Pollen Tube Growth and Early Seed Development in Eucalyptus regnans F. Muell. (Myrtaceae) in Relation to Ovule Structure and Preferential Outcrossing

1989 ◽  
Vol 37 (5) ◽  
pp. 397 ◽  
Author(s):  
M Sedgley ◽  
FC Hand ◽  
RM Smith ◽  
AR Griffin
Keyword(s):  
Pollen Tube ◽  
Phase Contrast ◽  
Pollen Tubes ◽  
Central Canal ◽  
Transmitting Tissue ◽  
Bright Field ◽  
Eucalyptus Regnans ◽  
Cross Pollination ◽  
Early Seed Development ◽  
Scanning Electron

Pistils of Eucalyptus regnans were observed by bright field, fluorescence, phase contrast, Nomarski, and scanning electron microscopy from 4 weeks prior to anthesis to 16 weeks after self- and cross- pollination. The transmitting tissue of the style had a central canal which extended for half its length. The unfertilised ovary contained a mean of 30.5 ovular structures with 16.5 normal ovules, 2.5 abnor- mal ovules, and 11.5 sterile ovulodes. The ovules were arranged in two rows in three (occasionally four) locules. The ovulodes always occupied positions at the stylar end of the ovary, but with this exception there was no pattern to the occurrence of the abnormal ovules. Pollen tubes grew between the cells'of the transmitting tissue, and not in the stylar canal. Penetration of the ovules had commenced by 5 days after both self- and cross-pollination. The early fertilised ovule contained a zygote and free-nuclear endosperm, and embryos with between 1 and 16 cells were present at 16 weeks after pollination. Not all normal ovules were fertilised, despite adequate numbers of pollen tubes. Ovulodes were never observed to be penetrated by a pollen tube, but with this exception there was no relationship between position on the placenta and either the penetration of ovules by a pollen tube or the occurrence of fertilised ovules. There was no difference between self- and cross-pollination in either the number of ovules penetrated by a pollen tube, or the number of fertilised ovules up to 16 weeks following pollination.

Coelomomyces canadense stat. et comb. nov. (Blastocladiales: Coelomomycetaceae) from Psectrocladius sp. G (Diptera: Chironomidae)

1978 ◽  
Vol 56 (18) ◽  
pp. 2303-2306 ◽  
Author(s):  
Richard A. Nolan
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Phase Contrast ◽  
Field Phase ◽  
Species Status ◽  
Bright Field ◽  
Latin Diagnosis ◽  
Taxonomic Criterion ◽  
Sporangial Wall ◽  
Scanning Electron

Resistant sporangia of Coelomomyces chironomi var. canadense Weiser and McCauley were examined by bright-field, phase-contrast, and scanning electron microscopy (SEM). The use of SEM facilitated the observation of previously undescribed complex furrows in the sporangial wall. The taxonomic criterion for varietal status is discussed, and the variety is elevated to species status. Coelomomyces canadense (Weiser and McCauley) Nolan stat. et comb. nov. is described with an emended Latin diagnosis.

scholarly journals The synstigma turns the fig into a large flower

2020 ◽  
Vol 195 (1) ◽  
pp. 93-105
Author(s):  
Simone P Teixeira ◽  
Marina F B Costa ◽  
João Paulo Basso-Alves ◽  
Finn Kjellberg ◽  
Rodrigo A S Pereira
Keyword(s):  
Pollen Tube ◽  
Pollen Grains ◽  
Pollen Tubes ◽  
Live Cells ◽  
Fig Wasp ◽  
Fig Wasps ◽  
Floral Structure ◽  
Transmitting Tissue ◽  
Transmission Electron ◽  
Large Flower

Abstract The synstigma is a structure formed by clusters of two to several stigmas, whether in the same or between different flowers. Although rare in angiosperms, synstigmas are found in c. 500 out of the c. 750 Ficus spp. (Moraceae). This floral structure is associated with fig-fig wasp pollinating mutualism. The synstigma structure and pollen tube pathways were studied in six Ficus spp. from Ficus section Americanae to test the hypothesis that the synstigma allows pollen grains deposited on a stigma to emit pollen tubes that can grow laterally and fertilize surrounding flowers. Syconia containing recently pollinated stigmas were collected and dissected, and the stigmas were processed for analyses with light and scanning and transmission electron microscopy. The arrangement of the synstigmas across species can be spaced or congested, with the number of stigmas per synstigma ranging from two to 20. Contact between the stigmas in a synstigma occurs by the intertwining of the stigmatic branches and papillae; their union is firm or loose. The pollen tube grows through live cells of the transmitting tissue until reaching the ovule micropyle. Curved pollen tubes growing from one stigma to another were observed in five out of the six species studied. The curvilinear morphology of pollen tubes probably results from competition by pollen between the stigmas composing a synstigma via chemotropic signals. The synstigma appears to be a key adaptation that ensures seed production by flowers not exploited by the fig wasps in actively pollinated Ficus spp.

