Pollen Tube Tip Research Articles

Combined Cytological and Transcriptomic Analysis Reveals a Nitric Oxide Signaling Pathway Involved in Cold-Inhibited Camellia sinensis Pollen Tube Growth.

Nitric oxide (NO) as a signaling molecule plays crucial roles in many abiotic stresses in plant development processes, including pollen tube growth. Here, the signaling networks dominated by NO during cold stress that inhibited Camellia sinensis pollen tube growth are investigated in vitro. Cytological analysis show that cold-induced NO is involved in the inhibition of pollen tube growth along with disruption of the cytoplasmic Ca2+ gradient, increase in ROS content, acidification of cytoplasmic pH and abnormalities in organelle ultrastructure and cell wall component distribution in the pollen tube tip. Furthermore, differentially expressed genes (DEGs)-related to signaling pathway, such as NO synthesis, cGMP, Ca2+, ROS, pH, actin, cell wall, and MAPK cascade signal pathways, are identified and quantified using transcriptomic analyses and qRT-PCR, which indicate a potential molecular mechanism for the above cytological results. Taken together, these findings suggest that a complex signaling network dominated by NO, including Ca2+, ROS, pH, RACs signaling and the crosstalk among them, is stimulated in the C. sinensis pollen tube in response to cold stress, which further causes secondary and tertiary alterations, such as ultrastructural abnormalities in organelles and cell wall construction, ultimately resulting in perturbed pollen tube extension.

The long pollen tube journey and in vitro pollen germination of Phalaenopsis orchids.

Key message Pollen biology in P. aphrodite.Orchids have a distinct reproductive program. Pollination triggers ovule development and differentiation within flowers, and fertilization occurs days to months after pollination. It is unclear how pollen tubes travel through the developing ovaries during ovule development and when pollen tubes arrive at the mature embryo sac to achieve fertilization. Here, we report a robust staining protocol to image and record the timing of pollen germination, progressive growth of pollen tubes in ovaries, and arrival of pollen tubes at embryo sacs in Phalaenopsis aphrodite. The pollen germinated and pollen tubes entered the ovary 3 days after pollination. Pollen tubes continued to grow and filled the entire cavity of the ovary as the ovary elongated and ovules developed. Pollen tubes were found to enter the matured embryo sacs at approximately 60–65 days after pollination in an acropetal manner. Moreover, these temporal changes in developmental events such as growth of pollen tubes and fertilization were associated with expression of molecular markers. In addition, we developed an in vitro pollen germination protocol, which is valuable to enable studies on pollen tube guidance and tip growth regulation in Phalaenopsis orchids and possibly in other orchid species.

Tip-localized receptors control pollen tube growth and LURE sensing in Arabidopsis.

Directional control of tip-growing cells is essential for proper tissue organization and cell-to-cell communication in animals and plants. In the sexual reproduction of flowering plants, the tip growth of the male gametophyte, the pollen tube, is precisely guided by female cues to achieve fertilization. Several female-secreted peptides have recently been identified as species-specific attractants that directly control the direction of pollen tube growth. However, the method by which pollen tubes precisely and promptly respond to the guidance signal from their own species is unknown. Here we show that tip-localized pollen-specific receptor-like kinase 6 (PRK6) with an extracellular leucine-rich repeat domain is an essential receptor for sensing of the LURE1 attractant peptide in Arabidopsis thaliana under semi-in-vivo conditions, and is important for ovule targeting in the pistil. PRK6 interacted with pollen-expressed ROPGEFs (Rho of plant guanine nucleotide-exchange factors), which are important for pollen tube growth through activation of the signalling switch Rho GTPase ROP1 (refs 7, 8). PRK6 conferred responsiveness to AtLURE1 in pollen tubes of the related species Capsella rubella. Furthermore, our genetic and physiological data suggest that PRK6 signalling through ROPGEFs and sensing of AtLURE1 are achieved in cooperation with the other PRK family receptors, PRK1, PRK3 and PRK8. Notably, the tip-focused PRK6 accumulated asymmetrically towards an external AtLURE1 source before reorientation of pollen tube tip growth. These results demonstrate that PRK6 acts as a key membrane receptor for external AtLURE1 attractants, and recruits the core tip-growth machinery, including ROP signalling proteins. This work provides insights into the orchestration of efficient pollen tube growth and species-specific pollen tube attraction by multiple receptors during male-female communication.

