A study of the soil water potential threshold values to trigger irrigation of ‘Shimizu Hakuto’ peach at pivotal fruit developmental stages

Water management is an important practice that affects fruit size and quality.Effective implementation of irrigation scheduling requires knowledge of the appropriate indicators and thresholds,which are established manly based on the effects of water deficits on final fruit quality.Few studies have focused on the real-time effects of water status on fruit and shoot growth.To establish soil water potential (ψ_(soil)) thresholds to trigger irrigation of peach at pivotal fruit developmental stages,photogrammetry,^(13)C labelling,and other techniques were used in this study to investigate real-time changes in stem diameter,fruit projected area,net leaf photosynthetic rate (P_(n)),and allocation of photoassimilates to fruit under soil water potential conditions ranging from saturation to stress in 6-year-old Shimizu hakuto’peach.Stem growth,fruit growth,and P_n exhibited gradually decreasing sensitivity to water deficits during fruit developmental stages I,II,and III.Stem diameter growth was significantly inhibited whenψ_(soil)dropped to-8.5,-7.6,and-5.4 k Pa,respectively.Fruit growth rate was low,reaching zero when theψ_(soil)was-9.0 to-23.1,-14.9 to-21.4,and-16.5 to-23.3 k Pa,respectively,and P_ndecreased significantly when theψ_(soil)reached-24.2,-22.7,and-20.4 kPa,respectively.In addition,more photoassimilates were allocated to fruit under moderateψ_(soil)conditions (-10.1 to-17.0 k Pa) than under otherψ_(soil)values.Our results revealed threeψ_(soil)thresholds,-10.0,-15.0,and-15.0 kPa,suitable for triggering irrigation during stages I,II,and III,respectively.These thresholds can be helpful for controlling excessive tree vigor,maintaining rapid fruit growth and leaf photosynthesis,and promoting the allocation of more photoassimilates to fruit.

Genomic analysis provides insights into the westward expansion of domesticated peaches in China

Peach, an economically important model plant of the Rosaceae family, has been domesticated and cultivated in China for approximately5 000 years. The Hexi Corridor, an important corridor connecting east-central China and the Tarim Basin, is the starting point of the Silk Road that links China and the Eurasian region. As a globally distributed fruit tree, the spread of peach was accomplished through historical trade routes in the Hexi Corridor and the Tarim Basin. However, knowledge of peach genetic diversity in these regions remains limited. In this study,we examined the relationships and the spread history of domesticated peaches through sequencing and genomic analysis of 161 peach accessions collected from Northwest China, including 43 from the Hexi Corridor and 104 from the Tarim Basin. The results indicate that peach landraces in the Hexi Corridor and the Tarim Basin are derivatives of peaches from the east and south of China (ESC). Notably, the genetic diversity of accessions from both the Hexi Corridor and the Tarim Basin was lower than that of ESC accessions. Reduction of diversity (ROD) and linkage disequilibrium (LD) analyses detected a genetic bottleneck in peaches from these regions. Additionally, these peaches have undergone varying degrees of selection from natural environment. Moreover, genes responsive to biotic and abiotic stresses were under selection, which could be the result of the climate change of Northwest China after the Last Glacial Maximum (LGM). Our findings provide a better understanding of the genetic basis of peach migration in Northwest China. Furthermore, this study expands the available genomic data for peaches and provides critical information for future peach breeding programs.

Peculiarity of transcriptional and H3K27me3 dynamics during peach bud dormancy

Bud dormancy facilitates the survival of meristems under harsh environmental conditions.To elucidate how molecular responses to chilling accumulation controlling dormancy in peach buds,chromatin immunoprecipitation sequencing to identify the H3K27me3 modifications and RNA sequencing of two peach cultivars with pronounced differences in chilling requirement were carried out,the results showed that genes associated with abscisic acid and gibberellic acid signal pathways play key roles in dormancy regulation.The results demonstrated that peach flower bud differentiation occurred continuously in both cultivars during chilling accumulation,which was correlated with the transcript abundance of key genes involved in phytohormone metabolism and flower bud development under adverse conditions.The more increased strength in high chillingrequirement cultivar along with the chilling accumulation at the genome-wide level.The function of the dormancy-associated MADS-box gene PpDAM6 was identified,which is involved in leaf bud break in peach and flower development in transgenic Nicotiana tabacum(NC89).In addition,PpDAM6 was positively regulated by PpCBF,and the genes of putative dormancy-related and associated with metabolic pathways were proposed.Taken together,these results constituted a theoretical basis for elucidating the regulation of peach bud dormancy transition.

Study on Germplasm Resources of Peach Cultivars

[Objectives]To study the germplasm resources of excellent peach cultivars.[Methods]Five peach cultivars were introduced,in-cluding‘Jinxiu’peach,‘Jinxiang’peach,‘Chunxiao’peach,‘Hujingmilu’peach and‘018 nectarine’peach.Then,these five cultivars were used to study the biological characteristics of peach trees,namely,as phenology,fruit quality,heat resistance,cold resistance and other resistance.[Results]Five cultivars of peach plants grew fast and robust,among which‘018 nectarine’had very crisp fruit,‘Jinxiu’,‘Jinxiang’,‘Chunxiao’and‘Hujingmilu’had very sweet fruitꎻthe peach trees of these five cultivars have good water resistance,heat resist-ance and cold resistance.[Conclusions]The results of this study can not only provide a reference for the introduction of peach trees,but also provide a practical basis for the large-scale planting of peach trees.

Evaluation of Trace Elements in the Soil of Typical Peach Orchards in Zunyi City

[Objectives]This study was conducted to clarify the enrichment and paucity of trace elements in the soil environment of peach orchards in Zunyi City,and to provide reference for supplementary application of microelement fertilizers and high-quality peach production in peach orchards.[Methods]Taking the soil of three typical peach orchards(Taoli Renjia peach orchard,Pengrui peach orchard and Taohuadao peach orchard)in Shenxi Town,Honghuagang District,Zunyi City as the research object,the contents of trace elements in soil were analyzed through field sampling and indoor determination of trace elements.[Results]The effective contents of trace elements in the soil of peach orchard bases in the study area were at a medium level,and the soil of the peach orchards was rich in available Fe and Se.The contents of available Cu,Mo and Mn were relatively rich.The contents of available B were not high overall.The contents of available Zn were at a moderate to low level overall.The soil of Taoli Renjia peach orchard was relatively rich in trace elements.[Conclusions]The research results can provide a scientific basis for the production of high-quality crispy peaches in peach orchards.

Color of the Year 2024: Peach Fuzz

Pantone has declared Pantone 13-1023Peach Fuzz as its Color of the Year for 2024.This soft peach tone reflects comforting warmth and represents a desire for unity,peace and personal well-being.The calming shade,a sublime blend of pink and orange,suggests fresh softness,signifying an environment that invites relaxation,reccovery and growth.The delicatehue of Pantone 13-1023 Peach Fuzz not only awakens our senses to the tactile and enveloping warmth of the color,but also influences our sense of peace and overall well-being.

PpMAPK6 regulates peach bud endodormancy release through interactions with PpDAM6

The MADS-box(DAM)gene PpDAM6,which is related to dormancy,plays a key role in bud endodormancy release,and the expression of PpDAM6 decreases during endodormancy release.However,the interaction network that governs its regulation of the endodormancy release of flower buds in peach remains unclear.In this study,we used yeast two-hybrid(Y2H)assays to identify a mitogen-activated protein kinase,PpMAPK6,that interacts with PpDAM6 in a peach dormancy-associated SSHcDNA library.PpMAPK6 is primarily located in the nucleus,and Y2H and bimolecular fluorescence complementation(BiFC)assays verified that PpMAPK6 interacts with PpDAM6 by binding to the MADS-box domain of PpDAM6.Quantitative real-time PCR(qRT-PCR)analysis showed that the expression of PpMAPK6 was opposite that of PpDAM6 in the endodormancy release of three cultivars with different chilling requirements(Prunus persica‘Chunjie’,Prunus persica var.nectarina‘Zhongyou 5’,Prunus persica‘Qingzhou peach’).In addition,abscisic acid(ABA)inhibited the expression of PpMAPK6 and promoted the expression of PpDAM6 in flower buds.The results indicated that PpMAPK6 might phosphorylate PpDAM6 to accelerate its degradation by interacting with PpDAM6.The expression of PpMAPK6 increased with decreasing ABA content during endodormancy release in peach flower buds,which in turn decreased the expression of PpDAM6 and promoted endodormancy release.

