Splicing factor proline and glutamine-rich is a prognostic biomarker and correlated with clinical pathologic features and immune infiltrates in hepatocellular carcinoma

Background:Hepatocellular carcinoma(HCC)is the fourth leading cause of cancer-related deaths globally.Splicing factor proline and glutamine-rich(SFPQ)is a multifunctional protein that controls various biological functions.As a potential therapeutic target and a promising prognostic indicator,the potential effects and processes of SFPQ in HCC require further investigation.Methods:The RNA sequencing data were obtained from the Gene Expression Omnibus,International Cancer Genome Consortium,and The Cancer Genome Atlas databases to analyze SFPQ expression and differentially expressed genes(DEGs).We utilized the LinkedOmics database to identify co-expressed genes.A Venn diagram was constructed to determine the overlapping genes between the DEGs and the co-expressed genes.Functional enrichment analysis was performed on the overlapping genes and DEGs.Furthermore,our study involved functional enrichment analysis,a protein-protein interaction network analysis,and an analysis of immune cell infiltration.The cBioPortal and Tumor Immune Single-cell Hub were utilized to investigate the genetic alterations of SFPQ and the single-cell transcriptome visualization of the tumor microenvironment.A ceRNA network was established with the assistance of the ENCORI website.Finally,we elucidated the clinical significance of SFPQ in HCC by employing Kaplan-Meier survival analysis,univariate and multivariate Cox regression,and prognostic nomogram models.Results:The expression of SFPQ in HCC tissues was significantly elevated compared to normal tissues.GSEA results indicated that increased expression of SFPQ was associated with pathways related to HCC.The ceRNA network,including SFPQ,hsa-miR-101-3p,AC023043.4,AC124798.1,AC145207.5,and GSEC,was constructed with the assistance of ENCORI.High SFPQ expression was related to a poor prognosis in HCC and its subtypes.Univariate and multivariate Cox regression analysis showed that elevated SFPQ expression is an independent predictive factor.Conclusions:The overexpression of SFPQ may serve as a potential prognostic biomarker,indicating a poor prognosis in HCC.

Melatonin treatment alleviates chilling injury in mango fruit 'Keitt' by modulating proline metabolism under chilling stress

Mangoes often suffer from low temperature-induced chilling injury (CI) during postharvest cold storage.Therefore,advanced techniques are crucial and in high demand to solve the chilling stress of mango fruit for a higher value.This study addresses chilling stress modulation by investigating the effects of melatonin treatment on CI,proline metabolism,and related gene expressions of ‘Keitt’ mango during cold storage after dipped in 0 (control),0.1 (MT1),and 0.2 mmol L^(-1)(MT2) melatonin solution for 30 min.The results revealed that melatonin treatment in MT1 significantly reduced CI development and increased proline content in mango fruit during cold storage compared to the control.These changes were along with increases in the activity of critical enzymes as well as the expression of encoding genes involved in proline biosynthesis,such as pyrroline-5-carboxylate synthetase (P5CS),pyrroline-5-carboxylate reductase (P5CR),ornithine D-aminotransferase (OAT),P5CS2,P5CR2,and OAT3.Additionally,proline dehydrogenase (PDH) activity and the expression of the PDH3 gene associated with proline dehydrogenation were lower in MT1-treated mangoes than the controlled group.Thus,melatonin treatment has regulated proline metabolism resulting in the accumulation of proline,subsequently contributing to enhancing the chilling tolerance of‘Keitt’mango fruit.

