Sporogenous Cells Research Articles

The Classification of the Hyphomycetes

The classification of the Hyphomycetes is discussed with special reference to spore types conidiophore behaviour and initiation and development of spores. Eight basic morphological spore types are recognized : the blastospore, the gangliospore, the phialospore, the porospore, the arthrospore, the meristem-arthrospore, the spiculospore and the chlamydospore. No taxonomic significance is attached to the chlamydospore. It is pointed out that the forms now placed in the Mucedinaceae the Dematiaceae, the Tuberculariaceae and the Stilhaceae of Saccardo may be placed in six Families as suggested by the author earlier : (i) the Torulaceae (Type genus, Tonila Pers. ex Fries) for forms producing blastospores ; (ii) the Bactridiaceae (Type genus, Bactridium Kunze ex Fries) for those producing gangliospores ; (iii) the Tuberculariaceae (Type genus, Tubercularia Tode ex Fries) for those producing phialospores ; (iv) the Helminthosporiaceae (Type genus, Helminthosporium Link ex Fries) for those producing porospores ; (v) the Geotrichaceae (Type genus, Geotrichum Link ex Sacc.) for those producing arthrospores ; and (vi) the Coniosporiaceae (Type genus, Coniosporium Link ex Fries) for those producing meristem-arthrospores. The Families are subdivided into Sections on the basis of characters of the conidiophore related to spore initiation and development, the presence or absence and nature of "sporogenous cells", the presence or absence of "separating cells" and certain distinct modes of spore formation which are outlined. Twenty-four Sections are delimited and tentatively keyed out : thirteen in the Torulaceae, four in the Bactridiaceae, two each in the Tuberculariaceae the Helminthosporiaceae and the Geotrichaceae, and one in the Coniosporiaceae. A separate Section is provisionally suggested for forms producing spiculospores. Typical examples of genera for each Section are given together with illustrations. Some of the difficulties still requiring solution are mentioned, including those relating to speculations about the classification of the Hyphomycetes vis-a-vis their perfect stages so far as known. It is emphasized that critical and thorough studies on generic types inadequately or imperfectly understood are an urgent necessity.

A Ceratopteris EXCESS MICROSPOROCYTES1 suppresses reproductive transition in the fern vegetative leaves

Land plant sexual reproduction involves the transition of cells from somatic to reproductive identity during post-embryonic development. In Arabidopsis, the leucine-rich repeat receptor-like kinase EXCESS MICROSPOROCYTES1 (EXS/EMS1) restricts the number of sporogenous cells during the transition from diploid tissue to haploid spore production by promoting the formation of the tapetum cell layer within the anther. Although all land plants studied contain EMS1 genes, its function is unknown beyond a few angiosperms. In the model fern Ceratopteris (Ceratopteris richardii), we discovered an EMS1 homolog (CrEMS1) that functions to suppress formation of reproductive structures on vegetative leaves of the fern sporophyte, a role not found in angiosperms. Suppression of CrEMS1 by RNAi did not affect sporogenesis on reproductive leaves but did affect antheridium production of the fern gametophyte. Expression patterns of CrEMS1 across developmental stages suggest threshold levels of CrEMS1 control the specification of reproductive organs during both generations of the fern. Additional EMS1 homologs present in the fern genome suggest a dynamic role of EMS1 receptors in the evolution of reproductive development in vascular plants.

How do fertile stamens and staminodes go differently in Kingdonia uniflora? Evidence from stamen numbers, ontogeny, and structure

Kingdonia uniflora is in Circaeasteraceae and has fertile stamens and staminodes which are both variable in number; however, the differentiating process of these two types of stamens and the nectariferous structure of staminodes are still unclear. Variation in number and ontogeny (including the degeneration stage of staminodes) of stamens in K. uniflora are investigated under SEM, TEM and LM. The results indicate that there are 63 floral formulas in 80 flowers counted, and the most frequent flower floral formula (4 flowers) is P5A°11A5G6. The correlation between the stamen number and the total floral organ number is high (0.61), while the highest correlation with the total number of floral organs is the number of carpels, and there is a weak correlation between the two types of stamens (-0.23). The stamen development period is divided into five stages, with differentiation of stamens occurring at stage 2. The anther wall formation of fertile stamens is of the basic type, and the simultaneous meiosis form tetrahedral tetrads, while mature pollens are 2-celled and tricolpate. Sporogenous tissue of staminodes fails to develop further at an earlier stage, without the formation of secondary sporogenous cells. The head of mature staminodes has nectary tissue consisting of the secretory epidermis (two types of secretory cells), nectary parenchyma (about 15 layers) and vascular tissue with vessel and sieve tube elements. There are well-developed microchannels in epidermal cell walls, and the cells related to secreting nectar are rich in mitochondria, endoplasmic reticula and small vesicles. In addition, microsporogenesis, male gametophyte development, the secretory function of staminodes, and other characteristics in K. uniflora are similar to those in Ranunculaceae. This study clarifies the differentiating stage of fertile stamens and staminodes and explores the new structure (nectary) that staminodes formed, and also, it enriched the secretion modes in Ranunculales.

