Morphological and physiological insights into coordination of anthocyanin deposition and cuticle formation in leaf development of Rosa chinensis

Juvenile leaves exhibit a red coloration due to the presence of anthocyanins, which assist plants in resisting various environmental stresses. This characteristic is common and visually striking among many woody species across various higher plant families. However, the mechanisms underlying leaf color change during development and the defense mechanisms of mature leaves remain unclear. In this study, we analyzed the mechanism of color change from red to green in Chinese Rose ( Rosa chinensis ) leaves and the development of cuticular wax in their natural state. The results show that anthocyanins and cuticular waxes are deposited at different stages of leaf development. During the red and young stage, anthocyanins are abundant in both the upper and lower epidermal cells of the leaves, while no cuticular wax is observed. As the leaves develop, the content of anthocyanins gradually decreases, leading the leaves to turn green. Anthocyanins first disappear from the upper epidermis, while the accumulation of cuticular wax begins at this stage. By the time the leaves are fully differentiated and green, anthocyanins have completely disappeared, and cuticular wax is deposited on both the upper and lower epidermis. The anthocyanins accumulated in the epidermal cells are primarily cyanidin, which is present in significantly higher content during the early stages of development compared to the later stages. Using gas chromatography-mass spectrometry (GC-MS) to determine the composition and content of leaf waxes, we found that alkanes and esters are the most prominent components present in the leaves. The content of waxes increases significantly in the later stages of development. In summary, our results indicate that the coordinated development of anthocyanins and cuticular wax provides a strategic mechanism to ensure the protection and functionality of Rosa chinensis leaves.