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This work aimed to establish the nutrient fertilization regime for indoor maintenance of Kappaphycus alvarezii seedlings during periods of low sea temperatures using biofloc effluent as a fertilizer. Moreover, we evaluated the development of seaweed seedlings after transplantation into the sea cultivation in Santa Catarina, Brazil. Seedlings were fertilized with biofloc effluent diluted by 25% in three different nutrient fertilization regimes for 4 weeks: single fertilization (SF): seedlings were fertilized for 1 week and remained in seawater for the following 3 weeks; alternating fertilization (AF): alternated 1 week with nutrient fertilization and 1 week without, and continuous fertilization (CF): seedlings were cultivated continuously with biofloc effluent. After this period, samples of each treatment were transferred into the sea cultivation and kept for 5 more weeks. The daily growth rates of plants cultivated in SF and AF were significantly higher than CF in indoor maintenance. However, in sea cultivation, the daily growth rates from AF and CF were significantly higher than SF. In both cases, there were no differences in the carrageenan yield between treatments. Light microscopy and quantification of floridean starch and pigments showed that after the sea cultivation period, floridean starch presence changed from cortical to medullar cells depending on the treatment, but no significant difference in the quantity was observed. Also, seedlings of SF treatment showed a significantly higher phycocyanin content compared to CF treatment. Based on the results, we suggest the continuous fertilization for indoor maintenance in tanks of seaweed seedlings with biofloc effluent.

Background Long non-coding RNAs (lncRNAs) participate in regulation of gene transcription, but little is known about the correlation among resveratrol and lncRNAs. This study aimed to identify and validate the key lncRNAs in resveratrol protect against IL-1β-treated chondrocytes. Methods In this experiment, high-throughput sequencing technique was performed to identify the differentially expressed lncRNAs, miRNAs, and mRNAs between IL-1β-treated chondrocytes with or not resveratrol. Moreover, gene ontology and KEGG pathway of the differentially expressed genes were carried out by R software. Then, lncRNA-miRNA-mRNA network was constructed by Cytoscape software. Venn diagram was performed to identify the potentially target miRNAs of LINC00654. Then, real-time polymerase chain reaction (RT-PCR) was performed to validate the most significantly differentially expressed lncRNAs. Results Totally, 1016 differentially expressed lncRNAs were identified (493 downregulated) between control and resveratrol-treated chondrocytes. Totally, 75 differentially expressed miRNAs were identified (downregulated = 54, upregulated = 21). Totally, 3308 differentially expressed miRNAs were identified (downregulated = 1715, upregulated = 1593). GO (up) were as follows: skin development, response to organophosphorus. GO (down) mainly included visual perception, single fertilization, and sensory perception of smell. KEGG (up) were as follows: TNF signaling pathway and TGF-beta signaling pathway. KEGG (down) were as follows: viral protein interaction with cytokine and cytokine receptor. We identified that LINC00654 and OGFRL1 were upregulated in resveratrol-treated chondrocytes. However, miR-210-5p was downregulated in resveratrol-treated chondrocytes. Conclusion In sum, the present study for the first time detected the differential expressed lncRNAs involved in resveratrol-treated chondrocytes via employing bioinformatic methods.

Even in stallions with sperm quality within normal reference ranges at ejaculation, subtle differences in sperm quality exist that in many cases lead to reduced time frames for conservation of the ejaculate and/or reduced fertility. The spermatozoon is a cell highly suitable for proteomics studies, and the use of this technique is allowing rapid advances in the understanding of sperm biology. The aim of the present study was to investigate differences among stallions of variable sperm quality (based on motility and sperm velocities), although all horses had sperm characteristics within normal ranges. The proteome was studied using UHPLC/MS/MS and posterior bioinformatic and enrichment analysis; data are available via ProteomeXchange with identifier PXD025807 . Sperm motility, linear motility and circular, straight line and average velocities (VCL, VSL, VAP) were measured using computer assisted sperm analysis (CASA). In stallions showing better percentages of motility, circular and average velocity predominated mitochondrial proteins with roles in the Citric acid cycle, pyruvate metabolism and oxidative phosphorylation. Interestingly, in stallions with better percentages of total motility, sperm proteins were also enriched in proteins within the gene ontology (G0) terms, single fertilization (G0: 0007338), fertilization (G0: 0009566), and zona pellucida receptor complex (GO:0002199). The enrichment of this proteins in samples with better percentages of total motility may offer a molecular explanation for the link between this parameter and fertility. Significance Proteomic analysis identified a high degree of specificity of stallion sperm proteins with discriminant power for motility, linear motility, and sperm velocities (VCL, VAP and VSL). These findings may represent an interesting outcome in relation to the molecular biology regulating the movement of the spermatozoa, and the biological meaning of the measurements that computer assisted sperm analysis (CASA) provide. Of a total of 903 proteins identified in stallion spermatozoa, 24 were related to the percentage of total motility in the sample; interestingly, gene ontology (G0) analysis revealed that these proteins were enriched in terms like single fertilization and fertilization, providing a molecular link between motility and fertility. Field studies indicate that the percentage of total motility is the CASA derived parameter with the best correlation with fertility in stallions.

