Bio151 - Plant Response Systems

Vocabulary flashcards covering plant signal transduction pathways, etiolation, de-etiolation, and the cellular mechanisms involved in plant response systems.

Plant Environmental Response

The process by which plants sense and integrate information from their environment by altering growth and development, unlike animals which typically respond by movement.

Etiolation

Morphological adaptations for growing in darkness, characterized in a sprouting potato by pale stems, unexpanded leaves, and short roots.

De-etiolation

The morphological changes a plant undergoes after exposure to light, during which shoots and roots begin to grow normally (also referred to as greening).

Cell Signal Processing Stages

The three sequential stages linking an environmental stimulus to a cellular reaction: reception, transduction, and response.

Reception

The detection of external or internal signals by receptors, which are proteins that change shape in response to specific stimuli.

Phytochrome

A photoreceptor protein capable of detecting light that serves as the receptor in the de-etiolation pathway.

Transduction

The second stage of cell signaling where second messengers transfer and amplify signals from receptors to specific proteins that cause responses.

Second Messengers

Small molecules or ions—specifically calcium ions ($Ca^{2+}$) and cyclic GMP (cGMP) in de-etiolation—that transfer and amplify signals from receptors within the cell.

De-etiolation Signal Transduction Pathway

A cellular pathway initiated by light-activated phytochrome that triggers the opening of $Ca^{2+}$ channels and the production of cGMP, activating protein kinases and transcription factors to produce de-etiolation response proteins.

Response

The final stage of a signal transduction pathway that leads to the regulation of one or more cellular activities, most commonly involving an increase in enzyme activity.

Transcriptional Regulation and Post-Translational Modification

The two primary mechanisms through which cellular responses stimulate and increase the activity of enzymes.

Plant Hormones

Chemical signals that modify or control one or more specific physiological processes within a plant

Auxin

Stimulates stem elongation (low concentration) promotes formation of lateral and adventitious roots

Cytokinins

Regulate cell division in shoots and roots

Gibberellins

Stimulate stem elongation pollen development pollen tube growth fruit growth and seed development and germination

Abrisic Acid

Inhibits growth promotes stomatal closure during drought stress

Ethylene

Promotes ripening of many types of fruits, leaf absission and inhibits stem elongation

Brassinosteroids

Promote cell expansion and cell division in shoots, promite root growth at low concentrations

Jasmonates

Regulate a wide variety of functions includijg fruit ripening floral development, pollen production; tendril coiling

Strigolactones

Promote seed germination, control of apical dominance, and attraction of mycorrhizal fungi to root

Tropism

Any response resulting in curvature of organs toward or away from a stimulus

Phototropism

plants response to light

Expansins

Enzymes that loosen the fabric of the cell wall

Cytokinens

Stimulate cytokinesis (cell divsion)

Gibberellins

Stem elongation, fruit growth, seed germination

Ethylene

Produced in response to stresses such as drought flooding mechanical pressure injury and infection