Question

How is triple fusion achieved in these plants ?

Hint:

Think of "triple" fusion as involving three nuclei: one male gamete + two polar nuclei (or one secondary nucleus which is already two fused). This results in the 3n endosperm.

Answer 1

Triple fusion is a key event during fertilization in angiosperms and occurs as follows: \newline 1. Pollen Tube Entry: The pollen tube releases two male gametes into the embryo sac. \newline 2. Syngamy: One male gamete fuses with the egg cell to form the diploid zygote (2n). \newline 3. Triple Fusion: The second male gamete (n) fuses with the central cell's polar nuclei. \newline \quad - If the central cell has two unfused haploid polar nuclei (n + n), the fusion with the male gamete (n) results in a triploid (3n) primary endosperm nucleus (PEN). \newline \quad - If the polar nuclei have already fused to form a diploid secondary nucleus (2n), the fusion with the male gamete (n) also results in a triploid (3n) primary endosperm nucleus (PEN). \newline This triple fusion is unique to angiosperms and leads to the formation of the endosperm, which nourishes the developing embryo.