The Role of EjSOC1s in Flower Initiation in Eriobotrya japonica

The MADS-box transcription factor SUPPRESSOR OF OVEREXPRESSION OF CONSTANS1 (SOC1) integrates environmental and endogenous signals to promote flowering in Arabidopsis. However, the role of SOC1 homologs in regulating flowering time in fruit trees remains unclear. To better understand the molecular mechanism of flowering regulation in loquat (Eriobotrya japonica Lindl.), two SOC1 homologs (EjSOC1-1 and EjSOC1-2) were identified and characterized in this work. Sequence analysis showed that EjSOC1-1 and EjSOC1-2 have conserved MADS-box and K-box domains. EjSOC1-1 and EjSOC1-2 were clearly expressed in vegetative organs, and high expression was detected in flower buds. As observed in paraffin-embedded sections, expression of the downstream flowering genes EjAP1s and EjLFYs started to increase at the end of June, a time when flower bud differentiation occurs. Additionally, high expression of EjSOC1-1 and EjSOC1-2 began 10 days earlier than that of EjAP1s and EjLFYs in shoot apical meristem (SAM). EjSOC1-1 and EjSOC1-2 were inhibited by short-day (SD) conditions and exogenous GA3, and flower bud differentiation did not occur after these treatments. EjSOC1-1 and EjSOC1-2 were found to be localized to the nucleus. Moreover, ectopic overexpression of EjSOC1-1 and EjSOC1-2 in wild-type Arabidopsis promoted early flowering, and overexpression of both was able to rescue the late flowering phenotype of the soc1-2 mutant. In conclusion, the results suggest that cultivated loquat flower bud differentiation in southern China begins in late June to early July and that EjSOC1-1 and EjSOC1-2 participate in the induction of flower initiation. These findings provide new insight into the artificial regulation of flowering time in fruit trees

Ⅰ-Ⅱ MIXED-MODE FRACTURE PROPERTY OF 2D-C/SIC COMPOSITES (MT)

In order to characterize the Ⅰ-Ⅱ mixed-mode fracture performance of 2D-C/SiC composites, Arcan butterfly specimens with unilateral cracks were used, and the mode-Ⅰ and mode-Ⅱ fracture shape factors of the specimen were calibrated through finite element model. The Arcan disc device was used to carry out mode-Ⅰ, mode-Ⅱ and Ⅰ-Ⅱ mixed-mode fracture tests upon 2D-C/SiC butterfly specimens, and the macroscopic and microscopic fracture modes and strength properties of the specimens under different loading paths were investigated. The results show that the fracture toughness of mode-II of 2D-C/SiC material is higher than that of mode-I. With increasing of the loading angle, the influence of shear stress on the crack propagation path increases, and meanwhile the fracture resistance of the specimens presents a tendency to increase. The applicability of several fracture criteria is demonstrated, and an Ⅰ-Ⅱ mixed-mode fracture criterion for 2D-C/SiC composites is suggested

The Role of EjSVPs in Flower Initiation in Eriobotrya japonica

Flowering plants have evolved different flowering habits to sustain long-term reproduction. Most woody trees experience dormancy and then bloom in the warm spring, but loquat blooms in the cold autumn and winter. To explore its mechanism of flowering regulation, we cloned two SHORT VEGETATIVE PHASE (SVP) homologous genes from ‘Jiefanzhong’ loquat (Eriobotrya japonica Lindl.), namely, EjSVP1 and EjSVP2. Sequence analysis revealed that the EjSVPs were typical MADS-box transcription factors and exhibited a close genetic relationship with other plant SVP/DORMANCY-ASSOCIATED MADS-BOX (DAM) proteins. The temporal and spatial expression patterns showed that EjSVP1 and EjSVP2 were mainly expressed in the shoot apical meristem (SAM) after the initiation of flowering; after reaching their highest level, they gradually decreased with the development of the flower until they could not be detected. EjSVP1 expression levels were relatively high in young tissues, and EjSVP2 expression levels were relatively high in young to mature transformed tissues. Interestingly, EjSVP2 showed relatively high expression levels in various flower tissues. We analyzed the EjSVP promoter regions and found that they did not contain the C-repeat/dehydration-responsive element. Finally, we overexpressed the EjSVPs in wild-type Arabidopsis thaliana Col-0 and found no significant changes in the number of rosette leaves of Arabidopsis thaliana; however, overexpression of EjSVP2 affected the formation of Arabidopsis thaliana flower organs. In conclusion, EjSVPs were found to play an active role in the development of loquat flowering. These findings may provide a reference for exploring the regulation mechanisms of loquat flowering and the dormancy mechanisms of other plants

Formation and Elimination of Satellite Droplets during Monodisperse Droplet Generation by Using Piezoelectric Method

One of the key questions in the generation of monodisperse droplets is how to eliminate satellite droplets. This paper investigates the formation and elimination of satellite droplets during the generation of monodisperse deionized water droplets based on a piezoelectric method. We estimated the effects of two crucial parameters—the pulse frequency for driving the piezoelectric transducer (PZT) tube and the volume flow rate of the pumping liquid—on the generation of monodisperse droplets of the expected size. It was found that by adjusting the pulse frequency to harmonize with the volume flow rate, the satellite droplets can be eliminated through their coalescence with the subsequent mother droplets. An increase in the tuning pulse frequency led to a decrease in the size of the monodisperse droplets generated. Among three optimum conditions (OCs) (OC1: 20 mL/h, 20 kHz; OC2: 30 mL/h, 30 kHz; and OC3: 40 mL/h, 40 kHz), the sizes of the generated monodisperse deionized water droplets followed a bimodal distribution in OC1 and OC2, whereas they followed a Gaussian distribution in OC3. The average diameters were 87.8 μm (OC1), 85.9 μm (OC2), and 84.8 μm (OC3), which were 8.46%, 6.14%, and 4.69% greater than the theoretical one (81.0 μm), respectively. This monodisperse droplet generation technology is a promising step in the production of monodisperse aerosols for engineering applications

