Biology subjects

Higashiyama, T.

Publications and source records attributed to Higashiyama, T..

At least 19 recordsLinked to original sources

bioRxiv2026

Calcium Dynamics During Pollen Tube Reception in Arabidopsis Ovules

In flowering plants, pollen tubes communicate with ovular cells to achieve precise one-to-one pollen tube reception. The final step of this communication between the pollen tube and synergid cells has been extensively investigated and visualized by calcium imaging. Synergid cells exhibit characteristic cytoplasmic calcium concentration oscillations, which are thought to play a critical role in pollen tube reception. However, their significance and relationship with calcium dynamics in the entire ovule remain unclear. Here, we show, using the calcium sensor GCaMP6s, that proteins involved in asparagine-linked glycosylation (N-linked glycosylation) are required for normal calcium oscillations in synergid cells but are not essential for pollen tube reception. Using a semi-in vivo assay in Arabidopsis thaliana, we found that the amplitude of these oscillations prior to rapid pollen tube growth across the filiform apparatus was reduced in mutants lacking the oligosaccharyltransferase (OST) 3/6 subunit or alpha1,2-glucosyltransferase (ALG) 10, both of which are involved in N-linked glycosylation. Notably, these mutants did not exhibit reduced fertility attributable to defects in the female gametophyte but instead showed a polytubey phenotype due to a sporophytic defect. These findings suggest that N-linked glycans mediate communication between synergid cells and the pollen tube and indicate that the typical pattern of calcium oscillations in synergid cells is not essential for triggering pollen tube rupture. Furthermore, we show that sporophytic tissues of the ovule exhibit calcium waves that propagate toward the funiculus in correlation with pollen tube contact and rupture, implying that ovular tissues can potentially transmit these signals distantly beyond the ovule. Together, these findings reveal previously unrecognized intercellular calcium signaling and its significance in pollen tube reception by the ovule.

plant biology↗

bioRxiv2026

A live-imaging system for Arabidopsis leaf primordia at early stages

Live imaging is one of the most powerful methods to reveal the morphogenesis of plant organs. However, the highly three-dimensional structure of plant organs always poses technical challenges. For example, the basal region of leaf primordia is rarely observed because of the shape of leaf primordia and the sudden shift in geometry at the point where the leaf primordium connects to the hypocotyl. In this work, we developed a new live-imaging system that is suitable for observing the developmental process of the basal region of Arabidopsis leaf primordia at early stages. Using this system, we achieved continuous observation of the basal region of early Arabidopsis leaf primordia for more than 50 hours.

plant biology↗

bioRxiv2026

Extracellular calcium modulates pollen tube growth and guidance in Arabidopsis thaliana

In angiosperms, pollen tubes deliver sperm cells to the ovule and communicate with the external environment as they elongate through the pistils. Although pollination alters Ca2+ conditions within the pistil, the effects of extracellular Ca2+ fluctuations on pollen tube growth and guidance remain largely unknown. In this study, we visualized intracellular Ca2+ dynamics using a semi-in vivo assay with the Ca2+-sensitive fluorescent protein GCaMP6s to investigate how pollen tubes respond to changes in extracellular Ca2+ levels. We found that the Ca2+ levels in the apical region of the pollen tubes reflected the extracellular Ca2+ concentrations. The pollen tube growth rate increased depending on the Ca2+ concentration in the growth medium. However, excessive Ca2+ affected the polar growth of pollen tubes. At elevated Ca2+ concentrations of 10 mM, the pollen tube exhibited coiling behavior and failed to maintain directional growth toward the ovule. Moreover, we provided the first evidence that Ca2+ oscillations are not restricted to the apical region but propagate as a wave, reaching 30-50 m from the apex toward the basal regions. As the pollen tube approached the ovule, it coincided with a substantial elevation in Ca2+ levels, which appeared to drive the accelerated nuclear migration toward the tube apex. Our findings demonstrate that the extracellular Ca2+ environment directly regulates intracellular Ca2+ levels in pollen tubes, thereby influencing their growth and guidance.

plant biology↗

bioRxiv2025

Intermediate Evolutionary State of Motile Sperm and Pollen Tubes in the Extant Gymnosperm Cycas revoluta

