Sexual Crosses Research Articles

Variation in pollen viability among Leptochloa crinita accessions: implications for directed crosses

ABSTRACT Leptochloa crinita, a native forage grass from American arid regions, is widely used for range grazing and revegetation of degraded lands. Despite its importance, progress in breeding and genetic research has been hindered by the difficulty of achieving sexual crosses between L. crinita plants. We hypothesize that factors associated with pollen quality can influence the effectiveness of directed sexual crosses in this species. Thus, the present study investigated pollen viability and longevity in a genetically diverse collection of 21 L. crinita accessions. Pollen viability was estimated at 0, 30, 60, and 180 minutes after anthers dehiscence (MAAD) by two methods: 1) acetocarmine staining; and 2) in vitro germination of pollen grains in culture media containing 0.4-1.0 M sucrose. The staining method overestimated pollen viability, whereas the in vitro germination assay provided accurate and reliable estimates, being 0.6 M the optimal sucrose concentration in the medium, in terms of germination rates and discriminatory power among the accessions. In all the accessions, pollen viability was highest at 0-30 MAAD, and decayed very rapidly, to reach levels below 5% at 180 MAAD. Significant (p<0.05) and broad variation for pollen viability was found among the accessions, with mean values in the range of 49-89% (0 MAAD), 32-76% (30 MAAD), 24-45% (60 MAAD), and 0.6-4.9% (180 MAAD), allowing the identification of six accessions exhibiting the greatest pollen viabilities. These results suggest 0-30 MAAD and using the selected (best) pollen donors, on emasculated female parentals, as the optimal conditions for attempting sexual crosses in L. crinita.

Location and timing govern tripartite interactions of fungal phytopathogens and host in the stem canker species complex

BackgroundLeptosphaeria maculans “brassicae” (Lmb) and Leptosphaeria biglobosa “brassicae” (Lbb) make up a species complex involved in the stem canker (blackleg) disease of rapeseed (Brassica napus). They coinfect rapeseed together, from the early stage of infection on leaves to the final necrotic stage at the stem base, and both perform sexual crossings on plant residues. L. biglobosa is suggested to be a potential biocontrol agent against Lmb, but there has been no mechanistic investigation of the different types of interactions that may occur between the plant and the two fungal species.ResultsWe investigated the bi- or tripartite interaction mechanisms by (i) confronting Lmb and Lbb in culture conditions or during cotyledon infection, with different timing and/or spore concentration regimes, (ii) performing RNA-Seq experiments in vitro or on the kinetics of infection of cotyledons infected by Lmb and/or Lbb to evaluate the transcriptomic activity and the plant response when both fungal species are inoculated together. Lbb infection of B. napus cotyledons was typical of a necrotrophic behavior, with a very early setup of one pathogenicity program and very limited colonization of tissues. This contrasted with the complex succession of pathogenicity programs of the hemibiotroph Lmb. During simultaneous co-infection by both species, Lmb was strongly impacted in its growth and transcriptomic dynamics both in vitro and in planta, while Lbb was unaffected by the presence of Lmb. However, the drastic inhibition of Lmb growth by Lbb was ineffective in the case of delayed inoculation with Lbb or a lower amount of spores of Lbb compared to Lmb.ConclusionsOur data suggest that Lmb growth inhibition by Lbb is the result of a combination of factors that may include competition for trophic resources, the generation by Lbb of an environment unsuitable for the lifecycle of Lmb or/and the effect on Lmb of plant defense responses induced by Lbb. It indicates that growth inhibition occurs in very specific conditions (i.e., co-inoculation at the same place of an equal amount of inoculum) that are unlikely to occur in the field where their coexistence does not prevent any species from completing their life cycle.