Vaporization, Diffusion and Combustion of Laser-Induced Individual Magnesium Microparticles in Inert and Oxidizing Atmospheres

Although the gas phase combustion of metallic magnesium (Mg) has been extensively studied, the vaporization and diffusive combustion behaviors of Mg have not been well characterized. This paper proposes an investigation of the vaporization, diffusion, and combustion characteristics of individual Mg microparticles in inert and oxidizing gases by a self-built experimental setup based on laser-induced heating and microscopic high-speed cinematography. Characteristic parameters like vaporization and diffusion coefficients, diffusion ratios, flame propagation rates, etc., were obtained at high spatiotemporal resolutions (μm and tens of μs), and their differences in inert gases (argon, nitrogen) and in oxidizing gases (air, pure oxygen) were comparatively analyzed. More importantly, for the core–shell structure, during vaporization, a shock wave effect on the cracking of the porous magnesium oxide thin film shell-covered Mg core was first experimentally revealed in inert gases. In air, the combustion flame stood over the Mg microparticles, and the heterogeneous combustion reaction was controlled by the diffusion rate of oxygen in air. While in pure O2, the vapor-phase stand-off flame surrounded the Mg microparticles, and the reaction was dominated by the diffusion rate of Mg vapor. The diffusion coefficients of the Mg vapor in oxidizing gases are 1~2 orders of magnitude higher than those in inert gases. However, the diffusive ratios of condensed combustion residues in oxidizing gases are ~1/2 of those in inert gases. The morphology and the constituent contents analysis showed that argon would not dissolve into liquid Mg, while nitrogen would significantly dissolve into liquid Mg. In oxidizing gases of air or pure O2, Mg microparticles in normal pressure completely burned due to laser-induced heating

The Influence of Exogenous Nitrogen Input on the Characteristics of Phytolith-Occluded Carbon in the <i>Kandelia obovata</i> Soil System

Phytolith-occluded Ccarbon (PhytOC) is an important carbon sink in wetland ecosystems and a mechanism for long-term carbon sequestration. In recent years, nitrogen pollution has become increasingly severe and poses a threat to the healthy development of coastal ecological environments and socio-economic development; therefore, studying the impact of nitrogen deposition on the sequestration potential of PhytOC in the soil of coastal wetlands is highly significant. In the present study, two indoor tidal simulation experiments were set up with and without the planting of vegetation. The sequestration capacity and factors that influence soil PhytOC in the Kandelia obovata soil system were compared and analyzed under five nitrogen concentrations. The analysis shows that with the introduction of Kandelia obovata, the occluded carbon content of the soil phytoliths was significantly increased by 31.45% compared with the non-plant group, and the PhytOC content of the soil increased by 7.94%. The exogenous nitrogen input reduced the PhytOC content of the soil, with a rate of decline exceeding 26%. The PhytOC of the soil phytoliths and the PhytOC content of the soil in the planting group increased with increasing nitrogen concentration, while that of the non-plant group decreased as the concentration of nitrogen increased. The non-plant group was more affected by the exogenous nitrogen concentration than the planting group, and the soil microbial biomass carbon and microbial biomass nitrogen were the main factors that influenced changes in the PhytOC. In conclusion, nitrogen input has a significant inhibitory effect on soil PhytOC sequestration potential in coastal wetlands. Planting Kandelia obovata helps to improve the stability of carbon in wetland soil

Selection of the optimal reference genes for expression analyses in different materials of Eriobotrya japonica

Abstract Background Loquat (Eriobotrya japonica) is a subtropical tree bearing fruit that ripens during late spring and early summer, which is the off-season for fruit production. The specific flowering habit of loquat, which starts in fall and ends in winter, has attracted an increasing number of researchers who believe that it may represent an ideal model for studying flowering shift adaptations to climate change in Rosaceae. These studies require an understanding of gene expression patterns within the fruit and other tissues of this plant. Although ACTINs (ACTs) have previously been used as reference genes (RGs) for gene expression studies in loquats, a comprehensive analysis of whether these RGs are optimal for normalizing RT-qPCR data has not been performed. Results In this study, 11 candidate RGs (RIBOSOMAL-LIKE PROTEIN4 (RPL4), RIBOSOMAL-LIKE PROTEIN18 (RPL18), Histone H3.3 (HIS3), Alpha-tubulin-3 (TUA3), S-Adenosyl Methionine Decarboxylase (SAMDC), TIP41-like Family Protein (TIP41), (UDP)-glucose Pyrophosphorylase (UGPase), 18S ribosomal RNA (18S), Glyceraldehyde-3-phosphate Dehydrogenase (GAPDH), Plasma Intrinsic Protein 2 (PIP2) and ACTIN(ACT)) were assessed to determine their expression stability in 23 samples from different tissues or organs of loquat. Integrated expression stability evaluations using five computational statistical methods (GeNorm, NormFinder, ΔCt, BestKeeper, and RefFinder) suggested that a RG set, including RPL4, RPL18, HIS3 and TUA3, was the most stable one across all of the tested loquat samples. The expression pattern of EjCDKB1;2 in the tested loquat tissues normalized to the selected RG set demonstrated its reliability. Conclusions This study reveals the reliable RGs for accurate normalization of gene expression in loquat. In addition, our findings demonstrate an efficient system for identifying the most effective RGs for different organs, which may be applied to related rosaceous crops