Stages Of Sexual Reproduction Research Articles

Differences in the seasonal development of perithecia by Neonectria ditissima on apple trees across Northern Europe

AbstractAscospores discharged at rainfall and dispersed by wind can provide long-distance spread of the European canker fungus, Neonectria ditissima. Ascospores are produced by perithecia which are the sexual reproductive stage. Diffuse knowledge exists on the seasonal pattern of perithecium formation under different climatic conditions. Therefore, the development of perithecia was observed for several successive seasons at five sites in three Northern European countries. In Norway and Finland, ripe perithecia were commonly recorded throughout the year, and on individual cankers continuously for up to 28 months. In contrast, asexual reproductive structures (sporodochia) were confined to the growing season in both countries. In Northern Germany an average of 51% of cankers developed ripe perithecia by late winter, and perithecial senescence ensued in late spring. On average, ripe perithecia were present on cankers for 22 weeks. In contrast, sporodochia were observed all year round. The timing of perithecium maturation correlated with the number of days with > 2 mm rainfall in July–September. The presence of mature perithecia and sporodochia for different lengths of time in different countries has implications for regional disease management strategies.

A novel method for extraction of high purity and high production Phytophthora sojae oospores

BackgroundPhytophthora sojae, a soil-borne oomycete pathogen, has been a yield limiting factor for more than 60 years on soybean. The resurgence of P. sojae (Phytophthora sojae) is primarily ascribed to the durable oospores found in soil and remnants of the disease. P. sojae is capable of infesting at any growth periods of the soybean, and the succeed infestation of P. sojae is predominantly attributed to long-lived oospores present in soil. Comprehending the molecular mechanisms that drive oospores formation and their significance in infestation is the key for effective management of the disease. However, the existing challenges in isolating and extracting significant quantities of oospores pose limitations in investigating the sexual reproductive stages of P. sojae.ResultsThe study focused on optimizing and refining the culture conditions and extraction process of P. sojae, resulting in establishment of an efficient and the dependable method for extraction. Novel optimized approach was yielded greater quantities of high-purity P. sojae oospores than traditional methods. The novel approach exceeds the traditional approaches with respect to viability, survival ability, germination rates of new oospores and the pathogenicity of oospores in potting experiments.ConclusionThe proposed method for extracting P. sojae oospores efficiently yielded a substantial quantity of highly pure, viable, and pathogenic oospores. The enhancements in oospores extraction techniques will promote the research on the sexual reproductive mechanisms of P. sojae and lead to the creation of innovative and effective approaches for managing oomycete diseases.

The massive 340 megabase genome of Anisogramma anomala, a biotrophic ascomycete that causes eastern filbert blight of hazelnut

BackgroundThe ascomycete fungus Anisogramma anomala causes Eastern Filbert Blight (EFB) on hazelnut (Corylus spp.) trees. It is a minor disease on its native host, the American hazelnut (C. americana), but is highly destructive on the commercially important European hazelnut (C. avellana). In North America, EFB has historically limited commercial production of hazelnut to west of the Rocky Mountains. A. anomala is an obligately biotrophic fungus that has not been grown in continuous culture, rendering its study challenging. There is a 15-month latency before symptoms appear on infected hazelnut trees, and only a sexual reproductive stage has been observed. Here we report the sequencing, annotation, and characterization of its genome.ResultsThe genome of A. anomala was assembled into 108 scaffolds totaling 342,498,352 nt with a GC content of 34.46%. Scaffold N50 was 33.3 Mb and L50 was 5. Nineteen scaffolds with lengths over 1 Mb constituted 99% of the assembly. Telomere sequences were identified on both ends of two scaffolds and on one end of another 10 scaffolds. Flow cytometry estimated the genome size of A. anomala at 370 Mb. The genome exhibits two-speed evolution, with 93% of the assembly as AT-rich regions (32.9% GC) and the other 7% as GC-rich (57.1% GC). The AT-rich regions consist predominantly of repeats with low gene content, while 90% of predicted protein coding genes were identified in GC-rich regions. Copia-like retrotransposons accounted for more than half of the genome. Evidence of repeat-induced point mutation (RIP) was identified throughout the AT-rich regions, and two copies of the rid gene and one of dim-2, the key genes in the RIP mutation pathway, were identified in the genome. Consistent with its homothallic sexual reproduction cycle, both MAT1-1 and MAT1-2 idiomorphs were found. We identified a large suite of genes likely involved in pathogenicity, including 614 carbohydrate active enzymes, 762 secreted proteins and 165 effectors.ConclusionsThis study reveals the genomic structure, composition, and putative gene function of the important pathogen A. anomala. It provides insight into the molecular basis of the pathogen’s life cycle and a solid foundation for studying EFB.