Integrated metabolomics and transcriptomics reveals difference involved in flavonoid and indole alkaloids biosynthesis in potato tuber flesh

Colored potatoes have garnered attention due to their higher nutrients compared to regular potatoes. This study describes a combined transcriptomic and metabolomic analysis of potato tubers originating from a single sexual cross between two parents with differing tuber skin and flesh colors. Through the use of RNA-seq, and UPLC-MS/MS metabolomics, this study aimed to elucidate the genetic and metabolic variations involved in the transmission of traits from tetraploid potato parents to hybrid F1 offspring. Our analysis revealed unique genes and metabolites associated with flavonoids and alkaloids within each group of offspring. Phenolic acids, flavonoids, and alkaloids are highlighted as key contributors to the positive heterosis observed in the tubers of potato hybrids, as assessed by calculating mid-parent heterosis for metabolites in three potato hybrids. At the overall metabolites level, hybrid SB (red-skinned and red-fleshed) exhibited a higher mid-parent heterosis than hybrid SA (purple-skinned and purple-fleshed) and SC (yellow-skinned and yellow-fleshed). Within hybrid SB tuber, specific accumulations of luteolin, salicin, isovitexin, and esculeoside B-5 were identified. Moreover, co-expression networks and correlation analysis pinpoint genes related to flavonoid and alkaloid biosynthesis. Notably, StDFR (dihydroflavonol reductase), a gene involved in flavonoid synthesis in potato tuber flesh, exhibits heightened expression in colored potato flesh. Additionally, we identified StYUCCA (indole-3-pyruvate monooxygenase), a gene regulating indole alkaloids synthesis, with elevated expression in yellow potato flesh. These findings provide insights into the utilization of heterosis breeding and the regulation of genes-metabolites in colored potato tuber flesh.

Screening and optimisation of in vitro pollen germination medium for sweetpotato (Ipomoea batatas)

BackgroundSweetpotato is an important vegetable and food crop that is bred through sexual crosses and systematic selection. The use of in vitro germination of sweetpotato pollen to test its viability has important theoretical and practical implications for improving the efficiency of sweetpotato crossbreeding by controlling pollination and conducting research on sweetpotato pollen biology.ResultsIn this study, we observed the morphological structure of sweetpotato pollen under a scanning electron microscope (SEM), developed an effective method for the in vitro germination of sweetpotato pollen, and examined the viability of sweetpotato pollen after treating plants at different temperatures before blossoming. Sweetpotato pollen grains are spherical, with an average diameter of 87.07 ± 3.27 μm (excluding spines), with multiple germination pores and reticulate pollen surface sculpture. We applied numerous media to sweetpotato pollen germination in vitro to screen the initial medium and optimised the medium components through single-factor design. The most effective liquid medium for in vitro sweetpotato pollen germination contained 50 g/L Sucrose, 50 g/L Polyethylene glycol 4000 (PEG4000), 100 mg/L Boric acid and 300 mg/L Calcium nitrate, with a pH = 6.0. The optimum growth temperature for pollen development in sweetpotato was from 25 to 30 °C. Neither staining nor in situ germination could accurately determine the viability of sweetpotato pollen.ConclusionsIn vitro germination can be used to effectively determine sweetpotato pollen viability. The best liquid medium for in vitro germination of sweetpotato pollen contained 50 g/L Sucrose, 50 g/L Polyethylene glycol 4000 (PEG4000), 100 mg/L Boric acid and 300 mg/L Calcium nitrate, with the pH adjusted to 6.0. This study provides a reliable medium for the detection of sweetpotato pollen viability, which can provide a theoretical reference for sweetpotato genetics and breeding.

Horizontally Transferred DNA in the Genome of the Fungus Pyricularia oryzae is Associated With Repressive Histone Modifications.

