1. Reproduction in Lower and higher plants

Chapter-1
Reproduction in Lower and Higher Plants
AKASH K. BAGADE
M.Sc. (Zoology), NET , SET and
GATE
Pursuing Ph.D. – S.P.P.U. Pune.

INTRODUCTION
Life span- The period of birth to natural death of an organism is called as life span.
No individual is immortal except unicellular organism.
Because it continue its life in progeny by fission.
The continuity of life on earth is achieved by the process of reproduction

Reproduction-
➢ It is biological process in which an organism gives rise to young ones or offspring similar to
itself.
➢ The offspring grow, mature and in turn produce new offspring.
➢ Thus there is cycle of birth, growth and death.
➢ Reproduction enables the continuity of species generation after generation.
➢ Reproduction is a fundamental feature of all known life.
➢ There is large diversity of in the biological world and each organism has evolved its own
mechanism to multiply and produce offspring.
➢ The organisms habitat, its internal physiology and several others factors are collectively
responsible for how it reproduce
Reproduction
Asexual
Fragmentation
Budding
Spore formation
Vegetative
Propagation
Sexual
Cutting
Grafting
Tissue
culture

ASEXUAL REPRODUCTION
➢ In this type, a single parent can produce offspring.
➢ No gamete formation takes place.
➢ Does not involve the fusion two compatible gamete or sex cells occurs.
➢ The produced offspring are clones of each other (i.e., Identical to each other and to the parent).
➢ They are morphologically and genetically similar.
➢ It is commonly seen in unicellular organisms belonging to Protista and Monera.
➢ Also seen in multicellular organisms.
➢ Here, the cell division itself is the mode of reproduction.

1. FRAGMENTATION
➢ Fragmentation is a type of asexual reproduction in which an organism simply breaks in
individual pieces at maturity.
➢ These individual small pieces then grow to form a new organism e.g., Spirogyra. Spirogyra
undergoes fragmentation which results in many filaments.
https://images.app.goo.gl/P78cCjKYng4WTn9D6

BUDDING-
➢ Daughter individual is formed from a small part or bud arising from parent body
➢ Budding in yeast- An outgrowth develops on one side of the cell and nucleus divides
mitotically.
➢ Nucleus shifts into outgrowths called bud.
➢ Occurs during favourable condition.
https://images.app.goo.gl/gQnypUdjdAWGiWLN6

SPORE FORMATION-
➢ Spore are minute, single celled, thin walled propagules.
➢ They are dispersive structures which also form new individuals.
➢ In Chlamydomonas asexual reproduction occurs by flagellated, motile zoospores which can
grow in independently into new individual.
➢ In Rhizopus, spores are formed in sporangia and after maturation sporangia will burst and all
spores will develops into new individual.
https://images.app.goo.gl/mbCb977qJLCq1mt59

VEGETATIVE PROPAGATION-
➢ Plants reproduce asexually through their vegetative parts. Hence the new plants formed are
genetically identical to their parents.
➢ Agriculture and horticulture exploit vegetative reproduction in order to multiply fresh stocks of
plants.
➢ Artificial methods are used to propagate desired varieties according to human requirements.
The various methods are as follows.
a. Cutting- A small piece of any vegetative part of a plant having one or more buds. A part of
stem is cut and the cut end grows into new plant when placed in moist soil
Ex. Rose- stem cutting , Sansvieria- leaf cutting, Blackberry- Root cutting
https://images.app.goo.gl/9VuajgtwXjap
MxwC8

Grafting-
➢ Here parts of two plants are joined in such way that they grow as one plant.
➢ In this method, part of the stem containing more than one bud i.e. scion is joined onto a rooted
plant called stock. This is called as grafting.
Ex. Apple, pear, rose etc.
https://images.app.goo.gl/U7sdrD2sR7gWMv
wm6

SEXUAL REPRODUCTION
➢ In this type two parents are involve i.e. biparental reproduction.
➢ Gamete formation takes place.
➢ Fusion two compatible gamete or sex cells occurs.
➢ The produced offspring are not identical.
➢ The flower is specialised reproductive structure of plant in which sexual reproduction takes
place.
➢ Flower produce gamete and ensure fertilization process.
➢ Typical flower consist of four different whorls. Viz. Calyx, Corolla, Androecium and
Gynoecium.
Calyx and corolla Androecium and
Gynoecium
Accessory Whorls Essential Whorls
Image taken from Pinterest