The transformation of male reproductive cells is a significant event in the evolution of land plant fertilization systems from zooidogamy to siphonogamy. Basal plants such as bryophytes and pteridophytes have motile sperm, whereas most seed plants have non-motile sperm, delivered by a pollen tube. Despite being seed plants, gymnosperm cycads and ginkgo uniquely form highly multi-flagellated and large motile sperm within pollen tubes. However, the evolutionary state of these male reproductive cells remains unknown. We clarified the gene expression profiles of Cycas revoluta pollen tubes and motile sperm that swam toward female reproductive cells. Male cycad cells had fewer genes associated with transcription, translation, and related processes, which is consistent across land plants. Similar to other male gametes, a sperm-specific histone variant may contribute to transcriptional regulation via chromatin condensation. Plasma membrane-localized proteins probably involving male-female interactions revealed that cycad sperm express both factors found in motile plant sperm and seed plant sperm cells, suggesting a transitional state from motile to non-motile male gametes. In contrast, cycad pollen tubes lacked plasma membrane-localized receptor genes previously reported in angiosperms and cell wall-associated factors involved in pollen tube tip growth. These results support the hypothesis that the function of the cycad pollen tube is confined to the haustoria as previously reported. These results indicate a molecular intermediate state of the cycad fertilization mechanism with motile sperm and pollen tubes, providing important insights into the evolution of land plant fertilization. Significant StatementCycads and ginkgo, which possess primitive motile sperm and derived pollen tubes, are important for understanding the evolution of land plant fertilization from zooidogamy to siphonogamy. We explored gene expression in living, capacitated motile sperm and pollen tubes of Cycas revoluta in a tissue-specific transcriptome analysis. Similar to other land plants, the transcriptional repression mechanism has been suggested in these male cells. Plasma membrane-localized genes revealed the characteristics of motile and non-motile sperm, while molecular evidence of pollen tube guidance and tip growth, as seen in angiosperms, was lacking in cycads. A molecular intermediate state of the cycad fertilization mechanism was clarified, providing important insights into the evolutionary process of land plant fertilization.

plant biology↗

bioRxiv2024

Brassinosteroids and Flavonols Confer Temperature Stress Tolerance to Pollen Tube Germination and Growth

Successful reproduction is a prerequisite for the maintenance of species in the era of climate change. In agriculture, temperature has a significant impact on pollen tube elongation and attraction, and consequently, on the efficiency of fruiting and crop yields. Brassinosteroids (BRs) are plant steroid hormones involved in pollen tube germination, elongation, and capacitation. To elucidate the effect of BR signaling in pistils during the reproductive process, transcriptome analysis of BR receptor (BRI1) mutant pistils was performed, which indicated that genes involved in flavonol biosynthesis were downregulated in bri1 pistils. Flavonols are essential for pollen tube growth in some plants and facilitate pollen tube elongation under high-temperature conditions. To investigate the effects of BR and flavonols on pollen tubes under temperature stress, in vitro assays were performed using both the compounds. Brassinolide (BL), which is the most active BR, promoted pollen tube germination at high, low, and optimal temperatures. Germination was further enhanced by the flavonol, quercetin, in the presence of BL especially at low temperatures. in vivo analysis supported the observation that when BL and quercetin were supplied concurrently, the pollen tube guidance rate was rescued at low temperatures. Quercetin enhanced pollen tube elongation under all the conditions tested at an optimal concentration of 15 M. BL elevated reactive oxygen species (ROS) under all temperature conditions, whereas quercetin regulated ROS synergistically with BR. Thus, BRs and flavonols supplied by pistils are suggested to function in pollen tube germination and elongation through the maintenance of ROS homeostasis.

plant biology↗

bioRxiv2024

Vesicle-Mediated Regulation of Pollen tube Growth in Torenia fournieri

In flowering plants, the growth of pollen tubes carrying sperm cells to the female gametophyte is necessary for double fertilization and seed development. The rate of growth of the pollen tube tip determines the fertility of many artificially cultivated plants and depends on the vesicle-mediated transport of cell membrane and cell wall components. However, the investigation of vesicle transport is hampered by the lack of transgenic methods for economically important plants. Here, we developed a method to transiently inhibit vesicle activity using brefeldin A (BFA) and antisense oligodeoxynucleotides (AS-ODNs) targeting key genes in the wishbone flower (Torenia fournieri), which has been used in studies of sexual reproduction in plants. BFA disrupted vesicle gradient homeostasis, thereby altering cell wall deposition and pollen tube morphology. The AS-ODN targeting Torenia fournieri ANXUR (TfANX), which is implicated in maintaining pollen tube growth and is used as a marker to assess inhibition by AS-ODNs, penetrated cell membranes and inhibited the expression of target genes. The treatment of pollen tubes with AS-ODN against TfRABA4D, which is specifically expressed in pollen and involved in regulating vesicle targeting, resulted in pollen tubes with a bulging phenotype and disrupted pectin deposition, effects similar to those of BFA. In summary, vesicle-mediated mechanisms regulate the patterning of the pollen tube cell wall in T. fournieri and our findings could facilitate the genetic manipulation of horticultural crops.

