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The Journal of Cell Biology Nov 2023The actin cytoskeleton is one of the targets of the pH gradient in tip-growing cells, but how cytosolic pH regulates the actin cytoskeleton remains largely unknown. We...
The actin cytoskeleton is one of the targets of the pH gradient in tip-growing cells, but how cytosolic pH regulates the actin cytoskeleton remains largely unknown. We here demonstrate that Arabidopsis ADF7 and ADF10 function optimally at different pH levels when disassembling actin filaments. This differential pH sensitivity allows ADF7 and ADF10 to respond to the cytosolic pH gradient to regulate actin dynamics in pollen tubes. ADF7 is an unusual actin-depolymerizing factor with a low optimum pH in in vitro actin depolymerization assays. ADF7 plays a dominant role in promoting actin turnover at the pollen tube apex. ADF10 has a typically high optimum pH in in vitro assays and plays a dominant role in regulating the turnover and organization of subapical actin filaments. Thus, functional specification and cooperation of ADF isovariants with different pH sensitivities enable the coordination of the actin cytoskeleton with the cytosolic pH gradient to support pollen tube growth.
Topics: Actins; Arabidopsis; Cell Differentiation; Cell Proliferation; Pollen Tube; Proton-Motive Force; Actin Depolymerizing Factors; Arabidopsis Proteins
PubMed: 37610419
DOI: 10.1083/jcb.202206074 -
BMC Plant Biology Dec 2023Under natural conditions, most Hibiscus syriacus L. individuals form very few mature seeds or the mature seeds that do form are of poor quality. As a result, seed yield...
Under natural conditions, most Hibiscus syriacus L. individuals form very few mature seeds or the mature seeds that do form are of poor quality. As a result, seed yield is poor and seeds have low natural germinability. These phenomena strongly hinder utilization of the excellent germplasm resources of H. syriacus. The study has shown that pollen activity and stigma receptivity were high on the day of anthesis, and the pistils and stamens were fertile. Pollen release and stigma receptivity were synchronous. But in styles following self and cross-pollination, pollen tube abnormalities (distortion and twisting of the pollen tubes) and callose deposition were observed. Cross-pollinated pollen tubes elongated faster and fewer pollen tube abnormalities were observed compared with self-pollinated pollen tubes. And during embryo development, abnormalities during the heart-shaped embryo stage led to embryo abortion. Imbalance in antioxidant enzyme activities and low contents of auxin and cytokinin during early stages of embryo development may affect embryo development. Therefore, a low frequency of outcrossing and mid-development embryo abortion may be important developmental causes of H. syriacus seed abortion. Nutrient deficiencies, imbalance in antioxidant enzyme activities, and a high content of abscisic acid at advanced stages of seed development may be physiological causes of seed abortion.
Topics: Antioxidants; Hibiscus; Pollen; Pollination; Seeds
PubMed: 38129795
DOI: 10.1186/s12870-023-04669-y -
Frontiers in Genetics 2024The gene plays an essential role in the gametophytic self-incompatibility (GSI) system of . It codes for the stylar-expressed S-RNase protein which inhibits the growth...
The gene plays an essential role in the gametophytic self-incompatibility (GSI) system of . It codes for the stylar-expressed S-RNase protein which inhibits the growth of incompatible pollen tubes through cytotoxicity and the induction of programmed cell death in the pollen tube. While research on the GSI system has primarily focused on the gene, there is still a lack of insight into its spatiotemporal expression profile and the factors that regulate it. Previous studies have suggested that expression in the style is influenced by pollination and is dependent on the compatibility type. We here continue on this basic hypothesis by analyzing the spatiotemporal expression of the alleles in "Conference" styles in response to different types of pollination; namely, upon full- and semi-compatible pollination and upon incompatible selfing. The results revealed that temporal dynamics of expression are influenced by the pollen's compatibility type, indicating the presence of a signaling mechanism between pollen and style to control production during pollen tube growth. In our experiment, expression continuously decreased after cross-pollination and in the unpollinated control. However, after a fully incompatible pollination, expression remained constant. Finally, semi-compatible pollination showed a initially constant expression for both alleles followed by a strong decrease in expression. Based on these results and previous findings, we propose a regulatory mechanism to explain the effect of pollination and the associated compatibility type on expression in the style. This proposed mechanism could be used as a starting point for future research.
PubMed: 38655055
DOI: 10.3389/fgene.2024.1360332 -
Plant Signaling & Behavior Dec 2023Although flavonoids play multiple roles in plant growth and development, the involvement in plant self-incompatibility (SI) have not been reported. In this research, the...
Although flavonoids play multiple roles in plant growth and development, the involvement in plant self-incompatibility (SI) have not been reported. In this research, the fertility of transgenic tobacco plants overexpressing the dihydroflavonol 4-reductase gene, , were investigated. To explore the possible physiological defects leading to the failure of embryo development in transgenic tobacco plants, functions of pistils and pollen grains were examined. Transgenic pistils pollinated with pollen grains from another tobacco plants (either transgenic or wild-type), developed full of well-developed seeds. In contrast, in self-pollinated transgenic tobacco plants, pollen-tube growth was arrested in the upper part of the style, and small abnormal seeds developed without fertilization. Although the mechanism remains unclear, our research may provide a valuable method to create SI tobacco plants for breeding.
