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MULTIPLICATION PROCESSES IN PLANTS
GENERAL PRINCIPLES OF
ANGIOSPERM SEED FORMATION
REPRODUCTION Î SEXUAL: SEEDS
Production of a new organism with active participation of
sexual nuclei or cells (the combination of a male and a
female gametes) Î there is a renewal of indiví
indivíduals
PROPAGATION
Julio Marcos Filho
DEPTO. PRODUÇ
PRODUÇÃO VEGETAL
USP/ESALQ
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Î ASEXUAL: PROPAGULES
Vegetative parts, cells or plant tissues, that possess
capacity of regeneration; there is no fusion of
sexual cells Î production of clones
FLORAL INDUCTION
FLORAL INITIATION
Physiological change that permits the development of
reproductive primordia.
primordia. This change is induced by
external stimuli.
Morphological expression of the induced state. Usually
occurs within the meristems of a plant.
- Types of plants: Annuals x biennials x perennials
- Water
- Photoperiod
FLOWERING Î PHASE OF THE PLANT LIFE CYCLE
THAT PROMOTES FRUIT AND SEED FORMATION
- Chemicals
a) THERMAL UNITS: energy accumulation
- Temperature
- Nutritional status
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SOME TYPES OF INFLORESCENCES
head
b) JUVENILLE PERIOD
SOME TYPES OF INFLORESCENCES
spike
panicle
raceme
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umbel
composite
umbel
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TYPES OF FLOWERS
TYPES OF FLOWERS ACCORDING TO SEXUAL STRUCTURE
HERMAPHRODITES
UNISEXUAL
- Complete: possess sepals, petals, stamens and
pistil
- Incomplete
TYPES OF PLANTS ACCORDING TO SEX
HERMAPHRODITES:
HERMAPHRODITES: all flowers are hermaphroditic
- Perfect: possess stamens and pistil
UNISEXUAL:
UNISEXUAL:
Monoecious:
Monoecious: maize, cucumber, Pinus
Dioecious:
Dioecious: papaya, pecan, Araucaria
- Imperfect: unisexual (lacks
(lacks either stamens or pistil)
pistil)
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PARTS OF FLOWER INVOLVED IN THE
REPRODUCTION PROCESS
stigma
pollen grain
style
anther
¾ ANDROECIUM
Set of stamens: Filament + Anther
petal
ovule
filament
embryo sac
ovary
¾ GYNOECIUM (pistil)
Stigma
Style
Ovary
sepal
micropyle
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TYPICAL COMPLETE FLOWER (Marcos Filho,
Filho, 2005)
gp
sp
lc
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ov
MICROSPOROGENESIS
and
MICROGAMETOGENESIS
fl
STAMEN
OVARY
ANTHER AND TRILOCULE OVARY CROSS SECTIONS (Marcos Filho,
Filho, 2005)
fl = filament; gp = pollen grain; sp = pollen sac; ov = ovule; lc = locule
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Anther Primodia
POLLEN GRAIN
Mother cells
differentiation
Characteristics of the Exine Î Importance
Pollen sac
Meiosis
Microspore mother
cell (2n)
Exine Porosity
Characteristics of the Intine Î Importance
Tetrad of
microspores (n)
Pore
Exine
Tétrades
generative (sperm)
cell (n)
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vegetative cell (n)
Intine
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Ovary
Ovule
Integuments
Ovule
Archesporial
cell (2n)
Functional
Megaspore
MEGASPOROGENESIS
and
MEGAGAMETOGENESIS
Micropyle
Egg cell (n)
Polar nuclei (2n)
Synergids (n)
Integuments
Embryo Sac
Ovary
Antí
Antípodals (n)
Nucellus
Funiculus
Ovule
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POLLINATION
TYPES
AGENTS
POLINNATION
9 WIND: pollen characteristics and flower structure
SELFSELF-POLLINATION: citrus, lettuce, tomato, okra,
tobacco, eggplant, cotton, soybean, rice, wheat,
peanut, field bean
CROSSCROSS-POLLINATION: maize, rye, Crotalaria juncea,
juncea,
sorghum, onion, cabbage, carrot, passion flower,
castor bean, sunflower, cucurbits, brassicas
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Pearl Millet
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POLLINATION
9 INSECTS: pollen characteristics and dispersion
Crotalaria juncea,
juncea, sunflower, onion, carrot,
cabbage, passion flower, cucumber
√ BIRDS; √ BATS; √ HUMAN; √ WATER
male flowers
female
flowers
LPV/USP
Plant of Vallisneria sp.
