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

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.

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

Journal of Experimental Botany ◽

10.1093/jxb/eraa367 ◽

2020 ◽

Vol 71 (20) ◽

pp. 6273-6281 ◽

Cited By ~ 4

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.

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

10.1101/774489 ◽

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.

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Differences in stomatal and pollen grain dimensions and pollen viability between Paspalum rawitscheri populations

Ciência e Natura ◽

10.5902/2179460x40749 ◽

2020 ◽

Vol 42 ◽

pp. e46

Author(s):

Jéssica Mena Barreto De Freitas ◽

Andrielle Wouters Kuhn ◽

Viviane Dal-Souto Frescura ◽

Liliana Essi ◽

Solange Bosio Tedesco

Keyword(s):

Grain Size ◽

Pollen Viability ◽

Pollen Grains ◽

Pollen Grain ◽

Low Fertility ◽

Leaf Epidermis ◽

Stomatal Size ◽

Pollen Grain Size ◽

Different Populations ◽

Santa Maria

The objective of this study was to evaluate stomatal and pollen grain size and to estimate pollen viability of individuals from different populations of Paspalum rawitscheri (Parodi) Chase ex G.H. Rua Valls. To analyze stomatal size, slides were made of the adaxial leaf epidermis using the epidermal impression method. The height and width of 100 stomata per population were analyzed. Pollen was obtained from inflorescences to evaluate pollen grain size and pollen viability. Pollen grains were stained with 2% acetic orcein, 2% acetic carmine, or Alexander’s reactive stain. Per population, 1600 grains of pollen were observed for viability, and 50 grains of pollen were measured. There were significant differences between populations in stomatal height and pollen grain height and width. The populations also differed in pollen viability, with the Santa Maria population showing the lowest viability. The differences in stomatal and pollen grain size suggest genetic variability in the evaluated populations. Moreover, low pollen viability in one population indicates that its decline may be related to low fertility. Keywords: Grass. Ploidy. Fertility. Threatened species.

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Pollen grain traits of oil species from the Novi Sad collection

Genetika ◽

10.2298/gensr0903263a ◽

2009 ◽

Vol 41 (3) ◽

pp. 263-270 ◽

Cited By ~ 3

Author(s):

Jovanka Atlagic ◽

Ana Marjanovic-Jeromela ◽

Radovan Marinkovic ◽

Sreten Terzic

Keyword(s):

Staining Method ◽

Pollen Viability ◽

Pollen Grains ◽

Grain Morphology ◽

Pollen Grain ◽

Viable Pollen ◽

Continuous Work ◽

Novi Sad ◽

Pollen Grain Morphology ◽

Specific Number

The collection of oil species in Novi Sad contains 12 species represented with 1-4 cultivars or landraces. In the continuous work on this collection in the sense of breeding of some of those species and their usage as a source of 'desirable genes' we analyzed pollen grain morphology (shape and size), as well as pollen viability. To determine mentioned pollen traits we used Axiovert 40C microscope together with a software package (AxioVision LE; Rel.4.3.) for measurement of pollen length and width. Pollen viability was determined using a staining method (ALEXANDER, 1969). The results showed that species differ by pollen grain shape (round, egg-shaped, triangular and rod) as well as by shape of exine (thick and spiky, thick to thin). In some species there was a specific number of apertures present (1-11). The size of viable pollen grains ranged from 29,10/12,58? (coriander) to 176,63/169,94? (oil gourd), while non-viable pollen grains were always smaller (27,27/10,97? to 119,62/100,86?) at the same plant species. Pollen viability of most species was around 80%. Lowest pollen viability was found in white flax (56,98%), and the highest in oil pumpkin (91,43%).

