The possible role of embryo sac degeneration in yield reduction of summer turnip rape cultivar Candle

1995 ◽  
Vol 75 (3) ◽  
pp. 595-598
Author(s):  
Xiuying Tian ◽  
L. Van Caeseele ◽  
M. J. Sumner
Keyword(s):  
Brassica Rapa ◽  
Seed Set ◽  
Embryo Sac ◽  
Pollen Tubes ◽  
Yield Reduction ◽  
Turnip Rape ◽  
Key Words:Brassica

When pollination occurred within 24 h after anthesis, 69.2% of the pods of Brassica rapa cultivar Candle contained at least 50% fertilized ovules. If pollination occurred later than 4 d after anthesis, an occasional ovule near the base of the pistil was fertilized; however, no significant seed set was observed. Pollen tubes were observed entering the locules of the ovary from pollinations carried out as late as 5 d after anthesis. At 3 d after anthesis, in unpollinated flowers, a general deterioration of the embryo-sac contents began and gradually increased to include integumentary cells by 6 d after anthesis. Some ovules swelled as though they were fertilized, but no embryos were present. The results suggest that yield reductions in this species may occur because of the reduction of fertilization potential through rapid degeneration of embryo sacs following anthesis. Key words:Brassica rapa, embryo sac, yield

Early events in the embryo sac after intraspecific and interspecific pollinations in Rhododendron kawakamii and R. retusum

1986 ◽  
Vol 64 (2) ◽  
pp. 282-291 ◽  
Author(s):  
V. Kaul ◽  
J. L. Rouse ◽  
E. G. Williams
Keyword(s):  
Seed Set ◽  
Embryo Sac ◽  
Pollen Tubes ◽  
Interspecific Crosses ◽  
Primary Endosperm Nucleus ◽  
Kalmia Latifolia ◽  
Taxonomic Grouping ◽  
Similarities And Differences ◽  
Normal Fertilization

Early events in the embryo sac of Rhododendron kawakamii and R. retusum have been studied after compatible self-pollinations and eight interspecific crosses, using sectioned ovaries, pistil squashes, and seed-set data. Ovules of Rhododendron kawakamii and R. retusum are anatropous, unitegmic, and tenuinucellate, with a typical eight-nucleate, seven-celled embryo sac. Fertilization normally occurs 4–5 days after pollination. The zygote lays down a callose wall but remains undivided during the first 13–15 days after pollination. The primary endosperm nucleus divides soon after fertilization, and development is cellular ab initio. Crosses of R. kawakamii (♂) with R. santapaui and R. retusum and crosses of R. retusum (♂) with R. kawakamii, R. santapaui, R. ovatum, and R. tashiroi showed apparently normal fertilization in a majority of ovules entered by pollen tubes. In crosses of R. kawakamii (♂) with R. quadrasianum and Kalmia latifolia entry of pollen tubes into ovules was delayed and frequently abnormal. Apart from compatible self-pollinations of R. kawakamii an R. retusum, only the cross of R. kawakamii (♂) with R. santapaui produced healthy seedlings. Of the remaining seven interspecific crosses only three showed significant embryo development in control pistils left to mature in situ. Similarities and differences in the breeding behaviour of R. kawakamii and R. retusum are discussed with reference to their taxonomic grouping within subsection Pseudovireya.

scholarly journals Paving the Way for Fertilization: The Role of the Transmitting Tract

2021 ◽  
Vol 22 (5) ◽  
pp. 2603
Author(s):  
Ana Marta Pereira ◽  
Diana Moreira ◽  
Sílvia Coimbra ◽  
Simona Masiero
Keyword(s):  
Pollen Tube ◽  
Pollen Tube Growth ◽  
Current Knowledge ◽  
Embryo Sac ◽  
Tube Growth ◽  
Signaling Cascades ◽  
Secretory Cells ◽  
Transmitting Tract ◽  
Specialized Tissue