Transcriptional chronology reveals conserved genes involved in pennate diatom sexual reproduction.

Sexual reproduction is a major driver of adaptation and speciation in eukaryotes. In diatoms, siliceous microalgae with a unique cell size reduction-restitution life cycle and among the world's most prolific primary producers, sex also acts as the main mechanism for cell size restoration through the formation of an expanding auxospore. However, the molecular regulators of the different stages of sexual reproduction and size restoration are poorly explored. Here, we combined RNA sequencing with the assembly of a 55 Mbp reference genome for Cylindrotheca closterium to identify patterns of gene expression during different stages of sexual reproduction. These were compared with a corresponding transcriptomic time series of Seminavis robusta to assess the degree of expression conservation. Integrative orthology analysis revealed 138 one-to-one orthologues that are upregulated during sex in both species, among which 56 genes consistently upregulated during cell pairing and gametogenesis, and 11 genes induced when auxospores are present. Several early, sex-specific transcription factors and B-type cyclins were also upregulated during sex in other pennate and centric diatoms, pointing towards a conserved core regulatory machinery for meiosis and gametogenesis across diatoms. Furthermore, we find molecular evidence that the pheromone-induced cell cycle arrest is short-lived in benthic diatoms, which may be linked to their active mode of mate finding through gliding. Finally, we exploit the temporal resolution of our comparative analysis to report the first marker genes for auxospore identity called AAE1-3 ("Auxospore-Associated Expression"). Altogether, we introduce a multi-species model of the transcriptional dynamics during size restoration in diatoms and highlight conserved gene expression dynamics during different stages of sexual reproduction.

Auxin and carbohydrate control flower bud development in Anthurium andraeanum during early stage of sexual reproduction

BackgroundFlower buds of Anthurium andraeanum frequently cease to grow and abort during the early flowering stage, resulting in prolonged planting times and increased commercialization costs. Nevertheless, limited knowledge exists of the mechanism of flower development after initiation in A. andraeanum.ResultsIn this study, the measurement of carbohydrate flow and intensity between leaves and flowers during different growth stages showed that tender leaves are strong sinks and their concomitant flowers are weak ones. This suggested that the tender leaves compete with their concomitant flower buds for carbohydrates during the early growth stages, potentially causing the abortion of the flower buds. The analysis of transcriptomic differentially expressed genes suggested that genes related to sucrose metabolism and auxin response play an important role during flower bud development. Particularly, co-expression network analysis found that AaSPL12 is a hub gene engaged in flower development by collaborating carbohydrate and auxin signals. Yeast Two Hybrid assays revealed that AaSPL12 can interact with AaARP, a protein that serves as an indicator of dormancy. Additionally, the application of exogenous IAA and sucrose can suppress the expression of AaARP, augment the transcriptional abundance of AaSPL12, and consequently expedite flower development in Anthurium andraeanum.ConclusionsCollectively, our findings indicated that the combination of auxin and sugar signals could potentially suppress the repression of AaARP protein to AaSPL12, thus advancing the development of flower buds in Anthurium andraeanum.