plant biology↗

bioRxiv2024

Brassinosteroids function as the plant male and female reproductive hormone coordinating gene expression.

Brassinosteroids (BRs) are steroid hormones identified in plants. Besides promoting cell elongation and division, BRs facilitate the development of both male and female reproductive tissues. In animals, reproductive steroid hormones play an essential role in reproductive tissue development by regulating gene expression. Here, we focused on the function of BRs during fertilization. We measured the content of biologically active BRs, brassinolide (BL) and castasterone (CS), in the reproductive tissues of Arabidopsis thaliana. Both BL and CS accumulated abundantly in pollen grains and in larger amounts in pistils than in leaves. To evaluate BL function during fertilization, we used an in vitro guidance assay with exogenously applied BL. Although pollen tubes need to be elongated through the pistils for efficient capacitation, BL treatment promoted pollen tube capacitation and improved attraction to ovules in vitro. Transcriptome analysis demonstrated that BL treatment induced the expression of half of the genes expressed in pollen tubes that elongated through the pistils. These results indicated that BL supplied from pistils is a key factor for pollen tube capacitation. However, using the bri1 mutant for the guidance assay resulted in reduced pollen tube capacitation, suggesting that BRI1-signaling in pistils is also important. Furthermore, BRs act on ovules. Exogenous BL application to ovules maintained guidance capacity by promoting the expression of small secreted proteins involved in pollen tube attraction and gamete fusion. Overall, BRs play a significant role as male and female reproductive hormones throughout the plant fertilization process.

plant biology↗

bioRxiv2024

HD-ZIP IV genes are essential for embryo initial cell polarization in the radial axis initiation in Arabidopsis

Plants develop along apical-basal and radial axes. In Arabidopsis thaliana, the radial axis becomes evident when the cells of the eight-cell proembryo divide periclinally, forming inner and outer cell layers. Although changes in cell polarity or morphology likely precede this oriented cell division, the initial events and the factors regulating radial axis formation remain elusive. Here, we report that three transcription factors belonging to class IV homeodomain-leucine zipper (HD-ZIP IV) family redundantly regulate radial pattern formation: HOMEODOMAIN GLABROUS11 (HDG11), HDG12, and PROTODERMAL FACTOR2 (PDF2). The hdg11 hdg12 pdf2 triple mutant failed to undergo periclinal division at the eight-cell stage and cell differentiation along the radial axis. Live-cell imaging revealed that this failure in radial axis formation can be traced back to the behavior of the embryo initial cell (apical cell), which is generated by zygote division. In the wild type, the apical cell grows longitudinally and then radially and its nucleus remains at the bottom of the cell, where the vertical cell plate emerges. By contrast, the mutant apical cell elongates longitudinally and its nucleus releases from its basal position, resulting in a transverse division. Computer simulations based on the live-cell imaging data confirmed the importance of the geometric rule (the minimal plane principle and nucleus-passing principle) in determining the cell division plane. We propose that HDG11, HDG12, and PDF2 promote apical cell polarization, i.e., radial cell growth and basal nuclear retention, as the initial event of radial axis formation during embryogenesis.

plant biology↗

bioRxiv2024

Simple prerequisite of presequence for mitochondrial protein import in the unicellular red alga Cyanidioschyzon merolae

