Sexual Reproduction Research Articles

First report of Colletotrichum perseae Causing Anthracnose Disease of Avocado (Persea americana) in Türkiye

Colletotrichum-induced anthracnose is a major disease of avocado (Persea americana), causing significant losses in production worldwide. In 2023, a survey of avocado fruits in markets within the Kızıltepe district of Mardin, Türkiye, revealed symptoms of anthracnose, characterized by brown-black lesions and internal necrosis. To identify the causal agent, 20 symptomatic avocado fruits were collected and fungal isolates resembling Colletotrichum species were obtained. Morphological characterization, multilocus sequence analysis of the internal transcribed spacer (ITS), actin (act), the apn2-Mat1-2 intergenic spacer (ApMat), and calmodulin (cal) loci, and pathogenicity testing were performed for only two representative isolates (Pa01 and Pa02). These analyses identified the pathogen as Colletotrichum perseae. The isolates readily formed ascomata on all culture media tested, suggesting a high capacity for sexual reproduction. Pathogenicity tests confirmed that C. perseae caused characteristic dark, sunken anthracnose lesions on avocado fruits. This is the first report of C. perseae causing anthracnose in avocados in Türkiye, expanding the known geographical distribution of this pathogen. The findings highlight the need for effective disease management strategies and further research to understand the pathogen’s lifecycle, environmental conditions favoring infection, and potential for seedborne transmission.

Imperiled wanderlust lichens in steppe habitats of western North America comprise geographically structured mycobiont lineages and a reversal to sexual reproduction within this asexual clade

The northern North American Cordillera is a globally significant center of endemism. In western North America, imperiled arid steppe habitats support a number of unique species, including several endemic lichens. However, processes driving diversification and endemism in this region remain unclear. In this study, we investigate diversity and phylogeography of the threatened wanderlust lichens (mycobiont = Rhizoplaca species) which occur unattached on calcareous soils in steppe habitats in western North America. Wanderlust lichens comprise three species of lichen-forming fungi (LFF) – Rhizoplaca arbuscula, R. haydenii, and R. idahoensis (endangered, IUCN Red List) – which occur in fragmented populations in Idaho and Wyoming, with more limited populations in southeastern Montana and northern Utah. These lichens reproduce almost exclusively via large, asexual vegetative propagules. Here, our aims were to (i) assess the evolutionary origin of this group and identify phylogeographic structure, (ii) infer ancestral geographic distributions for lineages within this clade, and (iii) use species distribution modeling to better understand the distribution of contemporary populations. Using a genome-skimming approach, we generated a 19.1 Mb alignment, spanning ca. half of the complete LFF genome, from specimens collected throughout the entire range of wanderlust lichens. Based on this phylogeny we investigated phylogeographic patterns using RASP. Finally, we used MaxEnt to estimate species distribution models for R. arbuscula and R. haydenii. We inferred a highly structured topology, with clades corresponding to distinct geographic regions and morphologies represented throughout the group’s distribution. We found that R. robusta, a sexually reproducing taxon, is clearly nested within this asexual lineage. Phylogeographic analyses suggest that both dispersal and vicariance played a significant role throughout the evolutionary history of the vagrant Rhizoplaca clade, with most of the dispersal events originating from the Salmon Basin in eastern Idaho – the center of diversity for this group. Despite the fact that wanderlust lichens are dispersal limited due to large, unspecialized vegetative propagules, we inferred multiple dispersal events crossing the Continental Divide. Comparing herbarium records with SDMs suggests that wanderlust lichens don’t fully occupy the areas of highest distribution probability. In fact, documented records often occur in areas predicted to be only marginally suitable. These data suggest a potential mismatch between contemporary habitats outside of the center of diversity in eastern Idaho with the most suitable habitat, adding to the vulnerability of this imperiled complex of endemic lichens.

The potential for evolutionary rescue in an Arctic seashore plant threatened by climate change.

