Asexual Reproduction of Aurelia coerulea Polyps in situ on Settling Plates in Jiaozhou Bay,China

Jellyfish blooms are increasingly prevalent coastal phenomena,with Aurelia coerulea being a significant contributor.The complex life history of jellyfish,featuring a sessile polyp stage,is a key factor in bloom formation,yet it is challenging to study in the field.This study aimed to describe the asexual reproduction of A.coerulea polyps in Jiaozhou Bay,China,and to assess their ability to form sedentary colonies and their relationship with environmental factors.Using settling plates,we observed polyps in situ and documented three asexual reproduction modes:budding,strobilation,and podocyst formation.Environmental parameters including temperature,salinity,dissolved oxygen(DO),chlorophyll a(Chl a),and the biomass of phytoplankton and zooplankton were monitored.Budding was the predominant reproductive method,featuring stolon budding in autumn and direct budding during the winter and spring seasons.Strobilation took place in the colder months,releasing ephyrae between April and May.Polyp abundance was positively correlated with seawater temperature and negatively correlated with DO concentration.Polyps at 1.0 m depth showed higher survivorship and proliferation over 8 months,whereas those at 2.0 m depth experienced a steady decline and died within 4 months.The study enhances our understanding of the life cycle and asexual reproduction strategies of A.coerulea polyps in the field,with implications for predicting and managing jellyfish blooms.The findings underscore the importance of temperature and DO in polyp survival and suggest that initial polyp population proliferation is crucial for long-term survival.

Transcriptome profiling of indole-3-butyric acid-induced adventitious root formation in softwood cuttings of walnut

Inducing adventitious root(AR)formation in mature walnut species(Juglans L.)is challenging.However,the AR formation of mature trees can be improved by rejuvenation.In rejuvenated cuttings,exogenous indole-3-butyric acid(IBA)is essential for AR formation,and the underlying mechanism is still not well understood.Therefore,we utilized transcriptome sequencing to investigate the mechanism of IBA-induced AR formation.Our results revealed that,in comparison to the control group,IBA treatment(9 mmol·L^(-1))significantly increased the endogenous indole-3-acetic acid(IAA)content,leading to an enhanced rooting rate.We performed RNA sequencing to identify differentially expressed genes(DEGs)between the IBA-treated and control(CK)groups at 1,2,3,and 5 days after cutting(DAC).The results showed that,compared to the control cuttings,there were 1539,889,785,and 984 up-regulated genes and 2791,2936,3017,and 1752 down-regulated genes,at 1,2,3,and 5 DAC,respectively.Analysis of RNA-seq data revealed that G-type ATP-binding cassette 36/37(ABCG36/37)and ATP-binding cassette subfamily D 1(ABCD1),associated with IBA transport,were down-regulated in the rejuvenation cuttings.In contrast,PIN-FORMED(PIN)and PINOID(PID),associated with auxin efflux,were up-regulated.We identified 49 auxin/indole-3-acetic acid(AUX/IAA)-encoding genes,including IAA1,IAA3,IAA5,IAA6,IAA8,IAA11,IAA12,IAA19,and IAA20,which were up-regulated at 1-5 DAC in the rejuvenated cuttings.This study highlights that the overexpression of JrWOX5/11 in poplar significantly enhance AR growth,as evidenced by increased root length,surface area,volume,and quantity.Moreover,the co-expression network analysis involving JrWOX11 and JrWOX5 in walnut cuttings elucidates complex genetic interactions,underscoring their pivotal role in the formation of AR.Our data supported the following molecular mechanism of IBA-induced adventitious root formation.Firstly,IBA is converted to free IAA in peroxisomes.Then,the highly concentrated IAA in the procambium and parenchyma cells induces WUSCHEL-related homeobox 11(WOX11)expression at two days.Finally,WOX11 acts redundantly to up-regulate WOX5,initiating the development of root primordia cells.

