IAA-miR164a-NAC100L1 module mediates symbiotic incompatibility of cucumber/pumpkin grafted seedlings through regulating callose deposition.

Grafting is one of the key technologies to overcome the obstacles of continuous cropping, and improve crop yield and quality. However, the symbiotic incompatibility between rootstock and scion affects the normal growth and development of grafted seedlings after survival. The specific molecular regulation mechanism of graft incompatibility is still largely unclear. In this study, we found that the IAA-miR164a-NAC100L1 module induced callose deposition to mediate the symbiotic incompatibility of cucumber/pumpkin grafted seedlings. The incompatible combination (IG) grafting interface accumulated more callose, and the activity of callose synthase (CmCalS1) and IAA content were significantly higher than in the compatible combination (CG). Treatment with IAA polar transport inhibitor in the root of the IG plants decreased CmCalS activity and callose content. Furthermore, IAA negatively regulated the expression of Cm-miR164a, which directly targeted cleavage of CmNAC100L1. Interestingly, CmNAC100L1 interacted with CmCalS1 to regulate its activity. Further analysis showed that the interaction between CmNAC100L1 and CmCalS1 increased the activity of CmCalS1 in the IG plants but decreased it in the CG plants. Point mutation analysis revealed that threonine at the 57th position of CmCalS1 protein played a critical role to maintain its enzyme activity in the incompatible rootstock. Thus, IAA inhibited the expression of Cm-miR164a to elevate the expression of CmNAC100L1, which promoted CmNAC100L1 interaction with CmCalS1 to enhance CmCalS1 activity, resulting in callose deposition and symbiotic incompatibility of cucumber/pumpkin grafted seedlings.

Radon exhalation behavior and determination of diffusion migration parameters in spherical porous emanation media.

There is a significant impact of the radon diffusion coefficient and the free radon production rate on the exhalation of radon from porous materials that can be regarded as spheres, hexahedrons, or cylinders. To understand this effect, the radon exhalation rules of spherical porous media with different radii were studied according to the radon diffusion migration theory. A specialized method for simultaneous determination of the radon diffusion coefficient and the free radon production rate of the spherical porous media was proposed, and applied to determine the above two parameters for two hemispherical test blocks with different radii. The results show that:(1) For spherical porous media with a certain radon diffusion length (Ld), as the radius (r0) of the sphere increases, the radon exhalation rate first increases, and tends to stabilize at r0≥6Ld; The free radon release share gradually decreases from approximately 1, and drops to a steady state at r0≥18Ld. (2) Compared with conventional methods, the relative error of the free radon production rate determined by the proposed method is within 3.9%, which verifies the reliability of the new method.

SlSAMS1 enhances salt tolerance through regulation DNA methylation of SlGI in tomato.

S-adenosylmethionine (SAM), which is synthesized from methionine and ATP catalyzed by S-adenosylmethionine synthetase (SAMS), is an important methyl donor in plants. SAMS and DNA methylation play an important role in the plant response to abiotic stresses. Previous studies have shown that SAMS improves salt tolerance in tomato plants, but it is not clear whether the DNA methylation pathway mediates SAMS-induced salt tolerance. This study confirmed that SlSAMS1-overexpressing plants exhibited improved salt tolerance. Through whole-genome bisulfite sequencing (WGBS) and transcriptome sequencing (RNA-seq) analysis, the study screened the circadian rhythm pathway and identified the gene SlGI in this pathway, which was regulated by SlSAMS1. The gene body region of SlGI, the core gene of the circadian rhythm pathway, was hypermethylated in SlSAMS1-overexpressing plants, and its expression level was significantly increased. Furthermore, the SlGI-overexpressing plants showed higher salt tolerance, less reduction in plant height and fresh weight, lower electrolyte leakage, malondialdehyde and H2O2 content, and higher antioxidant enzyme activity compared to wild type plants. Therefore, SlSAMS1-overexpressing plants regulated significant changes in CHG-type methylation sites of the SlGI gene body and its expression levels, leading to an enhanced salt tolerance of tomato plants.

ABI5 promotes heat stress-induced chlorophyll degradation by modulating the stability of MYB44 in cucumber.

