Differential responses of the pollen tube cell wall of Italian olive cultivars to UV-B radiation

The increasing impact of climate change poses a serious threat to olive cultivation, particularly through environmental stresses such as ultraviolet-B (UV-B) radiation. This study investigates the use of pollen as a marker to discriminate the UV-B tolerance of four Italian olive cultivars (Frantoio, Leccino, Olivastra Seggianese, and Pendolino). Pollen grains were exposed to UV-B radiation at varying durations (1, 2 and 3 h) and distances (10, 20, 30 and 40 cm) to evaluate viability, germination rate, pollen tube length, and cell wall composition, including the distribution of key structural elements such as pectins, cellulose, callose, arabinogalactan proteins, and polysaccharide-synthesizing enzymes. Results indicate that UV-B stress effects are highly cultivar-specific and exposure-dependent. Frantoio and Leccino show higher sensitivity to short-term, high-intensity UV-B, while Pendolino demonstrates greater resistance to prolonged exposure but unexpected sensitivity to low-intensity, short-duration UV-B. This multidimensional response underscores the complex interaction between cultivar and UV-B stress. These findings contribute to the sustainability of olive cultivation under changing environmental conditions by identifying more resilient cultivars.