Mitochondrial biogenesis relies on hundreds of proteins which are derived from genes encoded in the nucleus. According to characteristic properties of N-terminal targeting peptides (TP) and multi-step authentication by the protein translocase called the TOM complex, nascent polypeptides satisfying the requirements are imported into mitochondria. However, it has not been investigated whether the eukaryotic cell with a simple proteome and a single mitochondrion in a cell has a similar or simpler complexity of presequence requirements for mitochondrial protein import as other eukaryotes with multiple mitochondria. Based on the amino acid compositions of putative mitochondrial TP sequences in the unicellular red alga Cyanidioschyzon merolae, we designed the synthetic TP (synTP) and confirmed that synTP-fused mVenus were translocated into the mitochondrion in vivo. Through a series of experimental evaluations using modified synTPs, we showed that functional TP must have some basic residues, at least one, and compose the specific amino acid composition, but the physicochemical properties of net charge, hydrophobicity and hydrophobic moment are not strictly determined in C. merolae. Combined with the simple composition of the TOM complex in C. merolae, our results suggest that a regional positive charge in TP would be recognized and verified solely by TOM22 as a single-step authentication for mitochondrial protein import in C. merolae. The simple authentication mechanism indicates that the C. merolae cell, with its simple cell structure and genome, would not need to increase the cryptographic complexity of the lock-and-key for mitochondrial protein import.

cell biology↗

bioRxiv2024

Cluster effect through the oligomerisation of bioactive disaccharide AMOR on pollen tube capacitation in Torenia fournieri

ABSTRACRTArabinogalactan proteins (AGPs) are plant-specific glycoproteins involved in cellular mechanics and signal transduction. There has been major progress in understanding the structure, synthesis, and molecular functions of their carbohydrate chains; however, the mechanisms by which they function as signalling molecules remain unclear. Here, methyl-glucuronosyl arabinogalactan (AMOR; Me-GlcA-{beta}(1,6)-Gal), a disaccharide structure at the end of AGP carbohydrate chains, was oligomerised via chemical synthesis. The biological activity of AMOR oligomers was enhanced via clustering of the carbohydrate chains. Furthermore, AMOR oligomers yielded a pollen tube morphology (i.e., callose plug formation) similar to that when cultured with native AMOR, suggesting it may be functionally similar to native AMOR.

biochemistry↗

bioRxiv2023

Microfluidic device for simple diagnosis of plant growth condition by detecting miRNAs from filtered plant extracts

Plants are exposed to a variety of environmental stress and starvation of inorganic phosphorus can be a major constraint in crop production. In plants, in response to phosphate deficiency in soil, miR399, a type of microRNA (miRNA), is upregulated. By detecting miR399, the early diagnosis of phosphorus deficiency stress in plants can be accomplished. However, general miRNA detection methods require complicated experimental manipulations. Therefore, simple and rapid miRNA detection methods are required for early plant nutritional diagnosis. For the simple detection of miR399, microfluidic technology is suitable for point-of-care applications because of its ability to detect target molecules in small amounts in a short time and with simple manipulation. In this study, we developed a microfluidic device to detect miRNAs from filtered plant extracts for the easy diagnosis of plant growth conditions. To fabricate the microfluidic device, verification of the amine-terminated glass as the basis of the device and the DNA probe immobilization method on the glass was conducted. In this device, the target miRNAs were detected by fluorescence of sandwich hybridization in a microfluidic channel. For plant stress diagnostics using a microfluidic device, we developed a protocol for miRNA detection by validating the sample preparation buffer, filtering, and signal amplification. Using this system, endogenous sly-miR399 in tomatoes, which is expressed in response to phosphorus deficiency, was detected before the appearance of stress symptoms. This early diagnosis system of plant growth conditions has a potential to improve food production and sustainability through cultivation management.

plant biology↗

bioRxiv2023

Transcriptomic landscape of seedstick in Arabidopsis thaliana funiculus after fertilisation

In Angiosperms, the continuation of plant species is intricately dependent on the funiculus multifaceted role in nutrient transport, mechanical support, and dehiscence of seeds. SEEDSTICK (STK) is a MADS-box transcription factor involved in seed size and dehiscence, and one of the few genes identified as affecting funiculus growth. Given the importance of the funiculus to a correct seed development, allied with previous phenotypic observations of stk mutants, we performed a transcriptomic analysis of stk funiculi, using RNA-sequencing, to infer on the deregulated networks of genes. The generated dataset of differentially expressed genes was enriched with cell wall biogenesis, cell cycle, sugar metabolism and transport terms, all in accordance with stk phenotype. We selected eight differentially expressed genes involved with abscission, seed development or novel functions in stk funiculus, such as hormones/secondary metabolites transport, for transcriptome validation using qPCR and/or promoter reporter lines. Overall, the analysis performed in this study allowed delving into the STK-network established in Arabidopsis funiculus, fulfilling a literature gap. Simultaneously, our findings reinforced the reliability of the transcriptome, and identified processes and new candidate genes that will enable a better understanding on the role of this sporophytic structure and how seed development may be affected by it.

