Unit-II Plant Harmones and their functions.pptx

Unit-II Plant Harmones and their functions.pptx

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  PLANT HORMONES Mr Rahuldev Assistant Professor Gracious College of Pharmacy, Abhanpur
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  PARTS OF PLANT
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  PLANT HORMONES Plant hormones/Phytohormones are the organic compound (inter cellular messenger) which present in low concentration in plant and control physiological process (complete life cycle) on plants. •Plant hormones or phytohormones are chemicals that regulate plant growth. •Plant hormones are signal molecules produced within the plant and occur in extremely low concentrations. •Hormones regulate cellular processes in targeted cells locally and when moved to other locations, in other locations of the plant. They affect gene expression and transcription levels, cellular division and growth. Plant Growth Regulators:- 1. Native substance (Endogenous/Plant Hormones) 2. Synthetic substance (Exogenous) Class of Phytohormones : 3. Auxin 4. Cytokinins Plant Growth Promoters 5. Gibberellins 6. Abscisic Acid Plant Growth Inhibitor 7. Ethylene
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  PLANT HORMONES Role ofPlant Growth Regulators: 1. Regulate cell division and enlargement 2. Cell differentiation/ Organogenesis 3. Senescence (Aging) 4. Dormancy (Stopping of growth of plant parts) 5. Ripening of fruit 6. In Plant tissue culture 7. Enhance production of Secondary Metabolite.
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  PLANT HORMONES Auxin It isderived from Greek word “Auxein” which means “to grow”. It Promote elongation of Coleoptile tissue. Types:- 1. Natural Auxin: Indole-3-Acetic acid (IAA) 2. Synthetic Auxin: Indole-3-butyric acid (IBA) Napthyl acetic acid (NAA) 2,4 dichlorophenoxy acetic acid (2,4 D) Function of Auxin:- 1. It Stimulate internode alongation (cells). [Increase length of the stem] 2. It dominate Apical bud. [Increase in apical bud(vertical) growth and inhibit lateral bud growth] 3. It Promote Abscission of organs of plant. (Remove out older leaves, steam and fruits from trees). 4. It promote differentiation of vascular tissue. [xylem- tubular structure(Water transportation system of plants) and phloem(food transportation system of plants)] 5. It stimulate Root initiation on stem cutting propagation. (Vegetative Propagation). 6. It helps to produce Adventitious rooting in tissue culture. 7. It Delays senescence. (Aging) Fig:- Structure of IAA
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  PLANT HORMONES Auxin 8. Tropisticresponse of bending in response to gravity(Gravitropism) and light(Phototropism). • Gravitropism is a plants growth response to gravity, causing roots to grow downwards (Positive gravitropism) and shoots to grow upwards (Negative gravitropism). • Phtotropism is the growth or movement of a plant in response to a light stimulus. Most plants shoots exhibit positive phototropism, meaning they grow towards a light source. Roots, on the other hand, often exhibit negative phototropism, meaning they grow away from the light. Application: •It helps in Vegetative propagation (formation of roots from stem cutting) •It helps in Parthenocarpy fruit development. (seedless fruits development) •In higher concentration 2,4-D used as herbicide. •It helps in Plant tissue culture. •Helps in increase Production of secondary metabolites. (In Ergot- it increases Indole alkaloids, In Mentha piperata-It increase 40% of volatile oil when we use NAA).