A preliminary study on life history of marine red alga Stylonema alsidii(Zandardini)Drew f.ramosum Zheng et Li

Stylonema alsidii(Zandardini)Drew f.ramosum Zheng et Li is a common species in the genus Stylonema,but there are limited reports on morphological taxonomy and a lack of studies on life history and the regulation of early development.The early development,discoid formation,and erect thallus growth of Stylonema alsidii f.ramosum were observed under laboratory conditions.In addition,the influence of main environmental factors such as temperature and light intensity on its development was briefly studied,and various stages of its life history were observed.The result shows:(1)there are two reproductive modes:asexual reproduction and sexual reproduction;(2)the morphology of this species varies in different degrees under laboratory culture conditions;(3)sexual reproduction and asexual reproduction can coexist under suitable conditions.Five pathways of life history were inferred from experimental phenomena.Mature sporophytes form mature gametophytes by producing initially isolated or initially attached monospore,and mature gametophytes form mature sporophytes by fertilization of eggs and sperms.The sexual and asexual reproduction processes of Stylonema alsidii f.ramosum were reported for the first time,and this is also the first report on sexual reproduction in the genus Stylonema.

Biomass Allocation of Scirpus mariqueter Along an Elevational Gradient in a Salt Marsh of the Yangtse River Estuary

Scirpus mariqueter Tang et Zhang is a typical pioneer plant colonizing the bare beaches of the Yangtse River estuary. To explore the life history strategy of the species with reference to environmental physical stress, the biomass allocations to different plant components and some related morphological parameters were examined along an elevational gradient within a salt marsh. Authors found that S. mariqueter performed best at medium elevation within the marsh, with relatively high density of shoot and individual ramet dry mass. Biomass allocation to corm was the highest at low elevations, and the least at high elevations, suggesting that a conservative strategy was adopted by the species to cope with the harsh physical conditions at the low elevation. The investment in rhizome decreased from low to high elevations, while the proportion of inflorescence mass increased, indicating that during the life history, the species shifts from predominant asexual reproduction to predominant sexual reproduction. This may be favourable for the species to colonize larger area, and to spread and persist at a meta_population level. Correlation analyses showed that sexual reproduction was inversely related to growth and asexual reproduction. However, it is difficult to determine the relationship between asexual reproduction and growth possibly because of the varied function of the corms of the species in different life history stages.

Construction and Analysis of Asexual Mutant Population of Tetraploid Potato Longshu 7 Induced by EMS

[Objective] This study was conducted to detect the variation induction ability of ethyl methanesulfonate （EMS）, to construct a mutant population. [Method] 0.6%, 1.2% and 2.4% EMS solutions were used for inducing 2 400 stem segments of test-tube plantlets of tetraploid potato Longshu 7, and an asexual mutant population including leaf, plant type, stem, stolon, glandular hair traits was constructed. [Result] Twenty two mutation types, i.e. etiolated plantlet, albino plantlet, leaf-color gradient, etiolated vein, wrapped bud, lobed leaf, crinkled leaf, deformed compound leaf, cluster, branch, top enlargement, top bifurcation, succulent, stolon distortion, stolon shift, early tuberization, hair stolon, stem enlargement, vine stem, foliage stem, glandular hair and whorled leaf types were observed in total. There were 52 mutant single plants in total, with a mutation rate of 21.67‰. [Conclusion] The glandular hair, clustered short-stem, branched stem and early tuberization types of mutants have higher application value, and are anticipated to be used in potato functional genome research, gene improvement and germplasm innovation.

Molecular identification and culture observation on Acrochaete leptochaete (Chaetophoraceae, Chlorophyta) from China

Acrochaete leptochaete （Huber） Nielsen （Chaetophoraceae, Chlorophyta） was isolated from the macroalgae Chaetomorpha collected from intertidal pools in Rongcheng, Shandong, China. 18S rDNA combined with ITS regions were used to ascertain the morphological identification of the isolated material. Based on the unialgal culture, asexual reproduction and growth characteristics of A. leptochaete were investigated over wide ranges of temperature and irradiance. Results revealed that asexual reproduction of A. leptochaete could be realized by biflagellate zoospores. The zoospores germinated directly to give self- replicating generations. Zoospore germination was bipolar. A temperature range from 13-21 ℃ and a lower irradiance of 36 μmol/（m2.s） were most favorable for the growth ofA. leptochaete. Thallus organization, an important taxonomic criterion for the genus Acrochaete, was affected markedly by temperature and irradiance. Our results extend the knowledge about the species＇ general biology and its morphological plasticity. For classification and identification of a simple microphytic algae like A. leptochaete, which are traditionally placed in the class Chaetophoraceae, we propose that molecular tools associated with culture observations are applied.