(Bhojwani e Bhatagnar,
Bhatagnar, 1976)
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POLLINATION
DIFFICULTIES
POLLINATION
IMPORTANCE
ƒ GENETIC PURITY
‰ DICHOGAMY
Crop isolation
Wind direction
- PROTANDRY: maize, carrot, onion, pecan
Proportion of parental lines
- PROTOGYNY: mango, pearl millet, cauliflower
‰ GENETIC OR MORPHOLIGICAL SELF INCOMPATIBILITY:
cabbage, Crotalaria, passion flower, sunflower, radish,
rye, orange
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Split: maize, tomato, sorghum
Male sterility: maize, cabbage, carrot
Cucumber:
Cucumber: monoecious,
monoecious, androecious and gynoecious flowering habits
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Hybrid Corn
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Hybrid Sorghum
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POLLINATION
Hybrid Pearl Millet
IMPORTANCE
ƒ PRODUCTION
Presence of insects
Geography of Area
Insect control
Sowing date and climate during
flowering and fruit development
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Temperature x pollen viability
Tomato flower (A) and inflorescences with flower in different stages
stages of development (B)
Pistil
Petals
Stamens
Anther
cone
A
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P.C.T. Melo
Flower abortion
Sepals
Ovary
Abscission
layer
B
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P.C.T. Melo
FERTILIZATION
GERMINATION OF THE POLLEN TUBE
Anther
pollen
germination
Pollination
embryo sac
pollen tube
Pollen Tube
ovule
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ovary
Sperm cells
(n)
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Vegetative cell
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FERTILIZATION
SYNGAMY:
sperm cell (n) + egg cell (n)
ZYGOTE (2n)
EMBRYO
TRIPLE FUSION:
sperm cell (n) + polar nuclei (2n)
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ENDOSPERM NUCLEUS (3n)
ENDOSPERM (?)
ENDOSPERM DEVELOPMENT
ENDOSPERM NUCLEUS
A) STORAGE TISSUE
divisions
differentiation
TYPICAL EMBRYO DEVELOPMENT OF DICOTYLEDONOUS AND
MONOTYLEDONOUS SPECIES (Copeland and McDonald)
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Pericarp
coleoptile
plumule (primary
(primary leaves)
leaves)
Endosperm
Seminal roots
(cotyledonary node)
node)
ENDOSPERM
Cotyledon (scutellum
):
(scutellum):
protection of embryo
axis and reserve transfer
coleorhiza
radí
radícle
coleoptile
GERMINATION
plumule
seminal roots
¾ ALBUMINOUS SEEDS : monocotyledonous, castor bean,
coffee, rubber tree, tomato, sugar beet, lettuce
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primary root
MAIZE EMBRYO
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ENDOSPERM DEVELOPMENT
Plumule
Radicle
B) STORAGE TISSUE
Hypocotyl
EMBRYO DEVELOPMENT
Cotyledons
plumule + primary leaves
¾ EXALBUMINOUS SEEDS : in general, dicotyledonous
leguminous, malvaceous,
malvaceous, cucurbits, brassicas
cotyledons
hypocotyl
primary root
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FIELD BEAN
EMBRYO
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EMBRYO PARTS
PERISPERM
- RADICLE: produces the seedling root
Development of the nucellar tissue
- HYPOCOTYL: part between the cotyledons and radicle
Examples: coffee, sugar beet
- COTYLÉ
COTYLÉDON(S):
Dicotyledonous → storage of reserves or embryo leaves
Monocotyledonous → protection of embryo axis and transfer of
reserves from endosperm to
to embryo
Endosperm
Perisperm
- PLUMULE: mass of meristematic cells → major leaf bud of the seed
- EPICOTYL: the portion of the embryo above the cotyledons;
in general, is present in the plumule, as a meristematic
tissue or is well developed and visible
- Coleorhiza,
Coleorhiza, coleoptile,
coleoptile, seminal roots (cotyledonary
(cotyledonary node)
Embryo
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Longitudinal section of a sugar beet seed
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FRUIT AND SEED
SEED COATS
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PRIMINE
TESTA (External)
SECUNDINE
TEGMA (Inner)
A MATURE OVARY AND ASSOCIATED PARTS, WITH
ONE OR MORE SEEDS
FRUIT
PARTS:
PARTS:
Functions
EXOCARP
MESOCARP
a) PERICARP
ENDOCARP
- Cohesion among the seed parts
b) SEED
- Protection against the action of biotic and abiotic factors
SEED COAT
- Regulation of water and gaseous exchange
ENDOSPERM (?)