The yellowing of leaves caused by the decomposition of chlorophyll (Chl) is a characteristic event during senescence, which can be induced by various environmental stresses. However, the molecular mechanisms of high temperature-induced Chl degradation in horticultural plants remain poorly understood. Here, we found that heat stress induced Chl degradation and the expression of ABI5 and MYB44 in cucumber. Silencing of ABI5 compromised heat stress-induced Chl degradation, and the transcription of pheophytinase (PPH) and pheophorbide a oxygenase (PAO), two key genes in Chl catabolic pathway, but silencing of MYB44 exhibited the opposite results. Furthermore, ABI5 interacted with MYB44 in vitro and in vivo. ABI5 positively regulated heat stress-induced Chl degradation through two pathways. ABI5 directly bound to PPH and PAO promoters to promote their expression, leading to accelerating Chl degradation. On the other hand, the interaction between ABI5 and MYB44 reduced the binding of MYB44 to PPH and PAO promoters and led to the ubiquitination-depended protein degradation of MYB44, thereby alleviating the transcription inhibitory effect of MYB44 on PPH and PAO. Taken together, our findings propose a new regulatory network for ABI5 in regulating heat stress-induced Chl degradation.

Identification of cucumber S-adenosylmethionine decarboxylase genes and functional analysis of CsSAMDC3 in salt tolerance.

As one of the key enzymes in the biosynthesis of polyamines, S-adenosylmethionine decarboxylase (SAMDC) plays an important role in plant stress resistance. In this study, four SAMDC genes (CsSAMDC1-4) were identified in cucumber (Cucumis sativus L.) and divided into three groups (I, II, and III) by phylogenetic analysis. Motif analysis suggested the existence of many conserved motifs, which is compatible with SAMDC protein classification. Gene structure analysis revealed that CsSAMDC2 and CsSAMDC3 in group I have no intron, which showed a similar response to salt stress by gene expression analysis. CsSAMDC3 responded differently to hormone and stress treatments, and was more susceptible to salt stress. Compared with wild-type (WT) tobacco, the activities of superoxide dismutase, peroxidase, and catalase were increased in CsSAMDC3-overexpressing tobacco under salt stress, but the content of electrolyte leakage, malondialdehyde, and hydrogen peroxide were decreased, which alleviated the inhibition of growth induced by salt stress. Under salt stress, overexpression of CsSAMDC3 in transgenic tobacco plants exhibited salt tolerance, mainly in the form of a significant increase in dry and fresh weight, the maximal quantum yield of PSII photochemistry, the net photosynthetic rate and the content of spermidine and spermine, while the content of putrescine was reduced. In addition, the expression levels of antioxidase-related coding genes (NtSOD, NtPOD, NtCAT) and PAs metabolism-related coding genes (NtSAMS, NtSPDS, NtSPMS, NtPAO) in transgentic plants was lower than WT under salt stress, which suggested that overexpression of CsSAMDC3 affected the expression of these genes. In summary, our results showed that CsSAMDC3 could be used as a potential candidate gene to improve salt tolerance of cucumber by regulating polyamine and antioxidant metabolism.

CsbZIP2-miR9748-CsNPF4.4 Module Mediates High Temperature Tolerance of Cucumber Through Jasmonic Acid Pathway.

High temperature stress seriously affects the growth of cucumber seedlings, and even leads to a decline in yield and quality. miRNAs have been shown to be involved in regulating the response to stress in plants, but little is known about its effects on cucumber high temperature stress tolerance. Here, we found that high temperature stress induced the expression of miR9748 in cucumber. Overexpression of cucumber miR9748 in Arabidopsis improved high temperature tolerance. Transcriptome analysis revealed that miR9748 might mediate high temperature tolerance through plant hormone signal pathway. 5' RNA ligase-mediated rapid amplification of cDNA ends (5' RLM-RACE) and transient transformation technology demonstrated that CsNPF4.4 was the target gene of miR9748. CsNPF4.4 overexpression plants decreased high temperature tolerance accompanied by reducing the content of jasmonic acid (JA), but alleviated by foliar application of methyl jasmonate, indicating that CsNPF4.4 negatively regulated high temperature stress tolerance through inhibition JA signal pathway. Furthermore, high temperature stress also increased the expression level of CsbZIP2. Yeast one-hybrid and dual-luciferase assays showed that CsbZIP2 directly bound to the promoter of MIR9748 to induce its expression. Taken together, our results indicated that CsbZIP2 directly regulated miR9748 expression to cleave CsNPF4.4 to mediate high temperature tolerance through JA pathway.