During double fertilization in angiosperms, two male gametes (sperm cells), are released from a pollen tube into the receptive region between two female gametes; the egg cell and the central cell of the ovule. The sperm cells fertilize the egg cell and the central cell in a one-to-one manner to yield a zygote and an endosperm, respectively. The one-to-one distribution of the sperm cells to the two female gametes is strictly regulated, possibly via communication among the four gametes. Polyspermy block is the mechanism by which fertilized female gametes prevent fertilization by a secondary sperm cell, and has been suggested to operate in the egg cell rather than the central cell. However, whether the central cell also has the ability to avoid polyspermy during double fertilization remains unclear. Here, we assessed the one-to-one fertilization mechanism of the central cell by laser irradiation of the female gametes and live cell imaging of the fertilization process inArabidopsis thaliana. We successfully disrupted an egg cell within the ovules by irradiation using a femtosecond pulse laser. In the egg-disrupted ovules, the central cell predominantly showed single fertilization by one sperm cell, suggesting that neither the egg cell nor its fusion with one sperm cell is necessary for one-to-one fertilization (i.e., monospermy) of the central cell. In addition, usingtetrasporemutants possessing multiple sperm cell pairs in one pollen, we demonstrated that normal double fertilization was observed even when excess sperm cells were released into the receptive region between the female gametes. In ovules accepting four sperm cells, the egg cell never fused with more than one sperm cell, whereas half of the central cells fused with more than one sperm cell (i.e., polyspermy) even 1 h later. Our results suggest that the central cell can block polyspermy during double fertilization, although the central cell is more permissive to polyspermy than the egg cell. The potential contribution of polyspermy block by the central cell is discussed in terms of how it is involved in the one-to-one distribution of the sperm cells to two distinct female gametes.

Late planting of short-season cotton under high plant density and single fertilization after rapeseed harvest is a promising alternative to traditional relay intercropping of full-season cotton in the Yangtze River Valley of China. However, it is not clear if mepiquat chloride (MC) application is still necessary in the new system. We hypothesized that MC application might reduce leaf photosynthesis and economic yield and thus not be necessary in the new system. To test the hypothesis, short-season cotton was sown in mid-May at 10 plants m−2 and with 225 kg N ha−1 applied at early flowering, and MC was applied three times at five main-stem leaf intervals initiated from the 6th leaf stage at five dosages (MC0, MC30, MC60, MC90, and MC120 represent 0, 30, 60, 90, and 120 g ha−1, respectively) in a 2-year experiment. The photosynthesis, chlorophyll contents, carbohydrate contents, carbohydrate metabolic enzyme dynamics, and cotton yield under different MC treatments were determined. Photosynthesis was reduced by 1–28% and lint yield decreased by 6–29% as MC dosage increased. However, chlorophyll a, b, a + b, sucrose, glucose, fructose, and starch contents in the 4th leaf from the top were increased by 3–56%, 2–45%, 3–51%, 4–48%, 3–48%, 2–63%, and 2–43%, respectively. The activities of enzymes involved in carbohydrate metabolism decreased by 2–25% for sucrose phosphate synthase, but increased by 2–40%, 2–30%, and 3–52% for sucrose synthase, soluble acid invertase, and neutral invertase, respectively. These findings suggest that increased accumulation of sucrose, hexose, and starch in the leaf with MC application diminished photosynthesis and thus could explain the yield loss. Therefore, MC application is not necessary for late-planted cotton.

High input costs combined with multiple management and material inputs have threatened cotton productivity. We hypothesize that this problem can be addressed by a single fertilization at flowering with late sowing in a moderately populated plant stand. Field experiments were conducted to evaluate the cotton biomass accumulation, phosphorus dynamics, and fiber quality under three planting densities (low, 3 &times, 104, moderate, 6 &times, and dense, 9 &times, 104 ha&minus, 1) and two cultivars (Zhongmian-16 and J-4B). High planting density had 6.2 and 12.6% larger stems and fruiting nodes m&minus, 2, while low density produced a 37.5 and 59.4% maximum height node ratio. Moderate density produced 26.4&ndash, 15.5%, 24.7&ndash, 12.6%, and 10.5&ndash, 13.6% higher biomass accumulation rate at the peak bloom, boll set, and plant removal stages over low and high density in both years, respectively. J-4B produced a higher reproductive organs biomass yield when compared with Zhongmian-16 in both years. This higher biomass formation was due to both the higher average (0.8 VT kg&middot, ha&minus, 1&middot, d&minus, 1) and maximum (1.0 VM kg&middot, 1) reproductive organ phosphorus uptake, respectively. Plants with low density had 5.3&ndash, 18.5%, 9.5&ndash, 15%, and 7.8&ndash, 12.8% greater length, strength, and micronaire values over moderate and dense plants, respectively. Conclusively, moderate density with J-4B is a promising option for improved biomass, phosphorus acquisition, and fiber quality under a short season.

Made available in DSpace on 2021-06-25T11:02:26Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-06-01 Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) The intensification of pasture production has increased the use of N fertilizers—a practice that can alter soil greenhouse gas (GHG) fluxes. The objective of the present study was to evaluate the fluxes of CH4, CO2, and N2 O in the soil of Urochloa brizantha ‘Marandu’ pastures fertilized with different sources and doses of N. Two field experiments were conducted to evaluate GHG fluxes following N fertilization with urea, ammonium nitrate, and ammonium sulfate at doses of 0, 90, 180, and 270 kg N ha−1 . GHG fluxes were quantified using the static chamber technique and gas chromatography. In both experiments, the sources and doses of N did not significantly affect cumulative GHG emissions, while N fertilization significantly affected cumulative N2 O and CO2 emissions compared to the control treatment. The N2 O emission factor following fertilization with urea, ammonium nitrate, and ammonium sulfate was lower than the United Nations’ Intergovernmental Panel on Climate Change standard (0.35%, 0.24%, and 0.21%, respectively, with fractionation fertilization and 1.00%, 0.83%, and 1.03%, respectively, with single fertilization). These findings are important for integrating national inventories and improving GHG estimation in tropical regions. Departamento de Zootecnia Faculdade de Ciências Agrárias e Veterinárias UNESP—Universty Estadual Paulista Departamento de Zootecnia Faculdade de Ciências Agrárias e Veterinárias UNESP—Universty Estadual Paulista FAPESP: 2015/16631–5 FAPESP: 2017/02914–0 FAPESP: 2017/11274–5 FAPESP: 2017/20279–0 CNPq: 431713/2018–9

