Download "Solution Pharmacy" Mobile App to Get All Uploaded Notes, Model Question Papers, Answer Papers, Online Test and other GPAT Materials - play.google.co...
Plant hormones, also known as phytohormones, are chemicals that regulate plant cell processes. They are signal molecules produced within the plant functioning in extremely low concentrations
Five major types of plant hormones
1. Auxin
2. Gibberellin
3. Cytokinin
4. Ethylene
5. Abscisic acid
Plant growth regulators usually are defined as organic compounds, other than nutrients, that in small concentrations, affect the physiological processes of plants”.
1. Auxins
Compounds are generally considered as auxins if they are synthesized by the plant and have similar activity to Indole-3- acetic acid (IAA).
Functions of Auxin
The following are some of the responses that auxin is known to cause
1. Stimulates cell loosening, expansion and elongation.
2. Initiation of adventitious roots on stem cuttings
3. Lateral root development in tissue culture
4. Stimulates differentiation of phloem and xylem
5. Stimulation of abscission (young fruits) or delay of abscission
6. Stimulates cell division in tissue culture in combination with cytokinins
7. Mediates the tropistic response of bending in response to gravity and light
2. Gibberellins
Gibberellins are synthesized in young tissues of the shoots, uncertainly in roots and also in the developing seeds. There are also some evidences that leaves may be the source of some biosynthesis
Discovery of Gibberellins
A Japanese scientist E. Kurosawa in 1926 found that some of the rice seedlings grow taller than others. He discovered the seedlings to be infected by the pathogenic fungus Gibberella fujikuroi. In 1935, an agricultural chemist T. Yabuta isolated a non-crystalline material from the similar type of culture that he named as “gibberellins” All gibberellins are derived from the gibberellane skeleton. The gibberellins are named GA1, GA2, GA3, .., GAn in their order of discovery. Gibberellic acid -GA3, was first structurally characterised gibberellin. There are at present 136 GAs that have been identified from plants, fungi and bacteri.
Functions of Gibberellins
Physiological processes stimulated by active gibberellins depend on their types.
1-Stimulate cell elongation in stem
2-Breaks seed dormancy in some plants which requires light for germination
3-Stimulates alpha-amylase production in germinating cereal grains
4-Stimulates bolting/flowering in response to long days
5-Delay senescence in leaves and also in citrus fruits
6-Induces maleness in dioecious flowers
7-Play a role in development of seedless fruit (parthenocarpic).
3. Cytokinins
In Cytokinin, cyto = cell + kinin = division, i.e. meaning is cell division. Cytokinin is also called as cytokine. These are the compounds resembling with adenine (aminopurine) which stimulates cell division.
Functions of Cytokinins Physiological processes stimulated by cytokinins, Stimulates cell division Activates metabolite attraction (sink effect) Retardation of senescence (at low concentrations) Induction of apoptosis (at high concentrations) Stimulates morphogenesis in tissue culture
Get in touch with the solution by just clicking following links-
Facebook Group- / solutionpharamcy
Facebook Page- / pharmavideo
New channel (Pharmacy Dictionary) - / @pharmacydictionary
Instagram- / solutionpharmacy
E-Mail for official and other work - solutionpharmacy@gmail.com
LinkedIn- / pushpendrakpatel
#solutionpharmacy #Pharmacologyclass #GPATonlinetest
26 сен 2024
