L33: How Plants Perceive Light

Light Regulation

Light influences plant growth and development.

Hypocotyl

Stem of a seedling, elongated in darkness.

Cotyledons

Seed leaves that expand in light.

Chlorophyll

Green pigment essential for photosynthesis.

Gene Expression

Process by which genes are activated.

CAB Gene

Gene regulated by light in plants.

b-GLUCURONIDASE

Stable reporter gene for transcription studies.

Luciferase

Unstable reporter for monitoring gene transcription.

Transgenic Plants

Plants modified to express foreign genes.

Luciferin

Substrate used to measure luciferase activity.

Circadian Rhythms

Biological clock regulating daily processes.

Photoreceptors

Proteins that detect light signals.

Phytochromes

Photoreceptors for red and far-red light.

Cryptochromes

Photoreceptors for UV-A and blue light.

Phototropins

Photoreceptors controlling phototropism in plants.

UVR8

Photoreceptor for UV-B light detection.

Apoprotein

Protein component of a photoreceptor.

Chromophore

Light-absorbing molecule attached to apoprotein.

Pr Form

Inactive form of phytochrome in darkness.

Pfr Form

Active form of phytochrome after red light exposure.

Shade Avoidance Response

Growth response to detect neighboring plants.

R:FR Ratio

Ratio of red to far-red light.

Flavonoids

Compounds that protect plants from UV damage.

Gene Regulation

Control of gene expression by environmental factors.

Seed Germination

Initiated by light exposure in some species.

Transcription Monitoring

Tracking changes in gene expression over time.

Biological Responses

Reactions initiated by phytochrome activation.

UV-B Effects

Regulates gene expression and flavonoid biosynthesis.

Light Spectrum

Range of light wavelengths affecting plant growth.

Light Duration

Length of time light is present.

Light Quality

Wavelength composition of light received by plants.

Light Quantity

Intensity of light affecting plant processes.