Several shrubs in Paul’s garden are beginning to wilt, turn brown, and die. He has been watering, fertilizing, and caring for the plants daily, and cannot determine why the plants look so sickly. He takes several leaf samples to his local botanist where the botanist makes prepared slides of the tissue from the leaves. The botanist notices that the most of the cells have sustained damage to their dense supportive barrier. What organelle is damaged in these cells?