Drought Tolerance in Mung Bean is Associated with the Genotypic Divergence, Regulation of Proline, Photosynthetic Pigment and Water Relation

Drought is one of the critical conditions for the growth and productivity of many crops including mung bean(Vigna radiata L.Wilczek).Screening of genotypes for variations is one of the suitable strategies for evaluating crop adaptability and global food security.In this context,the study investigated the physiological and biochemical responses of four drought tolerant(BARI Mung-8,BMX-08010-2,BMX-010015,BMX-08009-7),and four drought sensitive(BARI Mung-1,BARI Mung-3,BU Mung-4,BMX-05001)mung bean genotypes under wellwatered(WW)and water deficit(WD)conditions.The WW treatment maintained sufficient soil moisture(22%±0.5%,i.e.,30%deficit of available water)by regularly supplying water.Whereas,the WD treatment was maintained throughout the growing period,and water was applied when the wilting symptom appeared.The drought tolerant(DT)genotypes BARI Mung-8,BMX-08010-2,BMX-010015,BMX-08009-7 showed a high level of proline accumulation(2.52–5.99 mg g^(−1) FW),photosynthetic pigment(total chlorophyll 2.96–3.27 mg g^(−1) FW at flowering stage,and 1.62–2.38 mg g^(−1) FW at pod developing stage),plant water relation attributes including relative water content(RWC)(82%–84%),water retention capacity(WRC)(12–14)as well as lower water saturation deficit(WSD)(19%–23%),and water uptake capacity(WUC)(2.58–2.89)under WD condition,which provided consequently higher relative seed yield.These indicate that the tolerant genotypes gained better physiobiochemical attributes and adaptability in response to drought conditions.Furthermore,the genotype BMX-08010-2 showed superiority in terms of those physio-biochemical traits,susceptibility index(SSI)and stress tolerance index(STI)to other genotypes.Based on the physiological and biochemical responses,the BMX-08010-2 was found to be a suitable genotype for sustaining yield under drought stress,and subsequently,it could be recommended for crop improvement through hybridization programs.In addition,the identified traits can be used as markers to identify tolerant genotypes for drought-prone areas.

Effect of Water Stress Induced by Polyethylene Glycol on Growth, Proline Accumulation in Agave americana L.

The effect of water deficit was determined on both in vitro and soil seedling as well as in cells in suspension of Agave americana L.In order to do the establishment of cells,the formation of callus was induced;for it two auxins were evaluated:2,4-dichlorophenoxyacetic acid(2,4-D)and 4-mino-3,5,6-trichloropicolinic acid(picloram)at three concentrations(0.25,0.5 and 0.75 mg L−1)in three explants(leaf,root and meristems)cultured in MS semisolid medium.The callogenesis response was related to the type and section of the explant,as well as the regulator used,and a cell suspension was established using 0.5 mg L−1 naphthaleneacetic acid(NAA)+0.5 mg L−1 Benzylaminopurine(BAP).Seedlings were exposed to polyethyleneglycol(15%and 30%w/v)with a water potential of−0.87 and−2.67 MPa,respectively,under soil conditions.Water stress was applied through restricted irrigation.Fresh weight,root system growth,and chlorophyll concentration were some of the parameters that were affected by the effect of water deficit on A.americana L.Chlorophyll concentration values were significantly decreased by 15 at 30%PEG(19.6 SPAD units)compared to the control treatment.In in vitro plants,the highest concentration of proline was found in the roots,being the treatment with 30%polyethylene glycol where the highest concentration of this osmoregulator was obtained(62.5 mg g−1 DW).Under restricted irrigation conditions,an increase in proline concentration was observed both in the aerial part(2.2μg 100 g−1 DW)and in the root system(1.8μg 100 g−1 DW).However,the concentrations found were approximately ten times greater,less than those found under in vitro conditions.Therefore,the accumulation of proline can be considered an indicator of stress in Agave Americana L.growth in vitro.