Electron microscopy of the uredinial and telial stages of the rust fungus, Puccinia imperatae

The purpose of this work was to assess the morphology and ontogeny of Puccinia imperatae urediniospores and teliospores growing on its host, Imperata cylindrica, for the first time using scanning (SEM) and transmission (TEM) electron microscopy. The first evidence of uredinial development is the aggregation of hyphae in host intercellular spaces under the epidermis to form an uredinial initial. Uredinial primordia become evident as compact masses of fungal hyphae. The mycelia are dikaryotic and originated from dikaryotic urediniospores, which infect a new host. Dikaryotic sporogenous cells begin to form from dikaryotic mycelium as the uredinium develops further. The fundamental cell in the urediniospore and teliospore formation is the sporogenous cell. The teliospores with their persistent pedicels arise from dense dikaryotic sporogenous tissue, which later becomes highly vacuolated. The sporogenous cell forms a spore bud, which later divides into a pedicel and teliospore mother cell with two nuclei that produce the mature teliospore. SEM examination revealed that the urediniospores are echinulate bearing conical spines on their surfaces, sometimes curving near their tips, and the echinulate ornaments are distributed over the entire urediniospore surface. SEM examination also indicated that the teliospore surface shows rugose ornamentations. This investigation proved that the morphology of the uredinia of different Puccinia species is not related to the host species, but to the rust species. The possibility of using this fungus as a biological control agent for the noxious weed, Imperata cylindrica, was also discussed.

The tapetal tissue is essential for the maintenance of redox homeostasis during microgametogenesis in tomato.

The tapetum is a specialized layer of cells within the anther, adjacent to the sporogenous tissue. During its short life, it provides nutrients, molecules and materials to the pollen mother cells and microsporocytes, being essential during callose degradation and pollen wall formation. The interaction between the tapetum and sporogenous cells in Solanum lycopersicum (tomato) plants, despite its importance for breeding purposes, is poorly understood. To investigate this process, gene editing was used to generate loss-of-function mutants that showed the complete and specific absence of tapetal cells. These plants were obtained targeting the previously uncharacterized Solyc03g097530 (SlTPD1) gene, essential for tapetum specification in tomato plants. In the absence of tapetum, sporogenous cells developed and callose deposition was observed. However, sporocytes failed to undergo the process of meiosis and finally degenerated, leading to male sterility. Transcriptomic analysis conducted in mutant anthers lacking tapetum revealed the downregulation of a set of genes related to redox homeostasis. Indeed, mutant anthers showed a reduction in the accumulation of reactive oxygen species (ROS) at early stages and altered activity of ROS-scavenging enzymes. The results obtained highlight the importance of the tapetal tissue in maintaining redox homeostasis during male gametogenesis in tomato plants.

Ultrastructural changes in developmental stages of anther and pollen grains as affected by short-term exposure to low temperatures in strawberry

Short-term exposure to low temperatures can lower pollen viability and germination in strawberry. Fruit malformation was found to be negatively correlated with pollen germination. Ultrastructural analysis was performed at various developmental stages of anthers and pollen grains of the strawberry upon exposure to short-term low temperature (STLT). ‘Maehyang’ strawberry was exposed to 2 oC from 6 pm to 9 am for 3 days during different flower developments before anthesis, whereas the plants in control remained in the greenhouse. The epidermis did not develop well and was deformed after STLT. The epidermis showed a significantly lower cell expansion index in the short-term low-temperature treatment than in control at the vacuolated microspore, bicellular pollen, and mature pollen stages, indicating significant deformation of the epidermal cells by low temperature. The projected area of starch was significantly greater in STLT treatment than in control at the mature pollen stage. The relative fluorescence intensity of anthers was significantly higher in STLT treatment than in control at the sporogenous cell and microspore mother cell stages, indicating that low temperature substantially inhibited anther development at early stages. The results showed that STLT stress caused abnormal development of the ultrastructure of the anther wall and pollen grains, along with starch over-accumulation during pollen development. These abnormal developments may lead to poor pollen germination and thus cause fruit malformation in strawberry.

