scholarly journals KAKU4-mediated deformation of the vegetative nucleus controls its precedent migration over sperm cells in pollen tubes

2019 ◽  
Author(s):  
Chieko Goto ◽  
Kentaro Tamura ◽  
Satsuki Nishimaki ◽  
Naoki Yanagisawa ◽  
Kumi Matsuura-Tokita ◽  
...  
Keyword(s):  
Competitive Ability ◽  
Pollen Grains ◽  
Nuclear Lamina ◽  
Pollen Tubes ◽  
Vegetative Nucleus ◽  
Sperm Cells ◽  
Wild Type ◽  
Cell Nuclei ◽  
In The Wild ◽  
Dense Accumulation

AbstractA putative nuclear lamina protein, KAKU4, modulates nuclear morphology in Arabidopsis thaliana seedlings but its physiological significance is unknown. KAKU4 was strongly expressed in mature pollen grains, each of which has a vegetative cell and two sperm cells. KAKU4 protein was highly abundant on the envelopes of vegetative nuclei (VNs) and less abundant on the envelopes of sperm cell nuclei (SCNs) in pollen grains and elongating pollen tubes. VN is irregularly shaped in wild-type pollen. However, KAKU4 deficiency caused it to become more spherical. These results suggest that the dense accumulation of KAKU4 is responsible for the irregular shape of the VNs. After a pollen grain germinates, the VN and SCNs migrate to the tip of the pollen tube. In the wild type, the VN preceded the SCNs in 91–93% of the pollen tubes, whereas in kaku4 mutants, the VN trailed the SCNs in 39–58% of the pollen tubes. kaku4 pollen was less competitive than wild-type pollen after pollination, although it had an ability to fertilize. Taken together, our results suggest that controlling the nuclear shape in vegetative cells of pollen grains by KAKU4 ensures the orderly migration of the VN and sperm cells in pollen tubes.HighlightThe nuclear envelope protein KAKU4 is involved in controlling the migration order of vegetative nuclei and sperm cells in pollen tubes, affecting the competitive ability of pollen for fertilization.

The nuclear envelope protein KAKU4 determines the migration order of the vegetative nucleus and sperm cells in pollen tubes

2020 ◽  
Vol 71 (20) ◽  
pp. 6273-6281 ◽  
Author(s):  
Chieko Goto ◽  
Kentaro Tamura ◽  
Satsuki Nishimaki ◽  
Daisuke Maruyama ◽  
Ikuko Hara-Nishimura
Keyword(s):  
Sperm Cell ◽  
Pollen Grains ◽  
Nuclear Lamina ◽  
Pollen Tubes ◽  
Pollen Grain ◽  
Vegetative Nucleus ◽  
Sperm Cells ◽  
Wild Type ◽  
Cell Nuclei ◽  
In The Wild

Abstract A putative component protein of the nuclear lamina, KAKU4, modulates nuclear morphology in Arabidopsis thaliana seedlings, but its physiological significance is unknown. KAKU4 was highly expressed in mature pollen grains, each of which has a vegetative cell and two sperm cells. KAKU4 protein was highly abundant on the envelopes of vegetative nuclei and less abundant on the envelopes of sperm cell nuclei in pollen grains and elongating pollen tubes. Vegetative nuclei are irregularly shaped in wild-type pollen. However, KAKU4 deficiency caused them to become more spherical. After a pollen grain germinates, the vegetative nuclei and sperm cells enter and move along the pollen tube. In the wild type, the vegetative nucleus preceded the sperm cell nuclei in >90% of the pollen tubes, whereas, in kaku4 mutants, the vegetative nucleus preceded the sperm cell nuclei in only about half of the pollen tubes. kaku4 pollen was less competitive for fertilization than wild-type pollen after pollination. These results led us to hypothesize that the nuclear shape in vegetative cells of pollen grains affects the orderly migration of the vegetative nucleus and sperm cells in pollen tubes.

scholarly journals Persistent directional growth capability in Arabidopsis thaliana pollen tubes after nuclear elimination from the apex

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Kazuki Motomura ◽  
Hidenori Takeuchi ◽  
Michitaka Notaguchi ◽  
Haruna Tsuchi ◽  
Atsushi Takeda ◽  
...  
Keyword(s):  
Arabidopsis Thaliana ◽  
Pollen Tube ◽  
Sperm Cell ◽  
Pollen Tubes ◽  
Vegetative Nucleus ◽  
Sperm Cells ◽  
Apical Region ◽  
Basal Region ◽  
Specific Expression ◽  
Directional Growth