Methods for the Determination of Stable Isotopes of Carbon and Nitrogen Directly in Valine, Proline, Glutamine, and Glutamic Acid

Amino acids are very important compounds for the body and are involved in important functions that keep us healthy. Amino acids are essential components such as valine, proline, glutamine and glutamic acid. They can be synthesized either naturally or artificially. To examine the metabolism and regulate the synthesis process, compounds labeled with nitrogen or carbon isotopes need to be used. These isotopic compounds allow for more extensive research and enable studies that would otherwise be impossible. However, their use is dependent on the availability of simple, efficient methods for isotopic analysis. Currently, the determination of the atomic fraction of carbon and nitrogen isotopes is only possible through their conversion into molecular nitrogen or carbon monoxide or carbon dioxide. This leads to the loss of information about isotopic enrichment in specific centers of the molecule. This article explores a new direct approach to determining the atomic fraction of carbon and nitrogen isotopes in the isotope-modified or identical centers of these compounds. This method eliminates the transfer process and dilution due to nitrogen and carbon impurities. It is now possible to simultaneously determine the atomic fraction of nitrogen and carbon isotopes in the research substance. This method can be applied to amino acids, making it an effective tool for proposing new research methods. Several articles [1] [2] [3] have proposed similar methods for organic compounds and amino acids.

小鼠腹膜内外不可吸收线结诱导局部早期迟发型超敏反应的组织学研究

目的探索和比较采用两种不可吸收丝线在小鼠腹壁腹膜内、外打结后线结诱导局部早发迟发型超敏反应的差异。方法取7只10~12周BALB/c小鼠,每只腹壁左向右纵向剪开3个腹壁切口(5 mm长),从左向右依次经3个腹壁皮肤切口处采用4-0带针慕斯线荷包缝合腹壁肌深面壁层腹膜后打结于腹膜外间隙(慕斯线腹膜外打结组)、打结于壁腹膜(慕斯线腹腔内打结组),经腹壁切口采用4-0 Proline线荷包缝合腹壁后打结于壁腹膜(Proline线腹膜内打结组)。术后7 d取材3组打结部位腹壁标本。结果免疫组织化学和半定量检测显示,Proline线腹膜内打结组线结周围抗原肽-主要组织相容性复合体(major histocompatibility complex,MHC)Ⅰ/Ⅱ类分子复合物、CD4^(+)、干扰素-γ(interferon-γ,IFN-γ)、淋巴毒素(lymphotoxinβ,LTβ)表达少于慕斯线腹膜外打结组和慕斯线腹腔内打结组,但慕斯线腹膜外打结组和慕斯线腹腔内打结组比较差异无统计学意义。Masson染色结果显示,Proline线腹膜内打结组线结周围可见片状纤维胶原条索,胶原纤维排列相对均一;慕斯线腹膜外打结组和慕斯线腹腔内打结组仅见散在纤维胶原条索,排列松散。结论Proline线较慕斯线诱导小鼠腹壁线结周围早期迟发型超敏反应轻微。腹腔镜监视下闭合内环口时,采用Proline线腹腔内荷包缝合打结较慕斯线腹膜外缝合和腹腔内荷包缝合打结线结超敏反应轻,相对更理想。

Overexpression of Proline Transporter Gene Isolated from Halophyte Confers Salt Tolerance in Arabidopsis

Proline is one of the most important and widespread osmolyte which functions in adaptation to adverse environmental stresses in many organisms. Also it is an important carbon and nitrogen resource in higher plants. Metabolism of proline has been elucidated in many plant species. However, transport of proline was poorly characterized although transport system plays an important role in proline distribution in different tissues. We isolated one full_length cDNA encoding proline transporter from the typical halophyte: Atriplex hortensis L. through cDNA library screening and 5′_RACE. The deduced amino acid sequence had eleven transmembrane domains, showed 60%-69% similarities to other ProTs and the gene was designated AhProT1. In the phylogenetic tree, higher plants' ProTs, e.g. AhProT1, showed more similar to ProP from microorganisms than ProT from mammalians. AhProT1 gene was transformed into Arabidopsis thaliana under 35S promoter. In MS medium containing [U_ 14 C] proline, AhProT1 + plants were able to accumulate much more radiolabeled proline in the roots than control plants. In MS medium containing different concentrations of NaCl, AhProT1 + plants could endure 200 mmol/L NaCl and keep development and biomass increase with proline supply, whereas control plants died back at 150 mmol/L NaCl.

