Stomates

Stomates

Pores that allow carbon dioxide to enter and water vapor to exit by the leaf by transpiration.

Stomate mechanism of opening

H+ pumps are activated in the membrane of the guard cell that pump H+ ions out of the cell, creating a gradient that allows K+ ions to flow in, leading to water influx and cell turgor pressure increase, causing stomate opening.

Light-induced stomatal opening

Photoreceptors inside guard cells absorb light and induce a signal transduction mechanism that activates H+ pumps in the guard cell membrane and induce stomatal opening

Blue-light absorbing photoreceptors

Phototropins that are the primary photoreceptors that induce stomatal opening

Effect of abscisic acid to stomate opening

Prevents stomatal opening by blocking the activity of the H+ pumps and activates proteins that cause the efflux of K+ ions out of the cell thereby blocking light induced stomatal opening