Mechanisms Of Morphogenesis Research Articles

Plant regeneration capacity in seeds of three species of Miconia (Melastomataceae) may be related to endogenous polyamine profiles.

In plant tissue culture, differences in endogenous levels of species-specific plant growth regulators (PGRs) may explain differences in regenerative capacity. In the case of polyamines (PAs), their dynamics and distribution may vary between species, genotypes, tissues, and developmental pathways, such as sexual reproduction and apomixis. In this study, for the first time, we aimed to assess the impact of varying endogenous PAs levels in seeds from distinct reproductive modes in Miconia spp. (Melastomataceae), on their in vitro regenerative capacity. We quantified the free PAs endogenous content in seeds of Miconia australis (obligate apomictic), Miconia hyemalis (facultative apomictic), and Miconia sellowiana (sexual) and evaluated their in vitro regenerative potential in WPM culture medium supplemented with a combination of 2,4-dichlorophenoxyacetic acid (2,4-D) and 6-benzylaminopurine (BAP). The morphogenic responses were characterized by light microscopy and scanning electron microscopy and discussed regarding the endogenous PAs profiles found. Seeds of M. sellowiana presented approximately eight times more putrescine than M. australis, which was associated with a higher percentage of regenerated calluses (76.67%) than M. australis (5.56%). On the other hand, spermine levels were significantly higher in M. australis. Spermine is indicated as an inhibitor of auxin-carrying gene expression, which may have contributed to its lower regenerative capacity under the tested conditions. These findings provide important insights into in vitro morphogenesis mechanisms in Miconia and highlight the significance of endogenous PA levels in plant regeneration. These discoveries can potentially optimize future regeneration protocols in Miconia, a plant group still underexplored in this area.

Transcriptional responses to salinity-induced changes in cell wall morphology of the euryhaline diatom Pleurosira laevis.

Diatoms are unicellular algae with morphologically diverse silica cell walls, which are called frustules. The mechanism of frustule morphogenesis has attracted attention in biology and nanomaterials engineering. However, the genetic regulation of the morphology remains unclear. We therefore used transcriptome sequencing to search for genes involved in frustule morphology in the centric diatom Pleurosira laevis, which exhibits morphological plasticity between flat and domed valve faces in salinity 2 and 7, respectively. We observed differential expression of transposable elements (TEs) and transporters, likely due to osmotic response. Up-regulation of mechanosensitive ion channels and down-regulation of Ca2+ -ATPases in cells with flat valves suggested that cytosolic Ca2+ levels were changed between the morphologies. Calcium signaling could be a mechanism for detecting osmotic pressure changes and triggering morphological shifts. We also observed an up-regulation of ARPC1 and annexin, involved in the regulation of actin filament dynamics known to affect frustule morphology, as well as the up-regulation of genes encoding frustule-related proteins such as BacSETs and frustulin. Taken together, we propose a model in which salinity-induced morphogenetic changes are driven by upstream responses, such as the regulation of cytosolic Ca2+ levels, and downstream responses, such as Ca2+ -dependent regulation of actin dynamics and frustule-related proteins. This study highlights the sensitivity of euryhaline diatoms to environmental salinity and the role of active cellular processes in controlling gross valve morphology under different osmotic pressures.

Endothelial cells regulate alveolar morphogenesis by constructing basement membranes acting as a scaffold for myofibroblasts