Actin3 promoter reveals undulating F-actin bundles at shanks and dynamic F-actin meshworks at tips of tip-growing pollen tubes

ABSTRACTThe dynamic actin cytoskeleton of pollen tubes is both the driver of the tip growth and the organizer of cell polarity. In order to understand this fast re-arranging cytoskeletal system, we need reliable constructs expressed under relevant promoters. Here we are reporting that the Lifeact reporter, expressed under the pollen-specific Actin3 promoter, visualizes very dynamic F-actin elements both in germinating pollen grains and tip-growing pollen tubes. Importantly, we have documented very active actin polymerization at the cell periphery, especially in the bulging area during pollen germination and in the apical clear zone. Expression of the Lifeact reporter under control of the pollen-specific Actin3 promoter revealed 2 new aspects: (i) long F-actin bundles in pollen tube shanks are dynamic, showing undulating movements, (ii) subapical ‘actin collars’ or ‘fringes’ are absent.

Cyclic nucleotide-gated channel 18 is an essential Ca2+ channel in pollen tube tips for pollen tube guidance to ovules in Arabidopsis

In flowering plants, pollen tubes are guided into ovules by multiple attractants from female gametophytes to release paired sperm cells for double fertilization. It has been well-established that Ca(2+) gradients in the pollen tube tips are essential for pollen tube guidance and that plasma membrane Ca(2+) channels in pollen tube tips are core components that regulate Ca(2+) gradients by mediating and regulating external Ca(2+) influx. Therefore, Ca(2+) channels are the core components for pollen tube guidance. However, there is still no genetic evidence for the identification of the putative Ca(2+) channels essential for pollen tube guidance. Here, we report that the point mutations R491Q or R578K in cyclic nucleotide-gated channel 18 (CNGC18) resulted in abnormal Ca(2+) gradients and strong pollen tube guidance defects by impairing the activation of CNGC18 in Arabidopsis. The pollen tube guidance defects of cngc18-17 (R491Q) and of the transfer DNA (T-DNA) insertion mutant cngc18-1 (+/-) were completely rescued by CNGC18. Furthermore, domain-swapping experiments showed that CNGC18's transmembrane domains are indispensable for pollen tube guidance. Additionally, we found that, among eight Ca(2+) channels (including six CNGCs and two glutamate receptor-like channels), CNGC18 was the only one essential for pollen tube guidance. Thus, CNGC18 is the long-sought essential Ca(2+) channel for pollen tube guidance in Arabidopsis.

Profilin Regulates Apical Actin Polymerization to Control Polarized Pollen Tube Growth

Pollen tube growth is an essential step during flowering plant reproduction, whose growth depends on a population of dynamic apical actin filaments. Apical actin filaments were thought to be involved in the regulation of vesicle fusion and targeting in the pollen tube. However, the molecular mechanisms that regulate the construction of apical actin structures in the pollen tube remain largely unclear. Here, we identify profilin as an important player in the regulation of actin polymerization at the apical membrane in the pollen tube. Downregulation of profilin decreased the amount of filamentous actin and induced disorganization of apical actin filaments, and reduced tip-directed vesicle transport and accumulation in the pollen tube. Direct visualization of actin dynamics revealed that the elongation of actin filaments originating at the apical membrane decreased in profilin mutant pollen tubes. Mutant profilin that is defective in binding poly-L-proline only partially rescues the actin polymerization defect in profilin mutant pollen tubes, although it fully rescues the actin turnover phenotype. We propose that profilin controls the construction of actin structures at the pollen tube tip, presumably by favoring formin-mediated actin polymerization at the apical membrane.

Class XI Myosins Move Specific Organelles in Pollen Tubes and Are Required for Normal Fertility and Pollen Tube Growth in Arabidopsis.

