Yes, magnesium deficiency can occur in Plumeria, and it may lead to interveinal chlorosis, where the leaf tissue between the veins turns yellow while the veins remain green. Magnesium is a vital component of chlorophyll, and its deficiency affects the plant’s ability to carry out photosynthesis properly. The yellowing symptoms start in older leaves and gradually progress to younger leaves. Addressing magnesium deficiency is crucial to ensure the plant’s energy production and overall growth.