scholarly journals Fused Vein Trait in Cucurbita pepo L. Associated with Subvitality of the Male Gametophyte

1996 ◽  
Vol 121 (1) ◽  
pp. 18-22 ◽  
Author(s):  
R. Bruce Carle ◽  
J. Brent Loy
Keyword(s):  
Pollen Tube ◽  
Seed Yield ◽  
Microscopic Examination ◽  
Cucurbita Pepo ◽  
Male Gametophyte ◽  
Pollen Competition ◽  
Pollen Load ◽  
Pollen Loads ◽  
Normal Pollen

Two experiments were conducted to test and delineate gametophytic subvitality of the fused vein trait in Cucurbita pepo. Gametophytic subvitality was verified by comparing pollen tube growth for fused vein and normal pollen in situ. Microscopic examination of partitioned, co-pollinated distillate flowers revealed inferior fused vein gametophyte performance. Normal pollen tubes grew faster and were significantly more abundant in the lower portion of the style. The consequences of gametophytic subvitality on seed yield and inheritance were shown by manipulating the severity of pollen competition. Fused vein, normal and F1 lines were pollinated with fused vein, normal, F and a 50:50 pollen mix at three different pollen loads. Fused vein pollen generated significantly fewer seed per fruit in all female genotypes. As a constituent in F, or mixed pollen, it produced significant seed yield reductions at the low pollen load. In F1 and testcross populations, a reduction in pollen load and therefore pollen competition significantly increased the number of fused vein individuals in segregating populations.

Demographics of pollen tube growth in Cucurbita pepo

1995 ◽  
Vol 73 (4) ◽  
pp. 583-589 ◽  
Author(s):  
James A. Winsor ◽  
Andrew G. Stephenson
Keyword(s):  
Pollen Tube ◽  
Pollen Tube Growth ◽  
Cucurbita Pepo ◽  
Uv Light ◽  
Pollen Tubes ◽  
Tube Growth ◽  
Pollen Competition ◽  
Stigmatic Surface ◽  
Germinated Pollen ◽  
Female Flowers

Pollen tube growth rates and pollen tube attrition were examined in Cucurbita pepo plants grown in an experimental garden. Two separate studies were performed utilizing controlled hand-pollinations. First, female flowers were hand-pollinated and collected at intervals over a 22-h period. Examination of stained pollen tubes in these pistils under reflected UV light revealed variation in growth rate: after approximately 7 h, the fastest growing pollen tubes grew at nearly twice the rate of the mass of the pollen tubes. The faster growing tubes reached the top of the ovary well ahead of most of the pollen tubes. Second, density of pollen application was varied and counts of germinated pollen and pollen tubes were made at four points from the stigmatic surface to the receptacle. Attrition was high for all pollen densities, but significantly higher rates occurred at high and medium densities just below the stigmatic surface. Pollen tube attrition at other points in the pistil was associated with constrictions in the stylar tissue and possibly with levels of nutrients in the pistil. Key words: Cucurbita pepo, pollen competition, pollen tube attrition.

scholarly journals GAMETOPHYTIC SELECTION OF THE FUSED VEIN TRAIT IN SQUASH

HortScience ◽  
1994 ◽  
Vol 29 (4) ◽  
pp. 245a-245
Author(s):  
R. Bruce Carle ◽  
J. Brent Loy
Keyword(s):  
Pollen Tube ◽  
Leaf Morphology ◽  
Cucurbita Pepo ◽  
Leaf Size ◽  
Leaf Number ◽  
Reproductive Competition ◽  
Gametophytic Selection ◽  
Pollen Loads ◽  
Loads Analysis ◽  
Selection Of

Three experiments were conducted to delineate gametophytic selection of the fused vein trait in Cucurbita pepo L. Gametophytic subvitality was verified by comparing fused vein and normal pollen tube growth. Microscopic examination of partitioned, co-pollinated flowers revealed fewer and slower growing fused vein tubes than normal. The effects of gametophytic subvitality on seed yield and inheritance were shown by manipulating the severity of reproductive competition. Fused vein, normal, and F1 lines were pollinated with fused vein, normal, 50:50 mix, and F1 pollen at three different pollen loads. Analysis showed that fused vein pollen generated significantly fewer seed per fruit in all lines. In ensuing F2 and testcross populations, a reduction in load and thus competition significantly increased the number of fused vein individuals. Leaf number and area for normal, fused vein, F1, F2, and testcross plants were assessed to test pleiotropic effects on growth common to gametophytic subvitals. Although normal and fused vein lines differed in leaf number and size, their total leaf areas were not significantly different. F2 and testcross plants showed no difference between normal and fused vein individuals; leaf size and number were independent of leaf morphology.