The impacts of climate change may be particularly severe for geographically isolated populations, which must adjust through plastic responses or evolve. Here, we study an endangered Arctic plant, Primula nutans ssp. finmarchica, confined to Fennoscandian seashores and showing indications of maladaptation to warming climate. We evaluate the potential of these populations to evolve to facilitate survival in the rapidly warming Arctic (i.e. evolutionary rescue) by utilizing manual crossing experiments in a nested half-sibling breeding design. We estimate G-matrices, evolvability and genetic constraints in traits with potentially conflicting selection pressures. To explicitly evaluate the potential for climate change adaptation, we infer the expected time to evolve from a northern to a southern phenotype under different selection scenarios, using demographic and climatic data to relate expected evolutionary rates to projected rates of climate change. Our results indicate that, given the nearly 10-fold greater evolvability of vegetative than of floral traits, adaptation in these traits may take place nearly in concert with changing climate, given effective climate mitigation. However, the comparatively slow expected evolutionary modification of floral traits may hamper the evolution of floral traits to track climate-induced changes in pollination environment, compromising sexual reproduction and thus reducing the likelihood of evolutionary rescue.

Conserved carotenoid pigmentation in reproductive organs of Charophyceae.

Sexual reproduction in Charophyceae abounds in complex traits. Their gametangia develop as intricate structures, with oogonia spirally surrounded by envelope cells and richly pigmented antheridia. The red-probably protectant-pigmentation of antheridia is conserved across Charophyceae. Chara tomentosa is, however, unique in exhibiting this pigmentation and also in vegetative tissue. Here, we investigated the two sympatric species, C. tomentosa and Chara baltica, and compared their molecular chassis for pigmentation. Using reversed phase C30 high performance liquid chromatography (RP-C30-HPLC), we uncover that the major pigments are β-carotene, δ-carotene and γ-carotene; using headspace solid-phase microextraction coupled to gas chromatography equipped with a mass spectrometer (HS-SPME-GC-MS), we pinpoint that the unusually large carotenoid pool in C. tomentosa gives rise to diverse volatile apocarotenoids, including abundant 6-methyl-5-hepten-2-one. Based on transcriptome analyses, we uncover signatures of the unique biology of Charophycaee and genes for pigment production, including monocyclized carotenoids. The rich carotenoid pool probably serves as a substrate for diverse carotenoid-derived metabolites, signified not only by (i) the volatile apocarotenoids we detected but (ii) the high expression of a gene coding for a cytochrome P450 enzyme related to land plant proteins involved in the biosynthesis of carotenoid-derived hormones. Overall, our data shed light on a key protection strategy of sexual reproduction in the widespread group of macroalgae. The genetic underpinnings of this are shared across hundreds of millions of years of plant and algal evolution. This article is part of the theme issue 'The evolution of plant metabolism'.

Zygospore formation in Zygnematophyceae predates several land plant traits.

Recent research on a special type of sexual reproduction and zygospore formation in Zygnematophyceae, the sister group of land plants, is summarized. Within this group, gamete fusion occurs by conjugation. Zygospore development in Mougeotia, Spirogyra and Zygnema is highlighted, which has recently been studied using Raman spectroscopy, allowing chemical imaging and detection of changes in starch and lipid accumulation. Three-dimensional reconstructions after serial block-face scanning electron microscopy (SBF-SEM) or focused ion beam SEM (FIB-SEM) made it possible to visualize and quantify cell wall and organelle changes during zygospore development. The zygospore walls undergo strong modifications starting from uniform thin cell walls to a multilayered structure. The mature cell wall is composed of a cellulosic endospore and exospore and a central mesospore built up by aromatic compounds. In Spirogyra, the exospore and endospore consist of thick layers of helicoidally arranged cellulose fibrils, which are otherwise only known from stone cells of land plants. While starch is degraded during maturation, providing building blocks for cell wall formation, lipid droplets accumulate and fill large parts of the ripe zygospores, similar to spores and seeds of land plants. Overall, data show similarities between streptophyte algae and embryophytes, suggesting that the genetic toolkit for many land plant traits already existed in their shared algal ancestor. This article is part of the theme issue 'The evolution of plant metabolism'.

Identification of Homeobox Transcription Factors in a Dimorphic Fungus Talaromyces marneffei and Protein-Protein Interaction Prediction of RfeB.

