Aleurone is a proteinaceous layer that surrounds the endosperm of monocotyledonous seeds. Its main function is to help in the proper development of the seed. In cereal crops aleurone layer also secretes organic acids that help in keeping the pH of grains balanced.
The development of the aleurone layer takes place after the double fertilization in which one sperm nucleus fuses with the egg cell while the other sperm cell fuses with the polar nuclei. The triple fusion between polar nuclei (2n) and sperm nucleus (haploid) leads to the formation of the primary endosperm nucleus with triploid nuclei. The ploidy of the aleurone layer is the same as that of the primary endosperm nucleus that is 3n.
