Thidiazuron combined with cyclanilide modulates hormone pathways and ROS systems in cotton, increasing defoliation at low temperatures.

Low temperatures decrease the thidiazuron (TDZ) defoliation efficiency in cotton, while cyclanilide (CYC) combined with TDZ can improve the defoliation efficiency at low temperatures, but the mechanism is unknown. This study analyzed the effect of exogenous TDZ and CYC application on cotton leaf abscissions at low temperatures (daily mean temperature: 15°C) using physiology and transcriptomic analysis. The results showed that compared with the TDZ treatment, TDZ combined with CYC accelerated cotton leaf abscission and increased the defoliation rate at low temperatures. The differentially expressed genes (DEGs) in cotton abscission zones (AZs) were subjected to Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses to compare the enriched GO terms and KEGG pathways between the TDZ treatment and TDZ combined with CYC treatment. TDZ combined with CYC could induce more DEGs in cotton leaf AZs at low temperatures, and these DEGs were related to plant hormone and reactive oxygen species (ROS) pathways. CYC is an auxin transport inhibitor. TDZ combined with CYC not only downregulated more auxin response related genes but also upregulated more ethylene and jasmonic acid (JA) response related genes at low temperatures, and it decreased the indole-3-acetic acid (IAA) content and increased the JA and 1-aminocyclopropane-1-carboxylic acid (ACC) contents, which enhanced cotton defoliation. In addition, compared with the TDZ treatment alone, TDZ combined with CYC upregulated the expression of respiratory burst oxidase homologs (RBOH) genes and the hydrogen peroxide content in cotton AZs at low temperatures, which accelerated cotton defoliation. These results indicated that CYC enhanced the TDZ defoliation efficiency in cotton by adjusting hormone synthesis and response related pathways (including auxin, ethylene, and JA) and ROS production at low temperatures.

Low Temperature Inhibits the Defoliation Efficiency of Thidiazuron in Cotton by Regulating Plant Hormone Synthesis and the Signaling Pathway.

Thidiazuron (TDZ) is the main defoliant used in production to promote leaf abscission for machine-picked cotton. Under low temperatures, the defoliation rate of cotton treated with TDZ decreases and the time of defoliation is delayed, but there is little information about this mechanism. In this study, RNA-seq and physiological analysis are performed to reveal the transcriptome profiling and change in endogenous phytohormones upon TDZ treatment in abscission zones (AZs) under different temperatures (daily mean temperatures: 25 °C and 15 °C). Genes differentially expressed in AZs between TDZ treatment and control under different temperatures were subjected to gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses to compare the enriched GO terms and KEGG pathways between the two temperature conditions. The results show that, compared with the corresponding control group, TDZ induces many differentially expressed genes (DEGs) in AZs, and the results of the GO and KEGG analyses show that the plant hormone signaling transduction pathway is significantly regulated by TDZ. However, under low temperature, TDZ induced less DEGs, and the enriched GO terms and KEGG pathways were different with those under normal temperature condition. Many genes in the plant hormone signal transduction pathway could not be induced by TDZ under low temperature conditions. In particular, the upregulated ethylene-signaling genes and downregulated auxin-signaling genes in AZs treated with TDZ were significantly affected by low temperatures. Furthermore, the expression of ethylene and auxin synthesis genes and their content in AZs treated with TDZ were also regulated by low temperature conditions. The upregulated cell wall hydrolase genes induced by TDZ were inhibited by low temperatures. However, the inhibition of low temperature on genes in AZs treated with TDZ was relieved with the extension of the treatment time. Together, these results indicate that the responses of ethylene and auxin synthesis and the signaling pathway to TDZ are inhibited by low temperatures, which could not induce the expression of cell wall hydrolase genes, and then inhibit the separation of AZ cells and the abscission of cotton leaves. This result provides new insights into the mechanism of defoliation induced by TDZ under low temperature conditions.

Development and internal validation of a Wasp Sting Severity Score to assess severity and indicate blood purification in persons with Asian wasp stings.