Overexpression of 7-hydroxymethyl Chlorophyll a Reductase from Cucumber in Tobacco Accelerates Dark-Induced Chlorophyll Degradation.

7-hydroxymethyl chlorophyll (Chl) a reductase (HCAR) plays critical roles in the Chl cycle and degradation during leaf senescence, however, its function in horticultural crops remains unknown. Here, we identified an HCAR gene (CsHCAR) from cucumber (Cucumis sativus L.) and investigated its roles in response to dark-induced Chl degradation. CsHCAR encoded 459 amino acids, which were orthologous to Arabidopsis HCAR, had the conserved domains, and localized in the chloroplast. Gene expression analysis showed that CsHCAR expression was the highest in senescent leaves and was responsive to different stresses and phytohormone treatments. Overexpression of CsHCAR in tobacco accelerated dark-induced Chl degradation through enhancing the expression of Chl catabolic genes. After 10 d of darkness treatment, the biomass of CsHCAR overexpression plants was reduced. Furthermore, the value of net photosynthetic rate, maximum quantum yield of photosystem II, and effective quantum yield of photosystem II in CsHCAR overexpression plants was significantly reduced in comparison to that in wild-type (WT) plants. The photosynthetic protein content, including Lhcb1, Lhcb2, Lhcb4, RbcS, and RbcL in CsHCAR overexpression plants exhibited a lower level as compared to that observed in WT plants. In addition, the expression of genes encoding these proteins in CsHCAR overexpression plants was significantly lower than that in WT plants. Moreover, CsHCAR overexpression plants inhibited the dark-induced accumulation of reactive oxygen species (ROS). These results indicate that CsHCAR affects the stability of photosynthetic proteins in chloroplasts, positively regulates Chl degradation, and plays an important role in maintaining ROS homeostasis in leaves.

Identification and population genetic analyses of copy number variations in six domestic goat breeds and Bezoar ibexes using next-generation sequencing.

BACKGROUND: Copy number variations (CNVs) are a major form of genetic variations and are involved in animal domestication and genetic adaptation to local environments. We investigated CNVs in the domestic goat (Capra hircus) using Illumina short-read sequencing data, by comparing our lab data for 38 goats from three Chinese breeds (Chengdu Brown, Jintang Black, and Tibetan Cashmere) to public data for 26 individuals from three other breeds (two Moroccan and one Chinese) and 21samples from Bezoar ibexes. RESULTS: We obtained a total of 2394 CNV regions (CNVRs) by merging 208,649 high-confidence CNVs, which spanned ~ 267 Mb of total length and accounted for 10.80% of the goat autosomal genome. Functional analyses showed that 2322 genes overlapping with the CNVRs were significantly enriched in 57 functional GO terms and KEGG pathways, most related to the nervous system, metabolic process, and reproduction system. Clustering patterns of all 85 samples generated separately from duplications and deletions were generally consistent with the results from SNPs, agreeing with the geographical origins of these goats. Based on genome-wide FST at each CNV locus, some genes overlapping with the highly divergent CNVs between domestic and wild goats were mainly enriched for several immunity-related pathways, whereas the genes overlapping with the highly differentiated CNVs between highland and lowland goats were mainly related to vitamin and lipid metabolism. Remarkably, a 507-bp deletion at ~ 14 kb downstream of FGF5 on chromosome 6 showed highly divergent (FST = 0.973) between the highland and lowland goats. Together with an enhancer activity of this sequence shown previously, the function of this duplication in regulating fiber growth deserved to be further investigated in detail. CONCLUSION: We generated a comprehensive map of CNVs in goats. Many genetically differentiated CNVs among various goat populations might be associated with the population characteristics of domestic goat breeds.

A laboratory method for concurrently determining diffusion migration parameters and water saturation effects of thoron in uranium tailings.