The Podostemaceae family is exceptional among angiosperms because of the absence of double fertilization, a remarkable characteristic that appears to extend to the entire family. A recent investigation of some members of the family, including Dalzellia zeylanica (Tristichoideae), Griffithella zeylanica, Polypleurum stylosum, Zeylanidium lichenoides, and Zeylanidium maheshwarii (Podostemoideae), revealed that the central cell in all of them is degenerated when the pollen tube arrives at the synergid. In the present work, we studied the ontogenetic development of the female gametophyte. We also conducted a terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay and an ultrastructural transmission electron microscopy (TEM) analysis of Marathrum schiedeanum (Podostemoideae) to determine the causes of central cell degeneration. The results show that in the early stage, the female gametophyte was 4-celled and 4-nucleated, but the central cell degenerated very quickly before the start of anthesis. The reduced mature female gametophyte is 3-nucleate, 3-celled. TUNEL staining and ultrastructural TEM analysis indicated that developmental programmed cell death (PCD) mediated the degeneration of the central cell. The central cell displayed a significant quantity of vacuoles containing some cellular material, and the compact chromatin was present in the nucleus and DNA fragmentation occurred. The factors that trigger PCD in the central cell are unknown, but the test results confirm that pollination is not necessary for it to occur. The death of the central cell before pollination prevents the possibility of double fertilization and consequently results in failure to form the endosperm.

In 2012, a thought experiment in this journal suggested that paternity cases involving monozygotic (MZ) twins as putative fathers could be solved by means of whole genome sequencing (WGS). Although arising from a single fertilization event, MZ twins nevertheless continue to acquire somatic mutations during their development, including those that occur in the germline. Provided that paternity had been narrowed down to the twin pair beforehand by classical DNA analysis, one post-zygotic mutation would suffice to assign the paternal compartment of an offspring genome unambiguously to either twin if that mutation is found in the offspring and one twin, but not in the other twin. Since the publication of a proof-of-principle report in 2014, we have worked up five additional cases of MZ twin germline discrimination in real life, four paternity disputes and one criminal case requiring the identification of a sperm trace donor among a pair of MZ twin brothers. In this opinion paper, we report on the experiences made in the course of our work and take a look at possibilities for further development of the approach.

Effective management of nitrogen (N) fertilizer application by farmers provides great potential for reducing emissions of the potent greenhouse gas nitrous oxide (N2O). However, such potential is rarely achieved because our understanding of what practices (or combination of practices) lead to N2O reductions without compromising crop yields remains far from complete. Using scenario analysis with the process-based model DNDC, this study explored the effects of nine fertilizer practices on N2O emissions and crop yields from two corn production systems in Canada. The scenarios differed in: timing of fertilizer application, fertilizer rate, number of applications, fertilizer type, method of application and use of nitrification/urease inhibitors. Statistical analysis showed that during the initial calibration and validation stages the simulated results had no significant total error or bias compared to measured values, yet grain yield estimations warrant further model improvement. Sidedress fertilizer applications reduced yield-scaled N2O emissions by c. 60% compared to fall fertilization. Nitrification inhibitors further reduced yield-scaled N2O emissions by c. 10%; urease inhibitors had no effect on either N2O emissions or crop productivity. The combined adoption of split fertilizer application with inhibitors at a rate 10% lower than the conventional application rate (i.e. 150kgNha-1) was successful, but the benefits were lower than those achieved with single fertilization at sidedress. Our study provides a comprehensive assessment of fertilizer management practices that enables policy development regarding N2O mitigation from agricultural soils in Canada.

International audience; AbstractKey messageK fertilization led to a significant increase in fine root biomass, fine root length, and root tip number in the mineral soil layer but does not affect the ecomycorrhizal community structure in the organic horizon.ContextPotassium (K) deficiency is common in Picea abies in the European Alps. Fertilization with other nutrients often influences fine root biomass and ectomycorrhizas, but less is known about the effects of K-fertilization.AimsThe aim of the investigation was to determine the effects of K-fertilization on stem growth and fine root biomass of Picea abies, as well as the influence on ectomycorrhizal community structure of the fine roots.MethodsEight years after a single fertilization of K-deficient Picea abies with 200 kg K ha−1, fine roots were collected from 7 control and 6 K-fertilized plots. Fine root biomass and morphology were determined. The identification of ectomycorrhizal taxa was determined by morphotyping and by amplification of the internal transcribed spacer region of the nuclear ribosomal DNA.ResultsK-fertilization did not affect the amount of fine root biomass and ectomycorrhizal community structure in the Oi + Oe and Oa layers but led to a significant increase in fine root biomass, fine root length, and root tip number in the mineral soil layer.ConclusionAn increase in growth due to K-fertilization leads to great exploration of the mineral soil by fine roots but does not affect the ectomycorrhizal community structure in the organic horizons.