Structure of Androecium
✓ The male reproductive whorl of flower is called androecium.
✓ Individual member of androecium is called stamen.
✓ Stamen consist of anther, filament and connective.
Stamen Filament (Long and slender stalk) + Anther (Fertile part produce pollens )
Structure of Anther-
Anther is bilobed structure.
Two lobes are separated by connective- contain vascular bundle.
Each anther lobe has two theca.
Each theca contain one microsporangia.
So anther is tetrasporongiate.
https://images.app.goo.gl/dni7M34t1JjGo7A79

T.S. OFANTHER
❑ The archesporial cell divides into an inner sprogenous cell and outer parietal cell.
❑ Sporogenous cell forms sprogenous tissue and these cells are capable of forming microspore
tetrad.
❑ Parietal cell undergoes division and anther wall layers.
❑ The wall of mature anther consists of four layers.
1.Epidermis- It is outermost protective layer made up of tabular cells.
2. Endothecium- It is sub epidermal layer made up of radially elongated cells with fibrous
thickenings.
3. Middle layer- made up of thin walled cells, 1-2 layer. Which may disintegrate in mature anther.
4. Tapetum- It is the innermost nutritive layer of anther wall.
❑ It is immediately encloses the sporogenous tissue.

MICROSPORENESIS
Archesporial cell
Sporogenous tissue
Microspore mother cell (MMC/ PMC)
Tetrad formation
Rounding off of induvial pollen grain
Mitosis
Mitosis
Meiosis

Structure of microspore
❑ Typical pollen grain is a non motile, haploid, unicellular body with single nucleus.
❑ Surrounded by two layered wall called sporoderm.
❑ The outer layer is Exine- thick and made up of complex non biodegradable substance called
sporopollenin.
❑ It may be smooth or sculptured pattern- characteristics of species.
❑ At some places exine is very thin showing thin areas known as germ pores. Which is useful to
growth of emerging pollen tube during germinating pollen grains.
❑ The inner wall layer is Intine- consist of cellulose and pectin
https://images.app.goo.gl/kxFyw4VKg9GPCk2t5

DEVELOPMENT OF MALE GAMETOPHYTE
❑ Pollen grain undergoes first mitotic division to produce bigger naked vegetative cell.
❑ And small thin walled generative cell.
❑ The vegetative cell is rich in food and having irregular shaped nucleus.
❑ The generative cells floats in the cytoplasm of vegetative cell.
❑ The second mitotic division concerned with the generative cells only and give rise to two non-
motile male gamete.
❑ The division of generative cell takes place either in pollen grains or in pollen tube.
https://images.app.goo.gl/nFhqibucD82xkjB26

✓ Female reproductive whorl of flower is gynoecium(Pistil) .
✓ The free unit of gynoecium is called as pistil.
✓ Individual member of gynoecium is called carpel.
✓ Pistil may be simple or compound, The simple pistil always monocarpellary. Eg. Pea, bean,
Gold Mohur etc.
✓ In monocarpellary or simple pistil the ovary is single chambered.
✓ The compound or polycarpellary pistil may be of two types :-
a) Apocarpous- In this condition, there are many carpels but they are all free and each carpel
forms a separate ovary. Eg, Rose, Lotus, Strawberry.
b) Syncarpous ;- In this condition, there are may be two or more carpels but they are always
more or less fused with one another to form single ovary. Eg, Mustard, Lady fingers.
https://images.app.goo.gl/XpTi7VyQdqbcHzek8

In angiosperms the ovule found is Anatropous and Bitegmic
• Funicle- It helps in the attachment of ovule with placenta.
Ovule is attached to ovary with placenta.
• Hilum- The body of the ovule fuses with funicle and the
point of attachment is called hilum.
• Nucellus- It provide nourishment to the developing
embryo. Sometimes the nucellus is less – Tenuinucellate.
And if nucellus is plenty- Crassinucellate.
• Micropyle end- The integument leaves a narrow passage
known as micropyle at one end of ovule. Pollen tube enters
to the embryo sac through micropyle aperture.
• Chalaza end- The place of origin of the integuments
usually lies at opposite end of micropyle, known as
chalaza.
• Integuments- Protects the inner tissue of ovule.
• Embryo sac- Contains embryo which develops into seed.
Cells of nucellus towards micropyle end get
changes into MMC and undergoes meiosis to
give rise to megaspore.
https://images.app.goo.gl/vSZHSCpXQdfcFm
En8

MEGA SPOROGENESIS-
✓ The process of formation of haploid megaspore from the diploid megaspore mother cell is
called mega sporogenesis.
✓ Generally a single megaspore mother cell ( MMC ) differentiate in the micropylar region of
the nucellus.
✓ The MMC undergoes meiotic divisions which results in the production of four haploid
megaspore.
✓ In majority of angiosperm, only one of the megaspore is functional while the other three
degenerate.
✓ During megaspore one nucellar cell at micropyle end form archesporial cell.
✓ This archesporial cell divides to form a primary parietal cell (stops further division) and
primary sporogenous cell which leads to the formation of MMC (2n) which undergoes 2
successive meiotic division to form 4 haploid megaspore which are arranged in linear tetrad.
✓ Out of four megaspore, three megaspore towards micropyle degenerate and one towards
chalaza enlarge and to form functional megaspore.