Environmental humidity has a significanteffect on changes in free 220Rn (thoron) production rate and effective diffusion coefficient of 220Rn in uranium tailings. To understand such changes, a closed cavity containing porous 220Rn media with finite thickness was studied. Based on the 220Rn diffusion migration theory in porous media with finite thickness, a model for calculating the uniform 220Rn activity concentration in a closed container with porous media of finite thickness was established. A laboratory method for concurrently determining free 220Rn production rate and effective diffusion coefficient of 220Rn was proposed and a corresponding experimental setup was made. With samples taken from a uranium tailing impoundment in southern China, water content, free 220Rn production rate, and effective diffusion coefficient of 220Rn in uranium tailings were determined under certain environmental temperature and humidity conditions. Results show that: (1) The method and experimental setup presented in this study can simultaneously determine free 220Rn production rate and effective diffusion coefficient of 220Rn in porous media such as uranium tailing; (2) The free 220Rn production rate in uranium tailings increases linearly with water saturation. Effective diffusion coefficient of 220Rn, on the other hand, decreases exponentially with the increase in water saturation.

Experimental study of the effect of water level and wind speed on radon exhalation of uranium tailings from heap leaching uranium mines.

Water level and wind speed have important influences on radon release in particle-packing emanation media. Based on radon migration theory in porous media under three water level conditions, an experimental setup was designed to measure the surface radon exhalation rate of uranium tailings from heap leaching uranium mine at different water levels and wind speeds. When the water level was at 0.3 m (overlying depth 0.05 m), radon transfer velocities at the gas-liquid interface were also measured at different wind speeds. Results show that when the water level was equal to or lower than the surface of the sample, the radon exhalation rate increased with increasing wind speed and decreased with increasing water level. When the water level was higher than the surface of the sample, radon exhalation rate of the water surface increased with increasing surface wind speed. The wind speed, however, was less influential on the radon exhalation rate as the depth of the overlying water increased, with a dramatic decrease in radon release. That said, at different wind speeds, radon transfer velocities at the gas-liquid interface were consistent with literature. On the other hand, changes in wind speed had significant influences on the radon transfer velocity at the gas-liquid interface, with the effect less pronounced at higher wind speeds.

Morphology Mapping of Nanoparticle-Filled Immiscible Polymer Blends in Flow: The Existence of a Critical Ratio between Nanoparticle Concentration and Droplet Concentration.

The delicate flow-induced morphology of immiscible polypropylene/polystyrene blends in the presence of silica nanoparticles (NPs) is investigated in a multiparameter space. The morphology map constructed based on in situ morphology observation reveals that a critical ratio of NP concentration to droplet concentration, which strongly depends on the NP surface chemistries and the ratio of the NP concentration to the droplet concentration, exists. Below or above the critical ratio, the NPs display diverse effects on the morphology (promote or suppress droplet coalescence). These results can be interpreted by the competition between the bridging mechanism (acceleratory effect) and the enhanced viscoelasticity (inhibitory effect) exerted by the NPs.

[Association between high sensitivity C-reactive protein and contrast induced acute kidney injury in patients with acute coronary syndrome undergoing percutaneous coronary intervention: impact of atorvastatin].

