Plant Responses: Hormones, Ripening, and Phototropism

In this video I discuss how plants respond to various stimuli such as water loss, air chemistry, herbivores, and the position of the Sun. Plants produce hormones to signal to other parts to respond, including when to begin the ripening process for their fruits. Some fruits ripen in a climacteric phase as ethylene gas production and CO2 rapidly increase, while non-climacteric fruit gradually decrease in gas production. Plants defend themselves from herbivores by producing toxins or bad tasting / smelling chemicals. Many plants have photoreceptor proteins which react to specific wavelengths of light, indicating the time of day and other information. Shoots typically grow towards the light (phototropism), while roots grow away from it (skototropism). Some flowering plants, such as daisies and sunflowers follow the Sun throughout the day, a phenomenon called heliotropism.

Time stamps:

Plants produce hormones in one part of its body to signal cells in another part to respond: 0:00
Comparison of climacteric and non-climacteric ripening and CO2 production: 1:44
Climacteric vs non-climacteric fruits: 3:16
Plants defend themselves by producing toxins and foul-tasting or smelling chemicals: 4:13
Diagram of a flowering plant moving towards the light while roots move away from light: 7:01
Diagram showing how auxin molecule distribution controls phototropism aligning with the Sun: 7:40
Daisy flowers facing the sun after opening in the morning: 9:18
Animation of sunflowers following the Sun: 10:11
Plants can sense the direction of gravity and orient themselves correctly: 10:55

Full video below: