The Relationship Between Senescence and Ca2+-ATPase Activity of Microsomal Membrane and Lipid Peroxidation in Harvested Peach Fruit

Peach fruit easily soften and have a short storage time at normal temperature. In this study, peach fruit (Prunus persica sieb et Zucc cv. Yingqing) were picked and stored at 25 and 4℃ to investigate the senescence in correlation with Ca2+- ATPase activity of microsomal membrane and lipid peroxidation during ripening and senescence. In comparison with that stored at 25℃, the fruit stored at 4℃ exhibited a higher flesh firmness, lower respiration rate, and generated the late bigger peak value of Ca2+-ATPase activity as well as maintained the higher activity of the enzyme. Meanwhile, the lower levels of super oxygen radical (O2-) production and content of malondialdehyde (MDA), a product of membrane lipid peroxidation were observed. Sodium orthovanadate (SO) and erythrosin B (EB), as Ca2+-ATPase inhibitors, could stimulate the respiration rate. The results suggested that the slower senescence rate of peach fruit was closely related to the higher peak value and longer duration of Ca2+-ATPase activity in microsomal membrane, with the slighter membrane lipid peroxidation and lower O2(-) production rate.     

Changes of Reactive Oxygen Species and Related Enzymes in Mitochondrial Respiration During Storage of Harvested Peach Fruits

Peach fruits [Prumus persica (L.) Batsch,cv.Yuhuasanhao] were used as materials to investigate the changes of reactive oxygen species (ROS) and related enzymes in mitochondria respiration during storage and then their influence on senescence of harvested Peach fruits was studied.The results showed that low temperature (50C) strongly inhibited the reduction of firmness and the increase in respiration rate.During storage at ambient temperature (200C),ROS had a cumulative process while malondialdehye (MDA) content continued to increase in associated with enhanced membrane lipid peroxidation.Lipoxygenase (LOX) activity was strongly inhibited under the low temperature condition.The activities of succinic dehydrogenase (SDH),cytochrome C oxidase (CCO),and Caz+-ATPase declined to a certain extent at ambient temperature,while they showed higher activities at low temperature,which may be related to lower membrane lipid peroxidation at low temperature.Higher Ca~(2+) content at ambient temperature may be responsible for impairment of mitochondrial function,thus,leading to fruit senescence.The results showed that under low temperature condition,the low accumulation of ROS and the low level of membrane lipid peroxidation could maintain the function of mitochondria that would help to delay the senescence of peach fruits.These suggested a close relationship existed between ROS metabolism and mitochondrial respiration.It can be inferred that the low temperature helps to delay senescence of peach fruits via suppression of ROS and related enzymes,maintain better homeostasis of Ca~(2+) in mitochondria and thus better mitochondrial functions.     

一氧化氮对低温贮藏桃果实线粒体氧化损伤的影响

【目的】分析一氧化氮(NO)对冷藏过程中桃果实线粒体氧化损伤的影响。【方法】分别用15 μmol/L NO、5 μmol/L c-PTIO (NO清除剂)、对照(去离子水)浸泡30 min处理桃果实。测定0℃下桃果实的线粒体完整性、活性氧含量、抗氧化酶的活性及相关品质指标。【结果】在桃果实低温冷藏过程中,NO处理可以维持桃果实硬度、色差L值及可溶性固形物含量,降低线粒体耗氧量和减少活性氧的积累,调节线粒体呼吸控制率(RCR)、线粒体膜电势,线粒体细胞色素C含量以及线粒体抗氧化酶活性。【结论】NO通过减少线粒体氧化损伤,维持线粒体的完整性,延长桃果实的贮藏期。     

The Relationship Between Senescence and Ca^2＋-ATPase Activity of Microsomal Membrane and Lipid Peroxidation in Harvested Peach Fruit