Horizontal gene transfer (HGT) is a means of exchanging genetic material asexually. The process by which horizontally transferred genes are domesticated by the host genome is of great interest but is not well understood. In this study, we determined the telomere-to-telomere genome sequence of the wheat-infecting Pyricularia oryzae strain Br48. SNP analysis indicated that the Br48 strain is a hybrid of wheat- and Brachiaria-infecting strains by a sexual or parasexual cross. Comparative genomic analysis identified several megabase-scale "insertions" in the Br48 genome, some of which were possibly gained by HGT-related events from related species, such as P. pennisetigena or P. grisea. Notably, the mega-insertions often contained genes whose phylogeny is not congruent with the species phylogeny. Moreover, some of the genes have a close homolog even in distantly related organisms, such as basidiomycetes or prokaryotes, implying the involvement of multiple HGT events. Interestingly, the levels of the silent epigenetic marks H3K9me3 and H3K27me3 in a genomic region tended to be negatively correlated with the phylogenetic concordance of genes in the same region, suggesting that horizontally transferred DNA is preferentially targeted for epigenetic silencing. Indeed, the putative HGT-derived genes were activated when MoKmt6, the gene responsible for H3K27me3 modification, was deleted. Notably, these genes also tended to be up-regulated during infection, suggesting that they are now under host control and have contributed to establishing a fungal niche. In conclusion, this study suggests that epigenetic modifications have played an important role in the domestication of HGT-derived genes in the P. oryzae genome.

Human adaptation and diversification in the Microsporum canis complex.

The Microsporum canis complex consists of one zoophilic species, M. canis, and two anthropophilic species, M. audouinii and M. ferrugineum. These species are the most widespread zoonotic pathogens causing dermatophytosis in cats and humans worldwide. To clarify the evolutionary relationship between the three species and explore the potential host shift process, this study used phylogenetic analysis, population structure analysis, multispecies coalescent analyses, determination of MAT idiomorph distribution, sexual crosses, and macromorphology and physicochemical features to address the above questions. The complex of Microsporum canis, M. audouinii and M. ferrugineum comprises 12 genotypes. MAT1-1 was present only in M. canis, while the anthropophilic entities contained MAT1-2. The pseudocleistothecia were yielded by the mating behaviour of M. canis and M. audouinii. Growth rates and lipase, keratinolysis and urea hydrolytic capacities of zoophilic M. canis isolates were all higher than those of anthropophilic strains; DNase activity of M. ferrugineum exceeded that of M. canis. The optimum growth temperature was 28°C, but 22°C favoured the development of macroconidia. Molecular data, physicochemical properties and phenotypes suggest the adaptation of zoophilic M. canis to anthropophilic M. ferrugineum, with M. audouinii in an intermediate position.

Current insights and advances into plant male sterility: new precision breeding technology based on genome editing applications.

Plant male sterility (MS) represents the inability of the plant to generate functional anthers, pollen, or male gametes. Developing MS lines represents one of the most important challenges in plant breeding programs, since the establishment of MS lines is a major goal in F1 hybrid production. For these reasons, MS lines have been developed in several species of economic interest, particularly in horticultural crops and ornamental plants. Over the years, MS has been accomplished through many different techniques ranging from approaches based on cross-mediated conventional breeding methods, to advanced devices based on knowledge of genetics and genomics to the most advanced molecular technologies based on genome editing (GE). GE methods, in particular gene knockout mediated by CRISPR/Cas-related tools, have resulted in flexible and successful strategic ideas used to alter the function of key genes, regulating numerous biological processes including MS. These precision breeding technologies are less time-consuming and can accelerate the creation of new genetic variability with the accumulation of favorable alleles, able to dramatically change the biological process and resulting in a potential efficiency of cultivar development bypassing sexual crosses. The main goal of this manuscript is to provide a general overview of insights and advances into plant male sterility, focusing the attention on the recent new breeding GE-based applications capable of inducing MS by targeting specific nuclear genic loci. A summary of the mechanisms underlying the recent CRISPR technology and relative success applications are described for the main crop and ornamental species. The future challenges and new potential applications of CRISPR/Cas systems in MS mutant production and other potential opportunities will be discussed, as generating CRISPR-edited DNA-free by transient transformation system and transgenerational gene editing for introducing desirable alleles and for precision breeding strategies.

Occurrence of Goniozus legneri (Hymenoptera: Bethylidae) and its association to lepidopteran pests in Northern cultivated oasis of Mendoza province, Argentina

Goniozus legneri Gordh (Hymenoptera: Bethylidae) is a larval ectoparasitoid of lepidopterans, with a worldwide history as a biocontrol agent of various agricultural pests. By means of extensive monitoring, this wasp was found in four distant districts of Mendoza province parasitizing three lepidopteran pests: Lobesia botrana (Den. et Shiff.) in grapevine, Ectomyelois ceratoniae (Zeller) in walnut and “espinillo” (Vachellia caven (Molina) Seigler et Ebinger) and Cydia pomonella (L.) in walnut. To corroborate the parasitoid species identification and to analyze its population viability in this region, studies of male genitalia and sexual crossings between wild and laboratory-reared wasps were conducted. Further, we report for the first time the natural host-parasitoid interaction of L. botrana with this parasitoid in vineyards from Argentina.

Epiphytic proliferation of Zymoseptoria tritici isolates on resistant wheat leaves

The wheat pathogen Zymoseptoria tritici is capable of a long period of pre-invasive epiphytic growth. Studies have shown that virulent isolates vary in the extent, duration and growth form of this epiphytic growth, and the fungus has been observed to undergo behaviours such as asexual reproduction by budding and vegetative fusion of hyphae on the leaf surface. This epiphytic colonisation has been investigated very little during interactions in which an isolate of Z. tritici is unable to colonise the apoplast, as occurs during avirulence. However, avirulent isolates have been seen to undergo sexual crosses in the absense of leaf penetration, and it is widely accepted that the main point of distinction between virulent and avirulent isolates occurs at the point of attempted leaf penetration or attempted apoplastic growth, which fails in the avirulent case. In this work, we describe extensive epiphytic growth in three isolates which are unable or have very limited ability to invade the leaf, and show that growth form is as variable as for fully virulent isolates. We demonstrate that during certain interactions, Z. tritici isolates rarely invade the leaf and form pycnidia, but induce necrosis. These isolates are able to achieve higher epiphytic biomass than fully virulent isolates during asymptomatic growth, and may undergo very extensive asexual reproduction on the leaf surface. These findings have implications for open questions such as whether and how Z. tritici obtains nutrients on the leaf surface and the nature of its interaction with wheat defences.

Mitochondrial Inner Membrane ABC Transporter Bcmdl1 Is Involved in Conidial Germination, Virulence, and Resistance to Anilinopyrimidine Fungicides in Botrytis cinerea.

Botrytis cinerea causes gray mold on thousands of plants, leading to huge losses in production. Anilinopyrimidine (AP) fungicides have been applied to control B. cinerea since the 1990s. Although resistance to AP fungicides was detected soon after their application, the mechanism of AP resistance remains to be elucidated. In this study, a sexual cross between resistant and sensitive isolates was performed, and the genomes of parental isolates and progenies were sequenced to identify resistance-related single nucleotide polymorphisms (SNPs). After screening and verification, mutation E407K in the Bcmdl1 gene was identified and confirmed to confer resistance to AP fungicides in B. cinerea. Bcmdl1 was predicted to encode a mitochondrial protein that belonged to a half-type ATP-binding cassette (ABC) transporter. Although Bcmdl1 was a transporter, it did not mediate resistance to multiple fungicides but mediated resistance specifically to AP fungicides. On the other hand, reductions in conidial germination and virulence were observed in Bcmdl1 knockout transformants compared to the parental isolate and complemented transformants, illustrating the biological functions of Bcmdl1. Subcellular localization analysis indicated that Bcmdl1 was localized in mitochondria. Interestingly, the production of ATP was reduced after cyprodinil treatment in Bcmdl1 knockout transformants, suggesting that Bcmdl1 was involved in ATP synthesis. Since Mdl1 could interact with ATP synthase in yeast, we hypothesize that Bcmdl1 forms a complex with ATP synthase, which AP fungicides might target, thereby interfering with the metabolism of energy. IMPORTANCE Gray mold, caused by B. cinerea, causes huge losses in the production of many fruits and vegetables. AP fungicides have been largely adopted to control this disease since the 1990s, and the development of resistance to AP fungicides initiates new problems for disease control. Due to the unknown mode of action, information on the mechanism of AP resistance is also limited. Recently, mutations in mitochondrial genes were reported to be related to AP resistance. However, the mitochondrial process of these genes remains to be elucidated. In this study, we identified several AP resistance-related mutations by quantitative trait locus sequencing (QTL-seq) and confirmed that mutation E407K in Bcmdl1 conferred AP resistance. We further characterized the expression patterns, biological functions, subcellular localization, and mitochondrial processes of the Bcmdl1 gene. This study deepens our understanding of the mechanism of resistance to and mode of action of AP fungicides.