Gigaspora polymorphira, a new species of arbuscular mycorrhizal fungi (Glomeromycota) from Fanjingshan National Nature Reserve in China

Gigaspora polymorphira, a new arbuscular mycorrhizal fungal species, has been described based on morphological and phylogenetic analyses, which was isolated from rhizosphere soil of Phyllostachys heterocycla and Cunninghamia lanceolata in Fanjingshan National Nature Reserve, Guizhou province, China. Spores are white to orange yellow, irregular to rarely subglobose, 260–390×480–570 µm in diameter, and spore wall consisting of two layers (SWL1+SWL2): SWL1 hyaline to pale yellow, permanent, about 1 µm thick; SWL2 laminate and extremely rigid, yellow, 10–27 µm thick, staining dark red to red-brown in Melzer’s reagent. Germinal wall is permanent, membranous, about 1 µm thick and smooth. The sporogenous cell pale yellow, ovoid to clavate of 80–120×40–75 µm in diameter and have two sporogenous cell wall layers. Phylogenetic analysis of the sequences based on the partial small subunit (SSU), internal transcribed spacer region (ITS1-5.8S-ITS2), and the partial large subunit (LSU) indicated that Gi. polymorphira in the genus Gigaspora, separated from other described Gigaspora species. Phylogenetically, it forms a monophyletic clade next to Gigaspora margarita, which can be distinct distinguished from Gi. polymorphira by its shape of globose to subglobose and warts projects on GW. An updated key for the Gigaspora species worldwide is provide.

Documenting the Sporangium Development of the Polypodiales Fern Pteris multifida.

Reconstructing the development of sporangia in seed-free vascular plants provides crucial information about key processes enabling the production of spores that are important in the life cycle of these plants. By applying fluorescence imaging in intact tissues using dyes and confocal microscopy, this study aimed to reconstruct the key steps during the development of sporangia. Special emphasis was taken on the cell wall structures of tapetum and spore mother cells that have been challenged by microscopical documentation in the past. After staining the cell wall and cytoplasm using calcofluor white and basic fuchsin, the sporangium development of Pteris multifida was observed using confocal microscopy. The clear cell lineages from the sporangial initial cell to stalk, epidermis, inner tapetum, outer tapetum, and sporogenous cells were revealed by confocal imaging. The sporangium development improved in this work will be useful for a general understanding of fern spore formation.

Dependence on clade II bHLH transcription factors for nursing of haploid products by tapetal-like cells is conserved between moss sporangia and angiosperm anthers.

Summary Clade II basic helix–loop–helix transcription factors (bHLH TFs) are essential for pollen production and tapetal nursing functions in angiosperm anthers. As pollen has been suggested to be related to bryophyte spores by descent, we characterized two Physcomitrium (Physcomitrella) patens clade II bHLH TFs (PpbHLH092 and PpbHLH098), to test if regulation of sporogenous cells and the nursing cells surrounding them is conserved between angiosperm anthers and bryophyte sporangia.We made CRISPR‐Cas9 reporter and loss‐of‐function lines to address the function of PpbHLH092/098. We sectioned and analyzed WT and mutant sporophytes for a comprehensive stage‐by‐stage comparison of sporangium development.Spore precursors in the P. patens sporangium are surrounded by nursing cells showing striking similarities to tapetal cells in angiosperms. Moss clade II bHLH TFs are essential for the differentiation of these tapetal‐like cells and for the production of functional spores.Clade II bHLH TFs provide a conserved role in controlling the sporophytic somatic cells surrounding and nursing the sporogenous cells in both moss sporangia and angiosperm anthers. This supports the hypothesis that such nursing functions in mosses and angiosperms, lineages separated by c. 450 million years, are related by descent.