scholarly journals Protein Analysis of Pollen Tubes after the Treatments of Membrane Trafficking Inhibitors Gains Insights on Molecular Mechanism Underlying Pollen Tube Polar Growth

2021 ◽  
Vol 40 (2) ◽  
pp. 205-222
Author(s):  
Monica Scali ◽  
Alessandra Moscatelli ◽  
Luca Bini ◽  
Elisabetta Onelli ◽  
Rita Vignani ◽  
...  
Keyword(s):  
Pollen Tube ◽  
Actin Cytoskeleton ◽  
Membrane Trafficking ◽  
Tip Growth ◽  
Male Gametophyte ◽  
Pollen Tubes ◽  
Structural Features ◽  
Two Dimensional Gel Electrophoresis ◽  
Depth Analysis

AbstractPollen tube elongation is characterized by a highly-polarized tip growth process dependent on an efficient vesicular transport system and largely mobilized by actin cytoskeleton. Pollen tubes are an ideal model system to study exocytosis, endocytosis, membrane recycling, and signaling network coordinating cellular processes, structural organization and vesicular trafficking activities required for tip growth. Proteomic analysis was applied to identifyNicotiana tabacumDifferentially Abundant Proteins (DAPs) after in vitro pollen tube treatment with membrane trafficking inhibitors Brefeldin A, Ikarugamycin and Wortmannin. Among roughly 360 proteins separated in two-dimensional gel electrophoresis, a total of 40 spots visibly changing between treated and control samples were identified by MALDI-TOF MS and LC–ESI–MS/MS analysis. The identified proteins were classified according to biological processes, and most proteins were related to pollen tube energy metabolism, including ammino acid synthesis and lipid metabolism, structural features of pollen tube growth as well modification and actin cytoskeleton organization, stress response, and protein degradation. In-depth analysis of proteins corresponding to energy-related pathways revealed the male gametophyte to be a reliable model of energy reservoir and dynamics.

The development of the male gametophyte and spermatogenesis in Taxus baccata L

1986 ◽  
Vol 228 (1250) ◽  
pp. 85-96 ◽  
Keyword(s):  
Pollen Tube ◽  
De Novo ◽  
Male Gametophyte ◽  
Generative Cell ◽  
Equal Size ◽  
Taxus Baccata ◽  
Transverse Wall ◽  
Proximal Pole ◽  
Spermatogenous Cell ◽  
Tube Cell

The development of the male gametophyte of Taxus baccata has been studied over a period of 20 weeks, from germination of the microspore in February to spermatogenesis in July. A few days after germination the microspore nucleus divides and a transverse wall forms at the equator cutting off the small generative cell and a large tube cell. The latter immediately begins to expand to form the pollen tube. The first division thus establishes the polarity of the gametophyte and the generative cell is regarded as proximal. The transverse wall is ephemeral, and within six weeks it has disappeared. The nucleus of the generative cell divides while still at the proximal pole. The two daughter nuclei are unequal in size, but they remain associated and together move distally. The larger nucleus eventually becomes the nucleus of the spermatogenous cell, and the smaller the sterile nucleus. The spermatogenous cell acquires a distinctive cytoplasm and becomes surrounded by a wall which arises de novo . The nucleus of the spermatogenous cell enlarges, but always remains towards one side of the cell so that at mitosis the spindle is contained within one hemisphere. After division the wall of the spermatogenous cell is ruptured and the two sperms are released as naked nuclei of equal size. The cytoplasm of the spermatogenous cell degenerates as it enters the tube, but remains recognizable until fertilization.