Talaromyces marneffei is a thermally dimorphic fungus that can cause life-threatening systemic mycoses, particularly in immunocompromised individuals. Fungal homeobox transcription factors control various developmental processes, including the regulation of sexual reproduction, morphology, metabolism, and virulence. However, the function of homeobox proteins in T. marneffei has not been fully explored. Here, we searched the T. marneffei genome for the total homeobox transcription factors and predicted their biological relevance by performing gene expression analysis in different cell types, including conidia, mycelia, yeasts, and during phase transition. RfeB is selected for further computational analysis since (i) its transcripts were differentially expressed in different phases of T. marneffei, and (ii) this protein contains the highly conserved protein-protein interaction region (IR), which could be important for pathobiology and have therapeutic application. To assess the structure-function of the IR region, in silico alanine substitutions were performed at three-conserved IR residues (Asp276, Glu279, and Gln282) of RfeB, generating a triple RfeB mutated protein. Using 3D modeling and molecular dynamics simulations, we compared the protein complex formation of wild-type and mutated RfeB proteins with the putative partner candidate TmSwi5. Our results demonstrated that the mutated RfeB protein exhibited increased free binding energy, elevated protein compactness, and a reduced number of atomic contacts, suggesting disrupted protein stability and interaction. Notably, our model revealed that the IR residues primarily stabilized the RfeB binding sites located in the central region (CR). This computational approach for protein mutagenesis could provide a foundation for future experimental studies on the functional characterization of RfeB and other homeodomain-containing proteins in T. marneffei.

Inheritance patterns of male asexuality in hybrid males of a water frog Pelophylax esculentus.

Gametogenesis produces gametes as a piece of genetic information transmitted to the offspring. While during sexual reproduction, progeny inherits a mix of genetic material from both parents, asexually reproducing organisms transfer a copy of maternal or paternal DNA to the progeny clonally. Parthenogenetic, gynogenetic and hybridogenetic animals have developed various mechanisms of gametogenesis, however, their inheritance is not fully understood. Here, we focused on the inheritance of asexual gametogenesis in hybrid Pelophylax esculentus (RL), emerging after crosses of P. lessonae (LL) and P. ridibundus (RR). To understand the mechanisms of gametogenesis in hybrids, we performed three-generation experiments of sexual P. ridibundus females and hybrids from all-male hybrid populations. Using fluorescent in situ hybridization, micronuclei analysis, flow cytometry and genotyping, we found that most adult hybrid males simultaneously produced two types of clonal sperm. Also, most male tadpole progeny in two successive backcrossed generations simultaneously eliminated L and R parental genomes, while some progeny produced only one type of sperm. We hypothesize that the reproductive variability of males producing two kinds of sperm is an adaptive mechanism to reproduce in mixed populations with P. ridibundus and may explain the extensive distribution of the all-male lineage across the European River Basin.

The synaptonemal complex aligns meiotic chromosomes by wetting.

During meiosis, the parental chromosomes are drawn together to enable exchange of genetic information. Chromosomes are aligned through the assembly of a conserved interface, the synaptonemal complex, composed of a central region that forms between two parallel chromosomal backbones called axes. Here we identify the axis-central region interface in C. elegans, containing a conserved positive patch on the axis component HIM-3 and the C-terminus of the central region protein SYP-5. Crucially, the canonical ultrastructure of the synaptonemal complex is altered upon weakening this interface. We developed a thermodynamic model that recapitulates our experimental observations, indicating that the liquid-like central region can assemble by wetting the axes without active energy consumption. More broadly, our data show that condensation drives tightly regulated nuclear reorganization during sexual reproduction.

Azolla as a Safe Food: Suppression of Cyanotoxin-Related Genes and Cyanotoxin Production in Its Symbiont, Nostoc azollae.