Alveologenesis is a spatially coordinated morphogenetic event, during which alveolar myofibroblasts surround the terminal sacs constructed by epithelial cells and endothelial cells (ECs), then contract to form secondary septa to generate alveoli in the lungs. Recent studies have demonstrated the important role of alveolar ECs in this morphogenetic event. However, the mechanisms underlying EC-mediated alveologenesis remain unknown. Herein, we show that ECs regulate alveologenesis by constructing basement membranes (BMs) acting as a scaffold for myofibroblasts to induce septa formation through activating mechanical signaling. Rap1, a small GTPase of the Ras superfamily, is known to stimulate integrin-mediated cell adhesions. EC-specific Rap1-deficient (Rap1iECKO) mice exhibit impaired septa formation and hypo-alveolarization due to the decreased mechanical signaling in myofibroblasts. In Rap1iECKO mice, ECs fail to stimulate integrin β1 to recruit Collagen type IV (Col-4) into BMs required for myofibroblast-mediated septa formation. Consistently, EC-specific integrin β1-deficient mice show hypo-alveolarization, defective mechanical signaling in myofibroblasts, and disorganized BMs. These data demonstrate that alveolar ECs promote integrin β1-mediated Col-4 recruitment in a Rap1-dependent manner, thereby constructing BMs acting as a scaffold for myofibroblasts to induce mechanical signal-mediated alveologenesis. Thus, this study unveils a mechanism of organ morphogenesis mediated by ECs through intrinsic functions.

A fitness landscape instability governs the morphological diversity of tip-growing cells

Cellular morphology affects many aspects of cellular and organismal physiology. This makes it challenging to dissect the evolutionary basis for specific morphologies since various cellular functions may exert competing selective pressures on this trait, and the influence of these pressures will depend on the specific mechanisms of morphogenesis. In this light, we combined experiment and theory to investigate the complex basis for morphological diversity among tip-growing cells from across the tree of life. We discovered that an instability in the widespread mechanism of "inflationary" tip growth leads directly to a bifurcation in the common fitness landscape of tip-growing cells, which imposes a strict global constraint on their morphologies. This result rationalizes the morphology of an enormous diversity of important fungal, plant, protistan, and bacterial systems. More broadly, our study elucidates the principle that strong evolutionary constraints on complex traits, like biological form, may emerge from emergent instabilities within developmental systems.

Mechanism of branching morphogenesis inspired by diatom silica formation

The silica-based cell walls of diatoms are prime examples of genetically controlled, species-specific mineral architectures. The physical principles underlying morphogenesis of their hierarchically structured silica patterns are not understood, yet such insight could indicate novel routes toward synthesizing functional inorganic materials. Recent advances in imaging nascent diatom silica allow rationalizing possible mechanisms of their pattern formation. Here, we combine theory and experiments on the model diatom Thalassiosira pseudonana to put forward a minimal model of branched rib patterns-a fundamental feature of the silica cell wall. We quantitatively recapitulate the time course of rib pattern morphogenesis by accounting for silica biochemistry with autocatalytic formation of diffusible silica precursors followed by conversion into solid silica. We propose that silica deposition releases an inhibitor that slows down up-stream precursor conversion, thereby implementing a self-replicating reaction-diffusion system different from a classical Turing mechanism. The proposed mechanism highlights the role of geometrical cues for guided self-organization, rationalizing the instructive role for the single initial pattern seed known as the primary silicification site. The mechanism of branching morphogenesis that we characterize here is possibly generic and may apply also in other biological systems.

ScRNA-seq reveals dark- and light-induced differentially expressed gene atlases of seedling leaves in Arachis hypogaea L.

Although the regulatory mechanisms of dark and light-induced plant morphogenesis have been broadly investigated, the biological process in peanuts has not been systematically explored on single-cell resolution. Herein, 10 cell clusters were characterized using scRNA-seq-identified marker genes, based on 13 409 and 11 296 single cells from 1-week-old peanut seedling leaves grown under dark and light conditions. 6104 genes and 50 transcription factors (TFs) displayed significant expression patterns in distinct cell clusters, which provided gene resources for profiling dark/light-induced candidate genes. Further pseudo-time trajectory and cell cycle evidence supported that dark repressed the cell division and perturbed normal cell cycle, especially the PORA abundances correlated with 11 TFs highly enriched in mesophyll to restrict the chlorophyllide synthesis. Additionally, light repressed the epidermis cell developmental trajectory extending by inhibiting the growth hormone pathway, and 21 TFs probably contributed to the different genes transcriptional dynamic. Eventually, peanut AHL17 was identified from the profile of differentially expressed TFs, which encoded protein located in the nucleus promoted leaf epidermal cell enlargement when ectopically overexpressed in Arabidopsis through the regulatory phytohormone pathway. Overall, our study presents the different gene atlases in peanut etiolated and green seedlings, providing novel biological insights to elucidate light-induced leaf cell development at the single-cell level.