Topics: Ginkgo biloba; Nicotiana; Pollen; Pollination; Phenotype
PubMed: 36630727
DOI: 10.1080/15592324.2022.2163339 -
PeerJ 2024One of the most vulnerable phases in the plant life cycle is sexual reproduction, which depends on effective pollen transfer, but also on the thermotolerance of pollen...
One of the most vulnerable phases in the plant life cycle is sexual reproduction, which depends on effective pollen transfer, but also on the thermotolerance of pollen grains. Pollen thermotolerance is temperature-dependent and may be reduced by increasing temperature associated with global warming. A growing body of research has focused on the effect of increased temperature on pollen thermotolerance in crops to understand the possible impact of temperature extremes on yield. Yet, little is known about the effects of temperature on pollen thermotolerance of wild plant species. To fill this gap, we selected s.l. (Fabaceae), a species common to many European habitats and conducted laboratory experiments to test its pollen thermotolerance in response to artificial increase in temperature. To test for possible local adaptation of pollen thermal tolerance, we compared data from six lowland (389-451 m a.s.l.) and six highland (841-1,030 m a.s.l.) populations. We observed pollen germination at 15 °C, 25 °C, 30 °C, and 40 °C. While lowland plants maintained a stable germination percentage across a broad temperature range (15-30 °C) and exhibited reduced germination only at extremely high temperatures (40 °C), highland plants experienced reduced germination even at 30 °C-temperatures commonly exceeded in lowlands during warm summers. This suggests that lowland populations of may be locally adapted to higher temperature for pollen germination. On the other hand, pollen tube length decreased with increasing temperature in a similar way in lowland and highland plants. The overall average pollen germination percentage significantly differed between lowland and highland populations, with highland populations displaying higher germination percentage. On the other hand, the average pollen tube length was slightly smaller in highland populations. In conclusion, we found that pollen thermotolerance of is reduced at high temperature and that the germination of pollen from plant populations growing at higher elevations is more sensitive to increased temperature, which suggests possible local adaptation of pollen thermotolerance.
Topics: Pollen; Thermotolerance; Lotus; Adaptation, Physiological; Global Warming; Germination; Altitude; Climate Change; Temperature; Acclimatization
PubMed: 38708360
DOI: 10.7717/peerj.17148 -
The Journal of Cell Biology Nov 2023In a recent study, Wang et al. (https://doi.org/10.1083/jcb.202206074) demonstrate that subtle differences between two ADF/cofilin isoforms allow fine spatial regulation...
In a recent study, Wang et al. (https://doi.org/10.1083/jcb.202206074) demonstrate that subtle differences between two ADF/cofilin isoforms allow fine spatial regulation of the actin cytoskeleton in pollen tubes. This article illustrates how two similar proteins have progressively evolved to adapt their localization and activity according to the cellular environment.
Topics: Actin Cytoskeleton; Actin Depolymerizing Factors; Actins; Microfilament Proteins; Pollen Tube; Protein Isoforms; Proton-Motive Force
PubMed: 37824163
DOI: 10.1083/jcb.202310012 -
Scientific Reports Mar 2024The involvement of Ca ions in angiosperms sexual processes is well established, while in gymnosperms, such knowledge remains limited and is still a topic of discussion....
The involvement of Ca ions in angiosperms sexual processes is well established, while in gymnosperms, such knowledge remains limited and is still a topic of discussion. In this study, we focused on Larix decidua, using Alizarin-red S staining and the pyroantimonate method to examine the tissue and subcellular distribution of free and loosely bound Ca ions at different stages of the male gametophyte's development and its interaction with the ovule. Our findings show that in larch, both the germination of pollen grains and the growth of pollen tubes occur in an environment rich in Ca. These ions play a crucial role in the adhesion of the pollen grain to the stigmatic tip and its subsequent movement to the micropylar canal. There is a significant presence of free and loosely bound Ca ions in both the fluid of the micropylar canal and the extracellular matrix of the nucellus. As the pollen tube extends through the nucellus, we observed a notable accumulation of Ca ions just above the entry to the mature archegonium, a region likely crucial for the male gametophyte's directional growth. Meanwhile, the localized presence of free and loosely bound Ca ions within the egg cell cytoplasm may inhibit the pollen tubes growth and rupture, playing an important role in fertilization.
Topics: Pollination; Larix; Pollen Tube; Pollen; Ions; Germination
PubMed: 38454044
DOI: 10.1038/s41598-024-54903-2 -
PloS One 2024The Quince (Cydonia oblonga Mill.), typically known for its self-compatibility, surprisingly presents a degree of self-incompatibility. This research focused on...