DEVELOPEMEANT OF FEMALE GAMETOPHYTE
✓ The functional gametophyte forms female gametophyte or embryo sac.
✓ Nucleus of megaspore divides mitotically (only karyokinesis, 3 times) to form 8 daughter
nuclei and all haploid.
✓ Three nuclei migrate to the micropyle end and get surrounded by cytoplasm to form egg
apparatus (middle cell forms the egg cell and other two forms synergids or helping cell)
✓ The other 3 nuclei migrate towards chalazal end and get surrounded by cytoplasm and form
3 antipodal cells.
✓ 2 nuclei migrate to the middle and form 2 polar nuclei (both are haploid or may fuse to form
a secondary nucleus (2n) with a central cell).
✓ Thus, 8 nucleated, 7 celled embryo sac is formed.
✓ This is monosporic (as it develops from one megaspore), 7 celled (3 antipodal +1 egg cell +2
synergid cell+ 1 secondary nucleus) and 8 nucleated embryo sac is called polygonum type of
embryo sac.

https://images.app.goo.gl/WzWVJ1uvfSBvL4E7A

POLLINATION
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POLLINATION-
❑ Pollination can be defined as the transfer of pollen grains from the anther to the stigma of
flower.
❑ Animals/ insects that are involve in the pollination are called Pollinators.
❑ It is the pre-requisite for fertilization because both the male and female gametes are
nonmotile.
❑ Pollen grains being non motile, angiosperms have evolved the strategy to use abiotic and
biotic agents to their flowers, feeding the visitors and exploiting their mobility for pollination
and also seed dispersal.
Types of pollination Pollination
Autogamy
Geitonogamy
Xenogamy
Self Pollination Cross pollination

AUTOGAMY- It is a type of pollination in which bisexual flower is pollinated by its own pollen grains. Offsprings
are genetically identical to their parents eg. Pea
Chasmogamous flower- flowers with exposed anther and stigma.
Cleistogamous flower- flowers that do not open at all, such flowers are purely autogamous.
GEITONOGAMY- Refers to transfer of pollen grains from the anther to the stigma of another flower of the same
plant. It is functionally cross pollination but genetically autogamy.
XENOGAMY- Refers to transfer of pollen grains from anther to the stigma of a different plants belonging to the
same species with the help of pollinating agent.
It is genetically varied offspring.
The agents responsible for pollination have been grouped into two main categories-
Pollinating agent
Abiotic
Wind
Water
Biotic
Insects
Birds
Bats

1.ABIOTIC AGENTS- These are non living agents which includes wind and water.
A. Pollination by wind Anemophily ;- most of the plants are wind pollinated, these includes
wheat, rice, corn, rye, barley and oats.
B. Pollination by Water- only found in 30 genera of aquatic plants eg. Vallisneria, Zostera,
Ceratophyllum
Anemophily- Pollination by wind.
ADAPTATIONS IN ANEMOPHILOUS FLOWERS-
❑ The flowers are small, inconspicuous , colorless, without nectar and fragrance.
❑ Pollen grain light in weight, dry and produced in large number.
❑ Anther are versatile i.e. free to move in all direction.
❑ Pollens are non sticky.
❑ Anthers are well exposed for easy dispersal of pollen grain
❑ Stigma is feathery to trap pollens carried by wind current.

Hydrophily-Pollination by water.
ADAPTATIONS IN HYDROPHILOUS FLOWERS-
❑ Flowers are small.
❑ Fragrance less and nectar less.
❑ Non wettable floral parts, except pollen grains and stigma.
❑ Stigma long and sticky.
Hydrophily is of two types-
1. Hypohydrophily-
• Pollination occurs below the water surface.
• Pollen grains are heavier than water, sink down and caught by stigma of female flowers
• Eg. Zostera sea grass the pollen grains are long, ribbon like and without exine.
2. Epihydrophily-
• The pollen grains float on the water surface and reach the stigma of female flower.
• Eg. Vallisneria is a submerged dioecious, freshwater aquatic plant which female flower reach
the water surface temporarily to ensure pollination and male flowers float on the surface of
water.

