Fertilization in Angiosperms

SHORT PRESENTATION OF FERTILIZATION IN ANGIOSPERMS

1. Presented By Dr . V. RAMSEH , Assistant Professor & Head i/c Department of Botany Vivekananda College Tiruvedakam West – 625 234 [email protected] [phone] FERTILIZATION IN PLANTS

2. What is Fertilization? Fusion of male and female gamete is called fertilization . Fertilization in angiosperms is double fertilization type.

3. Stages of fertilization Pollen on the stigma Pollens fall on the receptive stigma Receives stigmatic fluid in wet stigma and pellicle in dry stigma Recognition-rejection protein reaction Pollen wall proteins are released Pollen tube germination Pollen tube in the style Pollen tube enters into the style

4. Entry of pollen tube into the ovule pollen tube entry into the ovule Porogamy : pollen tube enters through the micropyle . Chalazogamy : pollen tube enters through the chalaza . Mesogamy : pollen tube enters through the integument.

5. Entry of pollen tube into embryo sac Pollen tube enter through obturator After reaching the embryo the content of the pollen tube (two male gametes, vegetative nucleus and cytoplasm) are discharged into the synergids

6. DOUBLE FERTILIZATION AND TRIPLE FUSION Fertilization in Angiosperm Double Fertilization S.G . Nawaschin and L.Guignard in 1898 and 1899, observed in Lilium and Fritillaria that both the male gametes released from a male gametophyte are involved in the fertilization . One male gametes fuses with the egg nucleus ( syngamy ) to form Zygote . S econd gamete fuses polar nuclei forms the primary endosperm nucleus (2N). This in volves the fusion of three nuclei triple fusion.

7. SIGNIFICANCE Embryo formation takes place Endosperm formation Production of viable seeds also the significance of double fertilization POST FERTILIZATION CHANGES

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