Effects of temperature and salinity on the asexual reproduction of Aurelia coerulea polyps

Aurelia coerulea polyp is an important stage in the outbreaks of this species.To test the combined effects of salinity and temperature on the survival and asexual reproduction of polyps,we maintained 864 polyps at various salinities(15,25,33,and 40)and temperatures(9,12,15,18,21,and 24℃).Polyps could mostly survive in all treatment combinations except in salinity 15 treatments with low temperatures(9-15℃).Budding occurred at all temperatures(9-24℃),while strobilation only occurred at the low temperatures(9-15℃).The range of 12-15℃was suitable for strobilation and ephyrae release.The optimal range of salinity for asexual reproduction was 25-33.Low(15)or high(40)salinity could significantly reduce the numbers of new buds or ephyrae,and low salinity of 15 retarded and even prevented strobilation at low temperatures.The optimal treatment for budding and strobilation was 21℃-salinity 25 and 12℃-salinity 33,respectively.Salinity had less of an impact than temperature on asexual reproduction,except for the polyps in high or low osmotic pressure conditions.

The putative elongator complex protein Elp3 is involved in asexual development and pathogenicity by regulating autophagy in the rice blast fungus

Autophagy is responsible for maintaining fundamental cellular homeostasis and is,therefore,essential for diverse development processes.This study reported that PoElp3,the putative catalytic subunit of Elongator complex,is involved in the maintenance of autophagy homeostasis to facilitate asexual development and pathogenicity in the rice blast fungus Pyricularia oryzae.It was found that the ΔPoelp3 strains were defective in vegetative growth,conidiation,stress response,and pathogenicity.The mutants exhibited hyper-activated autophagy in the vegetative hyphae under both nutrient-rich and nutrient-deficient conditions.The hyper-activation of autophagy possibly suppressed the production of vegetative hyphae in the ΔPoelp3 strains.Moreover,the ΔPoelp3 strains were found to be more sensitive to rapamycin during vegetative-and invasive-hyphal growth but have no effect on Target-of-Rapamycin(TOR)signaling inhibition.Taken together,these results demonstrated that PoElp3 is involved in asexual development and pathogenicity by regulating autophagy in the rice blast fungus.

Genetic Diversity of the Pepper Pathogen <i>Phytophthora capsici</i>on Farms in the Amazonian High Jungle of Peru

Phytophthora capsici is an important oomycete pathogen of Capsicum peppers worldwide. Populations of P. capsici recovered from coastal regions in Peru were previously shown to be dominated by a single clonal lineage referred to as PcPE-1. During 2008, 219 isolates of P. capsici were collected from Capsicum pubescens (Rocoto), C. annum (Pimento), and C. baccatum (Aji) at 9 farms in the Amazonian high jungle in the areas surrounding Oxapampa, and one coastal location, Carabayllo. Two isolates of P. capsici were also recovered from Cyclanthera pedata (Caigua fruit) near one field. All isolates were characterized using a panel of eight single nucleotide polymorphism (SNP) markers that are fixed for heterozygosity in the PcPE-1 lineage. A subset of isolates was also characterized using amplified fragment length polymorphism (AFLP) markers. Nine discreet SNP multi-locus genotypes were identified, and the PcPE-1 lineage was recovered from all of the field sites. Both A1 and A2 mating types were recovered from two sites. The implications of the genotypic diversity and distribution identified in this study are discussed.

