lecture 15: early development of the plant body

What are the key processes in early plant development?

Embryogenesis, Establishment of polarity, Tissue differentiation, Meristem formation

What is embryogenesis in plants?

The process where the zygote develops into an embryo with organized structure.

What is the first major event after fertilization?

Zygote undergoes its first division → establishes polarity (top vs bottom).

What are the two poles of the embryo?

Apical (top → shoot) and Basal (bottom → root).

Why is polarity important?

It determines the entire body plan of the plant.

What are key features of monocot embryo development?

One cotyledon and different structural organization than eudicots.

What are the stages of eudicot embryo development?

Globular stage, Heart stage, Torpedo stage, Mature embryo.

What is the 'heart stage'?

Stage where two cotyledons become visible (gives heart shape).

What patterns are established early in development?

Apical-basal pattern (top-bottom) and Radial pattern (center-outward).

What does radial patterning control?

Tissue layers (outer vs inner structures).

What is auxin's role in embryogenesis?

Establishes polarity, controls cell differentiation, guides development patterns.

Why is auxin so important?

It acts as a signaling molecule that tells cells what to become.

What are the 3 primary meristems?

Protoderm, Procambium, Ground meristem.

What does the protoderm become?

Epidermis (outer protective layer).

What does the procambium become?

Vascular tissue (xylem + phloem).

What does the ground meristem become?

Ground tissues (parenchyma, cortex, etc.).

How many genes control embryogenesis (approx)?

~750 genes coordinate embryo development.

What types of genes are involved in embryogenesis?

Transcription factors, Hormone signaling genes (auxin-related), Sterol synthesis genes, G-protein signaling.

What do these genes control?

Cell division, Cell fate, Tissue differentiation, Body patterning.

What happens after the embryo forms?

Seed matures, Nutrients stored, Dormancy may occur.

What is seed dormancy?

A resting state where growth is paused until conditions are favorable.

Why is dormancy important?

Prevents germination at wrong time and increases survival.

What structures are established in the embryo?

Shoot apical meristem, Root apical meristem, Cotyledons.

What do meristems do?

Regions of continuous cell division → growth.

Why is early embryogenesis so important?

It determines the entire structure and function of the plant.

How does auxin affect plant structure?

Controls directional growth and pattern formation.

Why are meristems essential?

They allow plants to grow continuously throughout life.

What is the difference between monocot and eudicot embryos?

Monocot → 1 cotyledon; Eudicot → 2 cotyledons + heart stage.