Differences in epicuticular wax layer in tulip can influence resistance to Botrytis tulipae

Botrytis tulipae is one of the major diseases of tulip. The pathogen is a necrotroph and infection normally results in host cell death, resulting in serious damage to plant tissues and culminating in rotten plants. Several defense strategies are required to counter attack this aggressive invader. Two different methods were used to proof if tulip wax layer had an influence on Botrytis resistance. Wet inoculation method (standard method) with removal of wax layer and dry inoculation method with no removal of wax layer were applied in cultivars Christmas Marvel, Leen van der Mark and Ile de France. The wet inoculation showed that Christmas Marvel was susceptible, Leen van der Mark was partial resistant and Ile de France was resistant. However, when dry method was applied in the same cultivars the level of resistance changed, leading to an increase of the level of resistance in Christmas Marvel, a decrease in Ile de France and equal levels in Leen van der Mark compared to the wet method. These results suggest that wet and dry inoculation altered the level of resistance, meaning that differences in the epicuticular wax layer provides an extra defense strategy against the pathogen in Christmas Marvel, enhanced infection in Ile de France and it had no effect in Leen van der Mark. Moreover, differences in the amount of wax layer in several species of the genus Tulipa are present. In general T. fosteriana is more susceptible to B. tulipae than T. gesneriana. The results showed that T. fosteriana had less wax layer than T. gesneriana. However, there was no complete correlation between amount of wax layer and resistance in all tested cultivar