Reacting to Non-Prototypical Victims: Blame, Empathy, and Willingness to Label Sexual Assaults of Men and Sexual Minority Victims.

Sexual assault is prevalent in the U.S. society, with an estimated 16% of women and 8% of men experiencing some form of sexual violence during their lifetime (Breiding, 2014). Sexual violence crosses all identity lines; however, legislation, cultural representation, and academic scholarship on sexual violence has historically been limited to assaults against women perpetrated by men. This dominant analysis of sexual assault focuses on the impact of sexism on sexual violence, neglecting the impact off other forms of oppression and attitudes related to sexuality and gender. This dominant representation leaves non-prototypical victims, such as men, people of other genders, and sexual minorities of all genders, less visible and less understood. This underrepresentation may lead to negative reactions toward these victims including blame, exoneration of the perpetrator, and reluctance to acknowledge assaults. In the current study, I explored the impact of both victim gender and sexual orientation on reactions to a hypothetical intimate partner sexual assault victim. Results indicated that perpetrators who assaulted a man were blamed less than those who assaulted a woman. Furthermore, study participants had more empathy for women who were assaulted than they did for men. There were no differences in participants' negative reactions to victims by sexual orientation. Results suggest that, while some advances have been made in public support for sexual assault victims, these advances may not extend yet to men as victims.

Multiple scenarios for sexual crosses in the fungal pathogen Zymoseptoria tritici on wheat residues: Potential consequences for virulence gene transmission

Little is known about the impact of host immunity on sexual reproduction in fungal pathogens. In particular, it is unclear whether crossing requires both sexual partners to infect living plant tissues. We addressed this issue in a three-year experiment investigating different scenarios of Zymoseptoria tritici crosses according to the virulence (‘vir’) or avirulence (‘avr’) of the parents against a qualitative resistance gene. Co-inoculations (‘vir × vir’, ‘avr × vir’, ‘avr × avr’) and single inoculations were performed on a wheat cultivar carrying the Stb16q resistance gene (Cellule) and a susceptible cultivar (Apache), in the greenhouse. We assessed the intensity of asexual reproduction by scoring disease severity, and the intensity of sexual reproduction by counting the ascospores discharged from wheat residues. As expected, disease severity was more intense on Cellule for ‘vir × vir’ co-inoculations than for ‘avr × vir’ co-inoculations, with no disease for ‘avr × avr’. However, all types of co-inoculation yielded sexual offspring, whether or not the parental strains caused plant symptoms. Parenthood was confirmed by genotyping (SSR markers), and the occurrence of crosses between (co-)inoculated and exogenous strains (other strains from the experiment, or from far away) was determined. We showed that symptomatic asexual infection was not required for a strain to participate in sexual reproduction, and deduced from this result that avirulent strains could be maintained asymptomatically “on” or “in” leaf tissues of plants carrying the corresponding resistant gene for long enough to reproduce sexually. In two of the three years, the intensity of sexual reproduction did not differ between the three types of co-inoculation in Cellule, suggesting that crosses involving avirulent strains are not anecdotal. We discuss the possible mechanisms explaining the maintenance of avirulence in Z. tritici populations and the potential impact of particular resistance deployments such as cultivar mixtures for limiting resistance breakdown.

Recovering triploid citrus hybrids from 2x × 2x sexual crosses with the aid of embryo rescue and flow cytometry in Turkey.