Genome sequencing revealed the red-flower trait candidate gene of a peach landrace

Peach(Prunus persica)is an economically important fruit crop globally and an excellent material for genomic studies.While considerable progress has been made in unveiling trait-associated genes within cultivars and wild relatives,certain novel genes controlling valuable traits in peach landraces,such as the red-flowering gene,remained unclear.In this study,we sequenced and assembled the diploid genome of the red-flower landrace‘Yingzui’(abbreviated as‘RedY’).Multi-omics profiling of red petals of‘RedY’revealed the intensified red coloration associated with anthocyanins accumulation and concurrent decline in f lavonols.This phenomenon is likely attributed to a natural variant of Flavonol Synthase(FLS)harboring a 9-bp exonic insertion.Intriguingly,the homozygous allelic configurations of this FLS variant were only observed in red-flowered peaches.Furthermore,the 9-bp sequence variation tightly associated with pink/red petal color in genome-wide association studies(GWAS)of collected peach germplasm resources.Functional analyses of the FLS variant,purified from procaryotic expression system,demonstrated its diminished enzymatic activity in f lavonols biosynthesis,impeccably aligning with the cardinal trait of red flowers.Therefore,the natural FLS variant was proposed as the best candidate gene for red-f lowering trait in peach.The pioneering unveiling of the red-flowered peach genome,coupled with the identification of the candidate gene,expanded the knowledge boundaries of the genetic basis of peach traits and provided valuable insights for future peach breeding efforts.

The Potential Efficacy of Glycyrrhizic Acid and Its Nanostructure Against Brown Rot of Peach fruits

Production of peaches(Prunus persica(L.)Batsch)for both local market and export is increasing each year in Egypt.Brown rot disease,caused by Monilinia laxa and Monilinia fructigena,is considered one of the most important postharvest rots affecting peaches in Egypt and economic losses are increasing.Antifungal activity of glycyrrhizic acid nanoparticles(GA-NPs)and glycyrrhizic acid(GA)at 0.2 and 0.4 mmol/L was investigated as a control for both these brown rot pathogens on peach fruits in both in vitro and in vivo studies.In the in vitro studies,GA-NPs were the most effective as shown by the ability to decrease linear growth of both brown rot pathogens in potato dextrose agar(PDA)amended with 0.4 mmol/L GA-NPs.Micrographs of M.fructigena exposed to 0.4 mmol/LGA showed mycelial deformations,nodule formation,detachment of the cell wall,shrinkage and inhomogeneous cytoplasmic materials with large vacuoles.Mycelium of M.laxa exposed to 0.4 mmol/LGA-NPs resulted in thinner and distorted hyphae,nodule formation,cell wall thinning,and swellings.The GANPs and GA treatments improved fruit quality by maintaining firmness and total soluble solids(TSS).GA-NPs were more effective in decreasing decay incidence than their bulk material.The 0.4 mmol/L GA-NPs completely inhibited the disease on naturally infected peach fruits for both seasons of 2018 and 2019.Furthermore,0.4 mmol/L GA-NPs reduced the disease incidence in inoculated fruits by 95(M.laxa)and 88%(M.fructigena)in 2018 season and 96(M.laxa)and 85%(M.fructigena)in 2019 season.In conclusion,GA-NPs could enhance the resistance of peaches against brown rot caused by M.laxa and M.fructigena.