Identification of a transcription factor AoMsn2 of the Hog1 signaling pathway contributes to fungal growth, development and pathogenicity in Arthrobotrys oligospora

IntroductionArthrobotrys oligospora has been utilized as a model strain to study the interaction between fungi and nematodes owing to its ability to capture nematodes by developing specialized traps. A previous study showed that high-osmolarity glycerol (Hog1) signaling regulates the osmoregulation and nematocidal activity of A. oligospora. However, the function of downstream transcription factors of the Hog1 signaling in the nematode-trapping (NT) fungi remains unclear. ObjectiveThis study aimed to investigate the functions and potential regulatory network of AoMsn2, a downstream transcription factor of the Hog1 signaling pathway in A. oligospora. MethodsThe function of AoMsn2 was characterized using targeted gene deletion, phenotypic experiments, real-time quantitative PCR, RNA sequencing, untargeted metabolomics, and yeast two-hybrid analysis. ResultsLoss of Aomsn2 significantly enlarged and swollen the hyphae, with an increase in septa and a significant decrease in nuclei. In particular, spore yield, spore germination rate, traps, and nematode predation efficiency were remarkably decreased in the mutants. Phenotypic and transcriptomic analyses revealed that AoMsn2 is essential for fatty acid metabolism and autophagic pathways. Additionally, untargeted metabolomic analysis identified an important function of AoMsn2 in the modulation of secondary metabolites. Furtherly, we analyzed the protein interaction network of AoMsn2 based on the Kyoto Encyclopedia of Genes and Genomes pathway map and the online website STRING. Finally, Hog1 and six putative targeted proteins of AoMsn2 were identified by Y2H analysis. ConclusionOur study reveals that AoMsn2 plays crucial roles in the growth, conidiation, trap development, fatty acid metabolism, and secondary metabolism, as well as establishes a broad basis for understanding the regulatory mechanisms of trap morphogenesis and environmental adaptation in NT fungi.

Defining a Lewy Body: Running Up the Hill of Shifting Definitions and Evolving Concepts.

Lewy bodies (LBs) are pathological hallmarks of Parkinson's disease and dementia with Lewy bodies, characterized by the accumulation of α-synuclein (αSyn) protein in the brain. While LBs were first described a century ago, their formation and morphogenesis mechanisms remain incompletely understood. Here, we present a historical overview of LB definitions and highlight the importance of semantic clarity and precise definitions when describing brain inclusions. Recent breakthroughs in imaging revealed shared features within LB subsets and the enrichment of membrane-bound organelles in these structures, challenging the conventional LB formation model. We discuss the involvement of emerging concepts of liquid-liquid phase separation, where biomolecules demix from a solution to form dense condensates, as a potential LB formation mechanism. Finally, we emphasize the need for the operational definitions of LBs based on morphological characteristics and detection protocols, particularly in studies investigating LB formation mechanisms. A better understanding of LB organization and ultrastructure can contribute to the development of targeted therapeutic strategies for synucleinopathies.

Fine mapping an AUXIN RESPONSE FACTOR, SmARF18, as a candidate gene of the PRICKLE LOCUS that controls prickle absence/presence on various organs in eggplant (Solanum melongena L.)

Prickle is a sharp protrusion that covering plant and fruit calyxes of eggplant are considered undesirable agronomic traits, for they bring troubles and create additional costs for farmers. However, little is known about its regulatory genes and molecular mechanism of morphogenesis. In this study, two eggplant inbred lines, prickly ‘140’ and prickleless ‘145’ were applied to construct F1, BC1, and F2 offspring populations. Genetic analysis results showed that prickle's absence/presence on various organs in eggplant was controlled by only one dominant nuclear gene. The PRICKLE LOCUS (Pl) was fine mapped into a candidate interval with 28.3 Kb on chromosome 6 ultimately by adopting bulked segregant analysis combined with genome walking strategy. An auxin response factor SmARF18 (Smechr0602826.1) was deduced to be a candidate gene encoded by Pl, which possesses a non-synonymous single nucleotide polymorphism co-segregating with prickle phenotype in F2 population. The finding here could provide a basis to reveal the molecular regulatory mechanism of prickle morphogenesis in plants and breed prickle-free eggplant cultivars.

