Plant Hormones and Signal Transduction - 12 Flashcards
Define signal
environmental input that initiates one or more plant responses
Define receptor
the physical component that biochemically responds to a signal
What do receptors consist of
proteins or pigments associated with proteins (if light receptors)
What are the 4 chain of events that the signal transduction pathways typically involve
signal -> receptor -> signal transduction -> response
signal transductions can cause both rapid and slow responses, explain the difference in responses
rapid responses involve electrochemical responses
longer/slower involve changes in gene expression
plant responses to environmental signals can differ ____ and/or ___
time or spatially
Define cell autonomous response vs. non-cell autonomous response (is how plant responses differ spatially) and examples
cell autonomous = response to environmental signal where both the signal reception and response occur in the same cell (ex. guard cell)
non-cell = signal reception occurs in one cell and the response occurs in a different cell (ex. stomata)
where are the 4 places receptors can be located
plasma membrane, cytosol, endomembrane system, or nucleus
or found in more than 1 cellular location!
Define kinase
an enzyme that catalyzes the transfer of a phosphate group from ATP to a specified molecule (most common modification)
Define secondary messenger and what is the most common one
Ca2+
released in response to the primary messengers which are transported to the site of action to evoke the main physiological response
What are strategies for kinases to amplify signal transduction pathways (2)
Kinases = elevate weak initial signaling events above the threshold of detection or to propagate throughout the cytoplasm
Explain the processes of activation and termination of the secondary messenger Ca2+
signal induced activation of Ca2+ permeable ion channels in cytoplasm, activated sensor proteins interact and link signals to changes in activity -> can activate calmodulin by binding or phosphorylate target proteins, pumps and exchangers remove Ca2+ from cytoplasm and terminate signal
What is the secondary messenger Ca2+ mostly involved in
plant defenses and symbiotic interactions
what other factor can regulate Ca2+ fluxes
membrane lipids
Aside from Ca2+, what is another important secondary messenger
protons
Define hormones as chemical messengers
chemical messengers produced in one cell and modulate cell processes in another cell. they interact with specific proteins that function as receptors linked to cell signal transduction pathways
Explain the pathway of hormones
signal perception increases hormone biosynthesis -> hormone transported to site of action -> perception of hormone occurs by the receptor -> results in transcriptional or posttranscriptional events that induce a response -> suppress synthesis by negative feedback by catabolism or sequestration -> ready for next signal input
Plant development is regulated by what 9 major hormones
- auxin
- gibberellins
- cytokinins
- ethylene
- abscisic acid
- brassinosteroids
- salicylic acid
- jasmonates
- strigolactones
Auxin function
plant growth, growth regulator, embryo development in seeds, lateral branching, delaying leaf senescence
define polar auxin transport
directional auxin movement that functions in development and growth responses
Gibberellins function
transition to flowering, fruit development, growth promoting regulators
Cytokinins function
breaking bud dormancy, leaf senescence, formation of apical meristems, produced during mycorrhizal formation
What can cytokinins do in the presence of auxins
can stimulate plant tissue to produce parenchyma cells in undifferentiated masses called callus (cells that cover plant wound)
Ethylene function
fruit ripening, leaf and flower senescence, epinasty
