Plant Hormones presentation--Grade 12, term 3

A slideshow that explains a few plant hormones as well as their functioning. The hormones covered are: Gibberellins; Brassinoosteroids; Abscisic Acid and Ethylene

1. Plant Hormones Unit 5 Presented by: Reproductive Rangers

2. Gibberellins

3. Gibberellins Gibberellins have a variety of effects, such as stem elongation, fruit growth, and seed germination

4. Main Functions Stem Growth 01 Gibberellins stimulate growth of leaves and stems In stems, they stimulate cell elongation and cell division 02 In many plants, both auxin and gibberellins must be present for fruit to set. Allows plants to germinate in the absence of favouribe conditions Gibberellins are used in spraying of Thompson seedless grapes Fruit growth

5. Functions Seed dormancy buds formed in autumn stay dormant till spring gibberellins can be used to overcome dormancy Root Growth high concentration of gibberellins can inhibit growth in some plant's roots. Commercial uses obtained from fung i-used to facilitate germination of seeds. Sprayed on grapevines used to make them grow larger . Sprayed on plants to allow constant flowering despite unfavorable conditions

6. Brassinosteroids

7. Look at the following images With Brassinosteroids Without Brassinosteroids

8. Functions Brassinosteroids are found within the cell membrane of plants This is a plat steroid It is like the stress hormone cortisol in humans- it raises phloem sugar levels to deal with environmental stress. Abiotic (environmental) stress weather; herbicides; water availability, and diseases Think of what steroids do in humans. BR makes plants grow larger; greener in colour; have stronger anchorage Brassinosteroids are chemically similar to the sex hormones of animals. Similar to Auxins - induce cell elongation and division in stem segments. Assist with Senescence (programmed death )

9. Functions

10. Abscisic Acid

11. Abscisic acid Abscisic acid (ABA) slows growth Two of the many effects of ABA: Seed dormancy Drought tolerance

12. Main Functions Seed Dormancy 01 Seed dormancy ensures that the seed will germinate only in optimal conditions In some seeds, dormancy is broken when ABA is removed by heavy rain, light, or prolonged cold. 02 ABA is the primary internal signal that enables plants to withstand drought Drought Tolerance

13. Ethylene

14. Ethylene Plants produce ethylene in response to stresses such as drought, flooding, mechanical pressure, injury, and infection The effects of ethylene include response to mechanical stress, senescence, leaf abscission, and fruit ripening

15. Functions of Ethylene Senescence programmed death of plant cells or organs. Affect leaf yellowing and shedding of leaves Associated with apoptosis , the programmed destruction of cells, organs, or whole plants Leaf Abcission Occurs because of environmental conditions, such as autumn temperatures . A change in the balance of auxin and ethylene =leaves to fall from the plant . Fruit Ripening A burst of ethylene production in a fruit triggers the ripening of fruits on plants Leads to changes in color; texture, and flavor .