Proteomics analysis of Toxoplasma gondii merozoites reveals regulatory proteins involved in sexual reproduction

Sexual reproduction plays a crucial role in the transmission and life cycle of toxoplasmosis. The merozoites are the only developmental stage capable of differentiation into male and female gametes, thereby initiating sexual reproduction to form oocysts that are excreted into the environment. Hence, our study aimed to perform proteomic analyses of T. gondii Pru strain merozoites, a pre-sexual developmental stage in cat IECs, and tachyzoites, an asexual developmental stage, using the tandem mass tag (TMT) method in order to identify the differentially expressed proteins (DEPs) of merozoites. Proteins functions were subjected to cluster analysis, and DEPs were validated through the qPCR method. The results showed that a total of 106 proteins were identified, out of which 85 proteins had quantitative data. Among these, 15 proteins were differentially expressed within merozoites, with four exhibiting up-regulation and being closely associated with the material and energy metabolism as well as the cell division of T. gondii. Two novel DEPs, namely S8GHL5 and A0A125YP41, were identified, and their homologous family members have been demonstrated to play regulatory roles in oocyte maturation and spermatogenesis in other species. Therefore, they may potentially exhibit regulatory functions during the differentiation of micro- and macro-gametophytes at the initiation stage of sexual reproduction in T. gondii. In conclusion, our results showed that the metabolic and divisional activities in the merozoites surpass those in the tachyzoites, thereby providing structural, material, and energetic support for gametophytes development. The discovery of two novel DEPs associated with sexual reproduction represents a significant advancement in understanding Toxoplasma sexual reproduction initiation and oocyst formation.

Salpa genome and developmental transcriptome analyses reveal molecular flexibility enabling reproductive success in a rapidly changing environment

Ocean warming favors pelagic tunicates, such as salps, that exhibit increasingly frequent and rapid population blooms, impacting trophic dynamics and composition and human marine-dependent activities. Salp blooms are a result of their successful reproductive life history, alternating seasonally between asexual and sexual protogynous (i.e. sequential) hermaphroditic stages. While predicting future salp bloom frequency and intensity relies on an understanding of the transitions during the sexual stage from female through parturition and subsequent sex change to male, these transitions have not been explored at the molecular level. Here we report the development of the first complete genome of S. thompsoni and the North Atlantic sister species S. aspera. Genome and comparative analyses reveal an abundance of repeats and G-quadruplex (G4) motifs, a highly stable secondary structure, distributed throughout both salp genomes, a feature shared with other tunicates that perform alternating sexual-asexual reproductive strategies. Transcriptional analyses across sexual reproductive stages for S. thompsoni revealed genes associated with male sex differentiation and spermatogenesis are expressed as early as birth and before parturition, inconsistent with previous descriptions of sequential sexual differentiation in salps. Our findings suggest salp are poised for reproductive success at birth, increasing the potential for bloom formation as ocean temperatures rise.

Discovery of microRNAs in Pyrus stigma exudates opens new research avenues in Horticulture.

In many plant species, flower stigma secretions are important in early stages of sexual reproduction. Previous chemical analysis and proteomic characterization of these exudates provided insights into their biological function. Nevertheless, the presence of nucleic acids in the stigma exudates has not been previously reported. Here, we studied the stigma exudates of Pyrus communis, Pyrus pyrifolia, and Pyrus syriaca and showed them to harbor extracellular RNAs of various sizes. RNA sequencing revealed, for the first time, the presence of known Rosaceae mature microRNAs (miRs), also abundant in the stigma source tissue. Predicted targets of the exudate miRs in the Arabidopsis thaliana genome include genes involved in various biological processes. Several of these genes are pollen transcribed, suggesting possible involvement of exudate miRs in transcriptional regulation of the pollen. Moreover, extracellular miRs can potentially act across kingdoms and target genes of stigma interacting organisms/microorganisms, thus opening novel applicative avenues in Horticulture.

Functional Characterization of Eight Zinc Finger Motif-Containing Proteins in Toxoplasma gondii Type I RH Strain Using the CRISPR-Cas9 System.