The floating freshwater fern Azolla is the only plant that retains an endocyanobiont, Nostoc azollae (aka Anabaena azollae), during its sexual and asexual reproduction. The increased interest in Azolla as a potential source of food and its unique evolutionary history have raised questions about its cyanotoxin content and genome. Cyanotoxins are potent toxins synthesized by cyanobacteria which have an anti-herbivore effect but have also been linked to neurodegenerative disorders including Alzheimer's and Parkinson's diseases, liver and kidney failure, muscle paralysis, and other severe health issues. In this study, we investigated 48 accessions of Azolla-Nostoc symbiosis for the presence of genes coding microcystin, nodularin, cylindrospermopsin and saxitoxin, and BLAST analysis for anatoxin-a. We also investigated the presence of the neurotoxin β-N-methylamino-L-alanine (BMAA) in Azolla and N. azollae through LC-MS/MS. The PCR amplification of saxitoxin, cylindrospermospin, microcystin, and nodularin genes showed that Azolla and its cyanobiont N. azollae do not have the genes to synthesize these cyanotoxins. Additionally, the matching of the anatoxin-a gene to the sequenced N. azollae genome does not indicate the presence of the anatoxin-a gene. The LC-MS/MS analysis showed that BMAA and its isomers AEG and DAB are absent from Azolla and Nostoc azollae. Azolla therefore has the potential to safely feed millions of people due to its rapid growth while free-floating on shallow fresh water without the need for nitrogen fertilizers.

Single-nucleus multiomics reveals the gene-regulatory networks underlying sex determination of murine primordial germ cells.

Accurate specification of female and male germ cells during embryonic development is critical for sexual reproduction. Primordial germ cells (PGCs) are the bipotential precursors of mature gametes that commit to an oogenic or spermatogenic fate in response to sex-determining cues from the fetal gonad. The critical processes required for PGCs to integrate and respond to signals from the somatic environment in gonads are not understood. In this study, we developed the first single-nucleus multiomics map of chromatin accessibility and gene expression during murine PGC development in both XX and XY embryos. Profiling of cell-type specific transcriptomes and regions of open chromatin from the same cell captured the molecular signatures and gene networks underlying PGC sex determination. Joint RNA and ATAC data for single PGCs resolved previously unreported PGC subpopulations and cataloged a multimodal reference atlas of differentiating PGC clusters. We discovered that regulatory element accessibility precedes gene expression during PGC development, suggesting that changes in chromatin accessibility may prime PGC lineage commitment prior to differentiation. Similarly, we found that sexual dimorphism in chromatin accessibility and gene expression increased temporally in PGCs. Combining single-nucleus sequencing data, we computationally mapped the cohort of transcription factors that regulate the expression of sexually dimorphic genes in PGCs. For example, the gene regulatory networks of XX PGCs are enriched for the transcription factors, TFAP2c, TCFL5, GATA2, MGA, NR6A1, TBX4, and ZFX. Sex-specific enrichment of the forkhead-box and POU6 families of transcription factors was also observed in XY PGCs. Finally, we determined the temporal expression patterns of WNT, BMP, and RA signaling during PGC sex determination, and our discovery analyses identified potentially new cell communication pathways between supporting cells and PGCs. Our results illustrate the diversity of factors involved in programming PGCs towards a sex-specific fate.

Invasion stage and competition intensity co-drive reproductive strategies of native and invasive saltmarsh plants: Evidence from field data

Biological invasion poses a significant threat to biodiversity conservation and also results in substantial economic loss including the excessive cost of management to control it. Still, its impact on plant sexual reproduction strategies remains underexplored in natural settings. We conducted a field experiment on native Phragmites australis and invasive Spartina alterniflora in Bohai Bay and assessed plant size (aboveground biomass and height) and sexual reproduction (ear biomass, reproductive allocation, etc.) in conjunction with water and soil properties. The results showed that during the early stage of invasion, the two species declined in size and sexual reproduction, with S. alterniflora showing a lesser decline than P. australis. However, in the late stage of invasion, S. alterniflora maintained its plant size by reducing its investment in sexual reproduction. Moreover, significant reproductive allometries were demonstrated by S. alterniflora under different competition intensities. P. australis displayed heightened sensitivity to water properties and soil non-resource conditions, while S. alterniflora adapted its inherent traits and environmental tolerance. S. alterniflora allocated more resources to thriving as an individual, while P. australis prioritized reproduction by increasing seed production. Overall, this study revealed the reproductive strategies that invasive and native species employ in response to competition and environmental factors, thereby offering crucial insights for conservation and management efforts.

