Ethylene induces fruit ripening
When the seeds are mature, ethylene production increases and builds–up within the fruit, resulting in a climacteric event just before seed dispersal.
The hormone ethylene is responsible for the ripening of fruits. Ethylene is the only plant hormone that is a gas at room temperature.
Normally, when the seeds are mature, ethylene production increases and builds–up within the fruit, resulting in a climacteric event just before seed dispersal. The saying, "One bad apple spoils the whole barrel" has its basis in ethylene gas. One rotting apple produces ethylene gas, which stimulates nearby apples to ripen and eventually spoil.
In some plant species, ethylene promotes abscission, which is the detachment of leaves, flowers, or fruits from a plant. Cherries and walnuts are harvested with mechanical tree shakers. Ethylene treatment increases the number of fruits that fall to the ground when the trees are shaken. Leaf abscission is also an adaptive advantage for the plant. Dead, damaged or infected leaves drop to the ground rather than shading healthy leaves or spreading disease. The plant can minimize water loss in severe winter, when the water in the plant is often frozen.