The Zinc finger protein (ZFP) family is widely distributed in eukaryotes and interacts with DNA, RNA, and various proteins to participate in many molecular processes. In the present study, the biological functions of eight ZFP genes in the lytic cycle and the pathogenicity of Toxoplasma gondii were examined using the CRISPR-Cas9 system. Immunofluorescence showed that four ZFPs (RH248270-HA, RH255310-HA, RH309200-HA, and RH236640-HA) were localized in the cytoplasm, and one ZFP (RH273150-HA) was located in the nucleus, while the expression level of RH285190-HA, RH260870-HA, and RH248450-HA was undetectable. No significant differences were detected between seven RHΔzfp strains (RHΔ285190, RHΔ248270, RHΔ260870, RHΔ255310, RHΔ309200, RHΔ248450, and RHΔ236640) and the wild-type (WT) strain in the T. gondii lytic cycle, including plaque formation, invasion, intracellular replication, and egress, as well as in vitro virulence (p > 0.05). However, the RHΔ273150 strain exhibited significantly lower replication efficiency compared to the other seven RHΔzfp strains and the WT strain, while in vivo virulence in mice was not significantly affected. Comparative expression analysis of the eight zfp genes indicates that certain genes may have essential functions in the sexual reproductive stage of T. gondii. Taken together, these findings expand our current understanding of the roles of ZFPs in T. gondii.

The Transcriptomic Signature of Cyclical Parthenogenesis.

Cyclical parthenogenesis, where females can engage in sexual or asexual reproduction depending on environmental conditions, represents a novel reproductive phenotype that emerged during eukaryotic evolution. The fact that environmental conditions can trigger cyclical parthenogens to engage in distinct reproductive modes strongly suggests that gene expression plays a key role in the origin of cyclical parthenogenesis. However, the genetic basis underlying cyclical parthenogenesis remains understudied. In this study, we characterize the female transcriptomic signature of sexual versus asexual reproduction in the cyclically parthenogenetic microcrustacean Daphnia pulex and Daphnia pulicaria. Our analyses of differentially expressed genes (DEGs), pathway enrichment, and gene ontology (GO) term enrichment clearly show that compared with sexual reproduction, the asexual reproductive stage is characterized by both the underregulation of meiosis and cell cycle genes and the upregulation of metabolic genes. The consensus set of DEGs that this study identifies within the meiotic, cell cycle, and metabolic pathways serves as candidate genes for future studies investigating how the two reproductive cycles in cyclical parthenogenesis are mediated at a molecular level. Furthermore, our analyses identify some cases of divergent expression among gene family members (e.g., doublesex and NOTCH2) associated with asexual or sexual reproductive stage, suggesting potential functional divergence among gene family members.

Reproductive phenology of a dominant crustose coralline alga, Sporolithon sp., from Taoyuan algal reefs in Northwest Taiwan

ABSTRACTSporolithon is a common genus of crustose coralline algae occurring at Taoyuan algal reefs in Northwest Taiwan. However, little is known of the reproductive cycles and growth pattern of the genus in relation to environmental changes. In this study, the asexual and sexual reproductive stages of a dominant species of Sporolithon (Sporolithon sp.) occurring in different seasons were documented in detail for the first time based on collections made from the reefs during 2020–2022. Sexual reproductive structures (spermatangial or carposporangial conceptacles) were found all year round, whereas asexual reproductive structures (tetrasporangial compartments) appeared only in the summer and autumn, when sea surface temperature rose above 25°C. These results suggest that the reproductive cycle of this dominant species of Sporolithon is largely affected by sea surface temperature, which ranged between 13.5 and 31.5°C. Furthermore, the high ratio of sterile thalli found in most seasons suggests that the dominant Sporolithon sp. can thrive in environments having variable temperature by vegetative growth. In addition, almost all old gametophytes of Sporolithon sp. have multiple bands of embedded spermatangial or carposporangial conceptacles (up to six layers), suggesting that Sporolithon sp. is a perennial species. Further investigation into the growth pattern and reproductive cycles for other reef-building crustose coralline species occurring in Taoyuan algal reefs is needed to establish a set of biological baseline data for future conservation plans and guidelines.

Soil-Borne Neosartorya spp.: A Heat-Resistant Fungal Threat to Horticulture and Food Production-An Important Component of the Root-Associated Microbial Community.