❑ Specific gravity of pollen grains is equal to that of water. That is why they are float on surface
of water.
❑ Some aquatic plants are Anemophilous eg. Potomogeton, Hologaris.
❑ Some aquatic plants are Entomophilous eg. Lotus, water hyacinth, water lily etc.

BIOTIC AGENT- It includes living agents. About 80% of plants depends on other living ,
moving creatures for pollination.
Entomophily- Pollination by insects.
ADAPTATION IN ENTOMOPHILOUS FLOWERS
1. They are large, showy and often brightly colored.
2. The flowers produce sweet odour and have nectar glands.
3. The pollen and stigmatic surface is sticky.
4. The pollens are spiny, surrounded by yellow sticky substances called pollen kit.
5. Some plants have special adaptations for insect visitors to help in cross pollination eg. Lever
mechanism.
6. Some flowers provide safe place to insects for laying eggs. Eg. Yucca and Amorphophallus
Images used for educational purpose only

Ornithophily- it is a mode of cross pollination performed by birds. Only few types of birds are
specialized for this(Humming bird, sun bird). They usually have small sized and long beak.
ADAPTATION IN ORNITHOPHILOUS FLOWER-
❑ Ornithophily flowers are usually brightly colored- red, orange, yellow , blue etc.
❑ The floral parts are commonly leathery.
❑ The ornithophilous flowers are secrete abundant watery nectar or have edible parts.
❑ Scent is often absent.

Chiropterophily- Chiropterophily is pollination of plants by bats. Bat pollination is most
common in tropical and desert areas that have many night-blooming plants.
ADAPTATION IN CHIROPTEROPHILOUS FLOWER-
❑ In these plants flowers are large, stout enough so that bats can hold on the flowers.
❑ These plants is nocturnal and open their flower only during night time.
❑ Flowers emit rotten fruit like odor.
❑ Flowers produce large amount of nectar.
❑ Flowers have large number of stamens to produce large number of pollen grains .

Other animals performe pollination and seed dispersal

Chapter-1
OUTBREEDING DEVICES AND POLLEN PISTIL
INTERACTION
AKASH K. BAGADE
M.Sc. (Zoology), NET , SET and GATE

OUTBREEDING DEVICE (CONTRIVANCES)
❑ Many plants have mechanism that discourage or prevent self pollination.
❑ To promote cross pollination and increase genetic diversity.
❑ Plants have evolved wide variety of sexual strategies.
❑ Genetic diversity is essential for evolution by natural selection.
❑ Continue Self pollination can cause inbreeding depression.
Plants developed many outbreeding devices to avoid self pollination and promote cross
pollination they are as follows-
a) Unisexuality
b) Dichogamy
c) Prepotency
d) Heterostyly
e) Herkogamy
f) Self incompatibility

UNISEXUALITY–
❑ In this case, the plants bears either male or female flower.
❑ It is also called as dioecism.
❑ Flower are unisexual
❑ Self pollination is not possible
❑ Plants may be monoecious or dioicous
❑ Ex. Maize and papaya respectively
DICHOGAMY–
❑ The stamens and carpels of a bisexual flower mature at different times.
❑ Hence cross pollination becomes inevitable
❑ Plants either protandrous like sunflower or protogynous like Michelia, Gloriosa
PROTANDRY PROTOGYNY
Male organs gain reproductive activity before female organ
EX. Sunflower
Female organ gain reproductive activity before the male
organ
EX. Gloriosa

PREPOTENCY-
❑ Pollen grains of other flowers germinate rapidly over the stigma than the pollen grains from the
same flower. Eg. Apple
HETEROSTYLY–
❑ This facilitate cross pollination. Pin eyed or long styled flowers and short stamens.
❑ Short styled flowers have short style and long stamens.
❑ Pollination occur between flower of same length of style and stamens.
❑ Ex. Primula
HERKOGAMY-
❑ It is a mechanical device to prevent self pollination in a bisexual plant.
❑ In plants natural physical barrier is present between two sex organs and avoid contact of pollen
with stigma of same flower.
❑ Ex. Calotropis.
SELF INCOMPATIBILITY(SELF STERILITY) - This is a genetic mechanism due to which
the generation of pollen of stigma of the same flower is inhibited. Eg. Tobacco, Thera