Ornithine Pathway in Proline Biosynthesis Activated by Salt Stress in Barley Seedlings

C-14-glutamate and C-14-arginine were spreaded on leaves of six-day old barley (Hordeum vulgare L.) seedlings that were treated with NaCl 200 mmol/L. The result showed that the pathway of arginine-->ornithine-->proline existed in the six-day old barley seedlings and was provoked remarkably by NaCl treatment. After seven days, proline accumulation contributed via the arginine-->ornithine-->proline pathway was 1.0 - 1.5 folds of that via the glutamate-->proline pathway. The activation of arginine-->ornithine-->proline pathway by salt stress in the salt-tolerant cultivar 'Jian 4' was 1.7 - 2.0 folds of that in the salt-sensitive cultivar 'KP 7', which suggested that the activation of arginine-->ornithine-->proline pathway in barley seedlings played an important role in improving salt tolerance of plants.

The Comparison of Contents of Malondialdehyde and Proline in the Area of Karst Area in Northweastern Guangxi Province

[Objective] To select excellent pioneer species of better ecological and economical comprehensive benefits from the common rock hill plants in Karst area in northwestern Guangxi Province.[Method] Determine the contents of malondialdehyde and proline in leaves of 65 strains of plants by thiobarbituric acid method and sultosalicylic acid method,analyze the relevance of the contents of malondialdehyde and proline by mathematics statistics and analyze the 65 kinds of rock hill plants by clustering [Result] The contents of malondialdehyde and proline are 0.005 2-0.038 1 μmol/g.There are comparably significant differences in the contents of malondialdehyde in different plants;The determination of proline contents in plant＇s leaves are 4.347-374.956 μg/ml.There are also significant differences in proline of different leaves of rock hill plants.The contents of malondialdehyde and proline can be used as a reference point in selecting pioneer plants in Karst area.But when we select the pioneer plants,not only the biological characters of the species themselves should be taken into consideration,but also the differences of Karst area environment,ecological and biological benefits and the reasonable distribution of species.[Conclusion] Pistacia chinensis,Zenia insignis,Acacia confusa,Itoa orientalis and Sophora japonica can be used as the first choices of excellent pioneer plants in Karst area in northwestern area which comparably consists with the real situation of afforestation of rock hills and recovery of plants in Guangxi.

CuI/Proline-catalyzed N-Arylation of Nitrogen Heterocycles

Ma＇s CuI/proline procedure for the catalytic cross coupling between nitrogen heterocycles and aryl halides was markedly improved. The key finding was that K3PO4 was a much better base than K2CO3 for the reaction. With this new reaction condition the cross coupling with aryl iodides could be accomplished in 1,4-dioxane instead of DMSO. This reactin also could be carried out in DMF. Furthermore, the coupling yields under the new conditions are usually higher than in Ma＇s original methods.

Effects of Paclobutrazol Seed Priming on Seedlings Quality,Physiological and Bakanae Disease Index Characteristics of Rice(Oryza sativa L.)

Rice(Oryza sativa L.)is one of the most important cereal crops in the world.Bakanae disease is a significant rice disease widely distributed in rice-growing regions worldwide.Therefore,the present investigation aimed to assess the optimal concentrations of paclobutrazol(PBZ)as a treatment for rice grains(cv.Sakha 108)to control bakanae disease,also evaluating its impact on grain germination,seedling growth parameters as well as disease index.Paclobutrazol concentrations had no significant impact on seed germination,regardless of whether the seeds were incubated with Fusarium fujikuroi or not.Application of PBZ,either alone or in combination with fungal pathogens,negatively impacted the rice seedlings’height.Paclobutrazol at 25,50 and 100 mg/L,combined with the fungal pathogen positively impacted root length.Paclobutrazol at 3 and 6 mg/L mitigated the adverse impact on chlorophyll pigments content in infected seedlings.The highest proline contents were achieved by 100 mg/L PBZ alone or in combination with fungal pathogens.It has been observed that the application of PBZ,either alone or in combination with a fungal pathogen,leads to the enhancement of catalase,peroxidase,and polyphenol oxidase activities.The median lethal concentration of PBZ was 0.874 mg/L;applying low concentrations of paclobutrazol effectively increased the percentage of fungal growth suppression.Application of PBZ,at higher concentrations(50 and 100 mg/L),decreased infection percentage and disease severity index(DSI)significantly.These findings suggest that PBZ can be an effective treatment for controlling bakanae disease and enhancing resistance in rice plants.