Soil-borne Neosartorya spp. are the highly resilient sexual reproductive stage (teleomorph) of Aspergillus spp. Fungi of this genus are relevant components of root-associated microbial community, but they can also excrete mycotoxins and exhibit great resistance to high temperatures. Their ascospores easily transfer between soil and crops; thus, Neosartorya poses a danger to horticulture and food production, especially to the postharvest quality of fruits and vegetables. The spores are known to cause spoilage, mainly in raw fruit produce, juices, and pulps, despite undergoing pasteurization. However, these fungi can also participate in carbon transformation and sequestration, as well as plant protection in drought conditions. Many species have been identified and included in the genus, and yet some of them create taxonomical controversy due to their high similarity. This also contributes to Neosartorya spp. being easily mistaken for its anamorph, resulting in uncertain data within many studies. The review discusses also the factors shaping Neosartorya spp.'s resistance to temperature, preservatives, chemicals, and natural plant extracts, as well as presenting novel solutions to problems created by its resilient nature.

Capitulum Development and Gametophyte Ontogeny: Histological Insight into the Reproductive Process of a Hexaploidy Population of Solidago canadensis in China.

Solidago canadensis L., native to North America, has become a troublesome invasive plant worldwide due to its strong sexual reproductive capacity. Although there have been studies on some stages of sexual reproduction, there has been no systematic description of the process. In this study, we observed capitulum development, the occurrence of megasporogenesis and microsporogenesis, and embryo development using a scanning electron microscope. The results showed that there was a close relationship between the length of the capitulum bud and the stage in the reproductive process. Capitulum development appeared when the length of the capitate inflorescence was less than 1.73 ± 0.08 mm. The meiosis of microspores occurred when the length of the capitate inflorescence ranged from 2.20 ± 0.07 mm to 3.50 ± 0.10 mm, and mature pollen grains and embryo sacs formed when the length of the capitate inflorescence was greater than 5.15 ± 0.14 mm. Based on the available information, a reproductive calendar showing the key reproductive events from capitulum development to seed formation has been prepared. These processes may be related to its inherent temperature adaptation and non-synchronization of flowering, which may avoid embryo abortion during embryo development and consequently as a key step for its successful invasion in China. These results open up new horizons for effective prevention and control of spread in the future.

Northward Expansion of a Warm-Water Doliolid Dolioletta gegenbauri (Uljanin, 1884) into a Temperate Bay, China

A warm-water doliolid species Dolioletta gegenbauri (Uljanin, 1884) was firstly recorded in Jiaozhou Bay (JZB) during the autumn of 2019–2020. As a warm-water species, its native habitat lies in the East China Sea Shelf, >1000 km south of JZB. Distribution, abundance, stage composition, size frequency distribution, and relationships with environmental factors were studied. Both asexual and sexual reproduction stages were observed. Gonozooids generally dominated the population, indicating an active population development status. Abundance was significantly correlated to temperature. Water temperature in the two consecutive years was among the highest levels during the recent 3–4 decades. The continuous warming trends both in the China coastal seas and JZB likely expanded the biogeographic range. The sub branches of a boundary current, the Kuroshio Current, especially the Yellow Sea Warm Current, may play a central role during the northward extension. Moreover, its feeding, growth, reproduction, and recruitment could also be benefited from the neritic food environment. Finally, when the temperature dropped below 15 °C in the early winter, it disappeared in JZB. The seasonal expansion of D. gegenbauri in JZB could be facilitated by current transportation, warming, and the neritic environment.

Label-free based comparative proteomic analysis of Morchella importuna development from the vegetative to the sexual reproductive stages

Morchella spp. are well-known and economically valuable edible mushrooms. The molecular mechanism of development in Morchella fungi is poorly understood, although it can be artificially cultivated. In this paper, the intracellular proteomes of three vegetative growth stages (mycelial, sclerotial initiation and maturation) and two sexual reproductive growth stages (young and mature ascocarp) of M. importuna were analyzed by LC-MS/MS. A total of 2060 credible proteins were identified. Label-free quantitative analysis showed that, consistent with physiological development, the number of differentially expressed proteins increased, which were mainly enriched in carbohydrate and amino acid metabolic pathways by GO and KAAS enrichment analysis. Besides, the categories for upregulated proteins enriched in were more in sexual reproduction stage, especially in the young ascocarp stage, than those in the vegetative growth stage, including aminoacyl-tRNA biosynthesis, histidine, peroxisome, beta-alanine metabolism, etc. In addition, the expression pattern of individual protein (top-20) suggested that the most abundant lectin protein (8.92%) played an important role in the development of M. importuna . This study comprehensively analyzed the whole developmental process of M. importuna at the proteome level, which may help us to better understand its nutrition metabolism and fruiting body development. • Intracellular proteomes of five developmental stages of M. importuna were analyzed. • Three velvet proteins were found and up-regulated in sexual reproductive stages. • A lectin protein (8.92%) was the most abundant and differentially expressed. • An abundant Woronin body major protein (3.02%) was differentially expressed.