Replacing sperm with genotyped haploid androgenetic blastomeres to generate cattle with predetermined paternal genomes

Abstract Although meiosis plays an essential role for the survival of species in natural selection, the genetic diversity resulting from sexual reproduction impedes human-driven strategies to transmit the most suitable genomes for genetic improvement, forcing breeders to select diploid genomes generated after fertilization, that is, after the encounter of sperm and oocytes carrying unknown genomes. To determine whether genomic assessment could be used before fertilization, some androgenetic haploid morula-stage bovine embryos derived from individual sperm were biopsied for genomic evaluation and others used to reconstruct “semi-cloned” (SC) diploid zygotes by the intracytoplasmic injection into parthenogenetically activated oocytes, and the resulting embryos were transferred to surrogate females to obtain gestations. Compared to controls, in vitro development to the blastocyst stage was lower and fewer surrogates became pregnant from the transfer of SC embryos. However, fetometric measurements of organs and placental membranes of all SC conceptuses were similar to controls, suggesting a normal post-implantation development. Moreover, transcript amounts of imprinted genes IGF2, IGF2R, PHLDA2, SNRPN and KCNQ1OT1 and methylation pattern of the KCNQ1 DMR were unaltered in SC conceptuses. Overall, this study shows that sperm can be replaced by genotyped haploid embryonic-derived cells to produce bovine embryos carrying a predetermined paternal genome and viable first trimester fetuses after transfer to female recipients.

Evolution of unexpected diversity in a putative mating type locus and its correlation with genome variability reveals likely asexuality in the model mycorrhizal fungus Rhizophagus irregularis

BackgroundArbuscular mycorrhizal fungi (AMF) form mutualistic partnerships with approximately 80% of plant species. AMF, and their diversity, play a fundamental role in plant growth, driving plant diversity, and global carbon cycles. Knowing whether AMF are sexual or asexual has fundamental consequences for how they can be used in agricultural applications. Evidence for and against sexuality in the model AMF, Rhizophagus irregularis, has been proposed. The discovery of a putative mating-type locus (MAT locus) in R. irregularis, and the previously suggested recombination among nuclei of a dikaryon R. irregularis isolate, potentially suggested sexuality. Unless undergoing frequent sexual reproduction, evolution of MAT-locus diversity is expected to be very low. Additionally, in sexual species, MAT-locus evolution is decoupled from the evolution of arbitrary genome-wide loci.ResultsWe studied MAT-locus diversity of R. irregularis. This was then compared to diversification in a phosphate transporter gene (PTG), that is not involved in sex, and to genome-wide divergence, defined by 47,378 single nucleotide polymorphisms. Strikingly, we found unexpectedly high MAT-locus diversity indicating that either it is not involved in sex, or that AMF are highly active in sex. However, a strongly congruent evolutionary history of the MAT-locus, PTG and genome-wide arbitrary loci allows us to reject both the hypothesis that the MAT-locus is involved in mating and that the R. irregularis lineage is sexual.ConclusionOur finding shapes the approach to developing more effective AMF strains and is highly informative as it suggests that introduced strains applied in agriculture will not exchange DNA with native populations.

Rare occurrence of only female flowers suggests a lack of sexual reproduction and potential clonality of the seagrass Halophila baillonii Asch. on the Pacific coast of Costa Rica

Halophila baillonii Asch. is a rare seagrass species found in the Caribbean, Atlantic, and Eastern Tropical Pacific (ETP). It is listed as Vulnerable in the IUCN Red List yet very little is known about its dispersal mechanisms. For this study, samples were collected at five sites on the Pacific coast of Costa Rica. Each site was visited once between 2019 and 2021 as part of a larger molecular study. At each site, H. baillonii foliar shoots were manually collected along three transects. Presence of flowers or fruits was assessed for 1292 foliar shoots using a dissecting microscope. Additionally, sediment samples were collected to assess seed density at three of the sites. Flowering frequency was very low overall (0.7 %), flowers were only found at two of the five sites, and only female flowers were present. There were no fruits or seeds at any of the sites. This is the first report of H. baillonii flowering on the Pacific coast of Costa Rica and within the ETP. Meanwhile, H. baillonii flowers of both sexes and fruits have been found from limited sampling efforts at multiple sites in the Caribbean and Brazil. The findings of this study suggest a lack of sexual reproduction and potential clonality of the seagrass H. baillonii on the Pacific coast of Costa Rica. This supports the recent notion that H. baillonii is the first non-native seagrass in the ETP, yet more detailed field and molecular studies are needed.

