This document discusses apomixis, a type of asexual reproduction in plants where seeds develop without fertilization. It has been identified in over 300 plant species across 30 families. There are several types of apomixis including adventive embryony, apospory, and diplospory. Apomixis has applications for crop improvement as it allows for the fixation of hybrid vigor and heterozygosity. However, utilizing apomixis requires changes to traditional plant breeding programs.

1. Apomixis and its Application for
crop improvement.
PRESENTED BY: Pawan Nagar
Reg. no.: 04-2690-2015
M.Sc.(Fruit Science)

2.  Apomixis refers to the development of
seed without sexual fusion (fertilization).
 In apomixis embryo develops without
fertilization.
 Thus apomixis is an asexual means of
reproduction.

3.  Identification in over 300 species belonging
to 30 families.
 Most frequently found in families like
Compositae, Rosaceae, Graminae,
Asteraceae.
 Thus it is not rare but relatively uncommon.

4.  Apomixis is potentially a powerful
breeding tool to fix heterosis.
 But it is nuisance when breeder desires to
obtain sexual progeny because
recombination of crossing is impossible.

5.  Adventive Embryony:-
 Embryo develop directly from vegetative cells
of ovule such as nucellus, integuments and
chalaza.
 No development of embryo sac.
 This is a type of Sporophytic budding.
 E.g. Citrus, Mango.

6.  Apospory:-
 Some vegetative cells of the ovule
develop into unreduced emrbyosac
without meiosis.
 Embryo then develops directly from
diploid egg cell without fertilization.
 E. g. Malus, Crepis, Poa, etc.

7.  Diplospory:-
 Embryosac is produced from the
megaspore which may be haploid or
more generally diploid.
 Diplospory leads to Parthenogenesis or
Apogamy.

8.  Parthenogenesis:-
 Development of embryo from the egg cell
without fertilization.
 Two types:- Haploid parthenogenesis
Diploid parthenogenesis
 Haploid parthenogenesis occurs in
Solanum nigrum.
 Diploid parthenogenesis occurs in
Taraxacum.

9.  In many species, e.g., Nicotiana, Datura,
Rice etc., pollen grains may be induced
invitro to produce haploid embryos or
plantlet; this is called Androgenesis.
 For this, anthers or pollen grains are
cultured on a suitable tissue culture
medium. This technique offers
possiblities for crop improvement.

10.  Apogamy :-
 The origin of embryo from either
synergids or antipodal cells of the
embryosac is called apogamy.
 Two types:- Haploid apogamy
Diploid apogamy
 Diploid apogamy has been reported in
Allium, Iris and many other species.

12.  Obligate apomictic:- Reproduction in
plant by only Apomixis.
 Facultative apomictic:- Sexual
reproduction also occurs in addition to
Apomixis.
 Many crop species show apomixis, but it
is generally facultative.

13.  Apomixis is used to achieve following
objectives:-
 Fixation of Heterosis.
 Fixation of Heterozygous state.
 Rapid Production of Homozygous Lines.
 Production of phenotypically stable
population called Vybrids.

14.  In case of obligate apomixis, progeny from
cross resemble female parent.
 In case of facultative apomixis, percent of
progeny identical to female parent gives the
degree of apomixis.
 In selfed generation, presence of plants
showing no inbreeding depreesion is
indicative of apomixis.
 Embryological studies of young ovules
confirm apomixis.

15.  A very complicated phenomenon. Its
utilization necessitates reorientation of
breeding program and seed certification.
 Estimation of apomixis in case of facultative
is tedious and time consuming.
 Genetic base of apomixis is not clear in
most cases.