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In vitro germination and viability of pea pollen grains after application of organic nano-fertilizers

Pesticidi i fitomedicina ◽

10.2298/pif1701061g ◽

2017 ◽

Vol 32 (1) ◽

pp. 61-65 ◽

Cited By ~ 1

Author(s):

Natalia Georgieva ◽

Ivelina Nikolova ◽

Valentin Kosev ◽

Yordanka Naydenova

Keyword(s):

Pollen Tube ◽

Pollen Germination ◽

Culture Media ◽

Pollen Viability ◽

Pollen Grains ◽

Pollen Grain ◽

In Vitro Germination ◽

Pisum Sativum L ◽

Pollen Tube Elongation

The objective of this study was to evaluate the influence of two organic nanofertilizers, Lithovit and Nagro, on in vitro germination, pollen tube elongation and pollen grain viability of Pisum sativum L cv. Pleven 4. The effect of their application was high and exceeded data for the untreated control (44.2 and 47.23 % regarding pollen germination and pollen tube elongation, respectively), as well as the effect of the control organic algal fertilizer Biofa (17.5 and 27.9 %, respectively). Pollen grains were inoculated in four culture media. A medium containing 15% sucrose and 1% agar had the most stimulating impact on pea pollen grains. Pollen viability, evaluated by staining with 1% carmine, was within limits of 74.72-87.97%. The highest viability of pollen grains was demonstrated after the application of Nagro organic nano-fertlizer.

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Quantitative methods in microscopy to assess pollen viability in different plant taxa

Plant Reproduction ◽

10.1007/s00497-020-00398-6 ◽

2020 ◽

Vol 33 (3-4) ◽

pp. 205-219

Author(s):

Lorenzo Ascari ◽

Cristina Novara ◽

Virginia Dusio ◽

Ludovica Oddi ◽

Consolata Siniscalco

Keyword(s):

Statistical Power ◽

Quantitative Methods ◽

Pollen Viability ◽

Crop Improvement ◽

Pollen Grains ◽

Pollen Sterility ◽

Pollen Grain ◽

Automated Image Analysis ◽

Future Research ◽

Sterile Pollen

AbstractHigh-quality pollen is a prerequisite for plant reproductive success. Pollen viability and sterility can be routinely assessed using common stains and manual microscope examination, but with low overall statistical power. Current automated methods are primarily directed towards the analysis of pollen sterility, and high throughput solutions for both pollen viability and sterility evaluation are needed that will be consistent with emerging biotechnological strategies for crop improvement. Our goal is to refine established labelling procedures for pollen, based on the combination of fluorescein (FDA) and propidium iodide (PI), and to develop automated solutions for accurately assessing pollen grain images and classifying them for quality. We used open-source software programs (CellProfiler, CellProfiler Analyst, Fiji and R) for analysis of images collected from 10 pollen taxa labelled using FDA/PI. After correcting for image background noise, pollen grain images were examined for quality employing thresholding and segmentation. Supervised and unsupervised classification of per-object features was employed for the identification of viable, dead and sterile pollen. The combination of FDA and PI dyes was able to differentiate between viable, dead and sterile pollen in all the analysed taxa. Automated image analysis and classification significantly increased the statistical power of the pollen viability assay, identifying more than 75,000 pollen grains with high accuracy (R2 = 0.99) when compared to classical manual counting. Overall, we provide a comprehensive set of methodologies as baseline for the automated assessment of pollen viability using fluorescence microscopy, which can be combined with manual and mechanized imaging systems in fundamental and applied research on plant biology. We also supply the complete set of pollen images (the FDA/PI pollen dataset) to the scientific community for future research.

