parasites without the host is impossible in vivo, but is
achievable in embryo culture.
CONCLUSION
Embryo culture is an important technique in the development of plant species, especially the
reproduction of plants whose reproduction is difficult or impossible by conventional techniques
or plant that produce seeds with low viability.