Peach fruit easily soften and have a short storage time at normal temperature. In this study, peach fruit （Prunus persica sieb et Zucc cv. Yingqing） were picked and stored at 25 and 4℃ to investigate the senescence in correlation with Ca^2＋- ATPase activity of microsomal membrane and lipid peroxidation during ripening and senescence. In comparison with that stored at 25~C, the fruit stored at 4℃ exhibited a higher flesh firmness, lower respiration rate, and generated the late bigger peak value of Ca^2＋-ATPase activity as well as maintained the higher activity of the enzyme. Meanwhile, the lower levels of super oxygen radical （O2^-.） production and content of malondialdehyde （MDA）, a product of membrane lipid peroxidation were observed. Sodium orthovanadate （SO） and erythrosin B （EB）, as Ca^2＋-ATPase inhibitors, could stimulate the respiration rate. The results suggested that the slower senescence rate of peach fruit was closely related to the higher peak value and longer duration of Ca^2＋-ATPase activity in microsomal membrane, with the slighter membrane lipid peroxidation and lower O2^-. production rate.     

Application of methyl jasmonate postharvest maintains the quality of Nanguo pears by regulating mitochondrial energy metabolism

The present study was conducted to investigate the effects of methyl jasmonate (MeJA) dipping treatment on mitochondrial energy metabolism and quality parameters of Nanguo pears during room temperature storage. The results showed that MeJA treatment suppressed the respiration rate and weight loss, and maintained the flesh firmness of Nanguo pears. MeJA also effectively maintained the content of ascorbic acid and titratable acidity in the fruit. Furthermore, the activities of H⁺-ATPase, Ca²⁺-ATPase, succinate dehydrogenase (SDH) and cytochrome C oxidase (CCO) of the MeJA-treated fruit were significantly higher than those of the untreated fruit. The contents of adenosine triphosphate (ATP) and adenosine diphosphate (ADP) and the energy charge were also enhanced by MeJA treatment. These results suggest that postharvest MeJA treatment could maintain the quality of Nanguo pears, in part by modulating mitochondrial energy metabolism during room temperature storage.     

桃果实成熟期的软化机理探讨

研究了在自然成熟和催熟条件下,大久保桃果实硬度与乙烯、脂肪氧合酶、多聚半乳糖醛酸酶及相关代谢的研究。结果表明桃果实软化是一个受多因素调节的生理过程,脂肪氧合酶可能与果实前期软化有关,酯肪氧合酶、乙烯、多聚半乳糖醛酸酶都参与了果实后期的软化过程。     

NO处理延缓采后枇杷果实木质化劣变及其与能量代谢的关系

【目的】枇杷果实采后生命活动旺盛,衰老速度快,常温下极易变质腐烂。低温贮藏虽然可以有效延长贮藏期,减少腐烂,但会出现果皮难以剥离、果肉木质化并褐变、质地糙硬少汁等品质劣变现象,这是造成冷藏枇杷商品性丧失和损失的主要原因,已成为其市场拓展的限制因素,是当前枇杷果实在冷链集散和流通中急需解决的关键问题。探讨外源NO处理对冷藏枇杷果肉木质化劣变进程的作用机制,并分析木质化劣变与能量代谢的关系,以期为进一步研究采后枇杷果实低温品质劣变进程调控的分子生物学机理和贮运保鲜技术奠定基础。【方法】将‘解放钟’枇杷（Eriobotrya japonica Lindl.）果实在密闭容器中用0（对照组）、15和25 μL•L-1 NO熏蒸2 h后,取出通风20 min,然后将各处理果实置于5℃、相对湿度85%条件下贮藏,测定冷藏期间各处理组果实细胞膜透性、硬度、出汁率、木质素含量、ATP含量、ADP含量、AMP含量、能荷值及琥珀酸脱氢酶（SDH）、细胞色素氧化酶（CCO）、H+-ATPase和Ca2+-ATPase活性的变化,并分析NO处理后木质素含量与能荷值间的相关性。【结果】随着贮藏时间的延长,枇杷果实细胞膜透性和硬度逐渐上升,出汁率逐渐下降,贮藏10 d后木质素含量迅速上升,果实冷害症状明显。与对照组相比, NO处理能延缓细胞膜透性和硬度的上升及出汁率的降低,显著抑制木质素的合成,较好地保持细胞膜的完整性,从而减轻果实冷害的发生。冷藏期间,枇杷果实ATP含量逐渐下降,贮藏前10 d ADP含量迅速下降并最终维持在较低水平,贮藏中后期（15-30 d）SDH、CCO、H+-ATPase和Ca2+-ATPase活性急剧下降,表明线粒体功能受损导致枇杷果实能荷水平迅速下降。与对照组相比,NO处理可以延缓ATP、ADP含量的下降,且显著抑制贮藏中后期SDH、CCO、H+-ATPase和Ca2+-ATPase活性的降低,保持枇杷果实较好的线粒体功能;贮藏30 d后,15 和25 μL•L-1 NO处理的枇杷果实能荷值分别比对照组高11.8%和12.9%。相关性分析表明,15和25 μL•L-1 NO处理的枇杷果实能荷值和木质素含量呈极显著负相关,相关系数（r）分别为 -0.715**、-0.598**。【结论】低温条件下,能量代谢失调与枇杷果实木质化劣变密切相关,NO处理可以通过调节SDH、CCO、H+-ATPase、Ca2+-ATPase线粒体代谢相关酶活性,维持较高的能量水平,从而有效地提高冷藏枇杷果实抗低温的能力,进而延缓果实木质化进程,其中以25 μL•L-1 NO处理效果较好。     

