Analysis of the impact of latitude on the structure and composition of tea leaves and associated cold resistance

In this study, we selected three tea (Camellia sinensis) varieties (Lucha 1, HuangJincha 2, Xueyacha 100). Lucha 1 exhibited the highest levels of sugars suggesting a link between the levels of these three sugars and cold resistance. Varying tea polyphenol and amino acid content in analyzed tea plant samples were associated with differences in leaf palisade tissue and spongy tissue thickness. The leaves of Lucha 1 were thicker, with thinning of the upper epidermis, thickening of the lower epidermis and spongy tissue, and tightening of the palisade tissue, increased stomatal density, and a waxy epidermis with visible crystals. Xueyacha 100 exhibited no epidermal waxy crystallization in the analyzed leaf tissues. Lucha 1 and Xueyacha 100 leaf cells contained chloroplasts rich in osmophilic granules, thylakoids, starch granules, and graminaceous granules. Latitude thus impacts tea leaf structure and composition and associated cold resistance, providing a foundation for selecting cold-resistant tea germplasm resources.