Angiosperm reproduction relies on the precise growth of the pollen tube through different pistil tissues carrying two sperm cells into the ovules’ embryo sac, where they fuse with the egg and the central cell to accomplish double fertilization and ultimately initiate seed development. A network of intrinsic and tightly regulated communication and signaling cascades, which mediate continuous interactions between the pollen tube and the sporophytic and gametophytic female tissues, ensures the fast and meticulous growth of pollen tubes along the pistil, until it reaches the ovule embryo sac. Most of the pollen tube growth occurs in a specialized tissue—the transmitting tract—connecting the stigma, the style, and the ovary. This tissue is composed of highly secretory cells responsible for producing an extensive extracellular matrix. This multifaceted matrix is proposed to support and provide nutrition and adhesion for pollen tube growth and guidance. Insights pertaining to the mechanisms that underlie these processes remain sparse due to the difficulty of accessing and manipulating the female sporophytic tissues enclosed in the pistil. Here, we summarize the current knowledge on this key step of reproduction in flowering plants with special emphasis on the female transmitting tract tissue.

Overgrowth of Pollen Tubes in Embryo Sacs of Rhododendron Following Interspecific Pollinations

1986 ◽  
Vol 34 (4) ◽  
pp. 413 ◽  
Author(s):  
EG Williams ◽  
V Kaul ◽  
JL Rouse ◽  
BF Palser
Keyword(s):  
Pollen Tube ◽  
Embryo Sac ◽  
Pollen Tubes ◽  
Egg Cell ◽  
Interspecific Crosses ◽  
Main Body

Frequent overgrowths of pollen tubes within the embryo sac are characteristic of a number of interspecific crosses in the genus Rhododendron (Ericaceae). The combined techniques of sectioning, squashing and whole-ovule clearing have confirmed that in ovules showing this phenomenon the pollen tube fails to terminate growth and release sperms on entry into a synergid; instead it continues to grow beyond the synergid and egg cell, often filling the main body of the embryo sac with a coiled and distorted mass. Such ovules fail to develop further. The occurrence and possible causes of this error syndrome are discussed.

Hysyn100 summer turnip rape

1996 ◽  
Vol 76 (1) ◽  
pp. 127-128 ◽  
Author(s):  
K. C. Falk ◽  
F. M. Stoenescu
Keyword(s):  
Key Words ◽  
Brassica Rapa ◽  
Western Canada ◽  
Turnip Rape ◽  
Cultivar Description ◽  
Canola Quality

Hysyn100 summer turnip rape (Brassica rapa L.) is a canola-quality population-synthetic (Syn1) with high oil and protein contents that is well adapted to the short- and mid-season growing areas of western Canada. Key words: Turnip rape (summer), synthetic, cultivar description

scholarly journals Abundance, species composition and daily pattern of bees visiting field bean, goat’s rue and turnip rape in southern Finland

1995 ◽  
Vol 4 (5-6) ◽  
pp. 473-478 ◽  
Author(s):  
Anna-Liisa Varis
Keyword(s):  
Apis Mellifera ◽  
Species Composition ◽  
Brassica Rapa ◽  
Basic Knowledge ◽  
Large Field ◽  
Field Bean ◽  
Turnip Rape ◽  
Bumblebee Species ◽  
Constant Rate ◽  
Galega Orientalis

