1. Plant Signaling and Response

2. Hormones Review chemical signals that coordinate parts of an organism produced in one part and transported to another often work together to induce a change minute amounts can induce substantial change

3. Signal Transduction

4. 1.Reception: signals are detected by receptor proteins 2.Transduction: second messenger chemicals transfer and amplify the signal from the receptor to proteins that cuase the specific response. 3.Response: regulation of cellular activities by proteins

5. Plant Hormone Carousel

6. Tropisms Any growth response that results in curvatures of whole plant organs toward or away from a stimuli

7. Phototropism Phototropism: growth of shoot toward light. Auxin plays a major role in this response. Darwin, Boysen-Jensen, and Went experiments with phototropism led to the discovery of plant hormones.

8. Phototropism Experiments

9. Gravitropism Gravitropism: a plant’s response to gravity. Roots display positive gravitropism. / Shoots display negative gravitropism. Auxin plays a major role in this response. Plants may be able to tell up from down by the settling of statoliths.

10. Thigmotropism Thigmotropism: directional growth in response to touch. Thigmomorphogensi s: changes in form that result from mechanical stimuli. Twining motions of vines video clipTwining motions of vines video clip (Circumnuation)

11. Another Touch Response Thygmonastic Movement ▫Use action potentials similar to animal nervous-system messages ▫Change the turgor pressure results in movement Fly Trap Video Clip

12. Photoperiodism Plants use the photoperiod (relative lengths of night and day) to detect the time of year. Photoperiodism: a physiological response to photoperiod Plants detect light with photoreceptors such as phytochrome and cryptochrome. Long day plants are actually short night plants.

13. Photoperiod and Flowering