Anatomical Characteristics of Petalized Anther Abortion in Male Sterile Camellia oleifera Plants

Petalized anther abortion is an important characteristic of male sterility in plants. The male sterile plants (HB-21) evincing petalized anther abortion previously discovered in a clone population of the Camellia oleifera cultivar Huashuo by our research group were selected as the experimental material in this study. Using plant microscopy and anatomic methods and given the correspondence between external morphology and internal structure, we studied the anatomic characteristics of petalized anther abortion (with a fertile plant as the control group) in various stages, from flower bud differentiation to anther maturity, in hopes of providing a theoretical basis for research on and applications of male sterile C. oleifera plants, a new method for the selection of male sterile C. oleifera cultivars, and improvements in the yield and quality of C. oleifera. In this study, the development of anthers in C. oleifera was divided into 14 stages. Petalized anther abortion in male sterile plants was mainly initiated in the second stage (the stage of sporogenous cells). Either the petalized upper anther parts did not form pollen sacs, or the entire anthers did not form pollen sacs. The lower parts of some anthers could form deformed pollen sacs and develop, and these anthers could be roughly divided into two types: fully and partially petalized anthers. Abnormal callose and the premature degradation of the tapetum occurred in the pollen sacs formed by partially petalized anthers during the development process, resulting in the absence of inclusions in the pollen grains formed. Small quantities of mature pollen grains withered inward from the germinal furrows, exhibiting obvious abortion characteristics. The relative in vitro germination rate of the pollen produced by the partially petalized anthers of sterile plants was 11.20%, and the relative activity of triphenyltetrazolium chloride was 3.24%, while the fully petalized anthers did not generate pollen grains. Either the petalized anthers in male sterile plants did not produce pollen, or the vitality of the small amounts of pollen produced by sterile plants was very low compared with that of fertile plants. Such male sterile plants could be used to select correct clones and have good prospects for application in production.

Transcriptomic analysis reveals candidate genes for male sterility in Prunus sibirica.

BackgroundThe phenomenon of male sterility widely occurs in Prunus sibirica and has a serious negative impact on yield. We identified the key stage and cause of male sterility and found differentially expressed genes related to male sterility in Prunus sibirica, and we analyzed the expression pattern of these genes. This work aimed to provide valuable reference and theoretical basis for the study of reproductive development and the mechanisms of male sterility in Prunus sibirica.MethodThe microstructures of male sterile flower buds and male fertile flower buds were observed by paraffin section. Transcriptome sequencing was used to screen genes related to male sterility in Prunus sibirica. Quantitative real-time PCR analysis was performed to verify the transcriptome data.ResultsAnther development was divided into the sporogenous cell stage, tetrad stage, microspore stage, and pollen maturity stage. Compared with male fertile flower buds, in the microspore stage, the pollen sac wall tissue in the male sterile flower buds showed no signs of degeneration. In the pollen maturity stage, the tapetum and middle layer were not fully degraded, and anther development stopped. Therefore, the microspore stage was the key stage for anther abortion , and the pollen maturity stage was the post stage for anther abortion. A total of 4,108 differentially expressed genes were identified by transcriptome analysis. Among them, 1,899 were up-regulated, and 2,209 were down-regulated in the transcriptome of male sterile flower buds. We found that “protein kinase activity”, “apoptosis process”, “calcium binding”, “cell death”, “cytochrome c oxidase activity”, “aspartate peptidase activity”, “cysteine peptidase activity” and other biological pathways such as “starch and sucrose metabolism” and “proteasome” were closely related to male sterility in Prunus sibirica. A total of 331 key genes were preliminarily screened.ConclusionThe occurrence of male sterility in Prunus sibirica involved many biological processes and metabolic pathways. According to the results of microstructure observations, related physiological indexes determination and transcriptome analysis, we reveal that the occurrence of male sterility in Prunus sibirica may be caused by abnormal metabolic processes such as the release of cytochrome c in the male sterile flower buds, the imbalance of the antioxidant system being destroyed, and the inability of macromolecular substances such as starch to be converted into soluble small molecules at the correct stage of reproductive development, resulting in energy loss. As a result, the tapetum cannot be fully degraded, thereby blocking anther development, which eventually led to the formation of male sterility.

Unraveling the Genetic Basis of Fertility Restoration for Cytoplasmic Male Sterile Line WNJ01A Originated From Brassica juncea in Brassica napus.