PM2002CC PROLINE故障检修一例

对我院PM2002CC PROLINE全景/头部测量X光机一失控故障进行检查分析,发现原因是准备键"常开"状态不良,对该键加垫处理使机器运转正常。

Proline rich结构域介导Nogo-A激活NF-κB信号

髓鞘来源的中枢神经再生抑制因子——Nogo-A被发现除表达于成熟的少突胶质细胞,还广泛高表达于多种类型的神经元中.目前,神经元中Nogo-A的功能还不明确.为探讨神经元内Nogo-A的功能,以HEK293FT细胞为模型,利用信号途径报告基因系统筛选过表达Nogo-A对多种信号途径的调控作用,发现过表达Nogo-A能特异激活NF-κB信号,利用不同的Nogo-A剪接体和截断体形式研究,证明Nogo-A激活NF-κB信号依赖于其氨基端的prolinerich结构域,进一步使用NF-κB信号途径相关分子显性突变体揭示IκBα、TRAF6、Rac/Cdc42参与Nogo-A激活NF-κB信号.结果提示,Nogo-A可以显著激活NF-κB信号,且依赖于Nogo-A氨基段的prolinerich结构域.

Phytotoxicity of cadmium on protein, proline and antioxidant enzyme activities in growing Arachis hypogaea L. seedlings

Phytotoxicity of cadmium on growing Arachis hypogaea L. seedlings was studied. Seeds were exposed to 25, 50, and 100 μmol/L CdCl2 concentrations, for a period of 10, 15, 20 and 25 d. The extent of damage to chlorophyll, protein, proline, nitrate and nitrite reductase, antioxidant enzyme activity in leaves and roots were evaluated after 10 d of cadmium stress. The higher concentration of cadmium （100 μmol/L） resulted （leaves and roots） total chlorophyll 91.01%, protein 79.51%, 83.61%, nitrate reductase 79.39%, 80.72% and nitrite reductase 77.07%, 75.88% activity decreased with increase in cadmium concentrations and exposure periods. Cadmium caused significant changes in the activity of antioxidative enzymes. Contrastingly Cd treated plant tissues showed an increase in proline 159.87%, 239.6%, gluthion reductase （GR） 337.72%, 306.14%, superoxide disumutase （SOD） 688.56%, 381.72%, ascorbate peroxidase （APX） 226.47%, 252.14%, peroxidase （POD） 72.19%, 60.29% and catalase （CAT） 228.96%, 214.74% as compared to control. Cadmium stress caused a significant increase in the rate of SOD activity in leaves and roots of plant species. Results show the crop A. hypogaea is highly sensitive even at very low cadmium concentrations.

Changes of Proline Content,Activity,and Active Isoforms of Antioxidative Enzymes in Two Alfalfa Cultivars Under Salt Stress

The plants of two elfalfa （Medicago sativa L.） cultivars differing in salt tolerance were subjected to three salt treatments, 70, 140, and 210 mM NaCl for 7 days. Root, shoot, and leaf growths were inhibited by increased salt treatments in both cultivars, and at 140 and 210 mM salt treatments, Zhongmu 1 had significantly higher root, shoot, and leaf dry weights per plant than Deft. The malondialdehyde （MDA） accumulation in Deft was considerably greater than in Zhongmu 1, indicating a higher degree of lipid peroxidation at 140 and 210 mM salt treatments. The changes in the activity and active isoforms of antioxidant enzymes such as superoxide dismutase （SOD, EC 1.15.1.1）, catalase （CAT, EC 1.11.1.6）, peroxidase （POD, EC 1.11.1.7）, and ascorbate peroxidase （APOX, EC 1.11,1.11）, accumulation of free proline, and rate of lipid peroxidation in leaves of two alfalfa cultivars were also investigated. After stress, the activity and active isoforms of antioxidative enzymes were altered and the extent of alteration varied between the cultivar Deft and Zhongmu 1. The proline accumulation in Deft was considerably greater than in Zhongmu 1 at 210 mM salt treatment. This indicated that proline accumulation may be the result, instead of the cause, of salt tolerance.