Life History of the Diatom Schizostauron trachyderma: Cell Size and Lipid Accumulation

The focus of this study was to determine the mating type of Schizostauron trachyderma and examine the relationship between cell size (life cycle), lipid droplet size, and lipid content among diatoms with similar cell dimensions. To accomplish that, we have chosen monoclonal cultures of two closely related diatom species, namely S. trachyderma and S. rawaii. In a series of experiments, we successfully induced sexual reproduction within S. trachyderma strains to reconstruct the whole cell cycle involving cells of the maximum (initial cells) and minimum viable size for a given species. The mating-type and sexual reproduction stages were described and documented. A unique experimental setting involved initial cell isolation and their lipid droplet examination using flow cytometry and confocal microscopy after Nile Red staining. The results of the series of experiments indicate correlations between cell size, the number of neutral lipids per cell, and the size of lipid droplets, suggesting that cell capacity for lipid accumulation is dependent on their position in the life cycle.

A Transcriptomic Atlas of the Ectomycorrhizal Fungus Laccaria bicolor.

Trees are able to colonize, establish and survive in a wide range of soils through associations with ectomycorrhizal (EcM) fungi. Proper functioning of EcM fungi implies the differentiation of structures within the fungal colony. A symbiotic structure is dedicated to nutrient exchange and the extramatricular mycelium explores soil for nutrients. Eventually, basidiocarps develop to assure last stages of sexual reproduction. The aim of this study is to understand how an EcM fungus uses its gene set to support functional differentiation and development of specialized morphological structures. We examined the transcriptomes of Laccaria bicolor under a series of experimental setups, including the growth with Populus tremula x alba at different developmental stages, basidiocarps and free-living mycelium, under various conditions of N, P and C supply. In particular, N supply induced global transcriptional changes, whereas responses to P supply seemed to be independent from it. Symbiosis development with poplar is characterized by transcriptional waves. Basidiocarp development shares transcriptional signatures with other basidiomycetes. Overlaps in transcriptional responses of L. bicolor hyphae to a host plant and N/C supply next to co-regulation of genes in basidiocarps and mature mycorrhiza were detected. Few genes are induced in a single condition only, but functional and morphological differentiation rather involves fine tuning of larger gene sets. Overall, this transcriptomic atlas builds a reference to study the function and stability of EcM symbiosis in distinct conditions using L. bicolor as a model and indicates both similarities and differences with other ectomycorrhizal fungi, allowing researchers to distinguish conserved processes such as basidiocarp development from nutrient homeostasis.

Spatial and temporal disequilibrium of nuclear distribution in heterothallic Morchella importuna

