Single fertilization

About: Single fertilization is a research topic. Over the lifetime, 105 publications have been published within this topic receiving 1203 citations.

Proper regulation of a sperm-specific cis-nat-siRNA is essential for double fertilization in Arabidopsis

Abstract: 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.

Co-digestion of animal slurry can increase short-term nitrogen recovery by crops.

Abstract: 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.

Soil Fertility under Native Cerrado and Pasture in the Brazilian Savanna

Abstract: In the Brazilian savanna, there is a risk that soil fertility of pastures declines to a level below that of the native savanna because of low fertilizer application. To evaluate biophysical pasture sustainability we compared regularly fertilized productive pasture (PP), degraded pasture fertilized 13 yr previously (DP), and native savanna (Cerrado, CE) in an on-farm experiment. We determined (i) biomass productivity of the pastures and (ii) nutrient concentrations in Anionic Acrustoxes from three plots under each of CE, DP, and PP. From the 0- to 2-m soil layer, we sampled solid phase in January 1998 and soil solution during two rainy seasons (1997-1998 and 1998-1999). The mean aboveground biomass production (dry weight) was 2.1 Mg ha -1 yr -4 for DP and 4.1 Mg ha -1 yr -1 for PP. In the solid phase of the 0- to 0.15-m layer, mean total N and S and exchangeable Ca and Mg concentrations increased in the order CE < DP < PP, while NaHCO 3 -extractable P was not significantly different among CE, DP, and PP. In the soil solution at 0.15-m depth, pH and concentrations of Ca and Mg also increased in the order CE < DP < PP. At the 2-m depth, only K, Mn, and NO 3 -N concentrations in soil solution were slightly higher under the pastures than under CE indicating an increased risk of leaching losses to below the rooting zone. Thus, topsoil fertility in both pastures is increased compared with CE, and little leaching occurs. Some fertility indicators in DP are still improved compared with CE 13 yr after a single fertilization.

The male gamete membrane protein DMP9/DAU2 is required for double fertilization in flowering plants.

Abstract: 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.

Responses of soil microbial resource limitation to multiple fertilization strategies

Abstract: 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.