Increased resistance of drought by Trichoderma harzianum fungal treatment correlates with increased secondary metabolites and proline content

Plant secondary metabolites play vital role in plant stress response. In this study we investigated whether root colonization of tomato （Solanum lycopersicum） infected by Trichoderma harzianum leads to alterations in the biosynthesis of secondary plant metabolites including phytohormones and osmolyte proline under drought stress. Exposure of tomato to drought caused a drastic decline in plant growth and physiological parameters. Tomato inoculated with T. harzianum showed increased root and shoot growth and chlorophyll pigments as compared to uninoculated controls as well as drought stressed plants. Proline and total soluble protein content was increased in plants inoculated with T. harzianum under both normal as well as drought conditions. An obvious increase in phenol and flavonoid content was observed due to T. haczianum. In addition, T. hat-zianum inoculated plants maintained higher levels of growth regulators indole acetic acid, indole butyric acid, and gibberellic acid under drought stress. Improved secondary metabolites which play an important role in plant stress tolerance by T. hat-zianum may have coordinately worked for bringing the growth regulation by protecting membranes from reactive oxygen species （ROS） and enhance plant growth through accessing more nutrients by root system.

Melatonin treatment induces chilling tolerance by regulating the contents of polyamine,γ-aminobutyric acid,and proline in cucumber fruit

The mechanism of melatonin(MT)induced chilling tolerance in harvested cucumber fruit was investigated at commercial maturity.In this study,cucumber fruits were treated with 100μmol L^(-1) MT at 4℃ and 90% relative humidity for 15 d of storage.In comparison with the control,cucumber treatment with MT resulted in reduced chilling injury(CI),decreased electrolyte leakage and enhanced firmness.The fruits treated with MT showed higher chlorophyll contents in storage conditions with suppressed chlorophyllase enzyme activity.MT treatment increased arginine decarboxylase(ADC)and ornithine decarboxylase(ODC)enzyme activities.Moreover,enhanced expression of the Cucumis sativus ADC(CsADC)and C.sativus ODC(CsODC)genes resulted in the accumulation of polyamine contents.Similarly,proline levels exhibited higher levels among treated fruits.Meanwhile,the proline synthesizing enzymes △1-pyrroline-5-carboxylate syntheses(P5CS)and ornithine aminotransferase(OAT)were significantly increased,while a catabolic enzyme of proline dehydrogenase(PDH)activity was inhibited by treatment.In addition,MT induced expression of C.sativus OAT(CsOAT)and C.sativus P5CS(CsP5CS)genes.Cucumber fruits treated with MT also exhibited higher γ-aminobutyric acid(GABA)content by enhanced GABA transaminase(GABA-T)and glutamate decarboxylase(GAD)enzyme activities and a higher C.sativus GAD(CsGAD)gene expression.To sum up,the results show that MT treatment enhanced chilling tolerance,which was associated with the regulation of polyamines,as well as proline and γ-aminobutyric acid.

Effects of Formulated Fertilizer Synergist on Abscisic Acid Accumulation, Proline Content and Photosynthetic Characteristics of Rice under Drought

To investigate the effects of formulated fertilizer synergist on the drought tolerance in rice, pot experiment was conducted to analyze the photosynthetic characteristics and the accumulation of abscisic acid （ABA） and proline in middle-season rice variety Peiliangyou 93. The synergist could improve the net photosynthetic rate, and coordination between the water loss and the CO2 absorption as well as reduce the harmful effect on photosynthetic process under drought conditions. Under drought, the ABA accumulated massively both in roots and leaves, while the ABA content in roots was far higher than that in leaves. The results indicate that synergist could increase the ABA accumulation, but reduce the proline accumulation in rice plant under drought.

