Fertilization in Plants Dr. Pramila Kudva

Structure of a mature pollen grain

Germination of Pollen Grain

Components of a mature pollen Mature pollen has Outer coveirng – Exine Inner covering – Intine An opening – Germ Pore A Generative and a tube nucleus Generative Nucleus divides into two Sperm Nuclei

Structure of a mature Ovule

2 protective integuments Integuments enclose Nucellus Small opening in the integument – Micropyle The Embryo Sac encloses – 3 antipodal cells – Central cell with 2 polar Nuclei – Egg cell and 2 synergids Components of a mature Ovule

Double Fertilization

To view video of double fertilization 4d1I 4d1I

Double fertilization includes two fertilizations Fertilisation 1 – Sperm nucleus [1N] fuses with the egg cell [1 N] to form the zygote [2N] Fertilisation 2 – Sperm nucleus [1N] fuses with the secondary nucleus [2N]. Triple Fusion - 2 polar nuclei unite to form a secondary nucleus and this unites with the sperm to form the endosperm cell. This involves the fusion of 3 nuclei and hence called Triple fusion

After fertilization – The corolla, stamens, style and stigma generally fall off. – The calyx may remain in some plants – Apple, Guava – Ovary enlarges to form a fruit – it could be hard or fleshy – Single ovule produces single seeded fruit – Many ovules produce many seeded fruit – Seeds are attached to the ovary by means of Placenta

Part of the FlowerAfter fertilisation 1. OvaryFruit 2. Ovary WallPericarp 3. OvuleSeed 4. PlacentaStalk of the seed 5. IntegumentsSeed coat 6. Secondary nucleusEndosperm [Food storing tissue] 7. Egg CellZygote