POLLEN-PISTIL INTERACTION
❑ It is the interaction of pollen grains with stigma.
❑ Begins with the pollination and ends with the fertilization.
❑ All the events from deposition of pollen grain on stigma to entry the entry of pollen tube in the ovule
are called as pollen pistil interaction.
❑ Pollination does not guarantee the transfer of right type of pollen land on stigma.
❑ The pistil has ability to recognise right pollen and accept the pollen of same species.
❑ So wrong type of pollen discarded by pistil.
❑ Compatibility and incompatibility of pollen-pistil is determined by the proteins.
❑ This process involves pollen recognition followed by promotion or inhibition of pollen.
❑ A physiological mechanism operates to ensure only intraspecific pollen germinate successfully.
❑ The compatible pollen absorb water and nutrients from surface of stigma, geminates and produce pollen
tube.
❑ Its growth through the style is determine by specific chemicals.
❑ The stigmatic surface provides essential prerequisites for successful germination, which are absent in
pollen.
❑ The pollen tube finally pushed through the ovule and reached the embryo sac.
❑ The tip of the pollen tube enters in one synergid and the rupture to release the contents.

POLLEN-PISTIL INTERACTION

ARTIFICIAL POLLINATION/HYBRIDIZATION
❑ Help in the plant improvement programme.
❑ A breeder is often interested in crossing different species of plant to combine desirable
characters producing superior varieties.
❑ Breeder wants to cross a particular plant with a desired pollen grain.
❑ So a bisexual flower is artificially transformed into the female flower.
This is done by—
Emasculation- i.e. Removal of stamens or anthers.
❑ Emasculated flower is immediately bagged to avoid pollination by unwanted pollen grain. This
is called bagging.

Chapter-1
DOUBLE FERTILIZATION AND ENDOSPERM
DEVELOPEMENT
AKASH K. BAGADE

DOUBLE FERTILIZATION
❑Complex process in angiosperms.
❑Also called as triple fusion- discovered by S.G. Nawaschin in family Liliaceae.
❑The process involve the joining of a female gametophyte with two male gametophyte.
❑It begins when a pollen grains adheres t the stigma of the carpel.
❑The pollen grain germinates to form pollen tube that extends down towards the ovary through
style.
❑The tip of the pollen tube then enters the ovary and penetrate through the micropyle opening in
the ovule.
❑Pollen tube may enter the ovule either from micropyle called Porogamy. Or from chalaza
called Chalazogamy or may be through any part/ integuments, called Mesogamy.

DOUBLE FERTILIZATION
❑ The pollen tube reached embryo sac and absorb watery substance from synergid cell and
release its content.
❑ The pollen tube contain two male gamete.
❑ The one haploid male gamete fuse or combine with haploid egg cell and form zygote. Called
syngamy
❑ The second male gamete fuse or combine with two haploid polar nuclei of the large central
cell-called triple fusion. and produce Primary endosperm Nucleus (PEN) which develops
into Triploid endosperm

Diagrammatic representation of Double fertilization

SIGNIFICANCE OF DOUBLE FERTILIZATION
❑ It is unique feature of angiosperm. It ensure that the parent plant invest a seed
with a food store, only if the egg is fertilized.
❑ The diploid zygote developed into an embryo and the it develop into new plant.
❑ The triploid PEN develops into nutritive endosperm tissue.
❑ It restore the diploid condition of plant. By the syngamy process.
❑ Is also helps to avoid polyembryony.
POST FERTILIZATION EVENT
The major event includes
1. Development of endosperm.
2. Development of embryo from diploid zygote.
3. Development of seed from ovule.
4. Development of fruit from ovary.

DEVELOPMENT OF ENDOSPERM
❑ The PEN starts dividing rapidly.
❑ It forms the food laden tissue which is used during development of growing
embryo in the seed.
❑ In angiosperm, endosperm is a post fertilization product (3n)
❑ In gymnosperm, it is pre- fertilization formed and is haploid (n)
Type of Endosperm
Nuclear Cellular Helobial

❑ Nuclear endosperm- observed in 161 angiosperm families.
❑ In the nuclear type of endosperm development , the primary endosperm nucleus divides by
repeated mitotic free nuclear division without the formation of walls.
❑ And produce large number of nuclei.
❑ A big central vacuole push all nuclei towards the periphery . Then wall form between nuclei.
❑ ex. Wheat, sunflower and coconut.
❑ Cellular type-
❑ In the cellular type of endosperm development, PEN divide mitotically and is immediately
followed by wall formation.
❑ So that the endosperm is cellular right from the beginning. It is mostly observed in 71 families
of dicot plant. Ex. Balsum, Adoxa.
Helobial type-
❑ It occurs in the order Helobiales of monocot.
❑ It is intermediate of nuclear and cellular type.
❑ After first division of PEN is followed by a transverse wall which divides the cell unequally.
❑ The smaller cell called chalazal cell and larger cell is micropylar cell. Ex. Asphodelus