AbstractDuring the double fertilization process, pollen tubes deliver two sperm cells to an ovule containing the female gametes. In the pollen tube, the vegetative nucleus and sperm cells move together to the apical region where the vegetative nucleus is thought to play a crucial role in controlling the direction and growth of the pollen tube. Here, we report the generation of pollen tubes in Arabidopsis thaliana whose vegetative nucleus and sperm cells are isolated and sealed by callose plugs in the basal region due to apical transport defects induced by mutations in the WPP domain-interacting tail-anchored proteins (WITs) and sperm cell-specific expression of a dominant mutant of the CALLOSE SYNTHASE 3 protein. Through pollen-tube guidance assays, we show that the physiologically anuclear mutant pollen tubes maintain the ability to grow and enter ovules. Our findings provide insight into the sperm cell delivery mechanism and illustrate the independence of the tip-localized vegetative nucleus from directional growth control of the pollen tube.

scholarly journals Two groups of Arabidopsis receptor kinases preferentially regulate the growth of intraspecies pollen tubes in the female reproductive tract

2020 ◽  
Author(s):  
Hyun Kyung Lee ◽  
Daphne R. Goring
Keyword(s):  
Pollen Tube ◽  
Reproductive Tract ◽  
Cell Communication ◽  
Pollen Grains ◽  
Pollen Tubes ◽  
Female Reproductive Tract ◽  
Wild Type ◽  
Knockout Mutant ◽  
Receptor Kinases ◽  
Compatible Pollen

SummaryIn flowering plants, continuous cell-cell communication between the compatible male pollen grain/growing pollen tube and the female pistil is required for successful sexual reproduction. In Arabidopsis thaliana, the later stages of this dialogue are mediated by several peptide ligands and receptor kinases that guide pollen tubes to the ovules for the release of sperm cells. Despite a detailed understanding of these processes, a key gap remains on the nature of the regulators that function at the earlier stages. Here, we report on two groups of A. thaliana receptor kinases, the LRR-VIII-2 RK subclass and the SERKs, that function in the female reproductive tract to regulate the compatible pollen grains and early pollen tube growth, both essential steps for the downstream processes leading to fertilization. Multiple A. thaliana LRR-VIII-2 RK and SERK knockout mutant combinations were created, and several phenotypes were observed such as reduced wild-type pollen hydration and reduced pollen tube travel distances. As these mutant pistils displayed a wild-type morphology, the observed altered responses of the wild-type pollen are proposed to result from the loss of these receptor kinases leading to an impaired pollen-pistil dialogue at these early stages. Furthermore, using pollen from related Brassicaceae species, we also discovered that these receptor kinases are required in the female reproductive tract to establish a reproductive barrier to interspecies pollen. Thus, we propose that the LRR-VIII-2 RKs and the SERKs play a dual role in the preferential selection and promotion of intraspecies pollen over interspecies pollen.

Development of sperm cells in barley

1975 ◽  
Vol 53 (10) ◽  
pp. 1051-1062 ◽  
Author(s):  
David D. Cass ◽  
Ilana Karas
Keyword(s):  
Cell Membrane ◽  
Vegetative Cell ◽  
Generative Cell ◽  
Pollen Grains ◽  
Complete Separation ◽  
Pollen Wall ◽  
Vegetative Nucleus ◽  
Sperm Cells ◽  
Subsequent Stage ◽  
Microspore Stage

Ultrastructural events in barley sperm development were examined from the uninucleate microspore stage to establishment of two mature sperm cells in pollen grains. Microspore mitosis produces a vegetative nucleus and a naked generative cell, both embedded in vegetative cell cytoplasm. The generative cell membrane is enclosed by vegetative cell membrane. The generative cell, at first apparently unattached, becomes attached to the pollen wall and acquires a cell wall by centripetal vesicle accumulation. Wall formation may be complete at the time of generative cell karyokinesis; karyokinesis occurs while the generative cell is attached to the pollen wall. Cytokinesis of the generative cell is delayed. The subsequent stage is a binucleate, attached generative cell with a wall. Generative cell cytokinesis appears to involve formation of a partition between the two sperm nuclei. Eventual complete separation of the sperm cells occurs only after the two-celled derivative of the generative cell detaches from the pollen wall. Final stages in sperm cell separation are considered to result from degradation of the partitioning and surrounding wall, not from furrowing of a naked binucleate generative cell according to previous suggestions. Mature plastids were not observed in the generative cell or the sperms.

scholarly journals Abnormal Microspore Development Leads to Pollen Abortion in a Seedless Mutant of ‘Ougan’ Mandarin (Citrus suavissima Hort. ex Tanaka)