Pollen tube growth is an essential aspect of plant reproduction because it is the mechanism through which nonmotile sperm cells are delivered to ovules, thus allowing fertilization to occur. A pollen tube is a single cell that only grows at the tip, and this tip growth has been shown to depend on actin filaments. It is generally assumed that myosin-driven movements along these actin filaments are required to sustain the high growth rates of pollen tubes. We tested this conjecture by examining seed set, pollen fitness, and pollen tube growth for knockout mutants of five of the six myosin XI genes expressed in pollen of Arabidopsis (Arabidopsis thaliana). Single mutants had little or no reduction in overall fertility, whereas double mutants of highly similar pollen myosins had greater defects in pollen tube growth. In particular, myo11c1 myo11c2 pollen tubes grew more slowly than wild-type pollen tubes, which resulted in reduced fitness compared with the wild type and a drastic reduction in seed set. Golgi stack and peroxisome movements were also significantly reduced, and actin filaments were less organized in myo11c1 myo11c2 pollen tubes. Interestingly, the movement of yellow fluorescent protein-RabA4d-labeled vesicles and their accumulation at pollen tube tips were not affected in the myo11c1 myo11c2 double mutant, demonstrating functional specialization among myosin isoforms. We conclude that class XI myosins are required for organelle motility, actin organization, and optimal growth of pollen tubes.

Arabidopsis Qc-SNARE genes BET11 and BET12 are required for fertility and pollen tube elongation.

Key message BET11 and 12 are required for pollen tube elongation.Pollen tubes are rapidly growing specialized structures that elongate in a polar manner. They play a crucial role in the delivery of sperm cells through the stylar tissues of the flower and into the embryo sac, where the sperm cells are released to fuse with the egg cell and the central cell to give rise to the embryo and the endosperm. Polar growth at the pollen tube tip is believed to result from secretion of materials by membrane trafficking mechanisms. In this study, we report the functional characterization of Arabidopsis BET11 and BET12, two genes that may code for Qc-SNAREs (soluble N-ethylmaleimide-sensitive factor attachment protein receptors). Double mutants (bet11/bet12) in a homozygous/heterozygous background showed reduced transmission of the mutant alleles, reduced fertilization of seeds, defective embryo development, reduced pollen tube lengths and formation of secondary pollen tubes. Both BET11 and BET12 are required for fertility and development of pollen tubes in Arabidopsis. More experiments are required to dissect the mechanisms involved.Electronic supplementary materialThe online version of this article (doi:10.1186/s40529-015-0102-x) contains supplementary material, which is available to authorized users.

Natural polyamines and synthetic analogs modify the growth and the morphology of Pyrus communis pollen tubes affecting ROS levels and causing cell death

Polyamines (PAs) are small molecules necessary for pollen maturation and tube growth. Their role is often controversial, since they may act as pro-survival factors as well as factors promoting Programmed Cell Death (PCD). The aim of the present work was to evaluate the effect of exogenous PAs on the apical growth of pear (Pyrus communis) pollen tube and to understand if PAs and reactive oxygen species (ROS) are interconnected in the process of tip-growth. In the present study besides natural PAs, also aryl-substituted spermine and methoctramine (Met 6-8-6) analogs were tested. Among the natural PAs, Spm showed strongest effects on tube growth. Spm entered through the pollen tube tip, then diffused in the sub-apical region that underwent drastic morphological changes, showing enlarged tip. Analogs were mostly less efficient than natural PAs but BD23, an asymmetric synthetic PAs bearing a pyridine ring, showed similar effects. These effects were related to the ability of PAs to cause the decrease of ROS level in the apical zone, leading to cell death, counteracted by the caspase-3 inhibitor Ac-DEVD-CHO (DEVD). In conclusions, ROS are essential for pollen germination and a strict correlation between ROS regulation and PA concentration is reported. Moreover, an imbalance between ROS and PAs can be detrimental thereby driving pollen toward cell death.

Bisphenol A affects germination and tube growth in Picea meyeri pollen through modulating Ca2+ flux and disturbing actin-dependent vesicular trafficking during cell wall construction

Bisphenol A (BPA), a widespread pollutant, is reportedly harmful to humans, animals and plants. However, the effect of BPA on plant pollen tube growth, as well as the mechanism involved, remains unclear. Here, we report that BPA significantly inhibited Picea meyeri pollen germination and tube elongation in a dose-dependent manner. Transmission electron microscopy showed that BPA was detrimental to organelles such as mitochondria and Golgi apparatus. Non-invasive detection revealed that BPA inhibited extracellular Ca2+ influx and promoted intracellular Ca2+ efflux at the pollen tube tip, thereby inducing a dissipated Ca2+ gradient. Fluorescence labeling showed that BPA disorganized actin filaments (AFs), which subsequently led to abnormal vesicle trafficking. Furthermore, BPA reduced the activity of acid phosphatase, a typical exocytosis enzyme. Moreover, Fourier transform infrared (FTIR) analysis and subsequent fluorescence labeling revealed that BPA induced an abnormal deposition of cell wall components, including pectins and callose. Taken together, our results indicate that BPA, a ubiquitous environmental pollutant, disturbs Ca2+ flux in P. meyeri pollen tubes, thus disrupting AF organization, resulting in abnormal actin-dependent vesicle trafficking and further affecting the deposition of cell wall components. These findings provide new insight into the mechanism of BPA toxicity in pollen tube tip growth.

