Spatial distribution of trichomes in tea plants (Camellia sinensis) and their adaptation to drought and shading

Trichomes in plants serve not only to secrete secondary metabolites and defend against biotic and abiotic stresses, but also influence the quality of processed products in species such as tea plants ( Camellia sinensis ). However, the distribution patterns of plant trichomes and the environmental adaptability of tea plant trichomes remain poorly characterized. This study reveals a distinct polar distribution of trichomes along the adaxial-abaxial, proximal-distal, and medial-lateral axes of tea plant leaves. Trichome density on both leaves and stems decreases with developmental maturation, while trichomes on leaves exhibit greater length but lower density compared to those on stems. The broad-sense heritability of trichome diameter, length, and density is remarkably high, although their coefficients of variation differ significantly. Tea plant cultivars can be classified into three categories: low trichome abundance, moderate abundance, and high abundance. Long-term drought significantly increased trichome length and density, whereas long-term shading exposure produced the opposite effect. Key trichome development genes exhibited differential responsiveness to tissue type, drought, and shade treatments in tea plants. These findings provide insights into the distributional principles of plant trichomes and facilitate the scientific utilization and genetic improvement of trichomes in tea plants.