BACKGROUND: In recent years, the incidence of wasp sting has increased annually in China. Organ damage and high mortality due to mass wasp envenomation remain major challenges. Timely and appropriate medical intervention can improve survival. However, there are currently no normalized tools for early assessment of severity. METHODS: The clinical data of wasp sting patients hospitalized from 2011 to 2019 were used as a training set. Logistic regression was used to explore major risk factors for the development of a severe case of wasp sting (SC). The Wasp Sting Severity Score (WSS) was determined considering these risk factors to identify SCs and was tested in a validation dataset that was prospectively collected in 2020. RESULTS: The data of 1131 wasp sting patients from 2011 to 2019 were included in the training set. Logistic regression analysis showed that tea-colored urine, number of stings, and lactate dehydrogenase and total bilirubin levels were risk factors for developing an SC. The WSS was developed considering these four risk factors, and the total possible WSS was 20 points. The WSS was tested using the validation dataset, comprising the data of 153 patients, in 2020, and we found that a WSS ≥3 points was an important indication for blood purification, with a sensitivity of 71.9%, specificity of 92.6% and an area under the curve of 0.918 (95% confidence interval 0.873-0.962). Among patients with more than 30 stings, mortality in those who underwent plasma exchange (PE) within 24 h after admission was significantly lower than that in those who did not receive PE treatment (14.3% versus 46.9%, P = 0.003). However, continuous venovenous hemofiltration (CVVH) (P = 0.317) and hemoperfusion (HP) (P = 0.869) did not significantly reduce mortality. CONCLUSIONS: Patients with WSS scores ≥3 should be considered for blood purification as early as possible in addition to routine treatment. In addition, PE is better than CVVH and HP at reducing mortality in patients suffering from severe wasp stings.

Factors Influencing Viral Clearance in Mild COVID-19 and Clinical Characteristics of Asymptomatic Patients.

BACKGROUND: The outbreak of coronavirus disease (COVID-19) has become a global public health emergency. OBJECTIVE: To evaluate the characteristics and outcomes of patients with COVID-19 in Anhui and to identify predictors of viral clearance. METHODS: We retrospectively analyzed the data collected from discharged patients with laboratory-confirmed SARS-CoV-2 infections. We compared clinical features between viral clearance and viral persistence, and evaluated factors associated with SARS-CoV-2 shedding using multiple linear regression. RESULTS: Among the 83 patients involved in the study, the median age was 43 years, while 60.2% were male, 35.4% had comorbidities, and the mortality was zero. The median time from illness onset to admission was 5 days (interquartile range (IQR), 2-7 days), and the median time from the illness onset to SARS-CoV-2 RNA detection was 16 days (IQR, 13-18 days). The factors influencing viral clearance were as follows: (1) delayed admission (beta 1.057, 95% CI 0.810-1.304; p ≤ 0.001) and (2) underlying comorbidities (beta 1.907, 95% CI 0.198-3.616; p = 0.029). No significant differences were observed in the length of stay (p = 0.246) and pneumonia between asymptomatic and symptomatic patients based on computed tomography (CT) (p = 0.124). CONCLUSIONS: Delayed admission and underlying comorbidities may effectively predict SARS-CoV-2 RNA clearance. For those infected with SARS-CoV-2, even asymptomatic patients without any clinical symptoms should be traced and isolated. This practice may reduce the spread of SARS-CoV-2 and slow the COVID-19 pandemic caused by the virus. Clinical Trial Registration Number: This trial is registered with 2020-051.

Natural polymorphisms in a pair of NSP2 homoeologs can cause loss of nodulation in peanut.