Crosses that lead to heterosis have been widely used in the rapeseed (Brassica napus L.) industry. Cytoplasmic male sterility (CMS)/restorer-of-fertility (Rf) systems represent one of the most useful tools for rapeseed production. Several CMS types and their restorer lines have been identified in rapeseed, but there are few studies on the mechanisms underlying fertility restoration. Here, we performed morphological observation, map-based cloning, and transcriptomic analysis of the F2 population developed by crossing the CMS line WNJ01A with its restorer line Hui01. Paraffin-embedded sections showed that the sporogenous cell stage was the critical pollen degeneration period, with major sporogenous cells displaying loose and irregular arrangement in sterile anthers. Most mitochondrial electron transport chain (mtETC) complex genes were upregulated in fertile compared to sterile buds. Using bulked segregant analysis (BSA)-seq to analyze mixed DNA pools from sterile and fertile F2 buds, respectively, we identified a 6.25 Mb candidate interval where Rfw is located. Using map-based cloning experiments combined with bacterial artificial chromosome (BAC) clone sequencing, the candidate interval was reduced to 99.75 kb and two pentatricopeptide repeat (PPR) genes were found among 28 predicted genes in this interval. Transcriptome sequencing showed that there were 1679 DEGs (1023 upregulated and 656 downregulated) in fertile compared to sterile F2 buds. The upregulated differentially expressed genes (DEGs) were enriched in the Kyoto Encyclopedia of Genes and Genomes (KEGG) lysine degradation pathway and phenylalanine metabolism, and the downregulated DEGs were enriched in cutin, suberine, and wax biosynthesis. Furthermore, 44 DEGs were involved in pollen and anther development, such as tapetum, microspores, and pollen wall development. All of them were upregulated except a few such as POE1 genes (which encode Pollen Ole e I allergen and extensin family proteins). There were 261 specifically expressed DEGs (9 and 252 in sterile and fertile buds, respectively). Regarding the fertile bud-specific upregulated DEGs, the ubiquitin–proteasome pathway was enriched. The top four hub genes in the protein–protein interaction network (BnaA09g56400D, BnaA10g18210D, BnaA10g18220D, and BnaC09g41740D) encode RAD23d proteins, which deliver ubiquitinated substrates to the 26S proteasome. These findings provide evidence on the pathways regulated by Rfw and improve our understanding of fertility restoration.

Reproductive cells and peripheral parietal cells collaboratively participate in meiotic fate acquisition in rice anthers.

In flowering plants, the transition from mitosis to meiosis is the precondition for gametogenesis, which is the most crucial event during sexual reproduction. Here, we report an intriguing mechanism whereby germ cells and surrounding somatic cells cooperatively involve in the meiotic switch during anther development in rice (Oryza sativa). In double mutants with loss function of both leptotene chromosome establishment- and somatic cell layer differentiation-associated genes, chromosome morphology in the reproductive cells remains the same as that in somatic cells, and sporogenous cells fail to differentiate into pollen mother cells. OsSPOROCYTELESS and MICROSPORELESS1, two pivotal genes involved in meiosis entry, are prominently downregulated in anthers of plants with mutations in both MULTIPLE SPOROCYTE1 and LEPTOTENE 1. In addition, the transcription of redox-related genes is also affected. Therefore, germ cells and the surrounding somatic cells collaboratively participate in meiosis initiation in rice.

Water disinfection under the helium influence

The object of research is the process of water disinfection at the influence of gas from bacteria of a particular genus with different amounts per unit volume of water. Due to the annual increase in the amount of pollutants in natural waters, new opportunities to improve microbiological indicators of water quality are being explored. There are many different ways to disinfect it, both physical and chemical. However, no single method has been found to purify aqueous media from microorganisms that would ensure their effective destruction. It is proposed to study the activity of specific microorganisms during the bubbling of inert gas through the aqueous medium. The microorganisms studied were rod-shaped sporogenic cells of Bacillus cereus bacteria type. The test gas was inert helium. The study used continuous gas bubbling throughout the process, which allowed to mix microbial water efficiently and prevent the formation of stagnant zones in the reaction medium. In particular, active gas mixing facilitates its access to each cell. The gas supply rate corresponded to 0.2 cm3/s, and its flow rate was 0.7 dm3 for one hour of bubbling through microbial water. The duration of the entire research process was 7200 s. The constant temperature of the microbial water (T=288±1 K) was maintained during the experiment by cooling the glass reactor with running water. An in-depth method of culturing bacterial cells was used. A decrease in the number of microorganisms was observed throughout the helium supply process, despite the different initial amounts in the water. The highest destruction degree of bacillus (77.06 %) was obtained at the lowest studied concentration in water (NM01=3.4·104 CFU/cm3). This is due to the fact that less microbial load provides better conditions for access of helium to the cell and their effective destruction. The proposed method of water purification allowed to achieve a sufficiently high degree of water disinfection from sporogenic rod-shaped bacteria after the action of helium alone. In particular, it has been experimentally proven that the efficiency of the water disinfection process depends on the concentration of microorganisms per unit volume of water. Due to the treatment of contaminated water with gas, it is possible to obtain high rates of its purification and the application of this method for practical purposes in water treatment technology.