Our previous study found that isolates from morel stipes showed a large proportion of mating type deletion, which implied the nuclear evolution and spatial heterogeneity. In this paper, the specific mating type genes of Mat1-1-1 and Mat1-2-1 in Morchella importuna were analyzed using the relative quantitative method of qRT-PCR to study the uneven nuclear distribution in morel life cycle. The results demonstrated obvious unbalanced distribution of two karyotypes in tested commercially cultivated strains and stipe issue isolates from cultivated ascocarps. The ratio of two mating type genes in tissue isolates from different parts of the ascocarps (base soil, inside and surface of stipe, inside and outside of cap pit) was also different. The disequilibrium also existed in primordium, young ascocarp and mature ascocarp. Moreover, the imbalance in different positions of mature ascocarp (base of stipe, middle of stipe, junction of stipe and cap, middle of cap, and top of cap) gradually converged from bottom to top with the largest difference in base of stipe and almost equal distribution of two mating types in morel caps, which indicated that the deviation of two kinds of nuclei in sexual reproduction stage slowed down. More than half of the protoplast regenerated strains from the heterokaryotic M04 strain were homokaryotic, with the dominant Mat1-1-1 genotype accounted for 85.7%. Overall, the Mat1-1-1 genotype nucleus dominated in all samples from different stage of the life cycle. The imbalance of nuclear distribution during the life cycle of M. importuna may imply the evolutionary-driven nuclear-level selection. This is the first study of spatial and temporal disequilibrium of nuclear distribution in macro-ascomycetes. For scale cultivation, it is necessary to perform genotype integrity testing in potential cultivated strains to ensure the existence of both mating type genes. • The two mating-type genes representing the karyotypes showed an obvious disequilibrium in the whole life cycle of Morchella importuna. • Serious disequilibrium even appear in tissue isolates, making it necessary to detect the integrity of mating type genes on isolates during spawn production. • The uneven distribution of the karyotype reflects the competition at the nuclear level.

LncRsp1, a long noncoding RNA, influences Fgsp1 expression and sexual reproduction in Fusarium graminearum.

Long noncoding RNAs (lncRNAs) are crucial regulators of gene expression in many biological processes, but their biological functions remain largely unknown, especially in fungi. Fusarium graminearum is an important pathogen that causes the destructive disease Fusarium head blight (FHB) or head scab disease on wheat and barley. In our previous RNA sequencing (RNA‐Seq) study, we discovered that lncRsp1 is an lncRNA that is located +99 bp upstream of a putative sugar transporter gene, Fgsp1, with the same transcription direction. Functional studies revealed that ΔlncRsp1 and ΔFgsp1 were normal in growth and conidiation but had defects in ascospore discharge and virulence on wheat coleoptiles. Moreover, lncRsp1 and Fgsp1 were shown to negatively regulate the expression of several deoxynivalenol (DON) biosynthesis genes, TRI4, TRI5, TRI6, and TRI13, as well as DON production. Further analysis showed that the overexpression of lncRsp1 enhanced the ability of ascospore release and increased the mRNA expression level of the Fgsp1 gene, while lncRsp1‐silenced strains reduced ascospore discharge and inhibited Fgsp1 expression during the sexual reproduction stage. In addition, the lncRsp1 complementary strains lncRsp1‐LC‐1 and lncRsp1‐LC‐2 restored ascospore discharge to the level of the wild‐type strain PH‐1. Taken together, our results reveal the distinct and specific functions of lncRsp1 and Fgsp1 in F. graminearum and principally demonstrate that lncRsp1 can affect the release of ascospores by regulating the expression of Fgsp1.

A novel antisense long non-coding RNA participates in asexual and sexual reproduction by regulating the expression of GzmetE in Fusarium graminearum.

Fusarium graminearum is an important worldwide pathogen that causes Fusarium head blight in wheat, barley, maize and other grains. LncRNAs play important roles in many biological processes, but little is known about their functions and mechanisms in filamentous fungi. Here, we report that a natural antisense RNA, GzmetE-AS, is transcribed from the opposite strand of GzmetE. GzmetE encodes a homoserine O-acetyltransferase, which is important for sexual development and plant infection. The expression of GzmetE-AS was increased significantly during the conidiation stage, while GzmetE was upregulated in the late stage of sexual reproduction. Overexpression of GzmetE-AS inhibited the transcription of GzmetE. In contrast, the expression of GzmetE was significantly increased in GzmetE-AS transcription termination strain GzmetE-AS-T. Furthermore, GzmetE-AS-T produced more perithecia and facilitated the ascospore discharge, resembling the phenotype of GzmetE overexpressing strains. However, overexpression of GzmetE-AS in ∆dcl1/2 strain cannot inhibit the expression of GzmetE, and the GzmetE nat-siRNA is also significantly reduced in ∆dcl1/2 mutant. Taken together, we have identified a novel antisense lncRNA GzmetE-AS, which is involved in asexual and sexual reproduction by regulating its antisense gene GzmetE through RNAi pathway. Our findings reveal that the lncRNA plays critical roles in the development of F. graminearum.