Development of Embryo
❑ The process of development of zygote into an embryo is called embryogenesis.
❑ The embryo developed at the micropylar end of the embryo sac.
❑ The growth of the embryo triggers only after certain amount of endosperm is formed.
❑ After fertilization the embryonic development begins.
❑ The zygote divides to form proembryo.
❑ The larger cell towards micropyle is called basal or suspenser initial cell and towards chalaza
end is called terminal or embryonal cell.
❑ The suspenser cell divides transversely and form 6-10 filamentous cells.
❑ The first cell of suspenser towards the micropyle end becomes swollen and function as
haustorium.
❑ The lowermost cell of suspenser cell towards the chalaza end becomes hypophysis.
❑ The suspenser helps in pushing the embryo in the endosperm.
❑ The embryonal initial undergoes three successive mitotic division to form octant.

Development of Embryo
❑ The lower tier of four cells of octant give rise to hypocotyl and radicle whereas four cells of
upper tier forms the plumule and the one or two cotyledons.
❑ The hypophysis by further division gives rise to the part of radicle and root cap.
❑ Cells of upper tier divides subsequently and formed heart shaped embryo which then formed
two lateral cotyledons.
❑ Further enlargement of hypocotyl and cotyledons result in a curvature of embryo and it
appears horse- shoe shaped.
❑ The embryo development is similar in both monocot and dicot up to the octant stage.
❑ The difference appears later. In monocot embryo, single cotyledon occupies terminal position
and plumule is lateral.
❑ The single shield shaped cotyledon called scutellum.
❑ The protective sheath of plumule is called coleoptile.
❑ The protective sheath of radicle is coleorhiza.
❑ Finally ovule is transformed into the seed and ovary into the fruit.

Development of embryo

Development of Seed and Fruit
❑ The goal of reproduction is to create offspring's for the next generation.
❑ One of the ways that plants can produce offspring's is by forming seeds.
❑ The flower must be pollinated in order to produce seeds and fruit. Seed development is
initiated by fertilization.
❑ The integuments of the fertilized ovule persist and get transformed into seed coat of mature
seed.
❑ Seed sometimes consist of two distinct coverings typical outer seed coat, the Testa and the
inner thin membranous Tegmen.
❑ The nucellus in the ovule may be persist in some genera like black paper and beet as thin,
papery layer the perisperm.

❑ In some seeds, the food reserves in the endosperm are partially used up in the development of
an embryo. Thus the resultant seed is Endospermic or Albuminous eg. Castor, Cocconut and
Maize etc.
❑ In other seeds, embryo absorbs food reserve from the endosperm completely during its
development stages. Thus endosperm disappears in mature seeds so the resultant seed in Non-
Endospermic or Exalbuminous eg. Pea, Bean etc.
❑ The cotyledons in some non endospermic seeds act as food storage and in others they are the
first photosynthetic organs.
❑ Micropyle persists as a small pore in seed coat to allow the entry of water and oxygen during
soaking.

❑ Fruit development is triggered by hormones produced by developing seeds.
❑ The ovary begins to differentiate into the fruit and ovary wall develops into pericarp.
❑ Pericarp basically three layered which get differentiated in the fleshy fruit like Mango and
Coconut etc.
SIGNIFICANCE OF SEED AND FRUIT
❑ Fruits provide nourishment to the developing seeds.
❑ Fruits protect the seeds in immature condition.
❑ Seeds serve as important propagating organs of plant.
❑ Seeds and fruits develops special devices for their dispersal and thus help in the distribution of
the species.

DORMANCY
❑ It is the state of metabolic arrest that facilitates the survival of the organism during adverse
environmental conditions.
❑ Structural or physiological adaptive mechanism for survival is called dormancy.
❑ Mature and viable seeds will not germinate even in the presence of favorable conditions and
they are dispersed at different places during dormancy.
❑ Viable seeds germinate only after the completion of dormancy period.
❑ Some examples of oldest mature seeds that have grown into viable plants-
Lupinus articus- 10000 years.
Phoenix dactylifera- 2000 years.

