Question

The pathogenic fungus Fusicoccumamygdalisecretes a toxin called fusicoccin that activates the plasma membrane proton pumps of plant cells and leads to uncontrolled water loss. Suggest a mechanism by which the activation of proton pumps could lead to severe wilting.

Short answer

Activation of the proton pump of the plants’ plasma membrane results in uncontrolled water loss. It is because activation of proton pump results in entry of potassium in stomata. The stomata remain open for a longer period and cause excessive loss of water from plants by evaporation.

Step-by-step solution

Fusicoccumamygdali

Fusicoccumamygdaliis a fungus belonging to the family Botryosphaeriaceae. It results in the opening of stomata by releasing the toxin fusicoccin. Thus, they are harmful to plants and called plant pathogens. They belong to kingdom fungi and phylum Ascomycota.

Effect of Fusicoccin on proton pump of plant cell

The plasma membrane of plant cells consists of a proton pump for their effective working. The proton pump maintains the exchange of ions across the cell to maintain the opening and closing of the stomata.

The toxin Fusicoccin acts on the proton pump of the plasma membrane and results in their activation. This results in the entry of potassium in the guard cell that leads guard cells to open. It results in the loss of water in large amounts from plants.

Mechanism by which wilting (loss of water) occurs in plant cells

Wilting occurs due to the opening of guard cells that lead to evaporation. When potassium is taken up by guard cells, they remain open. Their opening causes transpiration and evaporation of water from them. This results in the wilting of plants.