Floral Anatomy and Pollen Tube Growth in the Quandong (Santalum acuminatum (R. Br.) A. DC.)

1982 ◽  
Vol 30 (6) ◽  
pp. 601 ◽  
Author(s):  
M Sedgley
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Pollen Tube ◽  
Pollen Tube Growth ◽  
Floral Anatomy ◽  
Embryo Sac ◽  
Pollen Tubes ◽  
The Other ◽  
Tube Growth ◽  
Scanning Electron

Floral anatomy and pollen tube growth in the quandong were studied using light and scanning electron microscopy. The flowers had four perianth lobes and four stamens whose anthers dehisced by longitudinal slits. The pollen became caught in long unicellular hairs adjacent to the anthers. The central disc secreted nectar through raised stomata. The stigma papilla cells had a cuticle with a rough surface overlying thick PAS-positive walls. The half-inferior ovary normally contained two ovules. The embryo sac extended beyond the ovule at the micropylar end and into the placenta at the chalazal end. Half of the ovaries observed at both anthesis and 4 days following anthesis had no embryo sacs and the other half had one embryo sac. Occasional ovaries had two embryo sacs and some underdeveloped embryo sacs were observed that did not extend beyond the ovule or into the placenta. Pollen tubes had reached the ovary by 1 day following pollination and the stigma was receptive for 8 days following anthesis. Only half of the pistils had pollen tubes in the ovary. Unpollinated flowers had no pollen tube growth in the pistil.

Timetable of Stigmatic Receptivity and Development and Pollen Tube Growth in Chamelaucium uncinatum (Myrtaceae)

1996 ◽  
Vol 44 (6) ◽  
pp. 649 ◽  
Author(s):  
SP Obrien
Keyword(s):  
Pollen Tube ◽  
Pollen Tube Growth ◽  
Pollen Tubes ◽  
The Self ◽  
Transmitting Tissue ◽  
Short Side ◽  
Secondary Pollen Presentation ◽  
Pollen Presentation ◽  
Days After Anthesis ◽  
Chamelaucium Uncinatum

The stigma of Chamelaucium uncinatum Schauer is small and unreceptive at anthesis, but increases in size and becomes fully receptive 7 days after anthesis. After germination, pollen tubes grow intercellularly through the stigma and transmitting tissue of the style. Chamelaucium uncinatum has a single loculus containing six ovules with axile placentation. The transmitting tissue skews to one side within the ovary and the pollen tubes grow into the placenta via an invagination along one end of the loculus. Pollen tubes are smooth-walled in the transmitting tissue of the style and ovary, but within the loculus pollen tubes produce short side branches. Secondary pollen presentation occurs in C. uncinatum with the stigmatic region being used as a pollen presenter. If the self-pollen is not removed from the stigma prior to the onset of receptivity self-pollination may occur.

Late-acting self-incompatibility in tea plant (Camellia sinensis)

Biologia ◽  
2012 ◽  
Vol 67 (2) ◽  
Author(s):  
Xuan Chen ◽  
Shan Hao ◽  
Li Wang ◽  
Wanping Fang ◽  
Yuhua Wang ◽  
...  
Keyword(s):  
Pollen Tube ◽  
Camellia Sinensis ◽  
Pollen Tubes ◽  
Tea Plant ◽  
The Self ◽  
Self Incompatibility ◽  
Cross Pollination ◽  
Self Pollination ◽  
Hand Pollination ◽  
Pollen Tube Elongation

AbstractThe self-incompatibility of tea plant (Camellia sinensis (L.) O. Kuntze) was studied with the methods of aniline blue fluorescence assay and paraffin sections. The characteristics of pollen tube elongation after hand pollination was analyzed in 4 tea cultivars, including ‘Keemenzhong’, ‘Longjing-changye’, ‘Fuding-dabaicha’ and ‘Yabukita’, under self-pollination and cross-pollination, respectively. Although there were some difference among cultivars, pollen tubes elongated through the style and reach the ovary successfully at 48 h after pollination for both cross- and self-pollen tubes in all the four cultivars of tea. Pollen tubes entered into the ovule micropyles, however, only for cross-pollination, but not for self-pollination. Pollen tubes of selfing plants, failed in fertilizing, seemed have some difficulties to enter the ovule. All of which indicated that the self-incompatibility of tea plant is a late-acting self-incompatibility system (LSI) or an ovarian sterility (OS), in which the self incompatibility was due to none self pollen tube penetrating into the ovule and no fertilization.