In Vitro Germination of Eucalyptus Pollen: Response to Variation in Boric Acid and Sucrose

1989 ◽  
Vol 37 (5) ◽  
pp. 429 ◽  
Author(s):  
BM Potts ◽  
JB Marsden-Smedley
Keyword(s):  
Pollen Tube ◽  
Boric Acid ◽  
Pollen Tube Growth ◽  
Pollen Germination ◽  
Sucrose Concentration ◽  
Response Surfaces ◽  
Tube Growth ◽  
Pollen Competition

The effect of boric acid (0-450 ppm) and sucrose (0-40%) on pollen germination and pollen tube growth in Eucalyptus globulus, E. morrisbyi, E. ovata and E. tirnigera was examined in vitro. Over the con- centrations tested, sucrose had by far the largest effect upon both pollen germination and tube lengths. The optimum sucrose concentration for pollen germination (30%) and pollen tube growth (20%) differed markedly with very little (<lo%) germination occurring in the absence of sucrose. The interaction of sucrose and boric acid was significant. However, in general both pollen germination and pollen tube growth were increased by the addition of up to 100 ppm boric acid, but above this level the response plateauxed. The four species differed significantly in their pattern of response to both boric acid and sucrose and the predicted optima derived from analysis of response surfaces differed between species. The predicted sucrose concentration for optimal germination and growth of E. urnigera pollen was consistently less than the other species and in terms of the optimal level of boric acid for pollen tube growth species can be ranked in the order E. globulus > E. ovata > E. morrisbyi = E. urnigera. Pollen germination and tube growth of all four species on a medium comprising 20% sucrose and 200 ppm boric acid would not differ significantly from the observed maximum response of each species and this could suffice as a generalised medium. However, if only percentage germination is to be assessed 30% sucrose would be preferable. It is argued that subtle interspecific differences in optimal in vitro con- ditions for pollen germination and pollen tube growth are likely to reflect differences in pollen physiology which in vivo may have important implications for the success of hybridisation where pollen competition occurs.

Insemination of the archegonium and fertilization in Taxus baccata L

1988 ◽  
Vol 89 (4) ◽  
pp. 551-560
Author(s):  
ROGER I. PENNELL ◽  
PETER R. BELL
Keyword(s):  
Pollen Tube ◽  
Male Gametophyte ◽  
Sperm Nucleus ◽  
Taxus Baccata ◽  
Close Apposition ◽  
Cell Cytoplasm ◽  
Spermatogenous Cell ◽  
Tube Lumen ◽  
Sperm Nuclei ◽  
Progressive Enlargement

A study of fertilization in Taxus baccata in the electron microscope has revealed novel features. Insemination of the archegonium is facilitated by local perforation of the wall of the young pollen tube. Digestion of the wall begins before the pollen tube pierces the megaspore membrane but is not completed until its tip makes contact with the neck cells of the archegonium. As soon as a pore is formed a single sperm nucleus and some cytoplasm of the male gametophyte enter the archegonium. Which of the paired sperm nuclei move from the pollen tube into the archegonium appears to be a matter of chance. Close apposition of sperm nucleus and egg nucleus is followed by the formation of numerous points of contact between the two. The membranes fuse at these points and pores are rapidly formed. The progressive enlargement of these pores ultimately eliminates any partitions and yields the zygotic nucleus. There is a possibility that, as in some other gymnosperms, the plastids and mitochondria of the zygote come in part from the male gametophyte, but whether from the remains of the spermatogenous cell cytoplasm or from the. pollen tube lumen is not clear.

scholarly journals Microscopy of Living Bone Marrow In Situ

Blood ◽  
1971 ◽  
Vol 38 (1) ◽  
pp. 87-95 ◽  
Author(s):  
ROBERT S. MCCUSKEY ◽  
SAMUEL G. MCCLUGAGE ◽  
WALDO J. YOUNKER
Keyword(s):  
Bone Marrow ◽  
Microscopic Examination ◽  
Hemopoietic Cells ◽  
Highly Active ◽  
Preliminary Examination ◽  
Yellow Marrow ◽  
Living Bone

Abstract A chamber has been designed to permit chronic microscopic examination of living bone marrow in situ. The amount of metal adjacent to the tissue within the gap of the chamber appears to be critical if normal hemopoiesis is to occur, since excessive metal resulted in the regeneration of a hypocellular, gelatinous marrow. When the amount of metal was reduced, relatively normal marrow regenerated into the chamber. Most frequently this histologically resembled yellow marrow but on occasion highly active marrow was observed. Preliminary examination of the microvascular system confirmed previous reports that sinusoids generally were arranged in interconnecting polygonal networks surrounding individual or clusters of fat and hemopoietic cells. The sinusoids were lined by a definite endothelium. No "intersinusoidal capillaries" were observed.

Sign in / Sign up

Export Citation Format

Share Document