DEVELOPMENTAL BIOLOGY
stomium- Weak part of pollengrain from where pollentube develops.
→ Nourishment
→ Produce enzyme( callase), hormones
→ Ubish granulefrom exine (Sporopollenin)
→ Secret pollenkitt
Integument→ Gynoecium Unitegmic
Sporopollenin→ Hardest substance in plant.
Double fertilization
- → Discovered by Nawaschin in Lilium & Fritilaria
- → Syngamy+ Triple Fertilization
Study of pollengrain is palynology.
Pollengrain has 2 layered water.
Outer exine→ composed chiefly of sporopollenin.
Inner intine→ pectocellulosic in nature.
Generative cell gives 2 male gametes while vegetative cell forms pollen tube.
Orthotropous- Micropyle, funicle and chalaza in straight line.
Anatropous- Funicle and micropyle lie side by side.
Hemianatropous- Integuments and nucellus are at right angle to funicle.
Campylotropous ovule- Curved ( Horse shoe shaped)
Endothelium→ Nutritive formed by dissolution of innermost layer of integument.
Obturator→ Ovular structure, direct pollentube to micropyle.
Caruncle→ Develop from outer integument of ovule.
Perisperm→ Remanant of nucellus.
Aril→ Develop from funicle of ovule.
Herkogamy→ Prevent self pollination when reproduction part themselves behave as physical/ mechanical barren
Anemophily→ Graminae and Gymnosperm, Versatile anther, typical cross pollination in maize.
Entomophily→ Pollination in Yucca by Pronuba yuccasella ( Obligate symbiotic relation)
Epihydrophily→ Vallisneria
Hypohydrophily→ Zostera, Naja, Ceratophyllum (@ZNC)
Ornithophily→ Bird- Bombax, Bottle brush, Bigonia, Butea monosperma
Zoophily→ Rafflesia (by elephant)[ Carrion fly]
Ophiophily/ Serpentophily→ Arisaema( Snake plant or Cobra plant)
Malacophily→ Lemna, Colocasia
Chireptophily→ Sausage tree( Kigelia), Anthocephalus
Germination of pollengrain supported by Ba, Ca++
Porogamy→ Micrpyle
Basigamy→ Chalazae eg: Casuarina
Mesogamy→ Tntegument/ Funicle eg: Cucurbita
• Angiosperm has triploid endosperm (formed after fertilization) and gymnosperm (formed before fertilization)
Nuclear endosperm→ Most common type of endosperm
Coconut milk→ Liquid endosperm rich in cytokinin
Maize→ Zeatin (Cytokinin)
• Polyembryony:
→ Gymnosperm (common)
→ Discovered by Leewenhoek in Citrus
• Parthenocarpy→ Fruit from unfertilized ovary.
Natural parthenocarpy in banana, grapes, pineapple.
• Parthenogenesis→ Embryo from unfertilized egg.
Caruncle→ Castor
→ proliferation of outer integument
• Dicot plant one cotyledon→ Cuscuta, Monotrapa
• Dicot plant with unequal cotyledon→ Trapa
• Dicot plant with several cotyledon→ Loranthus
• Single shield shaped cotyledon of monocot→ Scutellum
• Tigellum→ Main axis of embryo
• Plumule of maize covered by coleoptiles and radical by Coleorhiza.
• Aleurone layer→ Triploid, proteinous layer present in maize (peripheral part of endosperm)
Floral Formula:
Cruciferae:
Solanaceae:
Compositae:
Ray Floret
Disc Floret
Fabaceae:
Graminae:
Liliaceae:
PGR AND HORMONES
Growth curve------------>’S’ shaped sigmoid curve
Phases of growh
- Lag phage------------>Initiating phase, Show cell division
- Deaccelerating phase------------>Decrease in growth rate
- Stationary phase------------>Constant growth
- Log phase------------>Maximum growth, fast cell division
Plant hormone
Termed hormone by Starling.
Growth hormone
- Growth inhibitors {Ethylene, Abscissic acid(ABA)}
- Growth promote {Auxin, Gibberellins, Cytokinin}
| Positive | Negative | |
| Apical dominance | Auxin | Cytokinin |
| Dormancy of seed | Abscissic acid, Auxin | Gibberelin, Cytokinin |
| Senescence or Ageing | Ethylene | Cytokinin |
| Parthenocarpy | Auxin, Gibberelin | |
| Abscission of plant | Ethylene, Abscissic acid | Auxin |
Main function of Cytokinin is to mobilize solute to different parts of plant and check senescence.
Flowering in short day plant is by cytokinin.
Rooting hormone------------>IAA
Fusarium moniliforme is the fungus from which Gibberelin was extracted by Yabuta and Suniki.
Food mobilization in germinating seed is by gibberelin.
Cytokinin synthesis is maximum in roots and if concentration of auxin is high and cytokinin is low root initiation occur.
Clinostat is used to study geotropism.
Stomata closure induced by abscission acid and gibberellins includes male flowers in place of female flowers and auxin make male flower into female flower.
Hapto or Thigmo------------> Response to touch
Nyctinasty or sleep movement------------>Night sensitive
Seismo------------>Shock
Nastic movement------------>Epinastic(More on adaxial surface) and Hyponastic(More on abaxial surface)