Hop glandular trichomes are developing on the epidermis of hop cones bracts. The anticline cross cut of hop peltate glandular trichomes in Environment Scanning Electron Microscopy (ESEM) observations confirmed spheroid shape of cells. In our research, length of internal peltate glandular trichomes cells varied from 16.00 to 21.47 μm, width from 4.21 to 4.70 μm and volume from 1.19 × 10-6 to 1.99 × 10-6 mm3. The diameter of cell walls varied from 2.11 to 2.94 μm. Volume of observed peltate glandular trichomes varied from 1.65 × 10-2 to 1.95 × 10-2 mm3. The cell structure of bulbous glandular trichomes in anticline cross cut was not observed. According to 121 observations, bulbs formation was visible on the surface of peltate glandular trichomes in the last phase of morphogenesis. Biosynthesis of hop secondary metabolites and activation of their genetic mechanisms are the most intensive at the end of technological maturity of hop cones of hop cultivar Aurora. It is possible that bulbous glandular trichomes represent the final stage of peltate glandular trichome morphogenesis, instead of being separate morphological formations. During biosynthesis of hops secondary metabolites partial pressures of liquids and gasses increase causing breakage of cell walls, which withdraw towards tunica and form papillary texture.

hop; Humulus lupulus; ESEM; peltate glandular trichomes; bulbous glandular trichomes; biosynthesis of hop secondary metabolites

Published by University of Zagreb, Faculty of Agriculture, Zagreb, CROATIA
Sponsored by Ministry Science and Education of the Republic of Croatia