Interplay between the plasma membrane and cell-cell adhesion maintains epithelial identity for correct polarised cell divisions.

Polarised epithelial cell divisions represent a fundamental mechanism for tissue maintenance and morphogenesis. Morphological and mechanical changes in the plasma membrane influence the organisation and crosstalk of microtubules and actin at the cell cortex, thereby regulating the mitotic spindle machinery and chromosome segregation. Yet, the precise mechanisms linking plasma membrane remodelling to cell polarity and cortical cytoskeleton dynamics to ensure accurate execution of mitosis in mammalian epithelial cells remain poorly understood. Here, we manipulated the density of mammary epithelial cells in culture, which led to several mitotic defects. Perturbation of cell-cell adhesion formation impairs the dynamics of the plasma membrane, affecting the shape and size of mitotic cells and resulting in defects in mitotic progression and the generation of daughter cells with aberrant architecture. In these conditions, F- actin-astral microtubule crosstalk is impaired, leading to mitotic spindle misassembly and misorientation, which in turn contributes to chromosome mis-segregation. Mechanistically, we identify S100 Ca2+-binding protein A11 (S100A11) as a key membrane-associated regulator that forms a complex with E-cadherin (CDH1) and the leucine-glycine-asparagine repeat protein LGN (also known as GPSM2) to coordinate plasma membrane remodelling with E-cadherin-mediated cell adhesion and LGN-dependent mitotic spindle machinery. Thus, plasma membrane-mediated maintenance of mammalian epithelial cell identity is crucial for correct execution of polarised cell divisions, genome maintenance and safeguarding tissue integrity.

Genetic mechanisms of petal morphogenesis in Eustoma grandiflorum

Eustoma grandiflorum, also known as lisianthus, is a popular ornamental plant belonging to the Gentianaceae family. Due to its diverse petal shapes, it is an excellent model for studying the genetic mechanisms of petal morphogenesis. In this study, we conducted a comparative morphological, anatomical, and transcriptional analysis of two cultivated varieties of lisianthus, ‘Wavy White’ with wavy petals and ‘Rosita White’ with flat petals. Cytological observations showed that the cells of both the epidermis (Ep) and parenchymatous tissue (Pt) at the bud stage, as well as the cell numbers of Ep at the mature stage existed difference between petals in ‘Rosita White’ and ‘Wavy White’. We found that genes involved in cell division, cell expansion, and microtubule-based processes, including genes in the CYCLIN D3 (CYCD3) family, EXPANSIN (EXP) family, and Tubulin/FtsZ family, were highly over-represented during the bud stage in ‘Wavy White’. At the bud stage, several specific genes, including EXP1, YABBY3 (YAB3), GROWTH-REGULATING FACTOR 1 (GRF1), LEAFY (LFY), LOB DOMAIN-CONTAINING PROTEIN 40 (LBD40), and PROTODERMAL FACTOR 2 (PDF2) were found to be highly expressed in the petals of ‘Wavy White’. Quantitative real-time polymerase chain reaction (qRT-PCR) analysis further confirmed significantly higher expression levels of LFY, PDF2, GRF1, and YAB3 in ‘Wavy White’ than those in ‘Rosita White’ at the bud stage. And we found that YAB3 was more highly expressed in petals in lisianthus cultivars with wavy petals than those in ‘Rosita White’; LFY was more highly expressed in petals in lisianthus cultivars with wavy petals except ‘Wavy Purple’ than those in ‘Rosita White’. Overall, our findings shed light on the genetic mechanisms of petal morphogenesis in lisianthus.

