Reproductive process that leads to the formation of fruit in flowering plants

– The process begins with transfer of pollen on to receptive stigma
– the pollen grain germinates producing pollen tube
– pollen tube grows down style in the ovary
– pollen tube contains leading tube nucleus at the tip
– generative nuclei divides mitotically giving two male gamete nuclei
– on reaching the ovary, pollen tube enters an ovule through chalaza or micropyle
– when tube reaches embryo sac it opens
– tube nucleus disintegrate
– male nuclei enter embryo sac
– one fuses with two polar nuclei to form a triploid nucleus known as primary endosperm nucleus
– the process is called double fertilization
– as a result of fertilization certain changes take place
– zygote divides mitotically and grows into embryo
– embryo has radicle/root pole and plumule/shoot pole
– it derives nourishment from embryo sac through suspensor
– primary endosperm nucleus develops into nourishing endosperm
– embryo sac expands as embryo and endosperm grow
– these fill up the whole area inside the integuments
– ovule develops into seed
– integument become the seed coat and outer integument become the testa
– both are lignified and tough for protection
– moisture content drastically reduce such that seed can withstand adverse condition
– ovary develop into fruit
– fruit vary with shape and size
– and function mainly to protect seed, aid in dispersal.

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