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Pollen Grain and Hybridization Studies in the Genus Capsicum

Notulae Scientia Biologicae ◽

10.15835/nsb819767 ◽

2016 ◽

Vol 8 (1) ◽

pp. 134-138 ◽

Cited By ~ 1

Author(s):

Tomi Lois OLATUNJI ◽

Joseph Akintade MORAKINYO

Keyword(s):

Success Rate ◽

Pollen Viability ◽

Pollen Grains ◽

Pollen Grain ◽

Interspecific Crosses ◽

Putative Hybrid ◽

Gene Exchange ◽

Viable Pollen ◽

Pollination Success ◽

Capsicum Species

The current study aimed to evaluate the pollen viability of the commonly cultivated varieties of Capsicum species and assessed the potentials for gene exchange among the genotypes through hybridization studies. Capsicum annuum var. abbreviatum, C. annuum var. acuminatum, C. annuum var. grossum and C. frutescens var. baccatum were the species and varieties used in this study. The present findings indicated that the percentage of pollen viability varied in the studied Capsicum genotypes. The highest pollen viability was obtained in C. annuum var. abbreviatum (96.3%), followed by C. annuum var. grossum (95%), and C. annuum var. acuminatum (91.1%). The lowest pollen viability was recorded in C. frutescens var. baccatum (86.2%). The pollen viability was high in most varieties indicating that meiosis is normal, resulting in viable pollen grains. Several intraspecific and interspecific crosses were performed among the Capsicum genotypes and three putative hybrid fruits were produced. Percentage successes obtained in the crosses were low and comparable in both intra and inter-specific crosses. In the entire crosses pattern, pollination success of 10% was recorded for C. frutescens var. baccatum and C. annuum var. acuminatum. Knowing the nature and viability of pollen grains may help in predicting the success rate of hybridization and the successful crosses between C. frutescens var. baccatum and C. annuum var. acuminatum suggest that these two varieties are the closest genetically.

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Evaluation of Pollen Quality and Self-Fertility in Selected Cultivars of Asian and European Pears

Notulae Botanicae Horti Agrobotanici Cluj-Napoca ◽

10.15835/nbha45210877 ◽

2017 ◽

Vol 45 (2) ◽

pp. 375-382 ◽

Cited By ~ 2

Author(s):

Monika BIENIASZ ◽

Tomas NECAS ◽

Ewa DZIEDZIC ◽

Ivo ONDRASEK ◽

Bożena PAWŁOWSKA

Keyword(s):

Pollen Germination ◽

Pollen Viability ◽

Pollen Grains ◽

Pollen Grain ◽

Germination Index ◽

Open Pollination ◽

Asian Pear ◽

Pollen Donor ◽

Pear Orchard ◽

Cultivation History

Asian pears have become increasingly popular in the European market, but their cultivation history in Europe is rather short. Pear is a demanding species in terms of pollen – donor cultivar. The self-fertility phenomenon in Asian pear cultivars is not currently known. The study was conducted in a 6-year pear orchard (of 23 Asian and 5 European cultivars) at the Mendel University in Lednice (Czech Republic). The following traits were assessed: number of pollen grains, pollen viability, pollen grain germination, self-fertility and the pollen germination index (PGI). European cultivar – ‘Clapp’s Favourite’ and Asian cultivars – ‘Zao Su Li’, and ‘Shinko’ were characterized by the highest number of pollen grains (over 50,000 grains). Asian cultivar ‘Dangshansu Li’ had the lowest number of pollen grains (less than 10,000 grains). The pollen viability of Asian pears ranged between 90 and 100%. Among European pears, ‘Williams Bon Chrétien’ and ‘Clapp’s Favourite’ exhibited the highest pollen viability (90%), while the lowest viability was observed for the pollen of cultivars ‘Beurré Bosc’ and ‘Alexander Lucas’ pear (60-70%). Additionally, it was found that the germination capacity of the latter two cultivars was very weak (40-70%). After open– pollination all investigated cultivars exhibited greater pollen germination index (PGI) comparing to self-pollination. After the cross-pollination the percentage of pollen tubes below the 20% value at half the length of the pistil suggested a strong incompatibility between the crossed cultivars. The results clearly showed that none of the Asian cultivars are self-fertile, and they require a pollen – donor to produce fruits.