Development and formation of wing cuticle based on transcriptomic analysis in Locusta migratoria during metamorphosis

Wings are an important flight organ of insects. Wing development is a complex process controlled by a series of genes. The flightless wing pad transforms into a mature wing with the function of migratory flight during the nymph-to-adult metamorphosis. However, the mechanism of wing morphogenesis in locusts is still unclear. This study analyzed the microstructures of the locust wing pads at pre-eclosion and the wings after eclosion and performed the comparative transcriptome analysis. RNA-seq identified 25,334 unigenes and 3,430 differentially expressed genes (DEGs) (1,907 up-regulated and 1,523 down-regulated). The DEGs mainly included cuticle development (LmACPs), chitin metabolism (LmIdgf4), lipid metabolism-related genes, cell adhesion (Integrin), zinc finger transcription factors (LmSalm, LmZF593 and LmZF521), and others. Functional analysis based on RNA interference and hematoxylin and eosin (H&E) staining showed that the three genes encoded zinc finger transcription factors are essential for forming wing cuticle and maintaining morphology in Locusta migratoria. Finally, the study found that the LmSalm regulates the expression of LmACPs in the wing pads at pre-eclosion, and LmZF593 and LmZF521 regulate the expression of LmIntegrin/LmIdgf4/LmHMT420 in the wings after eclosion. This study revealed that the molecular regulatory axis controls wing morphology in nymphal and adult stages of locusts, offering a theoretical basis for the study of wing development mechanisms in hemimetabolous insects.

Astrocyte morphology.

Astrocytes are predominant glial cells that tile the central nervous system (CNS). A cardinal feature of astrocytes is their complex and visually enchanting morphology, referred to as bushy, spongy, and star-like. A central precept of this review is that such complex morphological shapes evolved to allow astrocytes to contact and signal with diverse cells at a range of distances in order to sample, regulate, and contribute to the extracellular milieu, and thus participate widely in cell-cell signaling during physiology and disease. The recent use of improved imaging methods and cell-specific molecular evaluations has revealed new information on the structural organization and molecular underpinnings of astrocyte morphology, the mechanisms of astrocyte morphogenesis, and the contributions to disease states of reduced morphology. These insights have reignited interest in astrocyte morphological complexity as a cornerstone of fundamental glial biology and as a critical substrate for multicellular spatial and physiological interactions in the CNS.

Wnt4a Is Indispensable for Genital Duct Elongation but Not for Gonadal Sex Differentiation in the Medaka, Oryzias latipes.

In most vertebrates, the oviducts and sperm ducts are derived from the Müllerian ducts and Wolffian ducts, respectively. However, in teleosts, the genital ducts are formed by the posterior extension of gonads in both sexes. Whether the genital ducts of teleosts are newly evolved organs or variants of Müllerian ducts is an important question for understanding evolutionary mechanisms of morphogenesis. One of the genes essential for Müllerian duct formation in mice is Wnt4, which is expressed in the mesenchyme and induces invagination of the coelomic epithelium and its posterior elongation. Here, we addressed the above question by examining genital duct development in mutants of two Wnt4 genes in the medaka (wnt4a is orthologous to mouse Wnt4, and wnt4b is paralogous). The wnt4b mutants had a short body but were fertile with normal genital ducts. In contrast, both male and female wnt4a mutants had their posterior elongation of the gonads stopped within or just outside the coelom. The mutants retained the posterior parts of ovarian cavities or sperm duct primordia, which are potential target tissues of Wnt4a. The gonads of female scl mutants (unable to synthesize sex steroids) lacked these tissues and did not develop genital ducts. Medaka wnt4a was expressed in the mesenchyme ventral to the genital ducts in both sexes. Taken together, the data strongly suggest that the mouse Müllerian ducts and the medaka genital ducts share homologous developmental processes. Additionally, the wnt4a or wnt4b single mutants and the double mutants did not show sex-reversal, implying that both genes are dispensable for gonadal sex differentiation in the medaka.