Embryology of Eucalyptus Spathulata and E. platypus (Myrtaceae) Following Selfing, Crossing and Reciprocal Interspecific Pollination

1996 ◽  
Vol 44 (6) ◽  
pp. 661 ◽  
Author(s):  
M Sedgley ◽  
L Granger
Keyword(s):  
Pollen Tube ◽  
Embryo Development ◽  
Bright Field ◽  
Cross Pollination ◽  
Self Pollination ◽  
Bright Field Microscopy ◽  
Low Levels ◽  
Pollen Tube Penetration ◽  
Ovule Penetration

Embryology of Eucalyptus spathulata Hook. and E. platypus Hook. (subgenus Symphyomyrtus, section Bisectaria) was investigated by bright field microscopy to determine the cause of ovule failure at 2 months following selfing, crossing and reciprocal interspecific pollination. Eucalyptus spathulata retained more capsules and produced more seeds following cross- than self-pollination, whereas there was no difference between selfing and crossing for E. platypus. Both species produced seeds following interspecific pollination, but germination was low. Highest ovule penetration by a pollen tube, and ovule growth at 2 months, was observed following crossing of E. spathulata and following interspecific pollination of E. platypus. Most self-pollinated ovules of both species were degenerating and were either unfertilised or had undivided zygotes and free nuclear endosperm. Muticellular pro-embryos were more common in cross-pollinated and interspecific pollinated ovules than following selfing. It was concluded that ovule degeneration of E. spathulata and E. platypus following selfing resulted from low levels of pollen tube penetration and fertilisation, and that in those ovules which were fertilised, the zygote generally failed to divide. Degeneration following cross-pollination of E. spathulata also resulted from failure of the zygote to divide, and in E. platypus additional reasons were low levels of pollen tube penetration and fertilisation, and lack of cellularisation of the endosperm. Ovule degeneration of both species following interspecific pollination included failure of the zygote to divide, but in E. spathulata it also resulted from slower embryo development and reduced cellularisation of the endosperm.

Pollination, Fertilization, and Embryo Development in Southern China Fresh-eating Jujube

HortScience ◽  
2020 ◽  
pp. 1-8
Author(s):  
Fengxia Shao ◽  
Sen Wang ◽  
Zhiming Liu ◽  
Rongyan Hong ◽  
Tianjiao Zhao
Keyword(s):  
Pollen Tube ◽  
Embryo Development ◽  
Pollen Tube Growth ◽  
Southern China ◽  
Pollen Tubes ◽  
Tube Growth ◽  
Seed Abortion ◽  
Cross Pollination ◽  
Globular Embryos ◽  
Pollination And Fertilization

To explore the reasons for seed abortion in southern China fresh-eating jujube, improve its reproductive biology, and provide a theoretical basis for the crossbreeding of jujube, we carried out self-pollination and cross-pollination experiments with Ziziphus jujuba Mill. ‘Zhongqiusucui’ as the female parent. We observed the process of pollen tube growth in pistil and embryo development by fluorescence microscopy and paraffin section methods. The results show there were self- and cross-incompatibilities during pollination and fertilization, and there were no significant differences in pollen germination and pollen tube growth between self-pollination and cross-pollination. It took at least 4 hours for pollen and stigma to recognize each other, 6 hours for pollen to germinate on the stigma, and 12 hours for the pollen tube to penetrate the mastoid cells of the stigma. After 48 hours of pollination, the pollen tube reached one third of the style. The pollen tube remained stagnant 72 to 120 hours after pollination, and remained at one third of the stylar canal. Simultaneously, the pollen tubes on the stigma twisted and interacted with each other, and expanded into a spherical shape. A few pollen tubes reached the ovary and completed fertilization. However, some early globular embryos degenerated before forming into globular embryos and resulted in the formation of empty embryo sacs, which leads to seed abortion. In conclusion, the poor pollination and fertilization, and the blocked development of the embryo resulted in seed abortion in Z. jujuba ‘Zhongqiusucui’.

scholarly journals Ovary Signals for Pollen Tube Guidance in Chalazogamous Mangifera indica L.