Photosynthesis-Dependent Extracellular Ca2+ Influx Triggers an Asexual Reproductive Cycle in the Marine Red Macroalga Porphyra yezoensis

Asexual propagation to increase the number of gametophytic clones via the growth of asexual haploid spores is a unique survival strategy found in marine multicellular algae. However, the mechanisms regulating the asexual life cycle are largely unknown. Here, factors involved in the regulation of production and discharge of asexual spores, so-called monospores, are identified in the marine red macroalga Porphyra yezoensis. First, enhanced discharge of monospores was found by incubation of gametophytes in ASPMT1, a modified version of the previously established synthetic medium ASP12. Comparison of the compositions of ASPMT1 and our standard medium, ESL, indicated that the Ca2+ concentration in ASPMT1 was three times lower than that in ESL medium. Thus, we modified ASPMT1 by increasing its Ca2+ concentration, resulting in reduction of monospore discharge. These findings demonstrate the role of reduced Ca2+ concentrations in enhancing monospore production and release. Moreover, it was also observed that initiation of asexual life cycle required illumination, was repressed by DCMU, and was induced by a Ca2+ ionophore in the dark. Taken together, these results indicate that photosynthesis-dependent Ca2+ influx triggers the asexual life cycle by promoting the production and discharge of monospores in P. yezoensis.

Vegetative Compatibility and Asexual Recombination in Magnaporthe grisea from Jiangsu Province, China

Vegetative compatibility among isolates of different races in Magnaporthe grisea collected from Jiangsu Province and asexual recombination among compatible isolates by anastomosis were tested. Twenty isolates involving seven races from diseased rice plants were paired on polished rice rose bengal medium and incubated at 25℃ in darkness for 18 days. Among 173 pairings tested, solid hyphal fusion lines formed by anastomosis between 124 pairings, indicated that these isolates were vegetative compatible with each other. The result showed that most M. grisea isolates were vegetative compatible. Furthermore, 17 vegetative compatible pairings between monoconidial isolates with MBCsIPTr marker and isolates with MBCrIPTs marker were selected to detect the asexual recombination between the compatible isolates of different races. The asexual recombinants with MBCrIPTr marker were detected in single hyphal fragment progenies in thirteen of the seventeen pairings. The percentage of recombinants was about 0. 6 -11.3%. Results showed that vegetative compatibility was prevailing among isolates of M. grisea in Jiangsu Province in vitro. These results also suggested that asexual recombination may be an important mechanism for M. grisea to maintain genetic diversity in nature.

Advances in Research of Cutting Breeding Technology of Xanthoceras sorbifolium Bunge

Cutting breeding is an important method of asexual reproduction of Xanthoceras sorbifolium Bunge.At present,it has been found that the factors influencing the cuttings of X.sorbifolium mainly include cutting material type,substrate type,cutting season,cutting material length and thickness,mother tree age,cutting material pretreatment method,hormone species concentration and soaking time.Besides,different regions,control conditions,and germplasm types have different cutting rooting rates.This paper introduced some of the problems in the cuttings of X.sorbifolium,and came up with some recommendations to provide a reference for the future research and technical promotion of X.sorbifolium cuttings.

Indolbutyric Acid and Time of the Year Influence on Rooting of Chrysanthemum Cuttings

The objective of this study was to analyze the effect of the seasons and indol butyric acid (IBA), as well as the preparation of IBA solutions on rooting growth of “Fine Time” chrysanthemum cuttings. The first experiment was arranged in a 4 × 2 factorial scheme: IBA concentrations (0, 1000, 2000 and 3000 mg·L-1) during summer and winter with 4 replicates of two pots and six cuttings per pot. In the second experiment, the storage of IBA solution (1000 mg·L-1) at 15°C was studied with four replicates of 10 cuttings per plot in a period of four weeks. In the third experiment, dilution and supply of IBA (1000 mg·L-1 or 1000 mg·kg-1) were studied;there were eight treatments: (1) IBA mixed with industrial talc;(2) IBA diluted in 50% alcohol and oven dried at 30°C;(3) IBA diluted in 50% alcohol and oven dried at 70°C;(4) IBA diluted in NaOH and supplied via aqueous solution;(5) IBA diluted in acetone and supplied via aqueous solution;(6) IBA diluted in alcohol 92.8% and supplied via alcoholic solution;(7) IBA diluted in alcohol 50% and supplied via alcoholic solution;(8) IBA mixed and supplied via lanolin;with four replicates of 10 cuttings per plot. Twenty-one days after cutting implementation, the following variables were evaluated: rooting percentage, number, average length and root dry mass. Statistical analysis and time-of-year averages were compared using the Tukey test at 5%;polynomial regression for IBA concentration and preparation data. The means of dilution and delivery were compared by the Scott-Knott test. Treatment with IBA at a concentration of 3000 mg·kg-1 resulted in 90% rooting in the winter and 100% in the summer for all treatments. Results suggest the concentration of 2000 mg·L-1 in the summer and 2000 and 3000 mg·L-1 during the winter provided better quality for the root system. Cuttings treated with IBA diluted in 50% alcohol and oven dried at 30°C showed higher number, length and vigor of the roots.