Chapter-1
APOMIXIS, PARTHENOCARPY AND POLYEMBRYONY
AKASH K. BAGADE

APOMIXIS
❑ A few flowering plants have evolved mechanism to produce seeds without fertilization called
Apomixis.
❑ It is unusual sexual reproduction where there is no meiosis and syngamy.
❑ Apomixis is a form of asexual reproduction that mimics sexual reproduction.
❑ The term apomixis was first coined by Winkler in 1908.
❑ The plant which shows apomixis termed as apomictic plants.
❑ In apomixis, when a gametophyte organ or cell produces embryo like structure without
fertilization is called apogamy.
❑ And when diploid sporophyte cell produces a diploid gametophyte without undergoing meiosis
is called apospory. Eg. Orange, Mango.
There are several methods of apomictic development of seeds development are as follows.
1. Recurrent Apomixis- the embryo sac is generally rise from either archesporial cell or from
some other part of nucellus. In diplospory, condition embryo sac is formed from megaspore
mother cell. Eg. Taraxacum. In Apospory- The nucellar cells give rise to apopmictic embryo sac.

2.Non- Recurrent Apomixis- In this type, the megaspore mother cell undergoes usual meiotic division and a haploid
embryo sac is formed. Here the embryo arise either from the egg by parthenogenesis or from some other haploid
cells of gametophyte through apogamy. The plants produces by this methods are generally sterile and do not
reproduce sexually. Eg. Nicotiana
3. Adventive embryony- In this type , embryo may be develops from somatic nucellus or integuments along with
normal zygotic embryo. It is common in Mango, Orange, Lemon etc. It give rise to a condition called
polyembryony.
Genetically identical plants can be produced effectively and rapidly by apomixis.
PARTHENOCARPY-
❑ The process of formation of embryo without the fusion of gametes is known as parthenocarpy.
❑ The term coined by Noll in 1902.
❑ Fruits are formed without fertilization is called parthenocarpy fruits, such fruits either seed less or contain non
viable seeds.
❑ It occurs naturally in some varieties of pineapple, Banana, Papaya etc.
❑ In these plant the placental tissue in the unfertilized ovary produces Auxin (Indole-3-Acetic acid) which
responsible for enlargement of ovary into fruit.
❑ Parthenocarpic fruits have higher proportion of edible parts than normal fruits.

POLYEMBRYONY-
❑ It is the development of more than one embryo inside the seed.
❑ First noticed by Leeuwenhoek in 1719 in seeds of Citrus genus.
❑ It is occurrence of more than one embryo in the seed which further develop in to multiple
seedlings.
❑ The additional embryos result from the differentiation and development of various maternal
and zygotic tissues associated with the ovule of seed.
❑ Polyembryony may be true or false depending upon whether many embryos arise in the
same embryo sac or in different embryo sac in the same ovule.
❑ In adventive polyembryony, an embryo develops directly from diploid cell of nucellus and
integuments as in Citrus.
❑ In cleavage polyembryony- zygote proembryo sometimes divides into many parts or units.
Each unit then develops into an embryo.
❑ Polyembryony increases the changes of survival of the new plants.
❑ Nucellar adventive polyembryony is of great significance in horticulture.

EXERCISE
Chapter-1
Maharashtra state board
AKASH K. BAGADE
Bio- Geek YouTube Channel

Multiple Choice Questions
1.Insect pollinated flowers usually
posses ……….
a. Sticky pollens with rough surface.
b. Large quantities of pollens
c. Dry pollens with smooth surface
d. light colored pollens
2. In ovule , meiosis occurs in………
a. Integument b. Nucellus
c. Megaspore
d. Megaspore mother cell
3. The ploidy level is not the same in…
a. integuments and nucellus.
b. Root tip and shoot tip
c. Secondary nucleus and endosperm
d. Antipodals and synergids.
4.Which of the following types require
pollinator but result is genetically similar to
autogamy.
a. Geitonogamy b. Xenogamy c. Apogamy
d. Cleistogamy.
5. If diploid chromosome number in a flowering
plant is 12, then which one of the following will
have 6 chromosome.
a. Endosperm b. leaf cell c. Cotyledons d.
Synergids.
6.In angiosperm, endosperm is formed by to.....
a. Free nuclear division of megaspore b. polar
nuclei c. polar nuclei and male gamete d. pollen
grain
7.Point out the odd one……
a. Nucellus b. Embryo sac c Micropyle d. pollen
grain

Very Short Answer type Questions
1.Name the part of gynoecium that determines the compatible nature of pollen
grains.
Ans- Stigma.
2. How many haploid cells are present in a mature embryo sac.
Ans - Seven cell
3. Even though each pollen grain has 2 male gametes, why atleast 20 pollen grains
are require to fertilize 20 ovules in a particular carpel.
Ans - Because out of 2 male gamete one gamete fuse with egg cell and formed zygote and
another one fuse with polar nuclei so for 20 ovules, 20 pollen grains are require.
4. Define mega sporogenesis.
Ans - The process of formation of haploid megaspore from the diploid megaspore mother
cell is called mega sporogenesis
5. What is hydrophily
Ans - The pollination is carried out with the help of water is known as hydrophily.