Although split fertilizer applications have been suggested as a logical strategy to reduce nitrous oxide (N2O) emissions by decreasing soil nitrate concentrations, their efficacy remains unclear. A laboratory incubation experiment was performed to determine the effect of split fertilization vs. single fertilization on N2O emissions. The split urea application reduced the peak N2O emissions during the incubation period, and the cumulative N2O emissions were significantly reduced by 28% compared with the single fertilization, although these emissions were influenced by the N fertilizer rate and soil moisture. A higher percentage reduction in cumulative N2O emissions under the split fertilization occurred at the low (45%) compared with the high fertilizer rate (15%). At the low fertilizer rate (200 N), the split fertilization resulted in a significantly greater reduction in N2O emissions under the dry soil moisture regime (53%) compared with the wet soil moisture condition (37%). In addition, the split fertilization reduced the cumulative CO2 emissions by 9% compared with the single fertilization. Therefore, our laboratory results suggest that the split fertilization strategy appears to be a useful method to reduce greenhouse gas emissions in an irrigated agriculture ecosystem.

Fertilization is a key management practice for maintaining or improving soil fertility in agro-ecosystems. Nevertheless, how fertilization strategies impact the status of soil microbial resource limitation is poorly understood. Here, we investigated the effects of long-term (11 years) fertilization on microbial resource limitation in a karst cropland under maize–soybean rotation. Soil microbial resource limitation was assessed using enzymatic stoichiometry. Six fertilization strategies were included, i.e., i) no fertilization (control), ii) inorganic fertilizers only (NPK), iii) inorganic fertilizers plus a low amount of straw (LSNPK), iv) inorganic fertilizers plus a low amount of manure (LMNPK), v) inorganic fertilizers plus a high amount of straw (HSNPK), and vi) inorganic fertilizers plus a high amount of manure (HMNPK). Overall, soil microbes were not limited by nitrogen, but co-limited by carbon and phosphorus across the six fertilization strategies. However, the degrees of microbial resource limitations were different between the control and fertilizer treatments. Application with inorganic fertilizers only aggravated microbial carbon limitation, but combined application of inorganic fertilizers and organic matters did not change the status of carbon limitation relative to the control. None of the fertilizer treatments changed the status of microbial nitrogen limitation. The treatments of NPK, LSNPK and LMNPK alleviated microbial phosphorus limitation, but HSNPK and HMNPK had no significant effects on phosphorus limitation relative to the control. By contrast, the crop production had no significant difference among all fertilizer treatments in the current study. Together, our results indicate that fertilizations can change microbial resource limitation status, which might be a more sensitive indicator to identify effective fertilization strategies relative to the crop production. Here we suggest that karst croplands do not need too much nitrogen fertilizer due to the nitrogen-rich characteristic, and that combined inorganic and organic fertilization strategies are better than single fertilization strategy in karst croplands.

All flowering plants exhibit a unique type of sexual reproduction called ‘double fertilization’ in which each pollen tube-delivered sperm cell fuses with an egg and a central cell. Proteins that localize to the plasma membrane of gametes regulate one-to-one gamete pairing and fusion between male and female gametes for successful double fertilization. Here, we have identified a membrane protein from Lilium longiflorum generative cells using proteomic analysis and have found that the protein is an ortholog of Arabidopsis DUF679 DOMAIN MEMBRANE PROTEIN 9 (DMP9)/DUO1-ACTIVATED UNKNOWN 2 (DAU2). The flowering plant DMP9 proteins analyzed in this study were predicted to have four transmembrane domains and be specifically expressed in both generative and sperm cells. Knockdown of DMP9 resulted in aborted seeds due to single fertilization of the central cell. Detailed imaging of DMP9-knockdown sperm cells during in vivo and semi-in vitro double fertilization revealed that DMP9 is involved in gamete interaction that leads to correct double fertilization.

In vivo doubled-haploid technology is widely applied in commercial maize breeding programs because of its time-saving and cost-reducing features. The production of maize haploids primarily depends on the use of Stock6-derived haploid inducer lines. Although the gene underlying haploid induction, MTL/ZmPLA1/NLD, was cloned recently, the mechanism of haploid induction is still unknown. Hetero-fertilization can occur via a single fertilization, which provides a means to investigate single-fertilization events by studying the hetero-fertilization phenomenon. In this study, we found that the hetero-fertilization rate increased significantly when female maize lines were first individually crossed with pollen from the inducer CAU5 in dual-pollination experiments 4 h before a second pollination with common lines. We also examined embryogenesis during haploid induction by confocal laser-scanning microscopy and observed single-fertilized ovules, indicating that single fertilization occurred during haploid induction. We therefore postulate that both single fertilization and chromosome elimination contribute to haploid induction in maize. We also propose a scheme for the formation of hetero-fertilized and haploid kernels. Our results provide an efficient approach to identify hetero-fertilized kernels for research on interactions between embryo and endosperm.

PREMISE OF THE STUDY The female gametophyte of Welwitschia has long been viewed as highly divergent from other members of the Gnetales and, indeed, all other seed plants. However, the formation of female gametes and the process of fertilization have never been observed. METHODS Standard histological techniques were applied to study gametophyte development and the fertilization process in Welwitschia. KEY RESULTS In Welwitschia, fertilization events occur when pollen tubes with binucleate sperm cells grow down through the nucellus and encounter prothallial tubes, free nuclear tubular extensions of the micropylar end of the female gametophyte that grow up through the nucellus. Entry of a binucleate sperm cell into a vacuolate prothallial tube appears to stimulate the rapid coagulation of cytoplasm around a single female nucleus, which differentiates into an egg cell. One sperm nucleus enters the female gamete, while the second sperm nucleus remains outside and ultimately degenerates. Only a single fertilization event occurs per mating pair of pollen tube and prothallial tube. CONCLUSIONS Welwitschia lacks the gnetalean pattern of regular double fertilization, as found in Ephedra and Gnetum, involving sperm from a single pollen tube to yield two zygotes. Moreover, an analysis of character evolution indicates that the female gametophyte of Welwitschia is highly apomorphic both among seed plants, and specifically within Gnetales, but also shares several key synapomorphies with its sister taxon Gnetum. Finally, the biological role of prothallial tubes in Welwitschia is examined from the perspectives of gamete competition and kin conflict.