Knockin' on pollen's door: live cell imaging of early polarization events in germinating Arabidopsis pollen.

Pollen tubes are an excellent system for studying the cellular dynamics and complex signaling pathways that coordinate polarized tip growth. Although several signaling mechanisms acting in the tip-growing pollen tube have been described, our knowledge on the subcellular and molecular events during pollen germination and growth site selection at the pollen plasma membrane is rather scarce. To simultaneously track germinating pollen from up to 12 genetically different plants we developed an inexpensive and easy mounting technique, suitable for every standard microscope setup. We performed high magnification live-cell imaging during Arabidopsis pollen activation, germination, and the establishment of pollen tube tip growth by using fluorescent marker lines labeling either the pollen cytoplasm, vesicles, the actin cytoskeleton or the sperm cell nuclei and membranes. Our studies revealed distinctive vesicle and F-actin polarization during pollen activation and characteristic growth kinetics during pollen germination and pollen tube formation. Initially, the germinating Arabidopsis pollen tube grows slowly and forms a uniform roundish bulge, followed by a transition phase with vesicles heavily accumulating at the growth site before switching to rapid tip growth. Furthermore, we found the two sperm cells to be transported into the pollen tube after the phase of rapid tip growth has been initiated. The method presented here is suitable to quantitatively study subcellular events during Arabidopsis pollen germination and growth, and for the detailed analysis of pollen mutants with respect to pollen polarization, bulging, or growth site selection at the pollen plasma membrane.

Arabidopsis RIC1 Severs Actin Filaments at the Apex to Regulate Pollen Tube Growth.

Pollen tubes deliver sperms to the ovule for fertilization via tip growth. The rapid turnover of F-actin in pollen tube tips plays an important role in this process. In this study, we demonstrate that Arabidopsis thaliana RIC1, a member of the ROP-interactive CRIB motif-containing protein family, regulates pollen tube growth via its F-actin severing activity. Knockout of RIC1 enhanced pollen tube elongation, while overexpression of RIC1 dramatically reduced tube growth. Pharmacological analysis indicated that RIC1 affected F-actin dynamics in pollen tubes. In vitro biochemical assays revealed that RIC1 directly bound and severed F-actin in the presence of Ca(2+) in addition to interfering with F-actin turnover by capping F-actin at the barbed ends. In vivo, RIC1 localized primarily to the apical plasma membrane (PM) of pollen tubes. The level of RIC1 at the apical PM oscillated during pollen tube growth. The frequency of F-actin severing at the apex was notably decreased in ric1-1 pollen tubes but was increased in pollen tubes overexpressing RIC1. We propose that RIC1 regulates F-actin dynamics at the apical PM as well as the cytosol by severing F-actin and capping the barbed ends in the cytoplasm, establishing a novel mechanism that underlies the regulation of pollen tube growth.

A calcium sensor-regulated protein kinase, CALCINEURIN B-LIKE PROTEIN-INTERACTING PROTEIN KINASE19, is required for pollen tube growth and polarity.

Calcium plays an essential role in pollen tube tip growth. However, little is known concerning the molecular basis of the signaling pathways involved. Here, we identified Arabidopsis (Arabidopsis thaliana) CALCINEURIN B-LIKE PROTEIN-INTERACTING PROTEIN KINASE19 (CIPK19) as an important element to pollen tube growth through a functional survey for CIPK family members. The CIPK19 gene was specifically expressed in pollen grains and pollen tubes, and its overexpression induced severe loss of polarity in pollen tube growth. In the CIPK19 loss-of-function mutant, tube growth and polarity were significantly impaired, as demonstrated by both in vitro and in vivo pollen tube growth assays. Genetic analysis indicated that disruption of CIPK19 resulted in a male-specific transmission defect. Furthermore, loss of polarity induced by CIPK19 overexpression was associated with elevated cytosolic Ca2+ throughout the bulging tip, whereas LaCl3, a Ca2+ influx blocker, rescued CIPK19 overexpression-induced growth inhibition. Our results suggest that CIPK19 may be involved in maintaining Ca2+ homeostasis through its potential function in the modulation of Ca2+ influx.

