Breeding of Fruit and Plantation Crops

Development of apomictic embryo sac

Apospory
It involves the development of embryo sac either from the archesporial cell or from the nucellus, or from other cell. It is of two types:
(i)Generative or haploid apospory
If the embryo sac develops from one of the megaspores ( n ), the process is called generative or haploid apospory. Since it cannot regenerate, as it is haploid and fertilization fails, the process gives rise to non-recurrent apomicts.
(ii)Somatic or diploid apospory
When diploid embryo sac is formed from nucellus or other cells, the process is termed as somatic or diploid apospory. Since it regenerates without fertilization, it is recurrent.
Parthenogenesis
It can be defined as development of embryo from egg cell with or without pollination but without fertilization. Depending upon the ploidy levels of egg cell, parthenogenesis can be haploid (non-recurrent) or diploid (recurrent type) e.g. Mangosteen (Garcinia mangostana).
Apogamy
Development of embryo from synergids or antipodal cells within the embryo sac with or without pollination but without fertilization is termed as apogamy.
This type of apomixis is also grouped into haploid and diploid apogamy depending upon the ploidy level of cell. Diploid apogamy is recurrent type whereas, haploid apogamy is non-recurrent type.
Androgamy
Development of the embryo from male gametes inside or outside the embryo sac is known as androgamy. Since the cells are haploid in nature they, come under non recurrent type.