<i>In Vitro</i >Culture of <i>Plasmodium falciparum</i>: Obtention of Synchronous Asexual Erythrocytic Stages

Cultivation of the erythrocytic stages of Plasmodium parasites, specifically the most important and deadly for humans, Plasmodium falciparum, has required a lot of effort and time in order to develop a continuous in vitro culture. Moreover, the development of methods to synchronize P. falciparum parasites (which grow asynchronously in vitro) has become an essential tool in research to study different immulogical, biochemical or physiological aspects of the parasite. We have compared two different synchronization methods, one based on differential permeability of the membrane of parasitized erythrocytes, and the other on the sedimentation behavior in gelatin solution. An optimized method has been established which allows for maintaining a healthy, highly synchronous culture for longer periods of time. Asexual erythrocytic stages of a complete P. falciparum cycle have been obtained, which is the starting point of the stage-specific assays of the activity of new antimalarial drugs.

Influences of Different Habitats on Asexual Propagation of Wild Gastrodia elata f. glauca being Domesticated in Ganzi

[Objective] The influences of different habitats on asexual propagation of wild Geg(abbreviation for Gastrodia elata Bl. f. glauca S. Chow) being domesticated in Ganzi prefecture was studied. [Method] The research trial was carried out in the following three kinds of habitats at the same time: the plastic greenhouses, the birch forest of shady slope and the shrubbery of sunny slope, and the results were analyzed with group data average hypothesis test method. [Result] The overall tuber(the juvenile tuber, the immature tuber and the mature tuber) yield and the mature tuber yield were both very significantly higher in the plastic greenhouses than in the other two types of habitats, and respectively reached 9.52 and 6.70 kg/m2; the mature tuber drying rate was dramatically or very dramatically lower in the plastic greenhouses than in the other two types of habitats, and was 23.84%; the stabilities of the overall tuber yield, the mature tuber yield and the drying rate were all reduced in the order of greenhouses, birch forest and shrubbery; and the dry mature tuber yield of the plastic greenhouses was the highest in the three kinds of habitats, and was 1.60 kg/m2. [Conclusion] A good habitat had to be created or chosen in the domesticating cultivation of the wild Geg in Ganzi prefecture. The preferred choice was the plastic greenhouse, the alternative one was the deciduous broadleaved forest of shady slope. The imitating wild planting of the wild Geg should be done in the warm moist deciduous broad-leaved forest of shady slope.

Scale Breeding and Reproduction Technique of Ficus tikoua Bur.Container Seedlings

Based on the principle of asexual reproduction,a kind of scale breeding and reproduction technique of Ficus tikoua Bur.container seedlings was explored by using the characteristics of strong adaptability to the environment and fast growth and reproduction.Using non-woven bag as a breeding container for seedlings,the scale breeding and reproduction technique of F.tikoua container seedlings was summarized through the important links of seedling bed construction,seedling collection,soil configuration,container selection,cutting cultivation,field management,and disease and pest control.This technique can achieve differential,massive and sustainable efficient breeding and reproduction of F.tikoua seedlings in a short time.

Effect of Tree Species and Dosage of Rhizomorph Wood on Asexual Propagation of Wild Gastrodia elata. Bl. f. glauca S. Chow in Ganzi

The effects of the tree species and the dosages of Armillariella mellea rhizomoph wood on asexual propagation of wild Gastrodia elata Bl. f. glauca S. Chow were studied in Ganzi prefecture. The results showed that tree species had a very significant effect on asexual reproduction yield of wild Gastrodia elata Bl. f. glauca S. Chow. The drying rate and yield of Gastrodia elata Bl. f. glauca S. Chow cultured by close grained woods such as Quercus spinosa David ex Fr. was extremely significant higher than that cultured by coarse grained wood such as Betula platyphylla Suk. The dosage had a very significant effect on the yield of wild Gastrodia elata Bl. f. glauca S. Chow whereas it had no influence on the drying rate.