Turkey is one of the major exporters of mandarins in the Mediterranean region. Seedlessness in citrus, which is one of the most desired fruit quality traits, especially in fresh mandarin export markets, can be obtained via triploidy as in many fruit species. Triploid plants can be recovered by 2x × 2x hybridizations in citrus, as well as 2x × 4x and 4x × 2x crosses. Hence, we aimed to develop local triploid hybrids by using the embryo rescue technique in five crosses using eight different citrus varieties in the present study. Embryos isolated from abortive seeds derived by 135days after pollinations were cultured on modified Murashige and Tucker (MT) medium by adding different levels of GA3 to achieve a high germination rate. A population of 574 plants was developed as a result of embryo rescue. After screening the ploidy levels of this 574-plant population with the aid of flow cytometry, 4 triploids from 'Encore' × 'Murcott', 8 triploids from 'Fortune' ×'Willow leaf', 1 triploid from 'Kiyomi' × 'Murcott', and 1 triploid from 'Ortanique' × 'Murcott' hybridization were recovered. Triploid hybrid plants and related parents were analyzed with SSR markers heterozygotic for parental mandarin varieties. In addition, we evaluated stomatal characteristics of diploid and triploid hybrids obtained from different crosses. Stomatal traits of diploid and triploid hybrids in all crosses significantly differed except the stomata index. Genotyping of triploid plants confirmed using Simple Sequence Repeat (SSR) molecular markers and five SSRs were able to identify three alleles of triploid hybrids. Selected triploid mandarin hybrids have been grafted on several rootstocks for field trials and are in the process of yield and quality performances.

Evidence That 2n Eggs Explain Partial Hybrids between Medicago sativa and Medicago arborea.

Selected genotypes of alfalfa (Medicago sativa) produce partial hybrids in sexual crosses with Medicago arborea, as reported in Plants (2013). The hybrids contain mostly alfalfa DNA and traits, but also contain DNA and traits from M. arborea. It was proposed in 2008 that the partial hybrids could be explained by fertilization of 2n eggs in alfalfa by normal pollen from M. arborea, followed by partial loss of M. arborea chromosomes during embryogenesis. In this paper, we confirm the presence of 2n eggs in the first alfalfa parents that produced hybrids. The test for 2n eggs involved pollinating 4x alfalfa with pollen from 8x alfalfa. The production of 8x progeny in the cross proved that selected alfalfa parents produced 2n eggs. Thus, 2n eggs appear to explain how the partial hybrids (hereafter hybrids) contain mostly alfalfa DNA and traits. However, two of the six alfalfa plants that did not hybridize with M. arborea also had 2n eggs. Thus, although 2n eggs explain the alfalfa content of hybrids, 2n eggs are not the only factor involved in weakening the hybridization barrier, and in transferring genes to alfalfa from M. arborea.

The impact of wheat cultivar mixtures on virulence dynamics in Zymoseptoria tritici populations persists after interseason sexual reproduction

AbstractThis study follows on from a previous study showing that binary mixtures of wheat cultivars affect the evolution of Zymoseptoria tritici populations within a field epidemic from the beginning (t1) to the end (t2) of a growing season. Here, we focused on the impact of interseason sexual reproduction on this evolution. We studied mixtures of susceptible and resistant cultivars (carrying Stb16q, a recently broken‐down resistance gene) in proportions of 0.25, 0.5 and 0.75, and their pure stands. We determined the virulence status of 1440 ascospore‐derived strains collected from each cultivar residue by phenotyping on seedlings. Virulence frequencies in the ascospore‐derived population were lower in mixtures than in pure stands of the resistant cultivar, especially in the susceptible cultivar residues, as at t2, revealing that the impact of mixtures persisted until the next epidemic season (t3). Surprisingly, after sexual reproduction the avirulence frequencies on the resistant cultivar residues increased in mixtures where the proportion of the susceptible cultivar was higher. Our findings highlight two epidemiological processes: selection within the pathogen population between t1 and t2 driven by asexual cross‐contamination between cultivars (previous study) and sexual crosses between avirulent and virulent strains between t2 and t3 driven by changes in the probabilities of physical encounters (this study). Mixtures therefore appear to be a promising strategy for the deployment of qualitative resistances, not only to limit the intensity of Septoria tritici blotch epidemics, but also to reduce the erosion of resistances by managing evolution of the pathogen population at a pluriannual scale.

