EurekaMag.com logo
+ Site Statistics
References:
54,215,046
Abstracts:
30,230,908
PMIDs:
28,215,208
+ Search Articles
+ Subscribe to Site Feeds
EurekaMag Most Shared ContentMost Shared
EurekaMag PDF Full Text ContentPDF Full Text
+ PDF Full Text
Request PDF Full TextRequest PDF Full Text
+ Follow Us
Follow on FacebookFollow on Facebook
Follow on TwitterFollow on Twitter
Follow on LinkedInFollow on LinkedIn

+ Translate

Scanning electron microscopic studies of pollen from honey iii. the harmomegathy mechanism and its effect on the exine structure using different pollen types



Scanning electron microscopic studies of pollen from honey iii. the harmomegathy mechanism and its effect on the exine structure using different pollen types



Apidologie 21(4): 293-302



Pollen grains found in honey are subjected to changes in volume and shape by hydration of the plasma - the harmomegathy - which enable the pollen grain to harmonize with the surrounding forces. At dehiscence from the anther into the dehydrating atmosphere, pollen grains change their shape so that the apertures close (state of moisture stress = contraction). Conversely, the exine relaxes by hydration when the pollen is on the stigma of the blossom or has fallen into nectar. In addition to volume and shape, the surface pattern of the intercolpium may also change by harmomegathy. Pollen with different sculpturing types were analyzed by SEM in states of contraction and expansion. Contracted pollen grains were transferred into filtered honey for expansion and prepared for SEM after isolation into a wire screen. All tricolpate pollen grains were found to change their prolateoval into a spheroidal shape by harmomegathy. The analyzed sculpturing patterns (striate, reticulate, foveolate, echinate) show that there is no stretching of the general intercolpium. If such a stretching occurred, the striate sculpturing element should show tectate perforations more visible than in a state of contraction. However, fig 1 shows the opposite : In expanded pollen grains of Acer platanoides, the tectum is closed by supratectate valla. Fig 6 illustrates that the enlargement of the pollen circumference does not require a general stretching, but only a bending of the intercolpium which simultaneously opens the apertures. Due to this harmomegathy mechanism, the external regions of the sculpturing elements draw close as on the pollen of Verbesina persicifolia with its particularly elongated echinate elements (fig 5). Similarly, the expanded pollen of Ligustrum vulgare shows a lumina width decrease of the reticulate pattern (fig 2), and the Leucophyllum frutescens pollen an additional compressive strain of the muri (fig 3). The foveolate sculpturing elements on the Fagopyrum esculentum pollen undergo a compression important enough to induce considerable changes in lumina shape. The knowledge of pollen surface changes described in this study should facilitate the melissopalynological identification of pollen using SEM.

(PDF emailed within 1 workday: $29.90)

Accession: 007769573

Download citation: RISBibTeXText



Related references

Scanning electron microscopic studies of pollen from honey. III. The harmomegathy mechanism and its effect on the exine structure of different pollen types. Apidologie 21(4): 293-302, 1990

Scanning electron microscopic studies of pollen from honey ii. comparison of exine structures of dry and expanded pollen of several apple and crab apple cultivars. Gartenbauwissenschaft 52(6): 271-278, 1987

Scanning electron microscopic studies on pollen from honey. IV. Surface pattern of pollen of Sapium sebiferum and Euphorbia spp. (Euphorbiaceae). Apidologie 24(1): 59-66, 1993

Scanning electron microscopic studies of pollen honey i. comparison of different methods of preparation. Apidologie 16(3): 331-340, 1985

The sporoderm of Brazilian Symplocos pollen types (Symplocaceae) Exine and aperture stratifications, light, transmission electron and scanning electron microscopy. Grana 1(2): 65-69, 1982

Contribution of scanning electron microscopy to the knowledge of the structure of pollen exine of some Asian Caesalpiniaceae. Bulletin de la Societe botanique de France: ub 1977), 122 99-101, 1977

Exine structure of Archaeoperisaccus Naumova; the results of electron microscopic investigation of pollen grain sections. Pages 91-95 1984, 1984

Electron microscopic investigations on relationships between Theligonum and Rubiaceae: ultrastructure of sieve-Element plastids and aspects of pollen exine structure. 1975

Electron microscopic investigations on relationships between theligonum cynocrambe and rubiaceae ultrastructure of sieve element plastids and aspects of pollen exine structure. Plant Systematics and Evolution 123(4): 317-326, 1975

A study of the foraging behaviour of honeybees (Apis mellifera) by the scanning electron microscopic analysis of pollen in honey. Bee Craft 75(6): 170-175, 1993

Light microscopic and scanning electron microscopic studies on pollen of tetraplasandra d araliaceae d and relatives. American Journal of Botany 58(6): 505-516, 1971

Light microscopic and scanning electron microscopic studies on the pollen grains of trichodesma sedwickianum boraginaceae. Indian Journal of Botany 7(1-2): 74-76, 1984

Lens and electron microscopic scanning on the pollen morphology of different types and varieties of peanut (Arachis hypogaea L.). Journal of Fujian Agricultural College 16(4): 313-319, 1987

Scanning electron microscopic studies of Centaurea L. s.s. pollen. Giornale Botanico Italiano 116(5/6): 201-210, 1982

Scanning electron microscopic studies on the pollen of some clusiaceae. Proceedings of the Indian Academy of Sciences Plant Sciences 96(3): 217-226, 1986