Microbial symbiosis in legumes is achieved through nitrogen-fixing root nodules, and these are important for sustainable agriculture. The molecular mechanisms underlying development of root nodules in polyploid legume crops are largely understudied. Through map-based cloning and QTL-seq approaches, we identified a pair of homoeologous GRAS transcription factor genes, Nodulation Signaling Pathway 2 (AhNSP2-B07 or Nb) and AhNSP2-A08 (Na), controlling nodulation in cultivated peanut (Arachis hypogaea L.), an allotetraploid legume crop, which exhibited non-Mendelian and Mendelian inheritance, respectively. The segregation of nodulation in the progeny of Nananbnb genotypes followed a 3:1 Mendelian ratio, in contrast to the 5:3~1:1 non-Mendelian ratio for nanaNbnb genotypes. Additionally, a much higher frequency of the nb allele (13%) than the na allele (4%) exists in the peanut germplasm collection, suggesting that Nb is less essential than Na in nodule organogenesis. Our findings reveal the genetic basis of naturally occurred non-nodulating peanut plants, which can be potentially used for nitrogen fixation improvement in peanut. Furthermore, the results have implications for and provide insights into the evolution of homoeologous genes in allopolyploid species.

Prediction of the Risk of Hospital Deaths in Patients with Hospital-Acquired Pneumonia Caused by Multidrug-Resistant Acinetobacter baumannii Infection: A Multi-Center Study.

PURPOSE: To predict the risk of hospital deaths in patients with hospital-acquired pneumonia (HAP) caused by multidrug-resistant Acinetobacter baumannii (MDR-AB) infection. PATIENTS AND METHODS: A total of 366 patients who were diagnosed with HAP caused by MDR-AB infection were enrolled between January 2013 and December 2016. The sociological characteristics and clinical data of these cases were collected. Univariate and multivariate logistic analyses were used to explore the risk factors of hospital deaths before medication and after drug withdrawal. The receiver operating characteristic (ROC) curve and the area under the curve (AUC) were utilized to assess the predictive effectiveness of the models with or without the adjustment. RESULTS: Hospital deaths occurred in 142 cases (38.80%). The results showed that acute physiology and chronic health evaluation II (APACHE II) and sequential organ failure assessment (SOFA) scores before medication and after drug withdrawal were associated with the risk of hospital deaths. Adjusting the covariants including the age, autoimmune disease, venous cannula, transfer of patients from other hospitals, and APACHE II score at admission, then no differences were discovered in predicting the hospital deaths between adjusted APACHE II and adjusted SOFA scores before medication (AUC: 0.808 vs 0.803, P =0.614) and after drug withdrawal (AUC: 0.876 vs 0.878, P =0.789). CONCLUSION: Before medication or after drug withdrawal, the adjusted APACHE II and adjusted SOFA scores all performed well in determining the predictive effectiveness of the hospital deaths in patients with HAP caused by MDR-AB infection, indicating that the appropriate infection control may reduce the occurrence of nosocomial deaths and improve the prognosis.

The application of CRISPR/Cas9 in hairy roots to explore the functions of AhNFR1 and AhNFR5 genes during peanut nodulation.

BACKGROUND: Peanut is an important legume crop growing worldwide. With the published allotetraploid genomes, further functional studies of the genes in peanut are very critical for crop improvement. CRISPR/Cas9 system is emerging as a robust tool for gene functional study and crop improvement, which haven't been extensively utilized in peanut yet. Peanut plant forms root nodules to fix nitrogen through a symbiotic relationship with rhizobia. In model legumes, the response of plants to rhizobia is initiated by Nod factor receptors (NFRs). However, information about the function of NFRs in peanut is still limited. In this study, we applied the CRISPR/Cas9 tool in peanut hairy root transformation system to explore the function of NFR genes. RESULTS: We firstly identified four AhNFR1 genes and two AhNFR5 genes in cultivated peanut (Tifrunner). The gene expression analysis showed that the two AhNFR1 and two AhNFR5 genes had high expression levels in nodulating (Nod+) line E5 compared with non-nodulating (Nod-) line E4 during the process of nodule formation, suggesting their roles in peanut nodulation. To further explore their functions in peanut nodulation, we applied CRISPR technology to create knock-out mutants of AhNFR1 and AhNFR5 genes using hairy root transformation system. The sequencing of these genes in transgenic hairy roots showed that the selected AhNFR1 and AhNFR5 genes were successfully edited by the CRISPR system, demonstrating its efficacy for targeted mutation in allotetraploid peanut. The mutants with editing in the two AhNFR5 genes showed Nod- phenotype, whereas mutants with editing in the two selected AhNFR1 genes could still form nodules after rhizobia inoculation. CONCLUSIONS: This study showed that CRISPR-Cas9 could be used in peanut hairy root transformation system for peanut functional genomic studies, specifically on the gene function in roots. By using CRISPR-Cas9 targeting peanut AhNFR genes in hairy root transformation system, we validated the function of AhNFR5 genes in nodule formation in peanut.