Sexual attractions and boundary crossings among sport psychology graduate students and professionals

ABSTRACT The training relationship between sport psychology professionals (SPPs) and their students is a critical aspect of graduate training. Maintaining ethical, appropriate boundaries within training relationships is imperative, as boundary crossings can have deleterious effects on students. SPPs (N = 152) and Sport Psychology graduate students (N = 165) completed The Survey of Applied Sport Psychologists to explore their experiences and perceptions of sexual attractions and boundary crossings within training relationships. Nearly 30% of SPPs acknowledged sexual attractions toward their students, yet few students (8.5%) perceived such attractions. Compared to the SPPs, the students reported higher levels of anxiety regarding the SPP’s attraction toward them; both groups reported infrequent use of supervision for this attraction. Nine students and 13 SPPs reported engaging in sexual behaviors (e.g., kissing, dating, intercourse) with the other. Within the larger sample, the three most common nonsexual boundary crossings were becoming social friends, attending social gatherings, and the SPP initiating nonsexual touching. Both groups are advised to engage in ongoing monitor their behaviors, receive training specific to ethics within training relationships, and seek consultation/supervision to ensure appropriate boundaries remain intact.

Flower Bulb Waste Material is a Natural Niche for the Sexual Cycle in Aspergillus fumigatus.

With population genetic evidence of recombination ongoing in the natural Aspergillus fumigatus population and a sexual cycle demonstrated in the laboratory the question remained what the natural niche for A. fumigatus sex is. Composting plant-waste material is a known substrate of A. fumigatus to thrive and withstand temperatures even up to 70°C. Previous studies have shown indirect evidence for sexual reproduction in these heaps but never directly demonstrated the sexual structures due to technical limitations. Here, we show that flower bulb waste material from stockpiles undergoing composting can provide the conditions for sexual reproduction. Direct detection of ascospore structures was shown in agricultural flower bulb waste material by using a grid-based detection assay. Furthermore, we demonstrate that ascospores can germinate after exposure to 70°C for up to several days in contrast to asexual conidia that are unable to survive a two-hour heat shock. This indicates a sufficient time frame for ascospores to survive and escape composting stockpiles. Finally, sexual crosses with cleistothecium and viable ascospore formation could successfully be performed on flower bulb waste material. Recombination of A. fumigatus can now be explained by active sexual reproduction in nature as we show in this study that flower bulb waste material provides an environmental niche for sex.

Multiple Consciousness and Transnationalism in Iranian Armenian Cultural Productions

: A century ago, W.E.B. Du Bois coined the term ‘double consciousness’ to describe an individual with an identity with several facets, particularly in the context of African-American experiences. A century later, Du Bois’ theory was expanded into a concept called ‘triple consciousness’ to acknowledge the intersectional construction of identities where race might have intersected with ethnicity, gender, sexual orientation, etc. to generate complex, multivalent forms of subordination. Expanding Du Bois’ concept of ‘double consciousness’ to Chicana experiences, and disrupting nationalist Anglocentrism, in Borderlands/La Frontera, Gloria Anzaldúa theorized the ‘border’ as a metaphor for geographical transgressions, sexual boundary crossings, social displacements, and linguistic and cultural dislocations. In conversation with these theorists, I examine Iranian Armenian ‘multiple consciousnesses’, by highlighting their various expressions of diaspora, their many ways of longing to return to a homeland (Armenia and Iran), and their multiple collective consciousnesses, particularly the shared memories of the 1915 genocide. I also provide examples from cultural productions which demonstrate the diasporic transnationalism of Iranian Armenian authors who maintain ties with their homeland while are simultaneously anchored and settled in their host nations.

Ethics and Law.

Ethics and Law.

Multiple Scenarios for Sexual Crosses in the Fungal Pathogen Zymoseptoria Tritici on Wheat Residues: Potential Consequences for Virulence Gene Transmission

Multiple Scenarios for Sexual Crosses in the Fungal Pathogen Zymoseptoria Tritici on Wheat Residues: Potential Consequences for Virulence Gene Transmission