Apoplastic ROS production upon pollination by RbohH and RbohJ in Arabidopsis

Reactive oxygen species (ROS) accumulate at the tip of growing pollen tubes. In Arabidopsis, NADPH oxidases RbohH and RbohJ are localized at the plasma membrane of pollen tube tip and produce ROS in a Ca2+-dependent manner. The ROS produced by Rbohs and Ca2+ presumably play a critical role in the positive feedback regulation that maintains the tip growth. Ultrastructural cytochemical analysis revealed ROS accumulation in the apoplast/cell wall of the pollen grains on the stigmatic papillae in the wild type, but not in the rbohH rbohJ double mutant, suggesting that apoplastic ROS derived from RbohH and RbohJ are involved in pollen tube elongation into the stigmatic papillae by affecting the cell wall metabolism.

Functional analysis of related CrRLK1L receptor-like kinases in pollen tube reception.

The Catharanthus roseus Receptor-Like Kinase 1-like (CrRLK1L) family of 17 receptor-like kinases (RLKs) has been implicated in a variety of signaling pathways in Arabidopsis, ranging from pollen tube (PT) reception and tip growth to hormonal responses. The extracellular domains of these RLKs have malectin-like domains predicted to bind carbohydrate moieties. Domain swap analysis showed that the extracellular domains of the three members analyzed (FER, ANX1, HERK1) are not interchangeable, suggesting distinct upstream components, such as ligands and/or co-factors. In contrast, their intercellular domains are functionally equivalent for PT reception, indicating that they have common downstream targets in their signaling pathways. The kinase domain is necessary for FER function, but kinase activity itself is not, indicating that other kinases may be involved in signal transduction during PT reception.

BURSTING POLLEN is required to organize the pollen germination plaque and pollen tube tip in Arabidopsis thaliana.

Pollen germination may occur via the so-called germination pores or directly through the pollen wall at the site of contact with the stigma. In this study, we addressed what processes take place during pollen hydration (i.e. before tube emergence), in a species with extra-poral pollen germination, Arabidopsis thaliana. A T-DNA mutant population was screened by segregation distortion analysis. Histological and electron microscopy techniques were applied to examine the wild-type and mutant phenotypes. Within 1 h of the start of pollen hydration, an intine-like structure consisting of cellulose, callose and at least partly de-esterified pectin was formed at the pollen wall. Subsequently, this 'germination plaque' gradually extended and opened up to provide passage for the cytoplasm into the emerging pollen tube. BURSTING POLLEN (BUP) was identified as a gene essential for the correct organization of this plaque and the tip of the pollen tube. BUP encodes a novel Golgi-located glycosyltransferase related to the glycosyltransferase 4 (GT4) subfamily which is conserved throughout the plant kingdom. Extra-poral pollen germination involves the development of a germination plaque and BUP defines the correct plastic-elastic properties of this plaque and the pollen tube tip by affecting pectin synthesis or delivery.

RISAP is a TGN-associated RAC5 effector regulating membrane traffic during polar cell growth in tobacco.

RAC/ROP GTPases coordinate actin dynamics and membrane traffic during polar plant cell expansion. In tobacco (Nicotiana tabacum), pollen tube tip growth is controlled by the RAC/ROP GTPase RAC5, which specifically accumulates at the apical plasma membrane. Here, we describe the functional characterization of RISAP, a RAC5 effector identified by yeast (Saccharomyces cerevisiae) two-hybrid screening. RISAP belongs to a family of putative myosin receptors containing a domain of unknown function 593 (DUF593) and binds via its DUF593 to the globular tail domain of a tobacco pollen tube myosin XI. It also interacts with F-actin and is associated with a subapical trans-Golgi network (TGN) compartment, whose cytoplasmic position at the pollen tube tip is maintained by the actin cytoskeleton. In this TGN compartment, apical secretion and endocytic membrane recycling pathways required for tip growth appear to converge. RISAP overexpression interferes with apical membrane traffic and blocks tip growth. RAC5 constitutively binds to the N terminus of RISAP and interacts in an activation-dependent manner with the C-terminal half of this protein. In pollen tubes, interaction between RAC5 and RISAP is detectable at the subapical TGN compartment. We present a model of RISAP regulation and function that integrates all these findings.