2021 ◽  
Vol 11 ◽  
Author(s):  
Jorge Lora ◽  
Veronica Perez ◽  
Maria Herrero ◽  
Jose I. Hormaza
Keyword(s):  
Pollen Tube ◽  
Pollen Tube Growth ◽  
Mangifera Indica ◽  
Embryo Sac ◽  
Pollen Tubes ◽  
Tube Growth ◽  
Transmitting Tissue ◽  
Egg Apparatus ◽  
Pollen Tube Elongation

Most flowering plants show porogamy in which the pollen tubes reach the egg apparatus through the micropyle. However, several species show chalazogamy, an unusual pollen tube growth, in which the pollen tubes reach the embryo sac through the chalaza. While ovary signals for pollen tube growth and guidance have been extensively studied in porogamous species, few studies have addressed the process in chalazogamous species such as mango (Mangifera indica L.), one of the five most important fruit crops worldwide in terms of production. In this study, we characterize pollen–pistil interaction in mango, paying special attention to three key players known to be involved in the directional pollen tube growth of porogamous species such as starch, arabinogalactan proteins (AGPs), and γ-aminobutyric acid (GABA). Starch grains were observed in the style and in the ponticulus at anthesis, but their number decreased 1 day after anthesis. AGPs, revealed by JIM8 and JIM13 antibodies, were homogenously observed in the style and ovary, but were more conspicuous in the nucellus around the egg apparatus. GABA, revealed by anti-GABA antibodies, was specifically observed in the transmitting tissue, including the ponticulus. Moreover, GABA was shown to stimulate in vitro mango pollen tube elongation. The results support the heterotrophic growth of mango pollen tubes in the style at the expense of starch, similarly to the observations in porogamous species. However, unlike porogamous species, the micropyle of mango does not show high levels of GABA and starch, although they were observed in the ponticulus and could play a role in supporting the unusual pollen tube growth in chalazogamous species.

scholarly journals Pollen-pistil interactions in interspecific crosses of Populus (sections Aigeiros and Leuce): pollen adhesion, hydration and callose responses

1984 ◽  
Vol 72 (1) ◽  
pp. 173-184
Author(s):  
M. Gaget ◽  
C. Said ◽  
C. Dumas ◽  
R.B. Knox
Keyword(s):  
Pollen Tube ◽  
Cell Walls ◽  
Populus Deltoides ◽  
Pollen Tubes ◽  
Interspecific Crosses ◽  
Transmitting Tissue ◽  
Stigma Surface ◽  
The Cross ◽  
Plug Formation ◽  
Callose Plug

Intersectional crosses between species of sections Aigeiros (Populus deltoides, P. X euramericana or P. nigra) and Leuce (P. alba or P. tremuloides) are known to be reciprocally incompatible. The site of pollen tube arrest is on the stigma surface in pollinations between pistils of section Leuce and pollen of section Aigeiros; tubes failed to penetrate the stigma surface. In reciprocal matings, pollen of section Leuce germinated and tubes penetrated the stigma and style, where arrest occurred. Rejection may be accompanied by swelling of the tube tips, and callose plug formation. In the cross between P. deltoides and P. alba a callose response was detected in the cell walls of the transmitting tissue, adjacent to the rejected pollen tubes.

Pollen-Pistil Interactions as Reproductive Barriers

2021 ◽  
Vol 72 (1) ◽  
pp. 615-639
Author(s):  
Amanda K. Broz ◽  
Patricia A. Bedinger
Keyword(s):  
Pollen Tube ◽  
Mate Selection ◽  
Critical Role ◽  
Pollen Tubes ◽  
Reproductive Barriers ◽  
Transmitting Tissue ◽  
Active Systems ◽  
Heterospecific Pollen ◽  
Pollen Rejection ◽  
Cell Release

Pollen-pistil interactions serve as important prezygotic reproductive barriers that play a critical role in mate selection in plants. Here, we highlight recent progress toward understanding the molecular basis of pollen-pistil interactions as reproductive isolating barriers. These barriers can be active systems of pollen rejection, or they can result from a mismatch of required male and female factors. In some cases, the barriers are mechanistically linked to self-incompatibility systems, while others represent completely independent processes. Pollen-pistil reproductive barriers can act as soon as pollen is deposited on a stigma, where penetration of heterospecific pollen tubes is blocked by the stigma papillae. As pollen tubes extend, the female transmitting tissue can selectively limit growth by producing cell wall–modifying enzymes and cytotoxins that interact with the growing pollen tube. At ovules, differential pollen tube attraction and inhibition of sperm cell release can act as barriers to heterospecific pollen tubes.

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