Enhancement of hemostatic properties of Cyclotella cryptica frustule through genetic manipulation

BackgroundThe silicified cell wall of diatoms, also known as frustule, shows huge potential as an outstanding bio-nanomaterial for hemostatic applications due to its high hemostatic efficiency, good biocompatibility, and ready availability. As the architectural features of the frustule determine its hemostatic performance, it is of great interest to develop an effective method to modify the frustule morphology into desired patterns to further improve hemostatic efficiency.ResultsIn this study, the gene encoding Silicalemma Associated Protein 2 (a silicalemma-spanning protein) of Cyclotella cryptica (CcSAP2) was identified as a key gene in frustule morphogenesis. Thus, it was overexpressed and knocked down, respectively. The frustule of the overexpress lines showed no obvious alteration in morphology compared to the wild type (WT), while the size, specific surface area (BET), pore volume, and pore diameter of the knockdown strains changed greatly. Particularly, the knockdown frustules achieved a more pronounced coagulation effect and in vivo hemostatic performance than the WT strains. Such observations suggested that silicalemma proteins are ideal genetic encoding targets for manipulating frustule morphology associated hemostatic properties. Furthermore, the Mantel test was adopted to identify the key morphologies associated with C. cryptica bleeding control. Finally, based on our results and recent advances, the mechanism of frustule morphogenesis was discussed.ConclusionThis study explores a new strategy for enhancing the hemostatic efficiency of the frustule based on genetic morphology modification and may provide insights into a better understanding of the frustule morphogenesis mechanism.

Molecular mechanism of microRNA-mediated morphogenesis in plant reproductive organs: a review

Molecular mechanism of microRNA-mediated morphogenesis in plant reproductive organs: a review

Abstract P1180: Multi-scale Imaging And Analysis To Elucidate Cardiac Structure And Contractile Function

Heart failure remains the leading cause of mortality worldwide, largely due to the lack of regenerative capacity of mature cardiomyocytes. The advanced understanding of cardiac architecture and function is critical to uncover the underlying mechanism of cardiac morphogenesis and the remodeling process in response to myocardial infarction. Recent progress has demonstrated that zebrafish and neonatal mice have the capacity to restore cardiac function following the injury, laying the foundation to investigate the cues to structural and functional abnormalities. For this reason, we have developed a light-sheet fluorescence microscope along with the tailored computational methods to investigate the 3-dimensional (3D) architecture of the intact mouse heart, and 4D (3D spatial + 1D temporal) cardiac contractility in zebrafish larvae. This method provides us ~ 2 um isotropic spatial resolution across the atria and ventricles with minimal photo-damage and maximal penetration depth. In combination with established tissue clearing methods, we are able to investigate myocardial trabeculation and compaction in mouse hearts within the 2-minute laser scanning. To unravel the contractile dysfunction following the anticancer therapy, we have coupled our imaging system with retrospective synchronization algorithm for the 4D reconstruction of myocardial deformation from end-systole to end-diastole in zebrafish hearts. To further interpret the deluge of 3D and 4D images, we have also developed a machine learning-based platform for interactive image analysis. Collectively, our multi-scale imaging strategy provides an entry point to assess micro-architecture and cardiac contractile function in the entire heart without physical slicing, holding the great potential to uncover the process of cardiac morphogenesis and regeneration.

AXR1 modulates trichome morphogenesis through mediating ROP2 stability in Arabidopsis.

Cell differentiation and morphogenesis are crucial for the establishment of diverse cell types and organs in multicellular organisms. Trichome cells offer an excellent paradigm for dissecting the regulatory mechanisms of plant cell differentiation and morphogenesis due to their unique growth characteristics. Here, we report the isolation of an Arabidopsis mutant, aberrantly branched trichome 3-1 (abt3-1), with a reduced trichome branching phenotype. Positional cloning and molecular complementation experiments confirmed that abt3-1 is a new mutant allele of Auxin resistant 1 (AXR1), which encodes the N-terminal half of ubiquitin-activating enzyme E1 and functions in auxin signaling pathway. Meanwhile, we found that transgenic plants expressing constitutively active version of ROP2 (CA-ROP2) caused a reduction of trichome branches, resembling that of abt3-1. ROP2 is a member of Rho GTPase of plants (ROP) family, serving as versatile signaling switches involved in a range of cellular and developmental processes. Our genetic and biochemical analyses showed AXR1 genetically interacted with ROP2 and mediated ROP2 protein stability. The loss of AXR1 aggravated the trichome defects of CA-ROP2 and induced the accumulation of steady-state ROP2. Consistently, elevated AXR1 expression levels suppressed ROP2 expression and partially rescued trichome branching defects in CA-ROP2 plants. Together, our results presented a new mutant allele of AXR1, uncovered the effects of AXR1 and ROP2 during trichome development, and revealed a pathway of ROP2-mediated regulation of plant cell morphogenesis in Arabidopsis.