De novo sequencing and analysis of the lily pollen transcriptome: an open access data source for an orphan plant species.

Pollen grains of Lilium longiflorum are a long-established model system for pollen germination and tube tip growth. Due to their size, protein content and almost synchronous germination in synthetic media, they provide a simple system for physiological measurements as well as sufficient material for biochemical studies like protein purifications, enzyme assays, organelle isolation or determination of metabolites during germination and pollen tube elongation. Despite recent progresses in molecular biology techniques, sequence information of expressed proteins or transcripts in lily pollen is still scarce. Using a next generation sequencing strategy (RNAseq), the lily pollen transcriptome was investigated resulting in more than 50 million high quality reads with a length of 90 base pairs. Sequenced transcripts were assembled and annotated, and finally visualized with MAPMAN software tools and compared with other RNAseq or genome data including Arabidopsis pollen, Lilium vegetative tissues and the Amborella trichopoda genome. All lily pollen sequence data are provided as open access files with suitable tools to search sequences of interest.

Microsporogenesis, pollen mitosis and pollen tube growth in Gagea villosa (Liliaceae)

In this study, Gagea villosa (Bieb.) Duby was investigated by using light microscopy methods in cytological and cytoembryological respects. Anthers were tetrasporangiate. Anther wall was formed with an epidermis, endothecium, middle layer and tapetum. Tapetum was glandular type and it began to degenerate when microspores released from tetrads. Tapetum cells generally have one or two nuclei. Mitosis seen in tapetum cells was generally normal but micronuclei were found in some of them. Fibrous thickenings were determined in endothecium. Microsporogenesis and pollen mitosis were generally regular. Cytokinesis was successive type. Meiosis in pollen mother cells was asynchronous in one anther locus. Mature pollen grains were 2-celled. Pollen sterility was found to be 24%. Some of the fertile pollen grains, smaller than the normal were seen at the end of the pollen mitosis. Microgametophyte development was examined in vivo and in vitro. Germination ratio of pollen grains in vitro was 4%. Generally swollen pollen tube tips and weak development of some curled pollen tubes were seen. Callose plug formation was seen only in vivo pollen tube growth.

Transcriptional evidence for inferred pattern of pollen tube-stigma metabolic coupling during pollination.

It is difficult to derive all qualitative proteomic and metabolomic experimental data in male (pollen tube) and female (pistil) reproductive tissues during pollination because of the limited sensitivity of current technology. In this study, genome-scale enzyme correlation network models for plants (Arabidopsis/maize) were constructed by analyzing the enzymes and metabolic routes from a global perspective. Then, we developed a data-driven computational pipeline using the “guilt by association” principle to analyze the transcriptional coexpression profiles of enzymatic genes in the consecutive steps for metabolic routes in the fast-growing pollen tube and stigma during pollination. The analysis identified an inferred pattern of pollen tube-stigma ethanol coupling. When the pollen tube elongates in the transmitting tissue (TT) of the pistil, this elongation triggers the mobilization of energy from glycolysis in the TT cells of the pistil. Energy-rich metabolites (ethanol) are secreted that can be taken up by the pollen tube, where these metabolites are incorporated into the pollen tube's tricarboxylic acid (TCA) cycle, which leads to enhanced ATP production for facilitating pollen tube growth. In addition, our analysis also provided evidence for the cooperation of kaempferol, dTDP-alpha-L-rhamnose and cell-wall-related proteins; phosphatidic-acid-mediated Ca2+ oscillations and cytoskeleton; and glutamate degradation IV for γ-aminobutyric acid (GABA) signaling activation in Arabidopsis and maize stigmas to provide the signals and materials required for pollen tube tip growth. In particular, the “guilt by association” computational pipeline and the genome-scale enzyme correlation network models (GECN) developed in this study was initiated with experimental “omics” data, followed by data analysis and data integration to determine correlations, and could provide a new platform to assist inachieving a deeper understanding of the co-regulation and inter-regulation model in plant research.