Nectar Secretion, Morphology, Anatomy and Ultrastructure of Floral Nectary in Selected Rubus idaeus L. Varieties

Abstract

The distinctive features of floral nectaries facilitate identification of ecological and phylogenetic links between related taxa. The structure and functioning of nectaries determine the relationships between plants, pollinators, and the environment. The aim of the study was to determine and compare the micromorphology of the epidermis in the floral nectaries of six Rubus idaeus cultivars belonging to biennial (‘Glen Ample’, ‘Laszka’, ‘Radziejowa’) and repeated fruiting (‘Pokusa’, ‘Polana’, ‘Polka’) groups. Another objective was to characterize the cuticle ornamentation and stomatal morphology, the anatomy of the nectary epidermis, parenchyma, and sub-nectary parenchyma in the initial nectar secretion phase, as well as the ultrastructure of the nectary epidermis and parenchyma cells in the initial and full nectar secretion phases. The study was carried out using light, fluorescence, scanning and transmission-electron microscopy techniques. Semi-thin and ultrathin sections were used for the microscopic analyses. The cuticular ornamentation and stomatal morphology may be helpful elements in the identification of relatedness between Rubus species. The interaction of the extensive system of endoplasmic reticulum membranes, mitochondria, and Golgi apparatus indicates high metabolic activity, and the fusion of transport vesicles with the membrane suggests granulocrine nectar secretion. The results bring new data to the biology of plants.

The Morpho-Anatomy of Nectaries and Chemical Composition of Nectar in Pear Cultivars with Different Susceptibility to Erwinia amlylovora

“…Besides, Nagy Toth et al [33] studied the composition of floral nectar in pome Rosaceae fruits (apple, pear and quince) and proved that the presence of glucose and fructose is a general characteristic, but that sucrose is also present in some cultivars. A similar situation is in apricot and peach [63], raspberry [27] and blackberry nectar [21]. On the contrary, in the sour cherry nectar, glucose, fructose and sucrose were of the ratio 1:1:1 [24], which is most preferable by bees.…”

“…The investigation of floral nectaries in the Pyrus genus is important not only due to its role in sexual reproduction, but because it is the place for primary infection of Erwinia amylovora in the flowers [17]. Characteristics, micromorphology and ultrastructure of floral nectaries were studied in many cultivated and ornamental members of the Rosaceae family, such as representatives of the genuses Malus, Pyrus, Cydonia, Prunus, Rubus, Chaenomeles, Cotoneaster and Rosa [18][19][20][21][22][23][24][25][26][27][28].…”