Explain the development of a dicotyledonous embryo (embryogeny) from a zygote. Support your answer with a detailed description of the different stages involved and a suitable theoretical breakdown.

Q: Explain the development of a dicotyledonous embryo (embryogeny) from a zygote. Support your answer with a detailed description of the different stages involved and a suitable theoretical breakdown.

Introduction to Embryogeny\nEmbryogeny is the process of development of a mature embryo from a zygote (fertilized egg) inside the embryo sac of an ovule. In dicotyledonous plants, the mode of embryo development follows a specific pattern known as the crucifer or onagrad type. The zygote remains dormant for a brief period until a certain amount of endosperm is formed to provide nutrition. Stages of Dicot Embryo Development Polar Division of Zygote: The zygote undergoes an asymmetric transverse division to form two unequal cells: a large basal cell towards the micropylar end and a small apical cell (terminal cell) towards the chalazal end. Formation of Suspensor: The large basal cell divides repeatedly transversely to form a filamentous structure called the suspensor. The suspensor helps in pushing the developing embryo deep into the endosperm for optimal nutrition. The uppermost cell of the suspensor swells up to act as a haustorium, while the lowermost cell of the suspensor, known as the hypophysis, gives out the radicle and root cap. Globular Stage: The small apical cell undergoes successive mitotic divisions (vertical and transverse divisions) to form a multicellular, spherical, globular embryo. At this point, tissue differentiation has not yet occurred. Heart-Shaped Stage: Rapid division at the two lateral regions of the globular embryo leads to the formation of two cotyledons. This gives the embryo a distinct heart-shaped appearance. The region above the attachment of cotyledons is the epicotyl, and the region below is the hypocotyl. Mature Dicot Embryo: Continued growth and elongation result in a curved, fully mature dicot embryo possessing an embryonal axis, two cotyledons, a plumule (shoot tip), and a radicle (root tip covered by the root cap).

Question

Accepted Answer

Introduction to Embryogeny
Embryogeny is the process of development of a mature embryo from a zygote (fertilized egg) inside the embryo sac of an ovule. In dicotyledonous plants, the mode of embryo development follows a specific pattern known as the crucifer or onagrad type. The zygote remains dormant for a brief period until a certain amount of endosperm is formed to provide nutrition. Stages of Dicot Embryo Development Polar Division of Zygote: The zygote undergoes an asymmetric transverse division to form two unequal cells: a large basal cell towards the micropylar end and a small apical cell (terminal cell) towards the chalazal end. Formation of Suspensor: The large basal cell divides repeatedly transversely to form a filamentous structure called the suspensor. The suspensor helps in pushing the developing embryo deep into the endosperm for optimal nutrition. The uppermost cell of the suspensor swells up to act as a haustorium, while the lowermost cell of the suspensor, known as the hypophysis, gives out the radicle and root cap. Globular Stage: The small apical cell undergoes successive mitotic divisions (vertical and transverse divisions) to form a multicellular, spherical, globular embryo. At this point, tissue differentiation has not yet occurred. Heart-Shaped Stage: Rapid division at the two lateral regions of the globular embryo leads to the formation of two cotyledons. This gives the embryo a distinct heart-shaped appearance. The region above the attachment of cotyledons is the epicotyl, and the region below is the hypocotyl. Mature Dicot Embryo: Continued growth and elongation result in a curved, fully mature dicot embryo possessing an embryonal axis, two cotyledons, a plumule (shoot tip), and a radicle (root tip covered by the root cap).

MP Board · Class 12 · Biology · Sexual Reproduction in Flowering PlantsExplain the development of a dicotyledonous embryo (embryogeny) from a zygote. Support your answer with a detailed description of the different stages involved and a suitable theoretical breakdown.

Stages of Dicot Embryo Development