Sexual Reproduction in Flowering Plants
Post fertilization events - development of endosperm and embryo
- Post fertilization is accompanied by sudden increase in respiration and ethylene production after the withering of petals, stamens and style.
- In tomato and brinjal, calyx may persist and even they show growth in physalis and Dillenia.
- As a consequence of triple fusion, TPEN divides and forms a mass of nutritive cells called the endosperm.
- Based on the mode of its formation, angiospermic endosperm is of three types.
- Nuclear endosperm is the most common type, where TPEN divides repeatedly without wall formation to produce free nuclei in large number, where the multinucleate cytoplasm undergoes cleavage and give rise to multicellular tissue.
Eg: Wheat, maize, rice, sunflower, capsella, coconut. - In cellular endosperm, every division of TPEN is followed by cytokinesis and so the endosperm becomes cellular from the initial phase.
Eg : Balsam, Datura, Petunia. - If the endosperm is of intermediate type between cellular and nuclear, there exists 2 unequal cells with large micropylar and smaller chalazal end.
Eg: Hebbuli of monocot, Asphodelus. - Embryogenesis differ in monocot and Dicot, where the oospore or zygote develops into an embryo.
- Basal cell forms 6-10 celled suspensor in a dicot embryo, whereas it produces a single celled suspensor is monocot embryo.
- The first division of a terminal cell is longitudinal and transverse in dicot and monocot embryos respectively.
- Plumule is terminal (lies in between 2 elongated cotyledons) and appears lateral (due to excess growth of single cotyledon) in dicot and monocot embryos respectively.
Watch this video for the topic from 17:18 to 36:40
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