Double fertilization is a unique process in angiosperms where one male gamete fuses with the egg cell to form a diploid zygote, while the other fuses with the secondary nucleus to create a triploid primary endosperm nucleus. This process occurs when the pollen tube releases male gametes in the embryo sac, facilitated by synergids. The significance of double fertilization includes the development of fruits and seeds, restoration of the diploid condition, nourishment for the embryo, and genetic variation among offspring.

1. Double Fertilization
Department Of Botany
Prepared by
Dr. P. B. Cholke
(Assistant Professor in Botany)
Pune District Education Association’s
Anantrao Pawar College ,Pirangut,
Tal-Mulshi, Dist-Pune- 412115

2. • Double Fertilization
• Double fertilization is the process found in
angiosperms in which out of the two male
gametes released inside the embryo sac, one
fuses with the egg cell (syngamy) and another
fuses with secondary nucleus (triple fusion).

3. • Release of Male gametes inside embryo sac
• The pollen tube passes through the style and
enters the ovule through the micropyle
(porogamy). It penetrates the nucellus and enters
the embryo sac.
• It enters into one synergid through filiform
apparatus. The synergid provides moisture to the
tip of the pollen tube due to which it bursts open,
thereby releasing the male gametes inside the
embryo sac.
• The synergids direct one male gamete to the egg
cell and another male gamete to the secondary
nucleus. The synergids degenerate later

4. • Syngamy (First fertilization)
• Out of the two male gametes, one unites with
the egg cell(n) to form a diploid zygote(2n).
This is called syngamy or first fertilization.

5. • Triple fusion (Second fertilization)
• The second male gamete (n) unites with the
secondary nucleus (2n) to form a triploid (3n)
primary endosperm nucleus (PEN).
• Syngamy and triple fusion together represent
double fertilization which is a characteristic
feature seen in angiosperms.

6. • Significance of double fertilization is as follows:
1. It gives stimulus to the plant due to which ovary
develops into fruit and ovules develop into
seeds.
2. It restores the diploid condition by fusion of
haploid male and female gametes.
3. It results in the formation of diploid zygote,
which develops into an embryo and gives rise
to a new plant.
4. It results in the formation of triploid primary
endosperm nucleus (PEN) which develops into
endosperm in the seed. It provides nourishment
to the developing embryo.
5. It brings about recombination of characters
resulting in variation among the offspings.

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