Visits of honeybees (Apis mellifera L.) and bumblebees (Bombas spp.) to flowers of field bean (Vida faba L.), goat’s rue (Galega orientalis Lam.) and spring turnip rape (Brassica rapa ssp. oleifera DC.) were studied to get some basic knowledge about the species composition, abundance and daily rhythm of bees visiting these plants. The studies were made under field conditions. Only pollinating specimens were counted. Both on field bean and goat’s rue 44% of the visitors were honeybees, on turnip rape the proportion of honeybees was 96%. Field bean was visited by Bombas subterraneus (L.)/B, hortorum (L.) as well as by B. lucorum (L.). These species were also present on goat’s rue; the most numerous bumblebee species on this plant, however, was B. lapidarius (L.) which was also the only bumblebee species visiting turnip rape. The total number of bees was highest on goat’s rue. The visits of honeybees began on field bean at noon and were most numerous in the afternoon. On goat’s rue, the numbers were smaller in the mornings, whereas turnip rape was visited at a rather constant rate throughout the day. On field bean, the numbers of B. subterraneus/B. hortorum increased and those of B. lucorum decreased towards the afternoon. On goat’s rue, these species were present in the morning and in the afternoon. B. lapidarius was present on goat’s rue during the whole day, but on turnip rape only in the mornings. On the basis of these results and earlier investigations it is concluded that the numbers of natural pollinators are rather low to assure adequate pollination in turnip rape and large field bean areas under the conditions in southern Finland. If the growing of goat’s rue becomes more prevalent, its pollination requirements need further studies.

Buzz pollination in the Epacridaceae

2002 ◽  
Vol 50 (1) ◽  
pp. 83 ◽  
Author(s):  
T. F. Houston ◽  
P. G. Ladd
Keyword(s):  
Seed Set ◽  
Corolla Tube ◽  
Pollen Tubes ◽  
Pollination Syndrome ◽  
Native Bees ◽  
Buzz Pollination ◽  
The Family

Conostephium (Epacridaceae) has flowers that conform with a buzz-pollination syndrome but, unlike most plants with this form of pollination, the anthers are hidden within the corolla tube. Vibrations generated by bees grasping the apices of the corolla tubes must be transferred via short broad filaments to the anthers. The anthers do not have pores but each dehisces from the apex by a slit that elongates over the time the flowers take to senesce (up to 10 days). This may limit self-fertilisation as the stigma is receptive as soon as it appears from between the very short corolla lobes, so little pollen is released at first but later this would increase as the slit elongates. Visitation by pollinators has rarely been seen but several observations of native bees (Leioproctus and Lasioglossum) working the flowers are presented. The bees visit the nectarless flowers of Conostephium only for pollen and must forage at other kinds of flowers to obtain nectar. Pollen tubes occurred in the stigmas of most older flowers of C. pendulum, so pollen delivery does not seem to limit seed set. Despite this, the species sets few fruit. From examination of the taxonomic positions of likely buzz-pollinated taxa in the family, it appears that pollination by sonication has arisen independently several times in the Epacridaceae, with primarily two different floral configurations.

Ultrastructural Aspects of the Self-Incompatibility Mechanism in Lycopersicum Peruvianum Mill

1973 ◽  
Vol 12 (2) ◽  
pp. 403-419 ◽  
Author(s):  
D. DE NETTANCOURT ◽  
M. DEVREUX ◽  
A. BOZZINI ◽  
M. CRESTI ◽  
E. PACINI ◽  
...  
Keyword(s):  
Pollen Tube ◽  
Tube Wall ◽  
Degradation Mechanism ◽  
Embryo Sac ◽  
Pollen Tubes ◽  
Self Incompatibility ◽  
Weak Reaction ◽  
General Hypothesis ◽  
Incompatible Pollen ◽  
Compatible Pollen

The experimental results obtained show that the tip of the incompatible pollen tube bursts open after the outer-wall has considerably expanded in the intercellular spaces of the conducting tissue and the inner-wall has disappeared and numerous particles have accumulated in the tube cytoplasm. These particles, which measure approximately 0.2 µm in diameter and give a weak reaction to the test of Thiéry, differ in many respects from the vesicles normally present in compatible pollen tubes growing through the style; they appear to resemble, in some cases, the spheres which are discharged by the compatible pollen tubes after they have reached the embryo-sac. It is considered that these observations support the current belief that the tube wall is the site of action for the incompatibility proteins and suggest that self-incompatibility is not a passive process resulting from lack of growth stimulation but an active event which leads to the destruction of the incompatible pollen tubes. The degradation mechanism involved appears similar to the one which enables the compatible pollen tube to release its contents in the degenerated synergid and presents some analogies with the lytic process taking place in virus-infected cells. The general hypothesis is presented that the particles observed in the cytoplasm of self-incompatible pollen tubes consist of a mixture of incompatibility proteins and of basic constituents of the tube wall.