Study on soil phosphorus (P) fraction is an important aspect in probing the mechanisms of soil P accumulation in farmland and mitigating its losing risk to the environment. We used a sequential extraction method to evaluate the impacts of long-term fertilization and straw incorporation on inorganic, organic, and residual P (P i , P o , and P re ) fractions in the plow layer (0–20 cm) of acidic paddy soil in southern China. The experiment comprised of six treatments: (i) no fertilizer control (CK); (ii) straw incorporation and green manure (SG); (iii) nitrogen and P fertilizer (NP); (iv) NP+SG; (v) NP+K fertilizer (NPK); and (vi) NPK+SG. The results showed that, compared to the initial total soil P content (TSP, 600 mg kg −1 in 1990), long-term (20 years) combined continuous P fertilizer and SG significantly increased P accumulation (by 13–20%) while single fertilization (39.3 kg P ha −1 yr −1 ) could maintain soil P status at the most. The average soil P fractions comprised of extractable P i , P o , and P re by 51.7, 33.4, and 14.9% in total soil P, respectively. With comparison of no fertilizer addition (CK), long-term single fertilization significantly (P 3 − , NaOH − , and HCl − extractable P i fractions accounting for two- to three-fold, while SG increased the accumulation of NaHCO 3 − and NaOH − extractable P i and P o accounting for 12–60%. Though the mobilization of P re fractions was not significant (P>0.05), our data indicate that SG may partially substitute for fertilizer P input and minimizing soil P accumulation and subsequent environmental risk in the subtropical paddy soil.

The absence of double fertilization and lack of endosperm formation are key embryological features of Podostemaceae, which is unique among the angiosperms. Double fertilization fails in spite of the fact that two male gametes are carried in the pollen tube and the incipient embryo sac is equipped with an egg cell and a central cell. Little is known about the proximate causes of the failure of double fertilization. The female gametophyte of Zeylanidium lichenoides, (subfamily — Podostemoideae) has a monosporic mode of development resulting in an initial four-celled/four-nucleate condition. However, the central cell degenerates before the arrival of the pollen tube in the vicinity of micropyle, thus the mature and functional female gametophyte of Z. lichenoides is ontogenically a three-celled/three-nucleate structure. It is inferred that the formation of a highly reduced female gametophyte, presumably is a result of degeneration of the central cell.

Double fertilization of the egg cell and the central cell by two sperm cells, resulting in the formation of the embryo and the endosperm, respectively, is a defining characteristic of flowering plants. The Arabidopsis thaliana female gametophytic mutant glauce (glc) can exhibit embryo development without any endosperm. Here, we show that in glc mutant embryo sacs one sperm cell successfully fuses with the egg cell but the second sperm cell fails to fuse with the central cell, resulting in single fertilization. Complementation studies using genes from the glc deletion interval identified an unusual genomic locus having homology to BAHD (for BEAT, AHCT, HCBT, and DAT) acyl-transferases with dual transcription units and alternative splicing that could rescue the sterility defect of glc. Expression of these transcripts appears restricted to the central cell, and expression within the central cell is sufficient to restore fertility. We conclude that the central cell actively promotes its own fertilization by the sperm cell through a signaling mechanism involving products of At1g65450. Successful fertilization of the egg cell is not blocked in the glc mutant, suggesting that evolution of double fertilization in flowering plants involved acquisition of specific functions by the central cell to enable its role as a second female gamete.

Angiosperms are characterized by the occurrence of double fertilization. However, Podostemaceae is considered an exception with the presence of only single fertilization (syngamy) though two male gametes are formed conventionally. To determine the cause for the failure of double fertilization in Dalzellia zeylanica (Gardn.) Wight, we closely tracked the movement of the male gametes from the time of pollen tube initiation to the time of entry into the megagametophyte to affect fertilization. We report for the first time, the presence of a novel type of three-nucleate/three-celled mature megagametophyte consisting of two synergids and an egg cell in D. zeylanica. Therefore, of the two male gametes formed in this plant, one fuses with the egg cell resulting in syngamy, whereas the other male gamete eventually degenerates due to the absence of its partner i.e. single polar nucleus of the central cell that degenerates prior to the entry of the pollen tube into the synergid. The present work not only highlights the highly reduced nature of megagametophyte but also the occurrence of single fertilization resulting in sperm selection in D. zeylanica.

Species of barberry (Berberis vulgaris L. var. asperma) is cultivated in arid and semi arid areas of Iran (South Khorasan province). It is widely used as a food additive. Fruits of this species are seedless, while wild type barberries produce seeds in the same area. In this study, we investigated the mechanism of seedlessness in seedless barberry by pollen viability test, field pollination experiments and microscopic observation of pollen tube growth in pistil and ovule development. For comparison, we also examined ovule development in wild type barberry (B. crataegina DC). In seedless barberry pollen germination was about 54%. Seedless barberry produced 20% seeded fruits when pollinated with pollen of wild type barberry. There was a sharp decrease in fruit set in emasculated unpollinated flowers of seedless barberry. In seedless barberry, a large number of pollen grains (about 370) were observed on stigma of each flower at 12 h after balloon stage (ABS). Most of them germinated and penetrated intracellular area of stigma surface, but no pollen tube reached ovary. In seedless barberry, many ovules did not have any embryo sac or had a very small incomplete embryo sac. In addition, unfused polar nuclei were clearly recognized in some cases at 14 days after full bloom (AFB). However, in wild type, double fertilization was accompanied by disappearance of polar nuclei. In seeded barberry, the cellularized endosperm became apparent at seven days AFB. At 21 days AFB, all ovules of seedless barberry were degenerated, while at the same time in wild type, one or two ovules of each flower were normal and were developing into complete seeds. Results showed that self-incompatibility has a main role in seedlessness of seedless barberry. However, the high frequency of abnormal ovules and single fertilization can be considered as two other reasons of seedlessness. Due to our results, fruits of seedless barberry were set by stimulative parthenocarpy.