The Quince (Cydonia oblonga Mill.), typically known for its self-compatibility, surprisingly presents a degree of self-incompatibility. This research focused on exploring the diversity within the self-incompatibility gene locus (S) in various C. oblonga genotypes. Through meticulous DNA sequencing, the study sought to unearth potential novel S alleles. In the process of genotyping the S gene across multiple quince genotypes, not only were the previously documented S1 and S2 alleles identified, but this investigation also uncovered two previously unrecognized alleles, termed S4 and S5. These alleles, particularly S4, emerged as the most prevalent among the tested genotypes. To corroborate the findings derived from DNA sequencing, the study employed pollen tube growth germination assays. These assays elucidated a higher pollen germination rate in the Ardabil2 genotype in contrast to Behta. Additionally, the study involved assessing pollen tube growth in both Ardabil2 and Behta through cross-pollination techniques, meticulously tracking the development of pollen tubes at various stages. Remarkably, the outcomes demonstrated that the Behta genotype possesses self-incompatibility, whereas the Ardabil2 genotype showcases a notable degree of self-compatibility. This groundbreaking discovery of new S alleles in quince not only affirms the species' self-compatibility but also sheds light on the complexities of allelic diversity and its impact on self-incompatibility. Such insights are invaluable for enhancing the yield of quince orchards through strategic breeding programs.
Topics: Rosaceae; Alleles; Plant Breeding; Fruit; Pollen Tube
PubMed: 38330081
DOI: 10.1371/journal.pone.0297595 -
Plant Communications Jun 2024Transient heatwaves occur more frequently with climate warming, yet their impacts on crop yield are severely underestimated and even overlooked. Heatwaves spanning mere... (Review)
Review
Transient heatwaves occur more frequently with climate warming, yet their impacts on crop yield are severely underestimated and even overlooked. Heatwaves spanning mere days or even hours during sensitive stages (e.g., microgametogenesis and flowering) can significantly reduce crop yield by disrupting plant reproduction. Recently, advancements in multi-omics and GWAS analysis have shed light on specific organs (e.g., pollen, lodicule, and style), key metabolic pathways (sugar and reactive oxygen species (ROS) metabolisms, Ca homeostasis), and essential genes for transient heatwaves responses during the most sensitive stages in many crops. Based on this, this review places particular emphasis on the crop's heat-sensitive stages, using pollen development, floret opening, pollination, and fertilization as the central narrative thread. Complementing by key parts such as lodicule and tapetum, the multifaceted effects of transient heatwaves and their molecular basis are systematically demonstrated. A number of heat-tolerant genes for these processes have been identified in major crops such as maize and rice. The mechanisms and key heat-tolerant genes shared over different stages potentially facilitate the improvement of heat-tolerant crops more precisely.
PubMed: 38915200
DOI: 10.1016/j.xplc.2024.101009 -
BMC Plant Biology Jan 2024As a vital type of noncoding RNAs, circular RNAs (circRNAs) play important roles in plant growth and development and stress response. However, little is known about the...
BACKGROUND
As a vital type of noncoding RNAs, circular RNAs (circRNAs) play important roles in plant growth and development and stress response. However, little is known about the biological roles of circRNAs in regulating the stability of male fertility restoration for cytoplasmic male sterility (CMS) conditioned by Gossypium harknessii cytoplasm (CMS-D2) cotton under high-temperature (HT) stress.
RESULTS
In this study, RNA-sequencing and bioinformatics analysis were performed on pollen grains of isonuclear alloplasmic near-isogenic restorer lines NH [N(Rfrf)] and SH [S(Rfrf)] with obvious differences in fertility stability under HT stress at two environments. A total of 967 circRNAs were identified, with 250 differentially expressed under HT stress. We confirmed the back-splicing sites of eight selected circRNAs using divergent primers and Sanger sequencing. Tissue-specific expression patterns of five differentially expressed circRNAs (DECs) were also verified by RT-PCR and qRT-PCR. Functional enrichment and metabolic pathway analysis revealed that the parental genes of DECs were significantly enriched in fertility-related biological processes such as pollen tube guidance and cell wall organization, as well as the Pentose and glucuronate interconversions, Steroid biosynthesis, and N-Glycan biosynthesis pathways. Moreover, we also constructed a putative circRNA-mediated competing endogenous RNA (ceRNA) network consisting of 21 DECs, eight predicted circRNA-binding miRNAs, and their corresponding 22 mRNA targets, especially the two ceRNA modules circRNA346-miR159a-MYB33 and circRNA484-miR319e-MYB33, which might play important biological roles in regulating pollen fertility stability of cotton CMS-D2 restorer line under HT stress.
CONCLUSIONS
Through systematic analysis of the abundance, characteristics and expression patterns of circRNAs, as well as the potential functions of their parent genes, our findings suggested that circRNAs and their mediated ceRNA networks acted vital biological roles in cotton pollen development, and might be also essential regulators for fertility stability of CMS-D2 restorer line under heat stress. This study will open a new door for further unlocking complex regulatory mechanisms underpinning the fertility restoration stability for CMS-D2 in cotton.
Topics: Gossypium; RNA, Circular; Cytoplasm; Fertility; RNA; Heat-Shock Response
PubMed: 38183049
DOI: 10.1186/s12870-023-04706-w