Plant

Development

A member of the KingdomPlantae, a living organism thatutilizes photosynthesis, a process inwhich energy from sunlight isconverted to chemical energy(food). Plants are at the base ofthe food web and are autotrophs –organism that make their own food.

What Is A Plant?

Differences Between Plant And

Animal Development 1. Plants do not Gastrulate.2. Plants have sporic meiosis rather than gametic

meiosis.3. The life cycle of land plants ( as well as other

plants) includes both diploid and haploid multicellular stages.

4. Germ cells are not set aside early in development.

5. Plants undergo extended morphogenesis.6. Plants have tremendous development plasticity. 7. Plants may tolerate higher genetic loads than

animals.

A. Haploid Life Cycle

1. Gametophyte Phase 2. Begins with a haploid spore, produce

gametes by mitotic division and ends with fertilization producing a diploid zygote

3. Only have one set of chromosomes

B. Diploid Life Cycle

1. Sporophyte Phase 2. Begins from a diploid zygote and produces

haploid spores by meiotic division3. Having two haploid set of chromosomes

Moss Life Cycle • Moss are heterosporous

– make two distinct types of spores:Antheridia – male

gametophyte that produce sperm by mitosis

Archegonia - female gametophyte that produces eggs by mitosis

Examples

Fern Life Cycle• Ferns are

homosporous –produce one type of spore within a structure called sporangium. One gametophyte can produce both male and female sex organs.

Example

Angiosperm gametophytes are associated with flowersDevelopment of floral parts ( whorls of

organs of a flower) 1. Sepals – green outer leaf- like structures

present in a circle around the flower2. Petals – bright showy part of the flower3. Stamen – male reproductive organ of the

flower that consist of an anther and filament.

Gamete Production In Angiosperms

a. Anther – produces and releases sperm cells

b. Filament – support the anthersSTAMEN contains the following cells : Microsporangia (pollen sac)Microspores –male gametophytes

pollen grains4. Carpel – female reproductive organs of the

flower that consist of stigma, style and ovaryStigma – collects pollenStyle – tube that connects the stigma to the ovaryOvary – contain and protect the ovuleOvule- contains eggs for fertilization

Pollen grains are very fine usually yellow dust that is produce by a plant and that is carried to other plants of the same kind usually by wind or insects so that plants can produce seeds Consist of two cells:

• Tube cell- will make the tube though the style to the ovary

• Generative cell- will generate the sperms cells

Parts of pollen:• Exine – outer wall• Intine – inner wall

Pollen – Male Gametophyte

Inside the anther,

microspore mother cell

undergo meiosis to make haploid

microspores undergoing

mitosis to make pollen grains in

the stamen

Pollen Development

Ovary

Female Gametophyte

Provides protection for the developing embryo

Develop into a fruit

Seeds -fully developed ovules

Integuments – outer layer of ovule develop into a seed coat

Megasporangium- a sporangium that develops only megaspores

Megaspores- giving rise to female gametophyte

Micropyle- a minute opening in the integument of an ovule of a seed plant

Integuments – outer layer of ovule develop into a seed coat

Inside the ovary are ovules Megaspore mother cell undergoes

meiosis to make megaspores Typically one megaspore survives,

the other disintegrate Three rounds of mitosis but only 7

cells are formed Endosperm mother cell is prepared

inside the ovule for the sperm

Egg Development

Landing and subsequent germination of the pollen on the stigma Agents of Pollination

Wind Water Insects Few birds and animals

Pollination

A. Cross pollination – when a flower

is fertilized by another flower

B. Self-pollination – when a flower

fertilised itself

Kinds of Pollination

Complete/ Perfect – contains stamen, pistil, sepals and petals

Types Of Flowers

Incomplete/ Imperfect – if any part of the stamen or pistil is missing

Pistillate Flower – flowers containing functional pistils but no stamen

Staminate Flower – flowers containing functional stamen and but no pistil

Monoecious

Plants are thosewhere one planthas both maleand femaleflowers on thesame plant or inother words oneplant is bothmale and female.

Types of Plants

Dioecious –Plants are plants where one plant is male with only male flowers and another plant is female with only female flowers.

Involves the fusion of the male and female gametes

Takes place in the ovary Pollen lands on the female part

of the flower, and then it develops a pollen tube and burrows down to the ovary, where it fertilizes.

Fertilization

Unique process that involves the

joining of the female gametophyte

with two male gametophyte

That ultimately becomes the seed

and fruit of the plant

Double Fertilization

Covers development from thetime of fertilization untildormancy occurs

Embryogenesis

Formation of the plant embryo

Embryonic Development

Terminal cell- gives rise to the embryo proper

Basal cell- gives rise to the suspensor

Hypophysis- found at the interface between the suspensor and embryo proper

Suspensor- serves as a nutrient conduit for the developing embryo

Basic Body Plan Of The Angiosperm During

Embryogenesis

Globular Stage – embryo develops radial patterning through series of the cell division

Aplical layer produce cotyledons and shoot meristem

Heart Stage – bilateral symmetry is apparent

Torpedo- Cotyledonary – embryo complete its

growth by elongating and enlarging

Development of a plant from a seed

Germination requires conditions: Oxygen Water Temperature Light

Seed Germination

1. Dermal Tissue ( Epidermis) – form from the protoderm and contribute to the outer protective buyers of the plant

2. Ground Tissue (Cortex And Pith) – form from the ground meristem which lies beneath the protoderm

3. Vascular Tissue (Xylem And Phloem) – support and transport water and nutrients Procambium – forms at the core of the

embryo that gives rise to the vascular tissue

Three Tissue System Of The Plant

Meristem – composed of actively dividing cells, responsible for the production of cells.