- Regulation of germination and dormancy mechanisms
- Control of seed dispersion: wings, aculeus,
aculeus, hairs, mucilage
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schizocarp (carrot)
carrot), nuts
AXIS
COTYLEDON (s)
APOMIXIS
FRUIT AND SEED
DRY FRUITS : caryopsis (grasses).
grasses). achene (suflower,
suflower, lettuce),
lettuce),
EMBRYO
ASEXUAL DEVELOPMENT OF SEEDS WHOSE STRUCTURE
IS SIMILAR TO THOSE PRODUCED AFTER THE FUSION OF
THE EGG AND SPERM CELLS
SEEDS ARE FORMED FROM OVULE DIPLOID CELLS BY DIFFERENT
MECHANISMS, BUT FERTILIZATION DOES NOT OCCUR
CHARACTERISTICS OF THE PROCESS
- REPRODUCTION IS REPLACED BY ASEXUAL MULTIPLICATION
- THERE IS NO FUSION BETWEEN MALE AND FEMALE GAMETES
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- OCCURS IN PARTS OF PLANT USUALLY INVOLVED IN
REPRODUCTION
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Embryo axis
EXAMPLES OF SEED
STRUCTURE
Cotyledons
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PEA SEED
Seed coat
Endosperm
COTYLEDON
SEED COAT
Cotyledons
Embryo axis
EMBRYO AXIS
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PUMPKIN SEED
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CASTOR BEAN SEED
Cotyledon
SEED
MATURATION
Plumule
Endosperm
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ONION SEED
HypocotylHypocotyl-radicle axis
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SEED DEVELOPMENT OR MATURATION
Sequence of connected steps in preparation for
successful germination
Very important Î relationship to proper harvest
time and seed physiological potential
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Delouche (1971)
Seed maturation is a process which
includes a sequence of morphological,
physical, biochemical and physiological
changes from ovule fertilization to the
point when the seed becomes
physiologically independent of the parent
plant
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SEED DEVELOPMENT
MOISTURE CONTENT (%)
+ 80
1. Variations of seed moisture content
Seeds in fleshy or in dry fruits
Fleshy
Dry
TIME
Variations in moisture content during seed maturation in
fleshy and dry fruits
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2. Seed size changes
3. Seed dry weight
R5
Embryo dry weight
DRY MATTER ACCUMULATION
(PHASE
(PHASE III)
III)
R6
R6
R7
R8
53 Development of soybean seeds and legumes (Ritchie et al., 1994)
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CELL DIVISION AND
EXPANSION
(PHASES I e II)
II)
DESiCCATION
(PHASE
(PHASE IV)
IV)
Moisture content
Days after flowering
Dure III (1975)
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SEED DEVELOPMENT
moisture content
seed size
4. Germination
vigor
dry weight
germination
5. Vigor
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General alterations of seed characteristics during maturation
(Carvalho and Nakagawa, 2000)
SEED MATURITY x HARVEST TIME
DETERMINATION OF PHYSIOLOGICAL MATURITY
- Physiological Maturity: Identification
9 Black layer
9 Milk line
9 Soybean
9 Wheat, barley, oat
9 Vegetables, Fruits
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- Physiological Maturity: identification
SEED MATURITY x HARVEST TIME
- Determination of harvest time
Parameters
Seed moisture content
Seed and plant characteristics
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Ana Novembre
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CONCLUSION
™ CROP TECHNOLOGY
Climate, sowing time, sowing management, inspections, harvest
™ POLLINATION CONTROL
™ PRE AND POST HARVEST SEED MANAGEMENT
™ BASIS FOR DIAGNOSIS AND HARVEST DECISIONS
™ SEED TESTING: routine analysis and “in house”
house” quality control
™ BIOTECHOLOGY
Somatic embryogeny
Artificial seeds
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