The status of plant and microbial nutrient limitation have profound impacts on ecosystem carbon cycle in permafrost areas, which store large amounts of carbon and experience pronounced climatic warming. Despite the long-term standing paradigm assumes that cold ecosystems primarily have nitrogen deficiency, large-scale empirical tests of microbial nutrient limitation are lacking. Here we assessed the potential microbial nutrient limitation across the Tibetan alpine permafrost region, using the combination of enzymatic and elemental stoichiometry, genes abundance and fertilization method. In contrast with the traditional view, the four independent approaches congruently detected widespread microbial nitrogen and phosphorus co-limitation in both the surface soil and deep permafrost deposits, with stronger limitation in the topsoil. Further analysis revealed that soil resources stoichiometry and microbial community composition were the two best predictors of the magnitude of microbial nutrient limitation. High ratio of available soil carbon to nutrient and low fungal/bacterial ratio corresponded to strong microbial nutrient limitation. These findings suggest that warming-induced enhancement in soil nutrient availability could stimulate microbial activity, and probably amplify soil carbon losses from permafrost areas. 相似文献
Isolated microspore culture has been implemented in breeding programs to produce doubled haploid (DH) lines and thus accelerates the breeding process. However, low microspore embryogenesis frequency in flowering Chinese cabbage remains a key obstacle to the practical application of this technique. This study aimed to establish an efficient microspore culture protocol for flowering Chinese cabbage that would be applied for heterosis breeding. Microspores of five genotypes, 19AY05, 19AY06, 19AY10, 19AY12, and 19AY15, were successfully induced to produce embryos in NLN-13 medium. Microspores of two genotypes, 19AY05 and 19AY15, were cultivated in NLN-13 medium supplemented with different concentrations (0, 0.01, 0.05, 0.1, or 0.2 mg·L−1) of compound sodium nitrophenol (sodium nitrophenol, 5-nitrophenol) to enhance microspore embryogenesis and plant regeneration without an intervening callus phase. The results showed that 0.05 ~ 0.1 mg· L−1 sodium nitrophenol and 0.01 ~ 0.2 mg· L−1 of 5-nitrophenol significantly promoted the induction of microspore embryogenesis of two genotypes, and the best concentrations required for different genotypes are different. Moreover, 0.1 mg· L−1 sodium nitrophenol can significantly increase the plant regeneration rate of the two genetypes. The 5-nitrophenol at 0.01 mg·L−1 significantly increased rate of embryos directly convert to plant in 19AY15. In addition, the average doubled haploid rates in the five genotypes were close to 63%. Horticultural traits of DH lines from 19AY05 were identified and all of them were self-incompatible lines. They showed a high uniformity and consistency that can be directly used for hybrid breeding. Furthermore, the hybrid combination was prepared with the selected DH lines and the Guangdong nucleus genic sterile line GMS019 to screen the excellent hybrid combination for the flowering Chinese cabbage breeding program. This method accelerates the application of microspore culture in hybrid breeding of flowering Chinese cabbage.
Protoplasma - Microspore embryogenesis is an effective method of obtaining double haploid (DH) lines in only 1 year. However, the microspore embryogenesis protocol was not efficient in... 相似文献
The purpose of the paper is to find a new approach to measure 3D green biomass of urban forest and to testify its precision. In this study, the 3D green biomass could be acquired on basis of a remote sensing inversion model in which each standing wood was first scanned by Terrestrial Laser Scanner to catch its point cloud data, then the point cloud picture was opened in a digital mapping data acquisition system to get the elevation in an independent coordinate, and at last the individual volume captured was associated with the remote sensing image in SPOT5(System Probatoired''Observation dela Tarre)by means of such tools as SPSS (Statistical Product and Service Solutions), GIS (Geographic Information System), RS (Remote Sensing) and spatial analysis software (FARO SCENE and Geomagic studio11). The results showed that the 3D green biomass of Beijing urban forest was 399.1295 million m3, of which coniferous was 28.7871 million m3 and broad-leaf was 370.3424 million m3. The accuracy of 3D green biomass was over 85%, comparison with the values from 235 field sample data in a typical sampling way. This suggested that the precision done by the 3D forest green biomass based on the image in SPOT5 could meet requirements. This represents an improvement over the conventional method because it not only provides a basis to evalue indices of Beijing urban greenings, but also introduces a new technique to assess 3D green biomass in other cities. 相似文献
The mechanism of how SARS-CoV-2 causes severe multi-organ failure is largely unknown. Acute kidney injury(AKI) is one of the frequent organ damage in severe COVID-19 patients. Previous studies have shown that human renal tubule cells could be the potential host cells targeted by SARS-CoV-2. Traditional cancer cell lines or immortalized cell lines are genetically and phenotypically different from host cells. Animal models are widely used, but often fail to reflect a physiological and pathogenic status because of species tropisms. There is an unmet need for normal human epithelial cells for disease modeling. In this study, we successfully established long term cultures of normal human kidney proximal tubule epithelial cells(KPTECs) in 2 D and 3 D culture systems using conditional reprogramming(CR) and organoids techniques.These cells had the ability to differentiate and repair DNA damage, and showed no transforming property. Importantly, the CR KPTECs maintained lineage function with expression of specific transporters(SLC34 A3 and cubilin). They also expressed angiotensin-converting enzyme 2(ACE2), a receptor for SARS-CoV and SARS-CoV-2. In contrast, cancer cell line did not express endogenous SLC34 A3, cubilin and ACE2. Very interestingly, ACE2 expression was around twofold higher in 3 D organoids culture compared to that in 2 D CR culture condition. Pseudovirion assays demonstrated that SARS-CoV spike(S) protein was able to enter CR cells with luciferase reporter. This integrated 2 D CR and 3 D organoid cultures provide a physiological ex vivo model to study kidney functions, innate immune response of kidney cells to viruses, and a novel platform for drug discovery and safety evaluation. 相似文献