Kinds of Meristems:

1. Apical Meristem – found at the tip of stems and roots.

2. Lateral Meristem- aka cambia (singular cambium), found along the sides of roots and stem. Increase width or diameter of roots and stems.

3. Intercalary Meristem- found at the bases of young leaves and internodes.

Vegetative growth

Roots are the non-green undergrounddescending portions of the plant axis thatgive rise to similar types of endogenouslateral branches growing down into the soilor water.The roots functions are: Absorption of water and organic

nutrients Anchor and support the plant body to

the ground Storage of food and nutrients Vegetative reproduction

Root Development

1. Leaf Primordial – cluster of cells that will form leaves

2. Node – union of a leaf and the stem

3. Internode- stem tissue between nodes

4. Phyllotaxy- positioning of leaves on the stem

Shoot Development

Establishment of leaves axesGiving rise to tremendous diversity of leaf shapes Kinds of leaves:

Simple leaves – have a flat, undivided blade that is supported by a stalk called petiole

Compound leaves- have blades which are divided into leaflets which form in one plane and lack axillary buds.

Leaf Development

Plants undergo several developmental transitions during their life cycle.

Shoot of higher plants passes through 3 more or less distinct phases during its post embryonic development, and these are: 1. Juvenile Vegetative Phase where the plant is

not competent to flower 2. Adult Vegetative Phase where the plant can

respond to floral inductive signals3. Reproductive Phase where the flower is

produced to undergo reproduction

Plant Developmental Transition

Monocarpic- plants that flower once and then senesce.

Polycarpic- plants that live thousands of years and flower accidentally; death is by accident

Senescence-developmental Program

Leading To Death Of Plant

1. Histological Studies2. Culture Experiments3. InVitroFertilization Experiment4. Biochemical Analysis5. Genetic and molecular analyses

of developmental mutants6. Clonal analysis

Experimental Studies in Plants

Different parts of different plantsare capable producing new plants bythemselves. The process of producingplants through asexual reproduction isalso termed as regeneration. There areseveral methods by which plants can beregenerated such as cutting and grafting.

How Does Asexual Reproduction Take

Place In Plants?

Is a method in which a bud is

taken and then grafted onto the root

or the stem of the plant

Grafting

Hormones – Greek term that means “to excite” , it is a chemical signals that coordinate the different parts of an organism

Plant Hormones – produced by cells in one area of the plant such as the leaves, stems or root, and then transported to a different area of the plant in order to produce a response

Hormones produced in immature parts of plants that stimulate growth.

Commonly found in seed embryos, apical meristem and young leaves.

Stimulate cell differentiation which means this hormone helps decide if a cell will become ground tissue, vascular tissue or protective tissue.

Stimulate stem elongation, help regulate fruit development

Auxins

Produces in the roots Stimulate growth and development

of chloroplast responsible for photosynthesis

Produce anti- aging effects on some plant parts for plants to have healthier look

Cytokinins

Gibberellins

Produced in meristems of stems and roots regulate stem elongation

Ethylene

Produced in fruits, flowers and aging leaves that promotes fruit ripening

1. Plants are characterized by alternation of generation- diploid and haploid generations

2. Multicellular diploid sporophyte produces haploid spores via meiosis .These spores divide mitotically to produce haploid gametophyte. Mitotic divisions within the gametophyte produce the gametes.

3. the male gamete pollen, arrives at the style of the female gametophyte and effects of fertilization through the pollen tube. Two sperm cells move through the pollen tube, one joins with the ovum to form the zygote ,and the other is involved in the formation of the endosperm.

Summary

Summary 4.Plant embryos develop deeply

embedded in parental tissue. The parent tissue provides nutrients but only minimal patterning information.

5.Early embryogenesis is characterized by the establishment of the shoot-root axis and by radial pattern yielding three tissue systems. Pattern emerges by regulation of planes of cell division and the directions of cell expansion, since plant cells do not move during development.

Summary 6. As the embryo matures, a food reserve is

established. Only the rudiments of the basic body plan are established by the time embryogenesis ceases and the seed enters dormancy.

7.Pattern is elaborated during embryonic development, when meristems construct the reiterative structures of the plant.

8.The germ line is not reserved early in development. Coordination of signaling among leaves, roots and shoot meristems regulates the transition to the reproductive state reproduction may be followed by genetically programmed senescence of the parent plant.

Humankind has not woven the web of

life alone,

We are but one thread within it

Whatever we do to the web,

we do to ourselves

All things are bound together,

All things connect!

Thank You for

listening!!