Multi-stage nuclear transcriptomic insights of morphogenesis and biparental role changes in Lentinula edodes.

Based on six offspring with different mitochondrial (M) and parental nuclear (N) genotypes, the multi-stage morphological characteristics and nuclear transcriptomes of Lentinula edodes were compared to investigate morphogenesis mechanisms during cultivation, the key reason for cultivar resistance to genotype changes, and regulation related to biparental role changes. Six offspring had specific transcriptomic data and morphological characteristics that were mainly regulated by the two parental nuclei, followed by the cytoplasm, at different growth stages. Importing a wild N genotype easily leads to failure or instability of fruiting; however, importing wild M genotypes may improve cultivars. Major facilitator superfamily (MFS) transporter genes encoding specific metabolites in spawns may play crucial roles in fruiting body formation. Pellets from submerged cultivation and spawns from sawdust substrate cultivation showed different carbon metabolic pathways, especially in secondary metabolism, degradation of lignin, cellulose and hemicellulose, and plasma membrane transport (mainly MFS). When the stage of small young pileus (SYP) was formed on the surface of the bag, the spawns inside were mainly involved in nutrient accumulation. Just broken pileus (JBP) showed a different expression of plasma membrane transporter genes related to intracellular material transport compared to SYP and showed different ribosomal proteins and cytochrome P450 functioning in protein biosynthesis and metabolism than near spreading pileus (NSP). Biparental roles mainly regulate offspring metabolism, growth, and morphogenesis by differentially expressing specific genes during different vegetative growth stages. Additionally, some genes encoding glycine-rich RNA-binding proteins, F-box, and folliculin-interacting protein repeat-containing proteins may be related to multi-stage morphogenesis. KEY POINTS: • Replacement of nuclear genotype is not suitable for cultivar breeding of L. edodes. • Some genes show a biparental role-divergent expression at mycelial growth stage. • Transcriptomic changes of some sawdust substrate cultivation stages have been elucidated.

The epigenetic regulator Set9 harmonizes fungal development, secondary metabolism, and colonization capacity of Aspergillus flavus

As a widely distributed food-borne pathogenic fungus, Aspergillus flavus and its secondary metabolites, mainly aflatoxin B1 (AFB1), pose a great danger to humans. It is urgent to reveal the complex regulatory network of toxigenic and virulence of this fungus. The bio-function of Set9, a SET-domain-containing histone methyltransferase, is still unknown in A. flavus. By genetic engineering means, this study revealed that, through catalyzing H4K20me2 and -me3, Set9 is involved in fungal growth, reproduction, and mycotoxin production via the orthodox regulation pathway, and regulates fungal colonization on crop kernels through adjusting fungal sensitivity reactions to oxidation stress and cell wall integrity stress. Further domain deletion and point mutation inferred that the SET domain is the core element in catalyzing H4K20 methylation, and D200 site of the domain is the key amino acid in the active center of the methyltransferase. Combined with RNA-seq analysis, this study revealed that Set9 regulates the aflatoxin gene cluster by the AflR-like protein (ALP), other than traditional AflR. This study revealed the epigenetic regulation mechanism of fungal morphogenesis, secondary metabolism, and pathogenicity of A. flavus mediated by the H4K20-methyltransferase Set9, which might provide a potential new target for early prevention of contamination of A. flavus and its deadly mycotoxins.