Morphogenesis of the sporoderm of Pollinia of Anoectochilus roxburghii

The pollen grains of Anoectochilus roxburghii aggregate in pollinia. The aim of this study was to analyse the structural characteristics of pollinium development in A. roxburghii. Features of the pollinia begin to form in the sporogenous cells, in which some cell walls begin to differentiate to form the outline of the pollinia. During development of the microspore mother cells (MMCs), the nucleus and organelles penetrate the cell walls (cytomixis) between MMCs within a pollinium, but not between the MMCs among different pollinia. A thick callose wall forms on the surface of the pollinia, but not between MMCs inside the pollinium. After meiosis, a sporopollenin exine forms on the surface of the pollinia, but not on the surface of pollen grains inside the pollinium. The mature pollen of A. roxburghii is bicellular and consists of a vegetative cell and a generative cell.

Oxygen, secreted proteins and small RNAs: mobile elements that govern anther development

Correct anther development is essential for male fertility and subsequently agricultural yield. Defects in anther development range from the early stage of stamen formation until the late stage of tapetum degeneration. In particular, the specification of the four distinct somatic layers and the inner sporogenous cells need perfect orchestration relying on precise cell–cell communication. Up to now, several signals, which coordinate the anther´s developmental program, have been identified. Among the known signals are phytohormones, environmental conditions sensed via glutaredoxins, several receptor-like kinases triggered by ligands like MAC1, and small RNAs such as miRNAs and the monocot-prevalent reproductive phasiRNAs. Rather than giving a full review on anther development, here we discuss anther development with an emphasis on mobile elements like ROS/oxygen, secreted proteins and small RNAs (only briefly touching on phytohormones), how they might act and interact, and what the future of this research area might reveal.

Дія гелію на очищення води з різною концентрацією мікроорганізмів

The influence of bubbled inert gas on the viability process of rod-shaped microorganisms in the water has been studied. The micro-objects were resistant sporogenic cells of Bacillus cereus type, which belong to the Bacillaceae family, and the test gas was helium. Helium was fed at a rate of 0.2 cm3/s. Bacteria were added to distilled deaerated water, creating model aqueous media with different initial numbers of microorganisms (NM). The concentration of microorganisms per unit volume of water was within the same order: NM01 = 3.4 · 104 CFU/cm3, NM02 = 4.8 · 104 CFU/cm3 and NM03 = 7 · 104 CFU/cm3. An in-depth method of culturing bacterial cells was used. Conditions for culturing microorganisms was temperature of 37 °C, duration of 48 hours. NM values before and after experiments was determined by counting the colonies that grew on the nutrient medium on Petri dishes. The calculated number of cells was expressed in colony-forming units (CFU). During microscopic examinations, cells of the fixed preparations culture (1-day and 3-day) were studied. Fixed cell preparations at x1200 are shown. The shape and size of the cells of the fixed preparation are shown, as well as the shape and location of the spores inside the cells. Illustrative material shows the oval shape of the spores. It was found that the diameter of the spores is smaller than the cell diameter. The results of experimental studies show a change of NM values over time, during which there was a decrease of the cells number per unit volume of water during the two-hour duration of the process, regardless of the different NM0. The proportion of destroyed cells for each of their concentrations after every 30 minutes of water treatment was calculated and the values of the initial NM ratio to the current NM after each water sampling were given. The dependences of the proportion of destroyed cells of the treatment duration of microbial water with helium are graphically constructed. An increase in the proportion of destroyed cells with a decrease in the initial concentration of cells in the water was observed. The highest percentage of destroyed bacilli was reached at NM01 = 3.4 · 104 CFU/cm3, which was 77.06 %, while for NM02 = 4.8 · 104 CFU/cm3 and NM03 = 7 · 104 CFU/cm3 are 72.92 % and 47.72 %, respectively. Thus, a sufficiently high efficiency of helium alone during the treatment of microbial water containing resistant sporogenic bacteria has been experimentally shown.