plant biology↗

bioRxiv2023

The Chaperone NASP Contributes to De Novo Deposition of the Centromeric Histone Variant CENH3 in Arabidopsis Early Embryogenesis

The centromere is an essential chromosome region where the kinetochore is formed to control equal chromosome distribution during cell division. The centromere-specific histone H3 variant CENH3 (also called CENP-A) is a prerequisite for the kinetochore formation. Since CENH3 evolves rapidly, associated factors, including histone chaperones mediating the deposition of CENH3 on the centromere, are thought to act through species-specific amino-acid sequences. The functions and interaction networks of CENH3 and histone chaperons have been well-characterized in animals and yeasts. However, molecular mechanisms involved in recognition and deposition of CENH3 are still unclear in plants. Here, we used a swapping strategy between domains of CENH3 of Arabidopsis thaliana and the liverwort Marchantia polymorpha to identify specific regions of CENH3 involved in targeting the centromeres and interacting with the general histone H3 chaperone, NASP (nuclear autoantigenic sperm protein). CENH3s LoopN-1 region was necessary and sufficient for the centromere targeting in cooperation with the 2 region and was involved in interaction with NASP in cooperation with N, suggesting a species-specific CENH3 recognition. In addition, by generating an Arabidopsis nasp knockout mutant in the background of a fully fertile GFP-CENH3/cenh3-1 line, we found that NASP was implicated for de novo CENH3 deposition after fertilization and thus for early embryo development. Our results imply that the NASP mediates the supply of CENH3 in the context of the rapidly evolving centromere identity in land plants.

plant biology↗

bioRxiv2023

Seed size control via phloem end by callose deposition/degradation of β-1,3-glucanase

Seed formation is crucial for lives of plants as well as humans; however, the mechanisms governing seed size require further investigation. Here, we present a new mechanism to modify the seed size by the newly identified phloem end that support nutrient transport, at the chalazal end of the ovule, however, blocked by callose deposition. Callose is removed after central cell fertilization (open state), allowing nutrients to be transported to the seed. However, if fertilization fails, callose deposition persists (closed state), preventing the phloem end from transporting nutrients. {beta}-1,3-glucanase genes, including putative plasmodesmata-associated proteins (AtBG_ppap), were identified as regulators of callose removal. The Atbg_ppap mutant had the phloem end in the closed state and produced smaller seeds due to incomplete callose degradation. In contrast, the AtBG_ppap overexpression line produced larger seeds than the wild type due to continuous callose degradation, indicating that the phloem end regulates substance flow via callose deposition/degradation.

plant biology↗

bioRxiv2023

Swimming ability and flagellar motility of sperm packets of the volvocine green alga Pleodorina starrii

Eukaryotic flagella collectively form metachronal waves that facilitate the ability to cause flow or swim. Among such flagellated and planktonic swimmers, large volvocine genera such as Eudorina, Pleodorina and Volvox form bundles of small male gametes (sperm) called "sperm packets" for sexual reproduction. Although these sperm packets reportedly have flagella and the ability to swim, previous studies on volvocine motility have focused on asexual forms and the swimming characteristics of sperm packets remain unknown. However, it is important to quantify the motility of sperm packets and sperm in order to gain insights into the significance of motility in the sexual reproduction of planktonic algae. In this study, we quantitatively described the behavior of three flagellated forms of a male strain of Pleodorina starrii--asexual colonies, sperm packets, and single dissociated sperm--with emphasis on comparison of the two multicellular forms. Despite being smaller, sperm packets swam approximately 1.4 times faster than the asexual colonies of the same male strain. Body length was approximately 0.5 times smaller in the sperm packets than in asexual colonies. The flagella from sperm packets and asexual colonies showed asymmetric waveforms, whereas those from dissociated single sperm showed symmetric waveforms, suggesting the presence of a switching mechanism between sperm packets and dissociated sperm. Flagella from sperm packets were approximately 0.5 times shorter and had a beat period approximately twice as long as those from asexual colonies. The flagella of sperm packets were densely distributed over the anterior part of the body, whereas the flagella of asexual colonies were sparse and evenly distributed. The distribution of flagella, but not the number of flagella, appear to illustrate a significant difference in the speeds of sperm packets and asexual colonies. Our findings reveal novel aspects of the regulation of eukaryotic flagella and shed light on the role of flagellar motility in sexual reproduction of planktonic algae.

