EXERCISE NO. 4 Flashcards
Title of Exercise 4
DEFENSE MECHANISM IN PLANTS:
Adventitious Root formation in Response to Indole-3-acetic acid (IAA)
Roots may form from ____ or _____ tissues.
Root - Lateral roots
Stem - Adventitious roots
_______ serve several important functions for plants and are crucial for their growth, survival, and adaptation to changing environments.
Roots
The ability to cause _________ to form on stems is extremely useful in the production of plant clones for commerce, industry, and research.
adventitious roots
If one can produce roots on a stem cutting, then it is possible to make as large a clone as desired. As one takes cuttings from the “mother” plant, it branches due to loss of _______ _________, and provides even more cuttings.
apical dominance
function to coordinate plant growth and development
Phytohormones
example of growth hormones used is _____________ which is an _________
indole-3-acetic acid or auxin
are found in shoot and root tips and promote cell division, stem and root growth.
They can also drastically affect plant orientation by promoting cell division to one side of the plant in response to sunlight and gravity.
auxin
- influence the behavior of cells according to their preexisting identity.
- is one such growth coordinator—regulating where, when, how much, and what sort of growth should occur.
Auxins
plant used for the expirement
mung bean (Vignata radiata)
what are the 4 set ups?
1- 3ml control (distilled water)
2- 3ml 0.01% IAA
3- 3ml 0.001% IAA
4- 3ml 0.0001% IAA
(3 replicates each set-up)
What do you need to make sure when you let it stand under the light for a week?
Make sure that the tubes will not run dry by checking daily and adding equal volumes of IAA of the respective solution
what are the two things that are needed to be observed
stem growth and number of adventitious roots
Which concentrations of IAA produces the most number of roots?
.0001% IAA
Which concentrations of IAA produces the least number of roots?
.01%
How does IAA influence root formation?
IAA positively influences root formation by promoting cell elongation and division in the root tip, which results in the initiation and growth of new roots. Also helps in, direct root growth in response to gravity (gravitropism).
However, growth regulators such as the IAA can still inhibit growth through phytotoxicity depending on excessive use and timing
How does IAA influence stem growth?
at low concentrations (0.0001% IAA) primarily promotes cell elongation. It helps stimulate the expansion of cells in the stem, leading to increased stem length. It softens the cell walls in the stem, making them more flexible and allowing the cells to stretch. This results in increased stem length. Moderate concentrations of IAA (0.001% IAA) continue to promote cell elongation, contributing to stem growth.
Meanwhile, High concentrations of IAA (0.01% IAA) can have inhibitory effects on stem growth. Excessive IAA can disrupt normal growth processes and lead to stunted or abnormal stem development. It should be noted that growth regulators in excessive concentrations or improper typing can result in phytotoxicity
How is IAA different from Gibberellins and ethylene in terms of functions?
These three hormones play roles in regulating plant growth and development
IAA is primarily involved in
- promoting cell elongation
- phototropism (growth toward light)
- apical dominance (regulation of lateral bud growth),
- root development.
Gibberellin
- stimulates stem elongation and seed-related processes,
Ethylene
- involved in various growth and stress responses