Fatty acid production of thraustochytrids from Saudi Arabian mangroves.

This is the first report of thraustochytrids from Saudi Arabia. A total of 108 isolates of thraustochytrid were cultured from Syhat mangroves, Arabian Gulf, Saudi Arabia. Isolated thraustochytrids belonged to five genera: Aplanochytrium, Aurantiochytrium, Schizochytrium, Thraustochytrium and Ulkenia. Cultured thraustochytrids isolated from decaying leaves of Avicennia marina (77 isolates), sediment (15), seawater (10) and decaying thalli of Sargassum (6). Of the 108 isolates, three strains (SY25, SY38 and SY52) were selected based on their high biomass productivity and high percentages of PUFAs. Phylogenetic analyses based on 18S rDNA placed the three strains within the Aurantiochytrium clade with high statistical support. Species of Aurantiochytrium formed six separate clades, the two strains (SY38 and SY52) formed a separate clade that is a sister clade to the one that contains the type species A. limacinum, while SY25 grouped with Aurantiochytrium sp. TA4, that is also isolated from mangroves in Iran, Arabian Gulf. The strains (SY38 and SY52) shared the phylogenetic placement, their morphology and fatty acid profile. The strain SY25 have different shape of sporangia that divide to give zoospores directly, sporogenous cells are surrounded by thick gelatinous sheath and produce high levels of Linoleic and Oleic essential unsaturated fatty acids. The three studied strain produced high levels of Palmitic acid (ranged between 31.1 and 65.3 % of total fatty acids) that can be further optimized for biofuel production.

Transcriptome Analysis Reveals Important Transcription Factor Families and Reproductive Biological Processes of Flower Development in Celery (Apium graveolens L.)

There are few reports on the reproductive biology of celery, which produces small flowers in a long flowering period. Anther development was analyzed by paraffin sectioning and related genes were examined by transcriptome sequencing and qPCR. The development process was divided into nine stages based on the significant changes in the cell and tissue morphologies. These stages included: archesporial stage, sporogenous cell stage, microspore mother cell stage, dyad and tetrad stage, mononuclear microspore stage, late uninucleate microspore stage, binuclear cell stage, mature pollen stage, and dehiscence stage. A total of 1074 differentially expressed genes were identified by transcriptome sequencing in the early flower bud, middle flower bud, and early flowering period. Functional annotation indicated that these genes were involved in physiological and biochemical processes such as ribosomes metabolism, sugar metabolism, and amino acid metabolism. Transcription factors such as C2H2, AP2/ERF, bZIP, WRKY, and MYB played key regulatory roles in anther development and had different regulatory capabilities at various stages. The expression patterns based on qPCR and transcriptome data of the selected transcription factor genes showed consistency, suggesting that these genes played an important role in different flower development stages. These results provide a theoretical basis for molecular breeding of new celery varieties with pollen abortion. Furthermore, they have enriched research on the reproductive biology of celery and the Apiaceae family.

Cystomyces antheropori, a new rust fungus on Antheroporum glaucum from Thailand

Abstract A rust fungus was found on leaves of Antheroporum glaucum (Fabaceae, Faboideae) in Provinces of Petchaburi and Ratchaburi, western Thailand. No rust fungus was previously reported on this legume tree species. The new rust fungus was apparently microcyclic, producing telia surrounding dense aggregates of spermogonia, on the abaxial leaf surface. Teliospores were produced by sympodial proliferation from a basal sporogenous cell and mostly composed of three fertile cells subtended by two hygroscopic cysts. A germ slit was present near the septum in two of three fertile cells. A simple persistent pedicel was attached to the teliospore cysts. Because of resemblance in the teliospore morphology, this fungus was compared to Bibulocystis, Caetea, Cystomyces, and Spumula. Radially symmetric teliospores in the horizontal plane with three more or less globose fertile cells subtended by two hygroscopic cysts and the presence of a germ slit near the septum in fertile cells are the characteristics of the genus Cystomyces. Therefore, it was concluded that the fungus should be classified in Cystomyces, and a new name, C. antheropori was proposed.