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Effects of Ni2+ and Cu2+ on K+ and H+ currents in lily pollen protoplasts

Functional Plant Biology ◽

10.1071/fp17033 ◽

2017 ◽

Vol 44 (12) ◽

pp. 1171

Author(s):

Maria Breygina ◽

Denis V. Abramochkin ◽

Nikita Maksimov ◽

Igor Yermakov

Keyword(s):

Heavy Metals ◽

Membrane Potential ◽

Pollen Viability ◽

Control Level ◽

Pollen Grains ◽

Pollution Assessment ◽

Term Treatment ◽

Pollen Grain ◽

Patch Clamp Technique ◽

Short Term Treatment

Heavy metals affect plant development and reproduction if they are present in excessive amounts, a situation that is becoming increasingly common. Pollen is a convenient object for pollution assessment as it is in most cases a 2- or 3-cellular organism exposed to the environment. At the same time, pollen is a key stage in the life cycle of seed plants; pollen viability and efficiency of germination are crucial for reproductive success and crop yield. In the present study we reveal for the first time, to our knowledge, targets for heavy metals (Cu2+ and Ni2+) in the pollen grain plasma membrane using the patch-clamp technique. Ni2+ dramatically decreases K+ current in pollen grain protoplasts, whereas Cu2+ does not alter the current density. Instead, Cu2+ strongly enhances H+ current driven by H+-ATPase, whereas Ni2+ fails to affect this current. The short-term treatment with Cu2+ also leads to reactive oxygen species (ROS) accumulation in pollen grain protoplasts but intracellular pH and membrane potential remain unchanged. Ni2+ had no significant effect on ROS content or membrane potential. Thus, plasmalemma K+ channels in pollen grains are sensitive to Ni2+ and H+-ATPase is sensitive to Cu2+, possibly, in a ROS-mediated way. Both metals leave pollen viable since membrane potential is maintained at the control level.

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The Tension-sensitive Ion Transport Activity of MSL8 is Critical for its Function in Pollen Hydration and Germination

10.1101/084988 ◽

2016 ◽

Author(s):

Eric S. Hamilton ◽

Elizabeth S. Haswell

Keyword(s):

Pollen Germination ◽

Pollen Viability ◽

Point Mutations ◽

Normal Growth ◽

Loss Of Function ◽

Transport Activity ◽

Wild Type ◽

Gated Channel ◽

In The Wild ◽

Pore Lining

AbstractAll cells respond to osmotic challenges, including those imposed during normal growth and development. Mechanosensitive (MS) ion channels provide a conserved mechanism for regulating osmotic forces by conducting ions in response to increased membrane tension. We previously demonstrated that the MS ion channel MscS-Like 8 (MSL8) is required for pollen to survive multiple osmotic challenges that occur during the normal process of fertilization, and that it can inhibit pollen germination. However, it remained unclear whether these physiological functions required ion flux through a mechanically gated channel provided by MSL8. We introduced two point mutations into the predicted pore-lining domain of MSL8 that disrupted normal channel function in different ways. The Ile711Ser mutation increased the tension threshold of the MSL8 channel while leaving conductance unchanged, and the Phe720Leu mutation severely disrupted the MSL8 channel. Both of these mutations impaired the ability of MSL8 to preserve pollen viability during hydration and to maintain the integrity of the pollen tube when expressed at endogenous levels. When overexpressed in a msl8-4 null background, MSL8I711S could partially rescue loss-of-function phenotypes, while MSL8F720L could not. When overexpressed in the wild type Ler background, MSL8I711S suppressed pollen germination, similar to wild type MSL8. In contrast, MSL8F720L failed to suppress pollen germination and increased pollen bursting, thereby phenocopying the msl8-4 mutant. Thus, an intact MSL8 channel is required to for normal pollen function during hydration and germination. These data establish MSL8 as the first plant MS channel to fulfill previously established criteria for assignment as a mechanotransducer.

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