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  PLANT HORMONES Cytokinin Cytokinin derivedfrom two words : Cyto (Cell) + Kinin (Division)  Cytokinin Promotes Cell division in plants. It Found in young and actively dividing tissue. Types of Cytokinin:- 1. Natural : Zeatin, N6 dimethy aminopurine, isopentanyl aminopurine 2. Synthetic : Kinetin, N,N-diphenyl urea Function of Cytokinin:- 1. It stimulate cell division of plants. 2. It helps in Seed germination. 3. It helps in development of embryo during seed germination. 4. It stimulate morphogenesis. (means development of morphological part of plant like- leaf and stem) 5. It promotes growth of axillary bud (or adventetious bud) 6. It helps in leaf expansion (Leaf growth and Inlargement) 7. It helps in Chlorophyll synthesis. 8. It Delays senescence of plant. (Delay Aging) 9. It enhance stomatal opening in some species of plant. Fig:- Structure of Zeatin
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  PLANT HORMONES Cytokinin Application ofCytokinin:- 1. It enhance cell division in plant tissue culture. 2. Helps in shoot initiation in tissue culture and release of lateral bud dormancy. 3. It helps to increase the growth of vegetables and yield. 4. It helps to break the dormancy of seed. (It improve seed germinations) 5. It helps to increase in secondary metabolite (eg: increase in sennoside content in Tinnevelly senna). 6. It reduces rate and extant of chlorophyll and protein degradation and leaf drop.
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  PLANT HORMONES Gibberellin They Presentin young tissue, root, embryo, germinating seeds, shoot bud etc. They named as GA1, GA2, GA3……………… GAn (According to their order of discovery) GA3  is a Gibberellic acid which is frequently used . It Firstly discovered from fungus  named Gibbrella Fujikuroi  by Kurosawa – a Japanese physiologist  founded that fungus is grown on rice. Fig:- Structure of Gibberellic acid
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  PLANT HORMONES Gibberellin Function ofGibberellin:- 1. It promote stem alongation. (Drowart plant change in to the taller plant) and internal cell alongation. 2. It helps to break the seed & bud dormancy. (Dorment seeds becomes germinating seeds) (Buds converted into the shoots) 3. It helps to increase in the size of leaves. 4. Induction of parthenocarpy which means gibbrellin used to develop seedless fruits, and also increase size of fruits) 5. It Delays senescence(Aging) of leaves and citrus fruits. 6. It promotes bolting(Steam alongation before Flowering) and flowering of the long day plants. 7. When gibbrellin used in lower concentrations (dose) it increase yield of glycoside per shoot of digitalis. 8. It helps to increase production of Digoxin (Root and leaf culture of Digitalis). 9. It increases volatile oil content of Anethum species. 10. It increases height of the castor plant. 11. Helps to delay fruit maturity(ripening).
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  PLANT HORMONES Ethylene (C2H4) •Itis simple organic molecule present in the form of gas (Volatile Hormones). •Present in  ripening fruits, flowers, stem, root, tubes, seed, leaf etc. •Present in  aging part of plants. •Discovery  Gane(1934)  he found that a gas evolved from ripe apple can also effect the ripening of green apple and found that it was ethylene gas. Crocker(1935) recognized it as plant hormone. Function of Ethylene:- 1. It helps in Fruit ripening(Maturity). 2. It helps in abscission of leaf. 3. It Suppresses stem and root elongation. 4. It stimulates flower and leaf senescence. 5. It stimulates fruited leaf abscission. 6. It breaks the dormancy and helps on stem swelling. 7. When Ethylene + Auxin are used they supress auxillary bud formation. 8. It Stimulate latex(Milky white fluid) flow in rubber tree. 9. When ethylene is used at low concentration it increase sennoside in cassia angustifolia (Senna). 10. It affects flower opening and flower patle discoloration. Fig:- Structure of Ethylene
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  PLANT HORMONES Abscisic Acid(ABA) •It produced by aging leaves and fruits and when plants are stressed (Unfavorable Condition). That’s the reason we also called it Stressed hormone. •Scientist Waring and Robinson called it Dormin. •Discovery  Addicott and Associates (1963) first isolated Abscisin I and Abscisin II (Abscisic Acid) from cotton balls. Osborne found it in senescent leaves. Function of ABA:- 1. It promotes abscission of different organ(leaves, flowers, fruits etc). 2. It increase Seed and Bud Dormancy. 3. It inhibit Gibberelin synthesis of α-amylase and other hydrolytic enzyme (counter effect of gibberellin). 4. It acts as Anti-transpirant .(It promote closure of stomata) 5. ABA enhance in stress condition.(water deficiency, injury, freezing temperature) 6. ABA reverse the effect of other growth stimulating hormone. Fig:- Structure of Abscisic acid