Ward renovation and PPE use procedures to protect medical staff from COVID-19 infection.

In the early stages of the coronavirus disease 2019 (COVID-19) outbreak in Wuhan, many cross-infections occurred due to the limited number of wards and insufficient medical staff, which could not cope with the large number of patients visiting the hospital. A series of new infection control measures were implemented in our institution and a Wuhan hospital supported by our medical team, mainly including temporarily transforming the general ward into a passage for the staff to enter the infectious ward and standardizing the procedure for the wearing and removal of personal protection equipment (PPE). These measures significantly improved the situation, and no member of our medical staff was infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) during the middle and late stages of the disease epidemic. We hope that these experiences can provide references for medical institutions that may face an outbreak of COVID-19, especially those in underdeveloped countries and regions.

Addition of free poloxamer 407 to a new gene vector P407-PEI-K12 solution forms a sustained-release in situ hypergel that enhances cell transfection and extends gene expression.

To address the concern around the efficiency/cytotoxicity ratio and the tumor-targeting effects of polyethylenimine (PEI), is a non-viral gene vector used for the delivery of the cancer therapy gene, poloxamer 407 (P407)-PEI-K12, was synthesized by cross-linking low-molecular weight PEI with P407 and further coupling a bifunctional peptide, K12, which is comprised of the tumor-targeting peptide tLyP-1 and the nuclear localization sequence. Furthermore, the addition of free P407 into the polymer/DNA complex solution produced a temperature-sensitive in situ gel-P407/P407-PEI-K12/DNA complex, which improved the effects of sustained-release gene delivery and transfection efficiency. The specificity, cytotoxicity and gene transfection efficiency of P407-PEI-K12 was investigated in Hela cells in vitro. The polymer efficiently prevented the degradation of plasmid DNA by DNase I and had a marked ability for serum tolerance. Agarose gel electrophoresis revealed that plasmid DNA was efficiently condensed and protected. The higher transfection efficiency of P407-PEI-K12h (the molar ratio of P407-PEI and K12 is 1:10) was achieved with a polymer and plasmid DNA ratio (w/w) of 20:1. The ability of free P407 to promote the transfection of the polymer/DNA complex was high (0.09%). The half-life of the P407/P407-PEI-K12-h/DNA gel complex was 228 min, and the transfection efficiency of the P407/P407-PEI-K12-h/DNA complex was markedly higher compared to that of the P407-PEI-K12-h/DNA complex at various release times.

Characterization and anti-inflammatory effects of sulfated polysaccharide from the red seaweed Gelidium pacificum Okamura.

In the present study, crude polysaccharides were extracted from Gelidium pacificum Okamura, and further purified to obtain the sulfated polysaccharide with molecular weight of 28,807 Da. Its monosaccharide composition mainly consisted of xylose (7.1%), galactose (59.7%) and galacturonic acid (19.76%). And the sulfate ester content of the sulfated polysaccharide was estimated as 8.8%. Structure analysis showed that the sulfated polysaccharide comprised of 1,4-linked-α-D-Galp3S, 1,2-linked-α-D-Xylp and 1,3-linked-ß-D-GalpA residues, respectively. Its anti-inflammatory effects were investigated in LPS-stimulated human monocytic (THP-1) cells. The sulfated polysaccharide at a concentration of 5 µg/mL fully protected the THP-1 cells against LPS-stimulated cytotoxicity. Furthermore, the addition of sulfated polysaccharide resulted in a significant reduction of NO production in LPS-treated cells, and this effect appeared to be dose-related. The sulfated polysaccharide (5 µg/mL) significantly suppressed the mRNA and protein expression of toll-like receptor-4 (TLR-4), myeloid differentiation factor (MyD88) and tumor necrosis factor receptor-associated factor-6 (TRAF-6) in LPS-stimulated THP-1 cells. These results showed the sulfated polysaccharide not only provided a good protection against LPS-induced cell toxicity, but also exerted an anti-inflammatory effect via the TLR4 signaling pathway.