Growth and Quality of Clonal Plantlets of Conilon Coffee(Coffea canephora Pierre ex A.Froehner)Influenced by Types of Cuttings

To achieve high crop yieldin agriculture, the production of plantlets of superior quality is one of thebasic prerequisites. For conilon coffee, the current recommendation in theproduction of clonal plantlets through vegetative propagation is to usediagonal cuttings, in bevel form. However, there are indications that othertypes of cutting have been successfully used to produce plantlets. In thiscontext, this experiment was conducted with the objective of studying thedevelopment of plantlets of conilon coffee obtained by different types ofcuttings. The experiment was conducted in a greenhouse. The cuttings wereobtained from the middle portion of orthotropic stems of standardized plants.The experiment followed a split plot in time design, with three types ofcuttings (bevel, sharp bevel and straight) and two times of evaluation, withfour repetitions. At 30 and 120 days after planting, plantlets were collectedand evaluated. The results show the increase occurred in the variables due tothe straight cut when compared to the others, except for stem diameter.Emphasizing in this context, the straight cut promoted an increase in seedlingheight, production of biomass and in the Dickson’s quality index when comparedto cuttings in bevel and sharp bevel.

Differences in egg hatching time between cyclical and obligate parthenogenetic lineages of aphids

Many aphid species exhibit a variation in reproductive mode which is influenced by winter climate regimes,with cyclical parthenogenetic (CP)lines dominating in cold winter areas (because they produce cold-resistant eggs)and obligate parthenogenetic (OP) ones in mild winter regions (because of their parthenogenetic overwintering).Genetic studies on several aphid species have shown that the OP trait can be transmitted during sexual events involving the 2 types of lines.This genetic system could be considered as a local safeguarding mechanism for OP alleles in case severe frost would have killed all parthenogenetically overwintering individuals.However,this strategy would only be efficient in restoring local polymorphism in breeding systems if the newly hatched OP recombinants remain competitive over their CP counterparts.In this study we compared egg hatching sequences of CP and OP F1 clones from several crosses obtained for 2 cereal aphid species,Sitobion avenae (constant 5℃,8 h of light)and Rhopalosiphum padi (winter outdoor conditions).For S.avenae,we obtained F1 offspring from 6 crosses, involving 4 clones while in R.padi F1 were obtained from 11 crosses involving 14 clones. We showed that in both species proportions of OP clones were higher in the first half of the progeny relative to the second half.In addition,F1 OP clones hatched in the mean about a week earlier than their CP sibs,which gives them a demographic advantage at the start of the growth season.We then discussed the consequences of this fitness advantage for the maintenance and spread of the OP trait in aphid populations.

Production of asexual and sexual offspring in the triploid sexual planarian Dugesia ryukyuensis

Certain freshwater planarians reproduce asexually as well as sexually,and their chromosomal ploidies include polyploidy,aneuploidy and mixoploidy.Previously,we successfully performed an experiment in which a clonal population produced by asexual reproduction of the Dugesia ryukyuensis(OH strain)switched to the sexual mode of reproduction.Worms of this strain are triploid with a pericentric inversion on Chromosome 4.The worms were switched to sexual reproduction after being fed with sexually mature Bdellocephala brunnea,which is a sexually reproducing species.The resulting sexualized OH strain produced cocoons filled with several eggs.Two putative factors,Mendelian factor(s)and chromosomal control(s),have been proposed as determining the reproductive mode.The present study demonstrated that inbreeding of the resultant sexualized worms produced the following four types of offspring through sexual reproduction:diploid asexual worms,triploid asexual worms,diploid sexual worms and triploid sexual worms.The chromosomal mutation on Chromosome 4 was inherited by these offspring independent of their reproductive mode.These results provide two important pieces of information:(i)the putative genetic factor was not necessarily inherited in a Mendelian fashion;and(ii)the reproductive mode is not regulated by chromosomal changes such as polyploidy or chromosomal mutations.This suggests that asexuality in D.ryukyuensis is regulated by an unknown factor(s)other than a Mendelian factor or a chromosomal control.