Very Short Answer type Questions
6. Name the layer which supplies nourishment to the developing pollen grains
Ans - Tapetum
7. Define parthenocarpy
Ans - The process of formation of embryo without the fusion of gametes is known
as parthenocarpy. The term coined by Noll in 1902.
8. Are the pollination and fertilization is necessary in apomixis.
Ans- NO, because apomixis is production of seeds without fertilization.
9. Name the parts of pistil which develops into fruit and seeds.
Ans - Fruit developed from ovary and seed developed from ovule.
10. What is the function of filiform apparatus.
Ans- To guide entry of pollen tube and release of male gamete.

Short Answer Questions
1. How polyembryony can be commercially exploited.
Ans-
✓It is occurrence of more than one embryo in the seed which further develop in to multiple seedlings.
✓It can be commercially exploited in many ways, out of which are listed below-
a. It helps in plant breeding.
b. Polyembryony increases the changes of survival of the new plants
c. Nucellar adventive polyembryony is of great significance in horticulture
d. Plantlets obtained from these embryos are virus free and more vigorous, resulting in high productivity.
e. All these embryos can be isolated and grown on embryo culture to produce clones.
2. Pollination and seeds formation are very crucial for the fruit formation. Justify the statement.
Ans-
✓Pollination is the prerequisite for fertilization.
✓Fertilization is the phenomenon by which seeds and fruits are formed in flowering plants.
✓Fruit is the fusion product of ovary. Ovule is inside ovary. Seed is the product of ovule.
✓Fertilization stimulates the ovary to become fruit and ovule to become seed.

Short Answer Questions
3. Incompatibility is a natural barrier in the fusion of gametes. How will you explain this statement.
Ans-
✓ Incompatibility refers to the inability of certain gametes, even from genetically similar plant species, to fuse with each other.
✓ This is called intraspecific incompatibility, self sterility or self incompatibility.
✓ This is pre zygotic isolation in which pollen grains are not recognized by stigma.
✓ So no formation of pollen tube and hence no fusion of gamete takes place so it act as natural barrier in the fusion of gametes.
4. Describe three devices by which cross pollination is encouraged by avoiding self pollination.
Ans-
✓ Many plants have mechanism that discourage or prevent self pollination to promote cross pollination and increase genetic diversity
✓ 1.Unisexuality- It is also called as dioecism. Flower are unisexual so self pollination is not possible
✓ Plants may be monoecious or dioicous
✓ 2.Dichogamy- The stamens and carpels of a bisexual flower mature at different times, Hence cross pollination becomes inevitable.
Plants either protandrous like sunflower or protogynous like Michelia, Gloriosa
Protandry- Male organs gain reproductive activity before female organ EX. Sunflower
Nucellar adventive polyembryony is of great significance in horticulture
Protogyny- Female organ gain reproductive activity before the male organ EX. Gloriosa
✓ 3.Prepotency- Pollen grains of other flowers germinate rapidly over the stigma than the pollen grains from the same flower. Eg. Apple

Long Answer Questions
Q.1 Describe the process of double fertilization
Ans- YouTube lecture link --- https://youtu.be/9lGs4pbRKso
Q.2 Explain the stages of involved in the maturation of microspore into male gametophyte.
Ans- YouTube lecture link ------ https://youtu.be/mHIpBFgoi8Y
Q.3 Explain the development of dicot embryo.
Ans- YouTube lecture link ------ https://youtu.be/rSLRMlJW2wg
Q.4 Draw neat labelled diagram of the L.S. of anatropous ovule and list the component of embryo sac and mentation their fate after
fertilization.
Ans-

Fill in the blanksStigma
Androecium
Pollen grain
Male gamete
Pollination
Embryo sac
Fertilization
Pedicel
Calyx/ Sepals
Nectar
Fragrance
Corolla/ Petals
Male Gametes

LONG ANSWER QUESTIONS
EPICOTYL
HILUM
SEED COAT
RADICLE
COTYLEDONS
ENDOSPERM
HYPOCOTYLE

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