OBJECTIVE: To observe the association between preprocedural high sensitivity C-reactive protein (hs-CRP) level and incidence of contrast induced acute kidney injury (CI-AKI) in acute coronary syndrome (ACS) patients undergoing percutaneous coronary intervention (PCI) and the impact of atorvastatin pretreatment on CI-AKI. METHODS: According to the level of preprocedural hs-CRP, 270 ACS patients were divided into three groups: high hs-CRP group (hs-CRP ≥ 3 mg/L, n = 176), moderate hs-CRP group (hs-CRP 1-3 mg/L, n = 60) and normal hs-CRP group (hs-CRP < 1 mg/L, n = 34). According to the dosage of preprocedural atorvastatin, the high hs-CRP group was further divided into 10 mg group (n = 49), 20 mg group (n = 66) and 40 mg group (n = 61). Serum creatinine (Scr), blood urea nitrogen (BUN), cystatin C (Cys C), hs-CRP were measured at before and 24 hours, 48 hours after PCI. CCr and GFR were calculated according to Scr and Cys C. Risk factors for CI-AKI were determined by multivariate logistic regression analysis. RESULTS: (1) Cys C was significantly increased and GFR after PCI significantly reduced in high and moderate hs-CRP groups compared with normal hs-CRP group (P < 0.05). (2) Incidence of CI-AKI was 43.18%, 38.33%, 20.59% in high, moderate and normal hs-CRP groups, respectively (P < 0.05). (3) In high hs-CRP group, postprocedural GFR was significantly higher while postprocedural Cys C and hs-CRP were significantly lower in 40 mg statin subgroup than 10 mg and 20 mg statin subgroups (P < 0.05), similar trends were documented when comparing 20 mg statin subgroup with 10 mg statin subgroup (P < 0.05). (4) Multivariate logistic regression analysis showed that pretreatment with high dose atorvastatin was a protective factor for post CI-AKI (20 mg atorvastatin: OR = 0.15, 95%CI 0.06 - 0.33, P = 0.001; 40 mg atorvastatin: OR = 0.10, 95%CI 0.04 - 0.23, P = 0.001), while high levels of preprocedural hs-CRP (OR = 2.06, 95%CI 1.01 - 4.23, P = 0.048), diabetes mellitus (OR = 10.71, 95%CI 5.29 - 21.70, P = 0.001), advanced age (OR = 2.64, 95%CI 1.05 - 6.63, P = 0.038) and renal failure (OR = 5.14, 95%CI 1.13 - 23.39, P = 0.034) were independent risk factors of CI-AKI. CONCLUSION: High hs-CRP level is linked with the development of CI-AKI in ACS patients undergoing PCI and pretreatment with 40 mg atorvastatin is associated with lower incidence CI-AKI, possibly by reducing the postprocedural inflammation responses.

[Atorvastatin attenuated contrast induced renal function damage].

OBJECTIVE: To study the effects of atorvastatin on contrast induced renal function change and plasma hsCRP in patients undergoing coronary angiography. METHODS: 120 patients who underwent coronary angiography were randomized to receive atorvastatin (20 mg/qn, n = 60) or no atorvastatin (n = 60) treatment 2 to 3 days before coronary angiography. Urinary alpha1-MG, TRF and mALB were checked for evidence of tubular or glomerular damage at start, 1 day and 2 days after the administration of a radiocontrast agent. Serum creatinine, BUN, cystatin C and hsCRP levels were also assessed at the same time. Ccr and GFR were calculated according to Cockcroft-Gault and GFR (ml/min) = 74.835/Cys C(1.333) formulas basing on serum creatinine or cystatin C concentration. RESULTS: (1) In control group, comparison with the value before coronary angiography, urinary alpha1-MG, TRF and mALB or serum cystatin C and hsCRP significantly increased at day 1 after angiography (P < 0.01). In comparison to the levels at day 1 after angiography, urinary alpha1-MG, TRF, mALB, serum cystatin C significantly decreased at day 2 after angiography (P < 0.01), but alpha1-MG, cystatin C still exceeded the values before coronary angiography, TRF and mALB levels at day 2 after angiography had no significant change compared to baseline (P > 0.05), hsCRP level at day 2 after angiography had no significant change compared to that at day 1 after angiography (P > 0.05) too. (2) In comparison with the value before coronary angiography in atorvastatin-treated group, the levels of urinary alpha1-MG, TRF and mALB or serum cystatin C at day 1 and day 2 after angiography had no significant change compared to baseline (P > 0.05).Serum hsCRP significantly increased at day 1 after angiography compared to baseline (P < 0.01), but it had no significant change compared to day 2 after angiography (P > 0.05). (3) To compare to the atorvastatin-treated group, the values of urinary alpha1-MG, TRF and mALB or Cys C and hsCRP significantly increased at day 1 after angiography in control group (P < 0.01), the values of urinary alpha1-MG, cystatin C and hsCRP still significantly increased at day 2 (P < 0.01)too, but those of TRF and mALB had no significantly change at day 1 or day 2 after angiography between the two groups (P > 0.05). There was no significant change in BUN, Cr, Ccr levels before and after angiography between the two groups. CONCLUSIONS: Low dose contrast induces light renal function damage. Pretreatment with atorvastatin 20 mg/qn for 2 to 3 days could significantly reduce procedural inflammatory reaction, attenuate urinary protein and the effect of degrading GFR in coronary angiography patients.