2007 ◽  
Vol 132 (6) ◽  
pp. 777-782 ◽  
Author(s):  
Zhiyong Hu ◽  
Min Zhang ◽  
Qigen Wen ◽  
Jie Wei ◽  
Hualin Yi ◽  
...  
Keyword(s):  
Pollen Viability ◽  
Pollen Grains ◽  
Pollen Grain ◽  
Mature Pollen ◽  
Abnormal Development ◽  
Microspore Development ◽  
Wild Type ◽  
Pollen Abortion ◽  
Tetrad Stage ◽  
In The Wild

Seedlessness is of commercial importance in citrus (Citrus L.). Seedless ‘Ougan’ mandarin (C. suavissima) was selected from a bud sport mutation that occurred in ‘Ougan’ mandarin. We analyzed their pollen viability through KI-I2 and FDA staining, and examined the anthers of wild-type (seedy) and seedless mutant ‘Ougan’ mandarin using histological and cytochemical methods to characterize the process of pollen development. No pollen fertility was detected in this mutant. Pollen abortion in anthers of the mutant occurred at the tetrad stage of microspore development, and almost all the tetrads were abnormal. The mutant had heterogeneous microspore populations, including monads, dyads, triads, tetrads, and polyads in the same microsporangium. Pollen grain number per anther of the mutant was 21.9% less than the wild type. Morphology of mature pollen grains using SEM showed that the shape of mature pollen grains from both wild type and mutant is similar, but the microsporangia of the latter contained pollen grains of more variable sizes. At the early mature pollen grain stage, abundant starch grains and lipids appeared in the wild type's pollen, but fewer amounts were observed in the mutant. Moreover, the tapetal cells of the wild type accumulated lipids, but not those of the mutant. Results indicated that the abnormal development of the microspore led to pollen abortion in the mutant, and this could be the reason for its seedlessness. However, the genetic reasons for the aberrant tetrads are not clear and are under investigation.

scholarly journals Morbid mitosis and the activity of inert chromosomes in sorghum

1941 ◽  
Vol 130 (859) ◽  
pp. 127-150 ◽  
Keyword(s):  
Structural Changes ◽  
Wild Population ◽  
Specific Effect ◽  
Pollen Grains ◽  
Variable Number ◽  
Pollen Grain ◽  
Vegetative Nucleus ◽  
In The Wild ◽  
Primary Division ◽  
Generative Nuclei

Sorghum purpureo-sericeum has five paris of active, A , chromosomes and a variable number of extra, B , chromosomes in equilibrium in the wild population (Janaki-Ammal 1940; and table 7). The B -chromosomes vary in structure within and between plants owing to frequent spontaneous changes, including misdivision of the centromere. One is an iso-chromosome. The B 's are sex-limited so far as that is possible in a plant: they are confined to the germ track owing to loss by lagging elsewhere. They are lost in the radicle before seed ripening and in the shoot tissues as they reach maturity. Only in the anthers and ovaries are they regularly maintained. B -chromosomes pair with one another at meiosis when homologous, and the two arms of the iso-chromosome form chiasmata with one another. Pollen grains of plus plants (with extra B 's) have extra divisions of the vegetative nucleus rapidly following the primary division. The first pollen grain division is delayed by the presence of B -chromosomes. Its course is always normal. At the second division the B 's always pass to the generative pole undivided and so double its dose. When only two generative nuclei are formed, one or both may produce sperm. Three, four or five generative nuclei, however, kill the pollen grain. The extra divisions are thus malignant. The B -chromosomes as usual are heterochromatic. They have an abnormal nucleic acid cycle. Their action on the cells, containing them is non-specific and cumulative, and their apparently specific effect in stimulating mitosis in the pollen grains is possibly due to these being the only cells that contain them whose mitosis and growth are normally limited. Spontaneous structural changes in heterochromatic chromosomes are frequent at mitosis in plants and animals. Such changes could evidently establish malignant propensities in somatic cells by stimulating recurrent mitosis.

scholarly journals Role of MS1 homolog Ntms1 gene of tobacco infertility

2021 ◽  
Vol 16 (1) ◽  
pp. 815-826
Author(s):  
Qian Chen ◽  
Tingting Zhao ◽  
Lili Duan ◽  
Zejun Mo ◽  
Maozhu Tian ◽  
...  
Keyword(s):  
Male Sterility ◽  
Chemical Properties ◽  
Pollen Grains ◽  
Anther Wall ◽  
Wild Type ◽  
Knockout Mutant ◽  
Malondialdehyde Content ◽  
In The Wild ◽  
Physical And Chemical