β-Cyclodextrin-Based Nitrosoglutathione Improves the Storage Quality of Peach by Regulating the Metabolism of Endogenous Nitric Oxide, Hydrogen Sulfide, and Phenylpropane

Nitrosoglutathione(GSNO)andβ-cyclodextrin(β-CD)exhibit positive roles in regulating fruit quality.However,there are few reports about the effects of GSNO andβ-CD on enhancing storability and boosting nitric oxide(NO),hydrogen sulfide(H2S),and phenylpropane metabolism in fruits during storage.“Xintaihong”peach were treated with 0.5,1.0,1.5mmol L−1 GSNO in 0.5%(w/v)β-CD solution(GSNO/β-CD).The effects of GSNO/β-CD on endogenous NO,H2S,and phenylpropane metabolism were investigated.Treatment with GSNO/β-CD increased the color difference of peach and inhibited the increase of respiratory intensity,weight loss,and relative conductivity.Treatment with 1.0 mmol L−1 GSNO/β-CD increased the nitric oxide synthase(NOS-like)activity and L-arginine content,thereby promoting the accumulation of endogenous NO.By improving the activities of L-cysteine desulfhydrylase(L-CD),O-acetylserine sulfur lyase(OAS-TL),serine acetyltransferase(SAT),GSNO/β-CD increased the content of endogenous H2S in peach.Treatment with GSNO/β-CD increased the activities of phenylalanine ammonia-lyase(PAL),4-coumarate-CoA ligase(4CL),and cinnamic acid-4-hydroxylase(C4H),promoted the increase of total phenols,flavonoids,and lignin in peach.These results indicated that GSNO/β-CD treatment better maintained the quality of peach by improving the metabolism of endogenous NO,H2S,and phenylpropane during storage.

Identification of Early Peach Aphid Infestation Based on Hyperspectral Imaging Technology

Peach aphid is a common pest and hard to detect.This study employs hyperspectral imaging technology to identify early damage in green cabbage caused by peach aphid.Through principal component transformation and multiple linear regression analysis,the correlation relation between spectral characteristics and infestation stage is analyzed.Then,four characteristic wavelength selection methods are compared and optimal characteristic wavelengths subset is determined to be input for modelling.One linear algorithm and two nonlinear modelling algorithms are compared.Finally,support vector machine(SVM)model based on the characteristic wavelengths selected by multi-cluster feature selection(MCFS)acquires the highest identification accuracy,which is 98.97%.These results indicate that hyperspectral imaging technology have the ability to identify early peach aphid infestation stages on green cabbages.

Evaluation on Soil Improvement Effects of Organic Fertilization in Honey Peach Orchard in the Longquan Mountain

Combined application of organic fertilizer is an effective measure to improve the productivity and ecological effect of newly added soil.However,the effect of organic fertilizer application in newly added orchard soil is not clear.In this project,the soil of newly built peach orchard in the Longquan Mountain of Chengdu was applied with 45 t/hm 2 of organic fertilizer.After 9 months of planting 6 varieties of honey peach(Wanhujing,Baifeng,Zhongtao 13,Huangjinmitao 1,Zhongpan 101,Zhongpan 104),the locally well developed peach orchard was taken as the control.The physical and chemical properties of soil from four topography(top slope,middle slope,lower slope and flat land)of newly built peach orchard were analyzed,and the effect of organic fertilizer on soil was evaluated.The results showed that combined application of organic fertilizer had different effects on soils from orchards with different varieties of peach and from different terrain parts of the same peach variety.Specifically,it had the best effect on soil improvement in Baifeng(local variety),Zhongpan 101 and Zhongpan 104(introduced varieties).Meanwhile,the best effect of soil improvement was found on top slope.Cluster analysis divided newly built peach orchards,uncultivated soil,and locally well developed peach orchard into four groups,indicating that the selected amount of organic fertilizer application in this study has improved the soil of peach orchards to some extent,but it was still necessary to increase the application amount.It was better for 54 t/hm 2 amount of organic fertilization on the part of top and middle slope,and 60 t/hm 2 on the lower slope and flat land.The comprehensive ecological benefit assessment of organic fertilizer should be conducted based on long-term monitoring of peach orchard ecological environment,fruit tree growth,fruit yield and quality,which would provide scientific basis for peach orchard production and management.

