Investigations on the chemical composition of cuticular waxes in twelve Fragaria L. genotypes (Henning Wagner)
The important role of cuticular waxes in the defense systems of plants is undeniable. However, very little is known about the chemistry of cuticular wax in the genus Fragaria L. The epicuticular wax crystal morphology was determined using scanning electron microscopy. A wide range of different structures were described. Twelve strawberry genotypes, including ten wild species, one cultivar and one hybrid after wild species introgression, covered the detected range of epicuticular crystal structures. They were also chosen because of their susceptibility to spider-mites (Tetranychus urticae Koch) and powdery mildew (Podosphaera aphanis (Wallr.) U. Braun & S. Takam.). To study the chemical wax composition on leaves, extraction of the cuticular waxes was accomplished using chloroform as an organic unpolar solvent. The adaxial and abaxial leaf surfaces were analysed independently using gas chromatography coupled with flame ionisation detection. Single compounds were identified using coupled gas chromatography-mass spectrometry. Remarkable differences in total mass and qualitative composition between the ab- and adaxial leaf surfaces and between different genotypes were detected. Alkanes, fatty acid alkyl esters and aldehydes were detected as major components. Further different aliphatic compounds, triterpenoids and non-identified compounds were present in minor quantities. In addition, cinnamic acid alkyl esters were detected solely on adaxial leaf surfaces, whereas secondary alcohols were detected only on abaxial leaf surfaces. Additional inoculation trials with spider-mites and powdery mildew were performed to obtain data for later correlation studies. This study was funded by the German Federal Ministry of Education and Research (BMBF, FKZ 031A216 A and B).
Henning Wagner won an ISHS student award for the best oral presentation at the VIII International Strawberry Symposium in Canada in August 2016.
Henning Wagner, Humboldt-Universität zu Berlin, Albrecht Daniel Thaer-Institute of Agricultural and Horticultural Sciences, 10115 Berlin, Germany, e-mail: firstname.lastname@example.org