Isolation of polysaccharides from Dendrobium officinale leaves and anti-inflammatory activity in LPS-stimulated THP-1 cells.

Dendrobium officinale stem is rich in polysaccharides, which play a great role in the medicinal effects of this plant. However, little was known about the polysaccharides from Dendrobium officinale leaves. Two kinds of polysaccharides in the leaves, DLP-1 and DLP-2, were obtained by hot water extraction, alcohol sedimentation and chromatographic separation (DEAE-52 cellulose column and Sephadex G-100 column). The average molecular weights were determined as 28,342 Da and 41,143 Da, respectively. Monosaccharide compositions were analyzed using gas chromatography-mass spectrometer. DLP-1 was composed of D-(+)-galactose, DL-arabinose, and L-(+)-rhamnose with a molar ratio of 3.21:1.11:0.23, and traces of D-xylose, D-glucose, and D-(+)-mannose. DLP-2 was consisted of D-glucose and D-(+)-galactose with a molar ratio of 3.23:1.02, and traces of D-xylose, DL-arabinose. Then, we established inflammatory cell model by LPS acting THP-1 cells to investigate the anti-inflammatory effects of DLP-1 and DLP-2. The results indicated that DLP-1 (5 µg/mL) and DLP-2 (50 µg/mL) were effective in protecting THP-1 cells from LPS-stimulated cytotoxicity, as well as inhibiting reactive oxygen species formation. In addition, both DLP-1 (5 µg/mL) and DLP-2 (50 µg/mL) significantly suppressed toll-like receptor-4 (TLR-4), myeloid differentiation factor (MyD88) and tumour necrosis factor receptor-associated factor-6 (TRAF-6) mRNA and protein expression in LPS-stimulated THP-1 cells.

Factors Associated With Prolonged Viral Shedding in Patients With Avian Influenza A(H7N9) Virus Infection.

Background: Data are limited on the impact of neuraminidase inhibitor (NAI) treatment on avian influenza A(H7N9) virus RNA shedding. Methods: In this multicenter, retrospective study, data were collected from adults hospitalized with A(H7N9) infection during 2013-2017 in China. We compared clinical features and A(H7N9) shedding among patients with different NAI doses and combination therapies and evaluated factors associated with A(H7N9) shedding, using Cox proportional hazards regression. Results: Among 478 patients, the median age was 56 years, 71% were male, and 37% died. The median time from illness onset to NAI treatment initiation was 8 days (interquartile range [IQR], 6-10 days), and the median duration of A(H7N9) RNA detection from onset was 15.5 days (IQR, 12-20 days). A(H7N9) RNA shedding was shorter in survivors than in patients who died (P < .001). Corticosteroid administration (hazard ratio [HR], 0.62 [95% confidence interval {CI}, .50-.77]) and delayed NAI treatment (HR, 0.90 [95% CI, .91-.96]) were independent risk factors for prolonged A(H7N9) shedding. There was no significant difference in A(H7N9) shedding duration between NAI combination treatment and monotherapy (P = .65) or between standard-dose and double-dose oseltamivir treatment (P = .70). Conclusions: Corticosteroid therapy and delayed NAI treatment were associated with prolonged A(H7N9) RNA shedding. NAI combination therapy and double-dose oseltamivir treatment were not associated with a reduced A(H7N9) shedding duration as compared to standard-dose oseltamivir.

[Effects of brassinolide on leaf physiological characteristics and differential gene expression profiles of NaCl-stressed cotton].