基于PEACH理念的理工科类专业教学方法研究

教学方法改革是培养学生创新精神、实践能力和学习能力的有效举措,关系到教学改革的成败。针对我国高校理工科类专业教学方法存在的问题,借鉴国外先进教学理念,结合理工科类专业课程的特点,提出了基于PEACH理念的教学方法,涉及问题式或案例式、探究式、自我评估式、小组合作式和启发式教学方法等,为我国理工科类专业教学提供方法借鉴。

基于Peach Fuzz的媒体网关安全测试

随着互联网技术和计算机技术的发展,软件在各行各业的应用越来越广泛。随之而来的软件安全问题也越来越突出。在常见的软件安全测试工具中,Peach Fuzz是一款优秀的安全测试工具,能在多种操作系统上运行,支持多种协议的模糊测试。结合媒体网关安全测试工作实践,介绍了Peach Fuzz测试的基本结构和特点;介绍了H.248协议和SCTP协议;叙述了媒体网关的测试模型;详细叙述了基于Peach Fuzz的媒体网关安全测试过程,其主要内容包括搭建和部署Peach Fuzz测试执行机、测试执行机对接测试环境、Peach Fuzz测试套的调试和连跑、Peach Fuzz测试的观测方法、测试结果分析。最后介绍了一个测试案例。工作实践表明采用Peach Fuzz工具进行媒体网关安全测试,有助于提高媒体网关产品的安全可靠性,提升产品质量。

Polyphenol Oxidase, Peroxidase and PhenylalanineAmmonium Lyase Induced in Postharvest Peach Fruitsby Inoculation with Pichia membranefaciensor Rhizopus stolonifer

Rhizopus rot of peach fruits could be significantly suppressed by Pichia membranefaciens.Polyphenol oxidase (PPO), peroxidase (POD) and phenylalanine ammonium-lyase (PAL) activities inducedby inoculation with P. membranefaciens or R. stolonifer were studied in postharvest peach fruits. The activ-ities of PPO and PAL in peaches increased significantly after being inoculated with P. membranefaciens + R.stolonifer by 24 h, the activities maintained at a high level throughout the experiment. Under the condition ofinfected with R. stolonifer alone, activity of PPO and PAL could also increased, but the levels were lowerthan those treated with P. membranefaciens+ R. stolonifer. However, fruits inoculaed with P. membrane-faciens+ R. stolonifer or R. stolonifer alone did not stimulated POD activity. The results suggest that theactivation of these defense enzymes is involved in the action of P. membranefaciens against R. stolonifer.

Changes in Enzymatic Activity and Quality Attributes of Late-mature Peaches in Response to Controlled Atmosphere Conditions

Late-mature peaches (Prunus persica L. Batsch, cv. Dongxuemi ) were stored in air,modification atmosphere (MA) and controlled atmospheres (CA) at 1℃ to investigate enzymatic activities,flesh browning, quality attributes and fruit storability during storage periods. Peaches stored in CA conditions showed significant lower activities of polyphenol oxidase (PPO) and peroxidase (POD) compared to that kept in MA and in air during the early period of storage. CA treatments indicated a better result in maintaining fruit firmness, color and titratable acidity than MA and control treatments. But there was no significant difference in vitamin C and total soluble solids of peaches stored in CA, MA and air. Increasing PPO activity obviously stimulated flesh browning. Peach fruits stored in CA conditions showed a lower activity of POD and higher firmness in the early period of storage. The peaches stored in 5%CO2 + 5%O2 and 10%CO2 + 5%O2 for 92 days had a good quality without any off-flavor. The results indicated CA conditions obviously inhibited the enzymatic browning, delayed senescence and maintained quality of late-mature peaches.