桃果实成熟软化与细胞壁降解相关糖苷酶及乙烯生物合成的关系

【目的】研究不同溶质型桃成熟软化过程中β-半乳糖苷酶（β-Gal）和α-L-阿拉伯呋喃糖苷酶（α-Af）以及乙烯生物合成相关酶（ACC氧化酶ACO和ACC合成酶ACS）的变化。【方法】采用气相色谱测定乙烯释放量;采用常规理化分析方法测定相关酶活性;采用RT-PCR研究相关酶的定性表达,同时采用Real-time PCR分析其表达量的变化。【结果】不同桃品种之间软化特性存在较大差异,‘雨花3号’桃果实成熟过程中,随着果实硬度下降,乙烯释放量明显增加并出现峰值,‘加纳岩’桃果实在成熟过程中一直保持相对较高的硬度且乙烯释放量很低,其最高值不及‘雨花3号’桃果实乙烯释放量的1%;β-Gal基因表达量和活性在桃果实成熟软化前期较高,α-Af基因表达和活性在成熟软化后期较高,且α-Af的快速变化期滞后于乙烯及其合成相关酶的变化。【结论】β-Gal酶对桃果实早期阶段的软化启动有较大影响,且两类桃果实β-Gal基因表达和β-Gal活性可能存在不同的诱导机制; α-Af对桃果实成熟中后期快速软化影响更显著且α-Af的激活与果实内源乙烯的积累密切相关。     

活性氧与果实成熟衰老

活性氧在果实的成熟衰老过程中起着重要的作用。本文概述了活性氧对采后果实的伤害 ,活性氧与果实衰老、乙烯及 Ca2 的关系 ,并从自由基的角度对果实成熟衰老的可能机理进行了探讨。     

桃果实成熟软化过程中细胞壁多糖降解特性的研究

以雨花3号水蜜桃果实为试验材料,分步提取不同成熟度桃果实细胞壁物质(CWM)、4种果胶多糖(CDTA-1、CDTA-2、N a2CO3-1、N a2CO3-2)、3种半纤维素多糖(KOH-1、KOH-2、KOH-3)和纤维素多糖(CWM-残渣)。采用气相色谱法测定各种多糖组分中的单糖组成,探讨桃果实成熟软化过程中随果实硬度的下降,细胞壁各多糖成分含量及其单糖组成的变化。结果表明:在桃果实成熟软化过程中,富含半乳糖醛酸的果胶主链发生断裂,果胶、半纤维素、纤维素多糖中支链阿拉伯糖、半乳糖也发生不同程度的解离。细胞壁半乳糖醛酸和半乳糖的降解与桃果实软化的启动密切相关,而阿拉伯糖的降解则可能是桃果实后熟软化的重要因素。     