Abstract The sterile line is the basis of crop heterosis utilization. To broaden the sources of male sterility in tobacco, the Ntms1 (Nicotiana tabacum L. ms1) gene was cloned from the tobacco variety K326 by homologous cloning based on the Cams1 (Capsicum annuum L. ms1) gene sequence of male-sterility genes in pepper. The protein structure and physicochemical properties of the two genes were determined by bioinformatics analysis, and the function of the Ntms1 gene was verified by the CRISPR/Cas9 system. The results showed that the sequences of Ntms1 and Cams1 were 85.25% similar, and plant homeodomains were found in both genes; the physical and chemical properties were also very similar. It is speculated that the Ntms1 gene had the same function as the Cams1 gene in controlling male sterility. Compared to the wild-type plants, the filaments of the Ntms1 knockout mutant plants were shorter, and the stamen was shorter than the pistil. The anthers did not develop fully and had few viable pollen grains; the tapetum and the anther wall had developed abnormally, and the anther chamber was severely squeezed. The malondialdehyde content in the mutant plants was significantly higher than that in the wild-type plants, while self-fertility was significantly lower in the mutant plants. The results showed that the Ntms1 gene plays an important role in regulating fertility in tobacco.

scholarly journals A Tug-of-War Model Explains the Saltatory Sperm Cell Movement in Arabidopsis thaliana Pollen Tubes by Kinesins With Calponin Homology Domain

2021 ◽  
Vol 11 ◽  
Author(s):  
Saskia Schattner ◽  
Jan Schattner ◽  
Fabian Munder ◽  
Eva Höppe ◽  
Wilhelm J. Walter
Keyword(s):  
Arabidopsis Thaliana ◽  
Pollen Tube ◽  
Sperm Cell ◽  
Cell Movement ◽  
Pollen Tubes ◽  
Vegetative Nucleus ◽  
Sperm Cells ◽  
Calponin Homology Domain ◽  
Calponin Homology ◽  
Actin Cables

Upon pollination, two sperm cells are transported inside the growing pollen tube toward the apex. One sperm cell fertilizes the egg cell to form the zygote, while the other fuses with the two polar nuclei to form the triploid endosperm. In Arabidopsis thaliana, the transport of the two sperm cells is characterized by sequential forward and backward movements with intermediate pauses. Until now, it is under debate which components of the plant cytoskeleton govern this mechanism. The sperm cells are interconnected and linked to the vegetative nucleus via a cytoplasmic projection, thus forming the male germ unit. This led to the common hypothesis that the vegetative nucleus is actively transported via myosin motors along actin cables while pulling along the sperm cells as passive cargo. In this study, however, we show that upon occasional germ unit disassembly, the sperm cells are transported independently and still follow the same bidirectional movement pattern. Moreover, we found that the net movement of sperm cells results from a combination of both longer and faster runs toward the pollen tube apex. We propose that the observed saltatory movement can be explained by the function of kinesins with calponin homology domain (KCH). This subgroup of the kinesin-14 family actively links actin filaments and microtubules. Based on KCH's specific properties derived from in vitro experiments, we built a tug-of-war model that could reproduce the characteristic sperm cell movement in pollen tubes.

Freeze-substituted fungal cells of Nectria haematococca: A comparison of the macroconidial walls of the adhesion-competent wild type with an adhesion-reduced mutant

1990 ◽  
Vol 48 (3) ◽  
pp. 688-689
Author(s):  
Thecan Caesar-Ton That ◽  
Lynn Epstein
Keyword(s):  
Freeze Substitution ◽  
Uranyl Acetate ◽  
Wild Type ◽  
Nectria Haematococca ◽  
Fruit Extract ◽  
Dialysis Tubing ◽  
Tube Emergence ◽  
Contrast Microscopy ◽  
In The Wild ◽  
Freeze Damage

Nectria haematococca mating population I (anamorph, Fusarium solani) macroconidia attach to its host (squash) and non-host surfaces prior to germ tube emergence. The macroconidia become adhesive after a brief period of protein synthesis. Recently, Hickman et al. (1989) isolated N. haematococca adhesion-reduced mutants. Using freeze substitution, we compared the development of the macroconidial wall in the wild type in comparison to one of the mutants, LEI.Macroconidia were harvested at 1C, washed by centrifugation, resuspended in a dilute zucchini fruit extract and incubated from 0 - 5 h. During the incubation period, wild type macroconidia attached to uncoated dialysis tubing. Mutant macroconidia did not attach and were collected on poly-L-lysine coated dialysis tubing just prior to freezing. Conidia on the tubing were frozen in liquid propane at 191 - 193C, substituted in acetone with 2% OsO4 and 0.05% uranyl acetate, washed with acetone, and flat-embedded in Epon-Araldite. Using phase contrast microscopy at 1000X, cells without freeze damage were selected, remounted, sectioned and post-stained sequentially with 1% Ba(MnO4)2 2% uranyl acetate and Reynold’s lead citrate. At least 30 cells/treatment were examined.

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