Comparative assessment of physicochemical properties of unripe peach(Prunus persica) and Japanese apricot(Prunus mume)

Objective:To investigate the physicochemical properties of unripe peach-Pruuns persica cv.Mibaekdo(Mibaekdo) and Prunus persica cv.Nagasawa Hakuho(Nagasawa Hakuho) as an alternative to fowl supplement while Japanese apricot(Prunus mume cv.Backaha)(Backaha) was used as a control sample.Methods:The unripe fruits were analyzed for soluble solid(Brix).titratable acidity.pH,total polyphenol content,1,1-diphenyl-2-pierylhydrazyl(DPPH) radical scavenging activity,amygdalin content,free amino acid content,organic acid content,free sugar content,and α-amylase activities.Results:Total polyphenol content of unripe peach ranged between 137.27-151.64 μg/g whereas that of apricot was 160.73 μg/g.DPPH radical scavenging activities of Rackaha was the highest189.16%.) followed by Mibaekdo(85.03%) and Nagasawa Hakuho(41.30%).The highest amount of oxalic acid 1612.8 mg/100 g) was observed in Mibaekdo while that of Nagasawa llakuho and Backaha were(184.6±18.1) and(334.8±16.1) mg/100 g,respectively.Amygdalin contents of Mibaekdo.Nagasawa Hakuho and Backaha were 486.61,548.60 and 174.28 μg/g,respectively.Conclusions:The results suggest that the unripe fruit of peach has a significant biochemical potential of using as a food supplement with potential health benefit for human health.

Peach yield and fruit quality is maintained under mild deficit irrigation in semi-arid China

We conducted a two-year study of deficit irrigation impact on peach yield and quality in semi-arid northwest China. Over two years, four-year-old peach trees were irrigated at 100, 75, 50 and 25% of peach evapotranspiration(ET_c), here, ET_c= Coefficient(Kc)×Local reference evapotranspiration(ET_o). During the April-July fruit production season we measured root zone soil water depletion, sap flow velocity, net photosynthetic rate(P_n), transpiration rate(T_r), stomatal conductance(G_s), water use efficiency(WUE=P_n/T_r), fruit quality, and yield under a mobile rain-out shelter. Increased soil water depletion reasonably mirrored decreasing irrigation rates both years, causing progressively greater water stress. Progressive water stress lowered G_s, which in turn translated into lower T_r as measured by sap flow. However, mild deficit irrigation(75% ET_c) constricted T_r more than P_n. P_n was not different between 100 and 75% ET_c treatments in both years, and it decreased only 5–8% in June with higher temperature than that in May with cooler temperature. Concurrently under 75% ET_c treatment, T_r was reduced, and WUE was up to 13% higher than that under 100% ET_c treatment. While total fruit yield was not different under the two treatments, because 75% ET_c treatment had fewer but larger fruit than 100% ET_c trees, suggesting mild water stress thinned fruit load. By contrast, sharply decreased T_r and P_n of the driest treatments(50 and 25% ET_c) increased WUE, but less carbon uptake impacted total fruit yield, resulting 13 and 33% lower yield compared to that of 100% ET_c treatment. Irrigation rates affected fruit quality, particularly between the 100 and 75% ET_c trees. Fewer but larger fruit in the mildly water stressed trees(75% ET_c) resulted in more soluble solids and vitamin C, firmer fruit, and improved sugar:acid ratio and fruit color compared to the 100% ET_c treatment. Overall, trees deficit irrigated at 75% ET_c maintained yield while improving fruit quality and using less water.

Genetic Resources,Breeding Programs in China,and Gene Mining of Peach:A Review

Research on peach genetic resources and breeding has achieved remarkable progress in recent decades,especially in China.In this review,we first described the geographic distribution,ecology,phenotypes,and genetic diversity of peach landraces and wild relatives in China.We also discussed the almond.Subsequently,breeding programs of peaches in China are summarized,including breeding history,breeding targets,breeding institutes,elite breeding materials,breeding solutions,and domestically bred representative cultivars.Furthermore,we reviewed the genes or loci that have been mined using both linkage mapping and genome wide association study(GWAS)as well as the evolutionary genetics and domestication history of the peach.Finally,we gave our perspectives and suggestions for future breeding in terms of breeding material selection and breeding technology innovation.

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.