Assisted sexual coral recruits show high thermal tolerance to the 2023 Caribbean mass bleaching event.

Assisted sexual coral propagation, resulting in greater genet diversity via genetic recombination, has been hypothesized to lead to more adaptable and, hence, resilient restored populations compared to more common clonal techniques. Coral restoration efforts have resulted in substantial populations of 'Assisted sexual Recruits' (i.e., juvenile corals derived from assisted sexual reproduction; AR) of multiple species outplanted to reefs or held in in situ nurseries across many locations in the Caribbean. These AR populations provided context to evaluate their relative resilience compared to co-occurring coral populations during the 2023 marine heat wave of unprecedented duration and intensity that affected the entire Caribbean. Populations of six species of AR, most ranging in age from 1-4 years, were surveyed across five regions during the mass bleaching season in 2023 (Aug-Dec), alongside co-occurring groups of corals to compare prevalence of bleaching and related mortality. Comparison groups included conspecific adult colonies as available, but also the extant co-occurring coral assemblages in which conspecifics were rare or lacking, as well as small, propagated coral fragments. Assisted sexual recruits had significantly lower prevalence of bleaching impacts (overall pooled ~ 10%) than conspecific coral populations typically comprised of larger colonies (~ 60-100% depending on species). In addition, small corals derived from fragmentation (rather than sexual propagation) in two regions showed bleaching susceptibility intermediate between AR and wild adults. Overall, AR exhibited high bleaching resistance under heat stress exposure up to and exceeding Degree Heating Weeks of 20°C-weeks. As coral reefs throughout the globe are subject to increasingly frequent and intense marine heatwaves, restoration activities that include sexual reproduction and seeding can make an important contribution to sustain coral populations.

Steroidogenic differentiation of human amniotic membrane-derived mesenchymal stem cells into a progesterone-/androgen-producing cell lineage by SF-1 and an estrogen-producing cell lineage by WT1-KTS.

Sex steroid hormones, primarily synthesized by gonadal somatic cells, are pivotal for sexual development and reproduction. Mice studies have shown that two transcription factors, steroidogenic factor 1 (SF-1) and Wilms' tumor 1 (WT1), are involved in gonadal development. However, their role in human gonadal somatic differentiation remains unclear. We therefore aimed to investigate the roles of SF-1 and WT1 in human gonadal steroidogenic cell differentiation. Using a transient lentivirus-mediated gene expression system, we assessed the effects of SF-1 and WT1 expression on the steroidogenic potential of human amniotic membrane-derived mesenchymal stem cells (hAmMSCs). SF-1 and WT1-KTS, a splice variant of WT1, played distinct roles in human steroidogenic differentiation of hAmMSCs. SF-1 induced hAmMSC differentiation into progesterone- and androgen-producing cell lineages, whereas WT1-KTS promoted hAmMSC differentiation into estrogen-producing cell lineages. Our findings revealed that SF-1 and WT1-KTS play important roles in human gonadal steroidogenic cell differentiation, especially during ovarian development. These findings may pave the way for future studies on human ovarian differentiation and development.

Actomyosin contraction in the follicular epithelium provides the major mechanical force for follicle rupture during Drosophila ovulation

Ovulation is critical for sexual reproduction and consists of the process of liberating fertilizable oocytes from their somatic follicle capsules, also known as follicle rupture. The mechanical force for oocyte expulsion is largely unknown in many species. Our previous work demonstrated that Drosophila ovulation, as in mammals, requires the proteolytic degradation of the posterior follicle wall and follicle rupture to release the mature oocyte from a layer of somatic follicle cells. Here, we identified actomyosin contraction in somatic follicle cells as the major mechanical force for follicle rupture. Filamentous actin (F-actin) and nonmuscle myosin II (NMII) are highly enriched in the cortex of follicle cells upon stimulation with octopamine (OA), a monoamine critical for Drosophila ovulation. Pharmacological disruption of F-actin polymerization prevented follicle rupture without interfering with the follicle wall breakdown. In addition, we demonstrated that OA induces Rho1 guanosine triphosphate (GTP)ase activation in the follicle cell cortex, which activates Ras homolog (Rho) kinase to promote actomyosin contraction and follicle rupture. All these results led us to conclude that OA signaling induces actomyosin cortex enrichment and contractility, which generates the mechanical force for follicle rupture during Drosophila ovulation. Due to the conserved nature of actomyosin contraction, this work could shed light on the mechanical force required for follicle rupture in other species including humans.