Freeze-thaw injury is enhanced by post-thaw leaching in water

1994 ◽  
Vol 74 (2) ◽  
pp. 357-358 ◽  
Author(s):  
J. H. M. Willison ◽  
C. H. Cheung ◽  
M. I. N. Zhang ◽  
X. Xiao
Keyword(s):  
Brassica Rapa ◽  
Phosphate Buffer ◽  
Vital Staining ◽  
Deionized Water ◽  
Root Tissue ◽  
Plant Tissues ◽  
Triphenyltetrazolium Chloride ◽  
Freeze Thaw ◽  
Injured Tissue ◽  
Key Words:Brassica

Turnip (Brassica rapa L.) root tissue was exposed to freeze-thaw stresses of −7, −9, -−11 and −19 °C. The post-thawed tissues were either subjected to leaching in deionized water for 2 h or left at 100% humidity. Tissue survival was then assayed by vital staining using modified 2,3,5-triphenyltetrazolium chloride (TTC) staining in 0.2 M phosphate buffer. Tissue survival was significantly lower for leached samples than for non-leached samples. It is concluded that freeze-thaw injury in plant tissues is enhanced by post-thaw leaching in water. The 0.05 M phosphate buffer commonly used for TTC staining also damaged freeze-thaw injured tissue. Key words:Brassica rapa L., 2,3,5-triphenyltetrazolium chloride (TTC), freeze-thaw injury, leaching

scholarly journals Distinct Differentiation Characteristics of Endothelium Determine Its Ability to Form Pseudo-Embryos in Tomato Ovules

2019 ◽  
Vol 21 (1) ◽  
pp. 12 ◽  
Author(s):  
Inna Chaban ◽  
Ekaterina Baranova ◽  
Neonila Kononenko ◽  
Marat Khaliluev ◽  
Elena Smirnova
Keyword(s):  
Functional Organization ◽  
Embryo Sac ◽  
Secretory Activity ◽  
Parthenocarpic Fruit ◽  
Gene Encoding ◽  
Solanum Lycopersicum L ◽  
Embryo Cells ◽  
Additional Cell ◽  
Chitin Binding Protein

The endothelium is an additional cell layer, differentiating from the inner epidermis of the ovule integument. In tomato (Solanum lycopersicum L.), after fertilization, the endothelium separates from integument and becomes an independent tissue developing next to the growing embryo sac. In the absence of fertilization, the endothelium may proliferate and form pseudo-embryo. However, the course of the reorganization of endothelium into pseudo-embryo in tomato ovules is poorly understood. We aimed to investigate specific features of endothelium differentiation and the role of the endothelium in the development of fertilized and unfertilized tomato ovules. The ovules of tomato plants (“YaLF” line), produced by vegetative growth plants of transgenic tomato line expressing the ac gene, encoding chitin-binding protein from Amaranthus caudatus L., were investigated using light and transmission electron microscopy. We showed that in the fertilized ovule of normally developing fruit and in the unfertilized ovule of parthenocarpic fruit, separation of the endothelium from integument occurs via programmed death of cells of the integumental parenchyma, adjacent to the endothelium. Endothelial cells in normally developing ovules change their structural and functional specialization from meristematic to secretory and back to meristematic, and proliferate until seeds fully mature. The secretory activity of the endothelium is necessary for the lysis of dying cells of the integument and provides the space for the growth of the new sporophyte. However, in ovules of parthenocarpic fruits, pseudo-embryo cells do not change their structural and functional organization and remain meristematic, no zone of lysis is formed, and pseudo-embryo cells undergo programmed cell death. Our data shows the key role of the endothelium as a protective and secretory tissue, needed for the normal development of ovules.

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