Effects of Ca2+/CaM Messenger System Inhibitors on Ethylene-Induced Increase in Lycopene Content

The changes of lycopene content during ripening and senescence of tomato fruit and the relationship between ethylene glycol-bis (EGTA, Ca2+ chelator), verapamil (Vp, Ca2+ channel blockers), trifluoperazine (TFP), chloropromaize (CPZ) (CaM antagonism) and ethylene-induced increase in lycopene content in tomato fruit were investigated. Lycopene content accumulated obviously during ripening and senescence of tomato fruit after harvest at pink stage. Low temperature inhibited but ethylene enhanced the lycopene content.Meanwhile, ethylene also promoted calmodulin (CaM) content in tomato fruit, which was related to the concentration of ethylene. When EGTA, Vp, TFP and CPZ with ethylene were used to treat tomato fruit, ethylene-induced increase in lycopene content could be reversed, indicating that blocking Ca2+ channel in plasma membrane or chelating extracellular Ca2+ or inhibiting the activity of CaM could decrease the action of ethylene, and suggesting that Ca2+-CaM messenger system may be involved in lycopene increase inducedby ethylene.     

桃杂交后代基因性状遗传分析

分析了12个桃杂交组合(杂交亲本包括6个普通型、5个半矮化和2个矮化品种(系))F1的1 361单系5个数量性状的遗传力,包括盛花期,果实成熟期,果实大小、颜色和风味及果形、果肉硬度、果肉颜色,丰产性,核黏离性状,树体大小和果实品质的遗传规律。结果表明,盛花期、果实成熟期、果实大小和颜色的遗传力(H2)为0.3～0.5,果实风味遗传力较低;圆形果个体相对于椭圆形、卵圆形和扁圆形果个体呈显性,比例为76∶12∶8∶4;后代的平均果肉硬度较双亲平均果肉硬度低0.2级(最大为5级);所有黄肉亲本的F1个体果肉颜色广泛分离,黄肉个体显著高于白肉和红肉个体;子代的丰产性比双亲平均丰产性低1级,然而,亲本组合7310828(海尔×波南萨)×波南萨和49号(Fortyniner)×7310902(海尔×波南萨)组合获得丰产单系的几率高;通常离核相对于黏(半离)核呈显性,杂交组合7310828×波南萨的后代例外;F1群体的平均果实品质比亲本退化2级(最高为5级)左右;49号×7310828和亨利(O'Henry)自由授粉后代中获得全红、大果、黄肉优系的几率高;乔化单系的几率显著高于矮化、半矮化单系,其比例为82∶14∶4;柱型桃皮勒(Pillar)是强健、直立实生个体的理想亲本。     

Overexpression of the apple expansin-like gene MdEXLB1 accelerates the softening of fruit texture in tomato

Fruit firmness is an important quality trait of apple fruit texture, and the pre-harvest ripening period is the key period for the formation of apple fruit texture. Expansin is a cell wall loosing protein family that has four subfamilies: α-expansin (EXPA), β-expansin (EXPB), expansin-like A (EXLA), and expansin-like B (EXLB). In this study, we investigated the key period of pre-harvest texture formation in ‘Golden Delicious’ apples based on fruit longitudinal diameter, transverse diameter, firmness, tissue structure, respiration intensity, ethylene release rate, and expansin activity. Within the 10 days before harvest, the fruit was found to reach maturity. Semi-quantitative RT-PCR revealed that most of the expansins were expressed at the ripening stage before harvest. The biological function of the EXLB subfamily gene, MdEXLB1, was further identified, and its subcellular localization on the cell wall was confirmed by transient transformation experiments. Compared with the wild type (WT), the transgenic tomato lines overexpressing MdEXLB1 had lower plant height, earlier fruiting period, fewer days for fruit ripening, higher fruit maturity, lower fruit firmness, higher fruit expansin activity, more discrete flesh cell structure, and accelerated fruit ripening process. Overall, this is the first study to propose that the apple EXLB subfamily gene, MdEXLB1, has biological functions and plays an important role in promoting fruit ripening and softening.     