Viral gene drive spread during herpes simplex virus 1 infection in mice

Gene drives are genetic modifications designed to propagate efficiently through a population. Most applications rely on homologous recombination during sexual reproduction in diploid organisms such as insects, but we recently developed a gene drive in herpesviruses that relies on co-infection of cells by wild-type and engineered viruses. Here, we report on a viral gene drive against human herpes simplex virus 1 (HSV-1) and show that it propagates efficiently in cell culture and during HSV-1 infection in mice. We describe high levels of co-infection and gene drive-mediated recombination in neuronal tissues during herpes encephalitis as the infection progresses from the site of inoculation to the peripheral and central nervous systems. In addition, we show evidence that a superinfecting gene drive virus could recombine with wild-type viruses during latent infection. These findings indicate that HSV-1 achieves high rates of co-infection and recombination during viral infection, a phenomenon that is currently underappreciated. Overall, this study shows that a viral gene drive could spread in vivo during HSV-1 infection, paving the way toward therapeutic applications.

Does decline and recovery process affect clonal and genetic diversity of a coastal plant population?

The evaluation of genetic diversity is important for the conservation of species. However, changes in genetic diversity during conservation are complex processes that depend on the characteristics of the species and environment. To evaluate the changes in genetic diversity from decline to recovery, we surveyed the coastal herb Calystegia soldanella in areas with varying degrees of non‐coastal plant invasion. First, to evaluate genetic diversity before the conservation measures, the spatial clonal structure of adults was investigated in a population invaded by non‐coastal plants. Second, to evaluate genetic diversity after the conservation measures, the regenerated individuals were investigated in the restoration plot. Moreover, to predict future genetic diversity without conservation measures, the effects of non‐coastal plant invasion on the production and genetic diversity of seeds were investigated using individuals from areas with various levels of non‐coastal plant invasion. In the adult population, 16 genets were identified in an 80 m × 4 m area. The maximum genet size was 30.3 m, suggesting the importance of clonal reproduction for population maintenance. In the restoration plots comprising 10 m × 10 m × 3 replicates, many seedlings (1.14 ramets/m2) emerged, resulting in high clonal diversity compared to that of the adult population. Therefore, the biomass and genetic diversity were rapidly restored at the beginning of the conservation practice. Non‐coastal plant invasion did not affect the genetic diversity of the seeds. However, it significantly reduced seed production. This suggests that non‐coastal plant invasion reduces sexual reproduction, resulting in the long‐term loss of genetic diversity.

Cassava breeding: Classical to recent breeding approaches for food, industry and climate resilience

Cassava ranks as the fourth-most significant starchy root crop in underdeveloped countries in terms of future food and acting as a key source of income for small and marginal farmers. To meet the growing demands for food security and economic development, it is imperative to develop improved cassava varieties that offer higher yields, enhanced nutritional content, safer for consumption, greater resistance to diseases and climate change. The development of these improved varieties necessitates advancements in breeding techniques, leveraging both traditional methods and modern biotechnological tools. However, a major challenge in cassava breeding is heterozygous nature and the crop’s sparse flowering, which limits the potential for sexual reproduction, thereby constraining breeding efforts for predominantly clonal selection. The continuous clonal propagation impedes genetic diversity and the introduction of novel traits, narrowing the overall progress of breeding programs. Integrating genomic tools and accelerating the adoption of biotechnological advancements can overcome these limitations and expedite the development of superior cassava varieties. This review highlights the need of cassava breeding for addressing these challenges with conventional as well as with new breeding techniques with the aim to provide a comprehensive understanding of the current scenario and future directions of cassava breeding research. Key words: Climate change, CRISPR/Cas 9, New breeding techniques, PPD, speed breeding, Waxy cassava