Natural cis-antisense siRNAs (cis-nat-siRNAs) are a recently characterized class of small regulatory RNAs that are widespread in eukaryotes. Despite their abundance, the importance of their regulatory activity is largely unknown. The only functional role for eukaryotic cis-nat-siRNAs that has been described to date is in environmental stress responses in plants. Here we demonstrate that cis-nat-siRNA-based regulation plays key roles in Arabidopsis reproductive function, as it facilitates gametophyte formation and double fertilization, a developmental process of enormous agricultural value. We show that male gametophytic kokopelli (kpl) mutants display frequent single-fertilization events, and that KPL and a inversely transcribed gene, ARIADNE14 (ARI14), which encodes a putative ubiquitin E3 ligase, generate a sperm-specific nat-siRNA pair. In the absence of KPL, ARI14 RNA levels in sperm are increased and fertilization is impaired. Furthermore, ARI14 transcripts accumulate in several siRNA biogenesis pathway mutants, and overexpression of ARI14 in sperm phenocopies the reduced seed set of the kokopelli mutants. These results extend the regulatory capacity of cis-nat-siRNAs to development by identifying a role for cis-nat-siRNAs in controlling sperm function during double fertilization.

The process of double fertilization and the characters of embryo and endosperm development in an autotetraploid polyembryonic mutant rice IR36-Shuang were studied with a laser scanning confocal microscopy. Some abnormalities including degenerated ovary, abortive embryo sac, single fertilization, double-ovule and double-embryo and so on. were found during double fertilization and embryo development in IR36-Shuang. The rate of the abnormalities was 46.67% in IR36-Shuang, significantly higher than that in the control, an autotetraploid rice line IR36-4X (33.00%). Cytological and embryonic evidences were provided for seed setting decline and the initiation of additional embryo in IR36-Shuang.

Crown architecture and size influence leaf area distribution within tree crowns and have large effects on the light environment in forest canopies. The use of selected genotypes in combination with silvicultural treatments that optimize site conditions in forest plantations provide both a challenge and an opportunity to study the biological and environmental determinants of forest growth. We investigated tree growth, crown development and leaf traits of two elite families of loblolly pine (Pinus taeda L.) and one family of slash pine (P. elliottii Mill.) at canopy closure. Two contrasting silvicultural treatments -- repeated fertilization and control of competing vegetation (MI treatment), and a single fertilization and control of competing vegetation treatment (C treatment) -- were applied at two experimental sites in the West Gulf Coastal Plain in Texas and Louisiana. At a common tree size (diameter at breast height), loblolly pine trees had longer and wider crowns, and at the plot-level, intercepted a greater fraction of photosynthetic photon flux than slash pine trees. Leaf-level, light-saturated assimilation rates (A(max)) and both mass- and area-based leaf nitrogen (N) decreased, and specific leaf area (SLA) increased with increasing canopy depth. Leaf-trait gradients were steeper in crowns of loblolly pine trees than of slash pine trees for SLA and leaf N, but not for A(max). There were no species differences in A(max), except in mass-based photosynthesis in upper crowns, but the effect of silvicultural treatment on A(max) differed between sites. Across all crown positions, A(max) was correlated with leaf N, but the relationship differed between sites and treatments. Observed patterns of variation in leaf properties within crowns reflected acclimation to developing light gradients in stands with closing canopies. Tree growth was not directly related to A(max), but there was a strong correlation between tree growth and plot-level light interception in both species. Growth efficiency was unaffected by silvicultural treatment. Thus, when coupled with leaf area and light interception at the crown and canopy levels, A(max) provides insight into family and silvicultural effects on tree growth.

Since the first description of the double fertilization process in flowering plants (angiosperms) 110 years ago (Nawaschin in Bull Acad Imp Sci St Petersburg 9:377–382, 1898), little progress has been made during the following 100 years to understand the underlying molecular mechanisms. This seems to be in strong contrast to our steadily increasing knowledge of single fertilization in animals, where a large number of key players and the corresponding molecular mechanisms have been unclosed since the mid-1970s. Are the identified fertilization mechanisms ubiquitously dispersed, occurring also in higher plants? The past few years have seen a number of discoveries indicating that general principles of fertilization mechanisms in animals and flowering plants are more conserved than previously thought. Here, we compare the development and morphology of animal and flowering plant gametes, discuss cell–cell communication events between gametes and gametophytes as well as their physical interaction and fusion during single and double fertilization, respectively.

