The host range specificity of Agrobacterium with five
tea cultivars and an unrelated species (Artemisia parviflora) having extreme surface characteristics was evaluated in the present study. The degree of Agrobacterium
infection in the five cultivars of
tea was affected by leaf wetness, micro-morphology and surface chemistry. Wettable leaf surfaces of TV1, Upasi-9 and Kangra jat showed higher rate (75%) of Agrobacterium
infection compared to Upasi-10 and ST-449, whereas non-wettable leaves of A. parviflora showed minimum (25%)
infection. This indicated that the leaves with glabrous surface having lower q (larger surface area covered by water droplet), higher
phenol and wax content were more suitable for Agrobacterium
infection.
Caffeine fraction of
tea promoted Agrobacterium
infection even in leaves poor in wax (Upasi-10), whereas
caffeine-free wax inhibited both Agrobacterium growth and
infection. Thus, study suggests the importance of leaf surface features in influencing the Agrobacterium
infection in
tea leaf explants. Our study also provides a basis for the screening of a clone/cultivar of a particular species most suitable for Agrobacterium
infection the first step in Agrobacterium-mediated genetic transformation.