The role of sucrose in maintaining pollen viability and germinability in Corylus avellana L.: a possible strategy to cope with climate variability

In this work, we propose a possible correlation between carbohydrate content in hazelnut pollen (wild type) and viability/germinability, also in a perspective of adaptation to climate variability. Samples from four different cultivation fields in Italy showed values of pollen viability characterized by high levels, ranging between 77.3 and 98.4% and a unique trend during the flowering period for each accession. When subjected to dehydration in controlled environment, pollen reduced the levels of viability to almost zero but recovered the initial values when rehydrated. The presence of anomalous pollen was found to be not significant, always below 4% in all accessions. The analysis on starch content gave negative results both when it was determined biochemically and detected by histological staining. Sucrose content resulted always higher than glucose and fructose in all the accessions analyzed. Its concentration throughout the dispersal phases reflected the trend of both pollen viability and germinability. These data seem to suggest a direct involvement of sucrose in the protection of plasma membranes from dehydration and the maintenance of pollen viability and germinability. This study demonstrates the sensitivity of hazelnut pollen to climatic fluctuations, particularly to air dry condition, stressing a significant role of sucrose in maintaing viablity and germinabilty during all dispersal period.