biophysics↗

bioRxiv2023

HISTONE DEACETYLASE 19 REGULATES SHOOT MERISTEMLESS EXPRESSION IN THE CARPEL MARGIN MERISTEM CONTRIBUTING TO OVULE NUMBER DETERMINATION AND TRANSMITTING TRACT DIFFERENTIATION

The gynoecium is critical for the reproduction of flowering species as it contains the ovules and the tissues required for pollen germination and guidance. These tissues are collectively known as the reproductive tract (ReT) and comprise stigma, style and transmitting tract (TT). The ovules and the ReT originate from a meristem within the pistil named carpel margin meristem (CMM). SHOOT MERISTEMLESS (STM) is a key transcription factor required for meristem formation and maintenance. In all above-ground meristems, including the CMM, STM has to be locally downregulated to allow proper organ differentiation. However, how this downregulation is achieved in the CMM is unknown. In this work, we have studied HISTONE DEACETYLASE 19 (HDA19) role in ovule and ReT differentiation, based on the observation that hda19-3 mutant displays reduced ovule number and fails to properly differentiate the TT. Fluorescence activated cell sorting (FACS) coupled with RNA-seq revealed that in the CMM of hda19-3 mutant, genes promoting organ development are downregulated while meristematic markers, including STM, are upregulated. We found that HDA19 is fundamental to downregulate STM in the CMM, allowing ovule formation and TT differentiation. STM is ectopically expressed in hda19-3 at intermediate stages of pistil development, and its downregulation by RNA interference alleviated hda19-3 phenotypic defects. Furthermore, chromatin immunoprecipitation assays indicated that STM is a direct target of HDA19 during pistil development and that SEEDSTICK (STK) is required for the histone acetylation-mediated regulation of STM. Our results have led to the identification of the factors required for STM silencing in the gynoecium allowing organogenesis and tissue differentiation from the CMM.

plant biology↗

bioRxiv2023

Deep imaging revealed dynamics and signaling in one-to-one pollen tube guidance

In angiosperms, pollen tube guidance allows sperm cell delivery to the female gametes within the ovule, which are deeply embedded in a flower. However, when an ovary includes multiple pollen tubes and ovules, it is unclear how each ovule is fertilized one-to-one by a pollen tube. Here, our two-photon imaging revealed the pollen tube dynamics in living ovaries. The number of pollen tubes and ovule maturity affected the target selection among multiple ovules. On the inner surface of the septum epidermis within the transmitting tract, pollen tube behavior and emergence were regulated by the ovular sporophytic signals. In funicular guidance, the second pollen tube was strictly repelled by the FERONIA and LORELEI-dependent gametophytic signal, especially more than 45 minutes after the first pollen tube had passed. Such highly spatiotemporal regulation mechanisms in the one-to-one pollen tube guidance may allow angiosperms to produce more offspring in nature.

plant biology↗

bioRxiv2022

F-actin regulates polarized secretion of pollen tube attractants in Arabidopsis synergid cell.

Pollen tube attraction is a key event of sexual reproduction in flowering plants. In the ovule, two synergid cells neighboring the egg cell control pollen tube arrival via the active secretion of attractant peptides such as AtLURE1 and XIUQIU from the filiform apparatus facing toward the micropyle. Distinctive cell polarity together with longitudinal F-actin and microtubules are hallmarks of the synergid cell in various species, though functions of these cellular structures are still unclear. In this study we used genetic and pharmacological approaches to elucidate the roles of cytoskeletal components in filiform apparatus formation and pollen tube guidance in Arabidopsis thaliana. Inhibition of microtubule formation reduced invaginations of the plasma membrane but did not abolish micropylar AtLURE1.2 accumulation. In contrast, the expression of a dominant-negative form of ACTIN8 induced disorganization of the filiform apparatus and loss of polar AtLURE1.2 distribution toward the filiform apparatus. Interestingly, after pollen tube reception, F-actin became unclear for a few hours in the persistent synergid cell, which may be involved in pausing and resuming pollen tube attraction during early polytubey block. Our data propose the central role of F-actin in the maintenance of cell polarity and function of male-female communication in the synergid cell.

plant biology↗