This study analyzed the effects of brassinolide (BL) on Na⁺ accumulation, leaf physiological characteristics and differentially expressed genes (DEGs) of cotton leaves under NaCl stress. The results showed that NaCl stress increased the Na⁺, proline and MDA content in the leaves of Sumian 12 and Sumian 22, and changed the expression level of genes in cotton leaves. The application of BL counteracted the NaCl stress-induced growth inhibition in the two tested cotton cultivars. It reduced the accumulation of Na⁺, enhanced proline content, and resulted in a decrease in the MDA content of NaCl-stressed leaves, and the influence of BL on salt-stressed Sumian 12 plants was more pronounced than that on Sumian 22. The digital gene expression analysis in Sumian 12 indicated that BL application significantly influenced the gene expression in NaCl-stressed cotton leaves, the gene expression pattern as a result of the root applied BL on NaCl-stressed cotton treatment (BL+NaCl) was similar to the normal cotton plants (CK). Our results indicated that brassinolide alleviated NaCl stress on cotton through improving leaf physiological characteristics and gene expression, and resulted in an increase in biomass of NaCl-stressed cotton.

Transcriptome-wide identification of salt-responsive members of the WRKY gene family in Gossypium aridum.

WRKY transcription factors are plant-specific, zinc finger-type transcription factors. The WRKY superfamily is involved in abiotic stress responses in many crops including cotton, a major fiber crop that is widely cultivated and consumed throughout the world. Salinity is an important abiotic stress that results in considerable yield losses. In this study, we identified 109 WRKY genes (GarWRKYs) in a salt-tolerant wild cotton species Gossypium aridum from transcriptome sequencing data to elucidate the roles of these factors in cotton salt tolerance. According to their structural features, the predicted members were divided into three groups (Groups I-III), as previously described for Arabidopsis. Furthermore, 28 salt-responsive GarWRKY genes were identified from digital gene expression data and subjected to real-time quantitative RT-PCR analysis. The expression patterns of most GarWRKY genes revealed by this analysis are in good agreement with those revealed by RNA-Seq analysis. RT-PCR analysis revealed that 27 GarWRKY genes were expressed in roots and one was exclusively expressed in roots. Analysis of gene orthology and motif compositions indicated that WRKY members from Arabidopsis, rice and soybean generally shared the similar motifs within the same subgroup, suggesting they have the similar function. Overexpression-GarWRKY17 and -GarWRKY104 in Arabidopsis revealed that they could positively regulate salt tolerance of transgenic Arabidopsis during different development stages. The comprehensive data generated in this study provide a platform for elucidating the functions of WRKY transcription factors in salt tolerance of G. aridum. In addition, GarWRKYs related to salt tolerance identified in this study will be potential candidates for genetic improvement of cultivated cotton salt stress tolerance.

HIF-1α knockdown by miRNA decreases survivin expression and inhibits A549 cell growth in vitro and in vivo.

The present study examined the downregulation of survivin expression by hypoxia-inducible factor-1α (HIF-1α) miRNA and its effect in the inhibition of A549 cell growth in vitro and in vivo. Survivin expression, apoptosis, proliferation and migration under normoxic and hypoxic conditions were assessed by standard methods. Cotransfection and chromatin immunoprecipitation were used to observe the effects of HIF-1α on survivin transcription. HIF-1α knockdown in A549 cells were injected into nude mice to examine survivin expression and suppression of tumorigenicity. Transfection of A549 cells with HIF-1α miRNA led to decreased expression of HIF-1α and survivin mRNA and protein. Survivin overexpression is mediated by HIF-1α by direct binding to a putative binding site in the survivin core promoter. HIF-1α-miRNA induced apoptosis and inhibited proliferation of A549 cells under hypoxic, but not normoxic, conditions, whereas transfection by survivin expression vectors partly rescued the apoptotic phenotype and revived cell proliferation under hypoxic conditions. However, cell migration was substantially suppressed by HIF-1α silencing under normoxic and hypoxic conditions. After A549 cells were xenografted in nude mice, survivin expression in mice treated with HIF-1α miRNA was downregulated, and tumor growth was significantly inhibited. Silenced HIF-1α gene expression induced apoptosis and suppressed growth of A549 cells by downregulating survivin expression in vitro and in vivo. Our results also provide a basis to target the HIF-1α pathway in lung cancer therapy.

Protein expression changes during cotton fiber elongation in response to low temperature stress.