Co-digestion changes slurry characteristics and is supposed to increase short-term nitrogen (N) uptake by crops after application. A higher N uptake from slurry reduces the need for additional mineral N fertilizer. If farmers apply co-digested slurry (CS), a higher N recovery has to be taken into account to prevent losses to the environment. Since data on the effects of co-digestion on N recovery by crops are scarce, a pot experiment was performed. The apparent N recovery (ANR) of five different co-digested pig slurries was compared with their raw source slurries (RS) during 105 d after a single fertilization of ryegrass (Lolium perenne L.), grown under controlled conditions. Slurry was mixed with sandy soil and grass was cut every 35 d. The results show that co-digestion increased (p < 0.05) the ANR at first cut on average from 39 to 50%, at second cut from 7 to 9% (p < 0.05), and had no effect on ANR at third cut (3%). The ANR increase at first cut was likely due to an increase of the NH(4)-N/total N ratio along with a decrease of the organic C/total N ratio of slurry during co-digestion. Field application may under certain circumstances decrease N fertilizer value of CS, due to a higher NH(3) emission compared to RS. A potential ANR increase may then be reduced, absent, or even become a decrease. Under comparable NH(3) emissions, however, CS can in the short term be more valuable as an N fertilizer than RS, and fertilizer savings can likely be realized.

The field experiment of P and K fertilization was conducted in spring of 2004 (a = ordinary fertilization, b = a + P1, c = a + P2, d = a + P3 , e = a + P1, f = a + P2, g = a + P3 , h = a + P2K2. The amounts of added either/or phosphorus (P2O5) and potassium (K2O) were (kg ha-1) 500, 1000 and 1500, for the step 1, 2 and 3, respectively. The triplephoshate enriched with sulphur and zinc (45% P2O5 + 1. 2% S + 0.06% Zn) was used for P fertilization. Potassium salt (KCl containing 60% K2O) was source of K. Nitrogen amount was equilized for all treatments by adequate quatities of CAN (calcium ammonium nitrate: 27% N). The experiment was conducted in four replicates for crop rotation maize (2004) and soybean (2005: residual effects of the fertilization). Applied fertilization considerable influenced on increases of plant available P and K in soil, while differences of pH and humus among tretaments were in range of statistical error. Also, both P and K single fertilization gave tendency to decrease hydrolitical acidity. In general, grain yields of maize were high and ameliorative fertilization had moderate effects on maize yield as well as P and K in grain and leaves increases. Only applications of the highest K rate and PK combination resulted by significant yield increases, for 5% and 12%, respectively. Only application both P and K nutrients resulted by increase of grain quality (protein content). Residual influences of the fertilization were higher because soybean yields were increased up to 21% (influences of P), 17% (influences of K) and 30% (PK influences). However, protein and oil contents in grain were indenpendent on fertilization.

Temporal change in stem volume, basal area, diameter, and height are reported for stands of Pinus radiata growing near Canberra, ACT, Australia between the ages of 10 and 29 years. The stands were subjected to either a single fertilization (F) at age 10 years, irrigation (I), irrigation after a single fertilization at age 10 years (IF), irrigation with continuous liquid fertilization (IL), or no treatment (Control (C)). At age 15 years all the stands were thinned. At the same time, irrigation ceased in a duplicate IF stand, and irrigation and liquid fertilization ceased in a duplicate IL stand. Stem growth responded markedly to irrigation, with a strong interactive effect when combined with N fertilization. Over a 19 year treatment period (ages 10–29 years) the percentage gross underbark volume responses, relative to the control which had an annual growth rate of 19.3 m 3 ha −1 year −1 , were F (98%), I (132%), IF (184%), and IL (229%). Standing stem volumes (m 3 ha −1 ) at the end of the study were C (340), F (328), I (438), IF (624), and IL (776). The IF stand continued to grow at rates considerably greater than the I or F for the entire experiment, indicating efficient N cycling with increased water supply over a period of nearly 20 years. In non-irrigated stands, added N only increased growth during wet periods, and the response declined to be similar to the control within 5–8 years. Irrigation increased growth in the larger trees proportionally more than the smaller trees, resulting in an increased diameter distribution compared with the non-irrigated stands. Cessation of irrigation in combination with thinning after 5 years of treatment immediately reduced annual basal area growth to levels similar to the control for at least 2 years, but did not lead to tree mortality. Thinning reduced stand basal area increment for 2–3 years in treatments without adequate N supply, even if they were irrigated. The study demonstrates the importance of monitoring long-term growth to understand the changing interactions between water and N availability. For example, initial responses to irrigation only were markedly attenuated over time because of increasing N limitations, while irrigated and fertilized stands showed little or no change in the response pattern. Understanding the temporal change in water–N interactions has implications for modelling long-term forest growth, and forest management.

To effectively reduce the effects of nitrogen pollutants on water environment. Selecting the rice-growing area of Liaohe River estuary in Panjin City of Liaoning Province as the research object, Different sections and the different stages of a single fertilization in ditch is sampled to measure and analyze the three nitrogen of ditch system in different stages of fertilization; the paper investigated the reductive variation of nitrogen concentration in paddy fiel ds drainage. The results show that: Ammonia nitrogen concentration is on the decline in a whole, however, ammonia nitrogen was relaxedly increased in different periods, due to the variation of northern rice area is obvious in different stages of fertilization, fluctuations in paddy fields drainage on ammonia nitrogen. Nitrate nitrogen at the early stage of the basal period changes gently, after rising slowly towards stability. Nitrate nitrogen is decreasing along the way in Rice fertilizer period, but the trend is not obvious. At earing fertilizer period of Nitrate nitrogen is Firstly decline and then stabilize. The decision is ditches sediment microbial activity.