不同浓度茉莉酸甲酯对春蜜桃果实品质的影响

探讨不同浓度茉莉酸甲酯(MJ)对桃果实品质的影响,以早熟桃春蜜为试材,于果实发育S3时期(果实第二次快速生长期)用125、250、500、1 000和2 000 mg·L^-1 5个不同浓度MJ对早熟桃进行处理,研究果实发育期以及成熟期的单果质量、纵横径、可溶性固形物、可滴定酸、色泽、果实硬度等品质指标的变化。结果表明,与对照相比,250 mg·L^-1 MJ处理显著增大了春蜜桃果实的单果质量及纵横径,125和500 mg·L^-1 MJ处理则无显著变化,而1 000和2 000 mg·L^-1 MJ处理比对照显著减小;不同浓度MJ处理均增加了果实中可溶性固形物含量,降低了可滴定酸含量,但处理间无显著差异;250和2 000 mg·L^-1 MJ处理增大了果实硬度,其他处理与对照相比无显著差异;MJ处理对桃果实的着色影响不显著;在果实成熟期,单果质量、纵横径、果实硬度及着色研究效果与果实生长期结果相一致;不同浓度MJ处理增大了春蜜桃果实的固酸比,处理间差异不显著;不同浓度MJ处理对果实的果形指数、可溶性固形物、可滴定酸含量无显著影响(P>0.05)。综合来看,250 mg·L^-1 MJ处理浓度在早熟桃春蜜上有较好的应用效果。     

采前乙酰水杨酸处理对厚皮甜瓜果实后熟及软化的影响

【目的】研究果实发育期间乙酰水杨酸(ASA)4次喷施处理对厚皮甜瓜果实采收及贮藏期间后熟和软化的影响及作用机理,为采后调控提供参考。【方法】以‘玛瑙’厚皮甜瓜为试材,采用1 mmol·L-1 ASA分别在甜瓜幼果期(花后2周)、膨大期(花后3周)、网纹形成期(花后4周)及采前48 h四个时期连续喷施处理,测定果实采收及冷藏期间(7℃,RH 55%—60%)的呼吸强度和乙烯释放量,硬度、细胞壁组分以及细胞壁降解酶活性的变化。【结果】采前乙酰水杨酸处理可有效降低甜瓜果实采收时的呼吸强度和乙烯释放量,使果实贮藏期间呼吸和乙烯跃变峰的出现时间推迟1周。ASA处理提高了果实采收时的硬度及原果胶、纤维素、半纤维素和富含羟脯氨酸糖蛋白(HRGPs)含量,延缓了原果胶向可溶性果胶的转化,维持了较高的纤维素、半纤维素和HRGPs水平,有效保持了贮藏期间的果实硬度。采前ASA处理显著降低了采收时和贮藏期间甜瓜果实细胞壁降解酶的活性,主要抑制了果实果胶甲酯酶(PME)、多聚半乳糖醛酸酶(PG)、纤维素酶(Cx)和β-葡萄糖苷酶(β-Glu)的活性。相关性分析表明,处理果实的乙烯释放量和呼吸强度与多聚半乳糖醛酸酶(PG)活性呈显著正相关,与β-葡萄糖苷酶(β-Glu)活性呈极显著正相关;处理果实的硬度与果胶甲酯酶(PME)活性、原果胶和半纤维素含量呈极显著正相关,与纤维素酶(Cx)活性和可溶性果胶(WSP)含量呈显著正相关,与乙烯释放量和呼吸强度均呈显著负相关。【结论】采前ASA处理可促进甜瓜果实发育期间细胞壁物质的合成,有效抑制甜瓜果实采收及贮藏期间的呼吸强度和乙烯释放,降低胶甲酯酶(PME)、多聚半乳糖醛酸酶(PG)、纤维素酶(Cx)和β-葡萄糖苷酶(β-Glu)等细胞壁降解酶的活性,阻止细胞壁物质的释放,有效维持了冷藏期间的甜瓜果实硬度。     