Low temperature stress is one of the major abiotic stresses limiting the formation of cotton (Gossypium hirsutum L.) fiber qualities, especially fiber length. To investigate the molecular adaptation mechanisms of cotton fiber elongation to low temperature stress, two cotton cultivars, Kemian 1 (low temperature-tolerant) and Sumian 15 (low temperature-sensitive), were planted in the field at two sowing dates (25 April and 10 June). The two sowing dates resulted in different growing conditions and the main environmental difference between them was temperature, particularly the mean daily minimum temperature (MDTmin). When the sowing date was delayed, the MDTmin decreased from 26.9°C (25 April) to 20.6°C (10 June). Low temperature stress (MDTmin of 20.6°C) shortened the fiber length significantly in two cultivars, but the decreased extent was larger in Sumian 15 than that in Kemian 1. Proteomic analysis of three developmental stages (10, 15 and 20 days post-anthesis [DPA]) showed that 37 spots changed significantly (p<0.05) in abundance under low temperature stress and they were identified using mass spectrometry. These proteins were involved in malate metabolism, soluble sugar metabolism, cell wall loosening, cellulose synthesis, cytoskeleton, cellular response, and redox homeostasis. The results suggest that the enhancement of osmoticum maintenance, cell wall loosening, cell wall components biosynthesis, and cytoskeleton homeostasis plays important roles in the tolerance of cotton fibers to low temperature stress. Moreover, low levels of PEPCase, expansin, and ethylene signaling proteins may potentially lead to the low temperature sensitivity of Sumian 15 at the proteomic level.

[Low-temperature responses of enzyme activities related to fiber development of two cotton (Gossvpium hirsutum L.) cultivars with different temperature-sensitivity].

Taking two cotton cultivars with difterent temperature-sensitivity during tneir liner strength formation as test materials, a field experiment of different sowing dates was conducted in Nanjing of Jiangsu Province in 2006 and 2007 to study the effects of low temperature on the activities and gene expression of the enzymes related to fiber development. The low temperature induced by late sowing (with the mean daily minimum temperature being 21.1, 20.5, and 18.1 degrees C during fiber development period) had definite effects on the enzyme activities, and accordingly, the fiber strength formation. Low temperature increased the invertase and beta-1, 3-glucanase activities, decreased the sucrose synthase and sucrose phosphate synthase activities, prolonged the time with higher gene expression level of Expansin and sucrose synthase, and delayed the expression peak and decreased the gene expression quantity of beta-1,3-glucanase. There existed significant differences in the low-temperature responses of related enzymes activities between the two cultivars, with the change ranges of the enzyme activities being larger for temperature-sensitive cultivar Sumian 15 than for temperature-insensitive cultivar Kemian 1, which could be the main reasons leading to the different temnerature-sensitivitv of the two cotton cultivars during their fiber strength formation.

[Nitrogen absorption and allocation in cotton plant under effects of double-cropping wheat and cotton root mass].

By the methods of 15N-foliar feeding and 15N dilution, a pot experiment of double-cropping wheat and cotton was conducted to study the nitrogen absorption and allocation in cotton plant under effects of wheat and cotton root mass. Three treatments were installed, i.e., no separation of wheat and cotton roots (treatment I), separation with nylon net (treatment II), and separation with plastic film (treatment III). The results showed that both the competition of 15N absorption between wheat and cotton root, and the translocation of absorbed 15N from wheat root to cotton were existed in the wheat-cotton double-cropping system. The absorbed 15N by cotton root was mostly allocated in aboveground part, and less in root. The aboveground part of cotton had the highest N utilization rate (NUR) in treatment I and the lowest one in treatment III, but the Ndff was lower in treatment I than in treatments II and III. At the early flowering stage of cotton when wheat was harvested and its straw was amended in situ, the absorbed nitrogen by cotton was mainly from the applied 15N, but not from the amended wheat straw. The allocation of absorbed 15N in different organs of cotton was quite different, being much higher in reproductive organs than in other organs. The biomass of cotton plant was also higher in treatment I than in treatments II and III.