The structure of ovules that failed to form seeds after compatible pollination in double-flowered zinnias ( Zinnia violacea Cav.) was investigated by observing histological sections, and comparing the normal and abnormal development of the seeds. In an embryo sac of zinnia at anthesis, a large nucleus of fused polar nuclei was clearly recognized. Success in double fertilization was determined by the disappearance of this nucleus. In normally developing seeds, the cellular endosperm became vague at 5–6 days after pollination (DAP) and the developing embryos occupied the entire portion of the seeds up to 10 DAP. A number of ovules failed in fertilization for the lack of an embryo sac. In most of the aborted seeds, the embryo sacs degenerated, whereas the aborted embryos were still alive in a small number of aborted seeds. A small percentage of the aborted seeds exhibited an aborted embryo and an unfertilized fused nucleus of two polar nuclei or ‘single fertilization’. The three major problems suggested for the failure in seed formation in pollinated florets of zinnia included failure in fertilization, ovules lacking embryo sacs, and abortion of developing seeds.

Laboratory rearing and reconstruction of Laodicea undulata (Hydrozoa) life cycle led to the discovery for the first time in Leptomedusae of the potential for ontogeny reversal, i.e. the medusa stage can asexually transform back into the polyp stage. In turn, each rejuvenated polyp stage can newly activate the standard developmental programme towards colony morphogenesis and budding of secondary medusae. These can be considered as clonemates of the initial medusa batch, since they originate by asexual processes. In combination with the ordinary medusa budding process, the potential for reverse development might represent a tool to increase jellyfish population growth rate during the favourable season, but eventually it does not avoid jellyfish to die. Comparably to polyembryony, reverse development leads to offspring multiplication from a single fertilization event, with a wider dispersal of each single genotype; eventually, it favours the enhancement of the overall genetic diversity at small spatial scale. The life cycle of L. undulata from the Mediterranean Sea is re-described, linking previously uncoupled descriptions of either the polyp or the early medusa stages. Taxonomic considerations of the genus Laodicea and a comparison among the known Mediterranean species are also provided.

Reduced female gametophyte. Angiosperms are characterized by the phenomenon of double fertilization with Podostemaceae as an exception that appears to extend to the entire family. Our earlier work demonstrated the cause of failure of double fertilization and ascertained the occurrence of single fertilization in Dalzellia zeylanica (Tristichoideae, Podostemaceae). In continuation with this work, three more members, i.e., Griffithella hookeriana (Tul.) Warming, Polypleurum stylosum (Wight) Hall, and Zeylanidium lichenoides (Kurz) Engl. (Podostemoideae), have been investigated in the present work. We studied the ontogenetic development of female gametophyte and tracked the path of the two sperm cells from the time of their formation in the pollen tube through their entry into the synergid and gamete fusion. We report the occurrence of a remarkably reduced 3-nucleate, 3-celled mature female gametophyte consisting of an egg cell and two synergids in all the three genera. Interestingly, the central cell is formed during female gametophyte development, but exhibits a species-specific, limited life span, and eventually degenerates prior to the entry of the pollen tube into the synergid, resulting in a failure of double fertilization. Sperm dimorphism on the basis of fluorochrome stainability has been recorded in Z. lichenoides. Further, morphogenetic constraints on the part of male (sperm selection, functional reductionism) and female gametophyte (structural reductionism, inaccessibility of central cell) presumably ensure the failure of double fertilization in these species. Thus, loss of double fertilization in this family is likely a derived condition.

Nitrous oxide (N 2 O) emissions from several Italian croplands along a latitudinal gradient were analyzed and the fertilizer induced emission (FIE) factor, for each single fertilization event, was calculated. Data show that the average emission factor was between 0.7 and 0.3 %, hence much lower than the IPCC EF used for temperate croplands. The relationship between N 2 O production and applied N fertilization rate was exponential and not linear, although the rate of exponential increase was lower than previously reported. Maximum N 2 O emission rate was correlated with magnitude of the total FIE, whereas it was inversely related to the length of FIE, which varied from a minimum of 8–56 days. Overall data suggest that the internationally applied emission factors for temperate crops, which are empirically derived from sites with cooler and wetter climates than the Mediterranean, would overestimate N 2 O emissions for Italian crops, in particular those developing between spring and summer.

Rates of mass loss of foliar litter of trembling aspen (Populus tremuloides Michx.) were measured for 4 years after a single fertilization with N at 200 kg N/ha or a mix of N, P, K. Ca, Mg, S, and B. Foliar litter from fertilized plots had higher N concentrations than litter from control plots; litter from the nutrient-mix plots had higher concentrations of N, P, and Ca. The average rate of mass loss of aspen foliar litter was 60% after 4 years. The higher concentrations of nutrients in litter from fertilized plots did not affect the rate of decomposition. There was some difference in rates of decomposition of litter incubated in plots of the three treatments. Mass loss was significantly slower in the nutrient-mix plots after 12 and 18 months compared with control plots. This experiment provided no evidence that fertilization of boreal aspen forests will increase rates of litter decomposition.

Single fertilization events were detected in seven maize lines (Zea mays L.) of different genetic background. Detection of single fertilization was achieved by a dual pollination method, that is, pollen parent 1 (y1/y1, white endosperm) was pollinated onto the silks of Oh43 (Y1/Y1, yellow endosperm) and 24 h later the same silks were pollinated with pollen of X18G (R1-scm2/R1-scm2, purple aleurone and purple embryo). Seventy-nine kernels with purple aleurone and white scutellum (Pw) were observed in 29,999 examined kernels. Determination of chromosome numbers and progeny tests revealed that 31 plants were maternal haploid, 4 were monosomics between Oh43 and X18G, 36 originated from single fertilization events by pollen parent 1 (0.4%), and 5 triploids are thought to have originated from single fertilization by a diploid sperm cell of pollen parent 1. At least one-fifth of heterofertilization events in maize can be the result of single fertilization.