Proline Accumulation,Photosynthetic Abilities and Growth Characters of Sugarcane(Saccharum officinarum L.) Plantlets in Response to Iso-Osmotic Salt and Water-Deficit Stress

The aim of this study was to investigate the biochemical, physiological and morphological responses of sugarcane to iso- osmotic salt and water-deficit stress. Disease-free sugarcane plantlets derived from meristem cuttings were photo- autotrophically grown in MS media and subsequently exposed to -0.23 （control）, -0.67 or -1.20 MPa iso-osmotic NaCl （salt stress） or mannitol （water-deficit stress）. Chlorophyll a （Chl a）, chlorophyll b （Chl b）, total carotenoids （Cx＋c）, maximum quantum yield of PSII （Fv/Fm）, photon yield of PSII （ΦPSII）, stomatal conductance （Gs） and transpiration rate （E） in the stressed plantlets were significantly reduced when compared to those of plantlets of the control group （without mannitol or NaCl）, leading to net-photosynthetic rate （Pn） and growth reduction with positive correlation. In addition, physiological changes and growth parameters of plantlets in the salt stress conditions were more sharply reduced than those in waterdeficit stress conditions. On the other hand, the proline content and non-photochemical quenching （NPQ） in the leaves of stressed plantlets increased significantly, especially in response to iso-osmotic salt stress. The chlorophyll pigments in iso-osmotic stressed leaves were significantly degraded （r^2 = 0.93）, related to low water oxidation （r^2 = 0.87）, low net- photosynthetic rate （r^2 = 0.81）, and growth reduction （r^2 = 0.97）. The multivariate biochemical, physiological and growth parameters in the present study should be further used to develop salt, or drought, tolerance indices in sugarcane breeding programs.

Effects of 1-MCP on proline,polyamine,and nitric oxide metabolism in postharvest peach fruit under chilling stress

Peach(Prunus persica Batsch‘Yuhualu’)fruit are sensitive to chilling injury(CI).Proline,polyamine(PA),and nitric oxide(NO)are important small regulators of various metabolic pathways under chilling stress that mitigate CI.Ethylene is known to promote senescence and CI,while 1-methylcyclopropene(1-MCP)is an antagonist that inhibits the effects of ethylene.However,how1-MCP and ethylene affect proline,PA,and NO levels under chilling stress remains unclear.To address these questions,1-MCP(1μL·L^(−1))and ethylene(1μL·L^(−1))treatments were applied to peach fruit.Fruit were stored at 4°C for 28 d,then moved to 25°C for 3 d immediately after cold storage.Peach fruit exhibited CI symptoms after 7 d of cold storage with enhanced electrolyte leakage and malondialdehyde contents.The 1-MCP treatment significantly(P<0.05)restrained peach CI,and fruit did not exhibit CI symptoms until 14 d of cold storage.Proline and PAs in peach under chilling stress weremostly synthesized from glutamate and arginine,which were catalyzed by1-pyrroline-5-carboxylate synthetase and arginine decarboxylase,respectively.1-MCPtreated fruit exhibited higher proline and PA contents and enhanced chilling tolerance compared to the control,while ethylene-treated fruit had lower proline and PA contents and reduced chilling tolerance.Ethylene-treated fruit,which exhibited more severe CI symptoms compared to the control,had significantly(P<0.05)lower NO contents and NO synthase activities.However,NOmay not be a direct acting factor in 1-MCPinduced chilling tolerance,as 1-MCP-treated fruit had lower NO contents and NO synthase activities compared to the control.In conclusion,proline and PA clearly played direct and important roles in 1-MCP-induced peach chilling tolerance,while NO may not be actively involved.