钙处理对冷藏期间中华寿桃生理特性的影响

研究了不同浓度钙处理对冷藏条件下中华寿桃生理特性的影响。结果表明：中华寿桃冷藏35天,已表现出明显的冷害症状,失去软化能力,CaCl2处理对冷藏果实的硬度无影响;而采用CaCl2处理后的中华寿桃果实相对膜透性产生一定影响;在整个冷藏过程中,3%CaCl2处理对冷藏果实的乙烯释放量和呼吸强度有抑制作用。     

茉莉酸甲酯诱导的采后香蕉果实耐冷性与活性氧信号的关系

 【目的】探讨茉莉酸甲酯（MeJA）对采后香蕉果实耐冷诱导的效果及其对活性氧代谢、Ca2+-ATPase活性的影响。【方法】香蕉果皮用10 µmol•L-1 MeJA处理1 min,在20℃恒温培养1 d（取样作第0天）,然后置于7℃下离体培养10 d,测定果皮冷害指数、细胞膜透性、过氧化氢和超氧阴离子含量、过氧化氢酶（CAT）、抗坏血酸过氧化物酶（APX）、NADPH氧化酶以及Ca2+-ATPase活性的变化。【结果】与对照香蕉果皮相比,10 µmol•L-1 MeJA处理的冷害指数较低、细胞膜透性增加缓慢;MeJA处理诱导了果皮H2O2含量和 产生速率的提高,并维持了前4 d的高水平,而MeJA处理降低了CAT和APX的活性,并在前4 d维持了较低的水平;研究还发现,MeJA处理还诱导了NADPH氧化酶和Ca2+-ATPase活性的升高。【结论】MeJA诱导的活性氧猝发可能作为信号分子参与诱导了香蕉果皮冷害和耐冷诱导,并可能与钙信号相关。     

桃低温贮藏中生理变化与冷害发生的关系

本实验研究了不同温度 (8℃、 5℃、 2℃ )下 ,桃果大久保和明星贮藏期间生理变化与冷害发生的关系 ,结果进一步验证 :桃属于典型的呼吸跃变型果实。 8℃下 ,两品种桃的呼吸强度变化均呈现双峰曲线。 2℃低温明显抑制了桃果的呼吸作用 ,且呼吸高峰比 8℃下分别延缓 6天和 4天出现。 5℃下 ,两品种桃均出现了呼吸作用的异常反应 ,呼吸高峰出现早 ,且峰值高 ,同时果肉组织的细胞膜透性增大 ,这可能与冷害发生有关     

1-MCP对‘绿宝石’梨采后成熟衰老期间H2O2含量及其相关酶活性的影响

为探讨1-甲基环丙烯(1-MCP)对梨果实采后成熟衰老过程中过氧化氢(H2O2)代谢的作用,试验以‘绿宝石’梨为材料,用1.0 μL/L 1-MCP密封处理24 h,空气密封为对照,研究1-MCP对‘绿宝石’梨室温(25±2)℃贮藏过程中果实硬度、可溶性同形物含量(SSC)、呼吸速率、H2O2含量、抗氧化酶活性[超氧化...     

早熟有明桃在不同条件下果实硬度变化规律研究

以早熟有明桃为试材,研究了室温、冷藏和树上条件下果实硬度的变化规律。结果表明：早熟有明桃为高硬度、长采收期和长货架期品种。早熟有明桃果实在室温、冷藏和树上条件下的果实硬度均呈下降趋势,只是不同条件下的下降速度和趋势不同而已,其中冷藏条件下果实硬度下降最慢,室温条件下果实硬度下降最快。常温、冷藏和树上的果实硬度均无明显的果实硬度下降过程,该类型可能为无呼吸高峰类型。