钙和ABA在番茄果实乙烯生物合成中的相互作用

研究了钙和ABA对不同成熟阶段和不同成熟模式番茄(Lycopersicon esculentum cv．Lichun)果实乙烯生成的影响，分析两者在乙烯生物合成系统中的相互作用。普通番茄绿熟果实组织圆片在用100μmol／L ABA和100mmol/L钙处理后，乙烯生成均很快增加。当用这两种试剂同时处理番茄果实圆片时，乙烯生成增加量明显比单一处理增加量大，表明两者在对绿熟番茄果实乙烯生成的影响中有协同作用关系。钙离子鳌合剂EGTA(乙二醇双乙胺醚-N，N’-四乙酸)对乙烯生成有抑制作用，用ABA和EGTA同时处理番茄圆片时，乙烯的生成量比EGTA单一处理的生成量要高。当用这些试剂处理未成熟番茄果实则产生不同的效果，ABA明显抑制乙烯生成，而钙却依然促进乙烯的生物合成，ABA和钙同时处理果实时，乙烯生成量介于二者单一处理之间，表明ABA和钙在未成熟番茄果实乙烯生成中表现出相互抑制作用。在转反义ACS番茄中，ABA和钙抑制未成熟果实的乙烯生成，而都促进了绿熟果实的乙烯生成。这表明ABA和钙在番茄果实不同成熟阶段和不同成熟模式的乙烯生物合成过程中有着不同的相互作用关系。     

红熟番茄果实多酚氧化酶酶学特性

多酚氧化酶（Polyphenol oxidase,PPO,EC 1.14.18.1 or 1.10.3.2）与果蔬加工制品的色泽、抗氧化能力关系密切。果蔬PPO酶学特性分析和活性控制越来越受到关注,为设计、开发番茄加工技术和工艺提供理论依据,该文采用光谱法,研究了红熟番茄（Lycopersicum esculentum Mill. cv 918）果实PPO的酶学特性。研究结果表明红熟番茄果实PPO的最适反应pH值是6.0,反应温度是40℃,耐热性较好,50℃加热10 min仍保有88%的活性。红熟番茄果实PPO对一元酚、二元酚和三元酚均有催化氧化能力,最适底物是儿茶酚,其最大反应速率和米氏常数分别是226.30 U/min和 6.00 mmol/L。抗坏血酸、β-巯基乙醇或L-半胱氨酸可抑番茄PPO活性,十二烷基硫酸钠可显著增强其活性。     

葡萄ACO家族基因过量表达对番茄乙烯释放速率的影响

乙烯是启动和促进果蔬成熟和衰老的内源激素,ACC氧化酶(1-aminocyclopropane-1-carboxylic acid oxidase,ACO)是乙烯生物合成中的一个关键限速酶.葡萄ACO基因拥有一个基因家族,其中VvACO1和VvACO2基因在果实转色时期出现转录高峰,是葡萄果实发育过程中造成乙烯含量发生变化的关键基因.为验证葡萄(Vitis vinifera)ACO家族基因过量表达对番茄(Solanum locopersicum)乙烯释放速率的影响,本研究通过根癌农杆菌(Agrobacterium tumefaciens)介导法将葡萄ACO基因导入番茄基因组中,进行了PCR和RT-PCR分子检测,并对分子检测阳性的转基因番茄植株叶片的ACO酶活性和乙烯释放速率进行了分析.RT-PCR检测表明,在3个VvA CO1、4个VvACO2和6个VvACO3转基因番茄植株中目的基因均有一定的表达.所有转基因番茄植株的ACO酶活性和乙烯释放速率均比对照有所提高,其中以VvACO1基因的过量表达对叶片ACO酶活和乙烯释放速率增加的幅度最大,VvACO3基因的过量表达对果实的ACO酶活和乙烯释放速率增加的幅度最大,而转化VvACO2基因的番茄植株ACO酶活性和乙烯释放速率最低,比对照略有升高,且植株呈现矮化现象.本研究通过观察转基因番茄的生长状况以及测定转基因番茄的生理指标,探讨葡萄ACO家族基因的过量表达对番茄的影响,来预测葡萄ACO基因的初步功能.     

乙烯受体基因LeETR1和LeETR4的克隆及在番茄果实中的表达

摘要：为研究野生型番茄（Lycopersicon esculentum Mill. cv . Lichun）和转反义ACS 番茄果实中乙烯受体基因LeETR1和LeETR4的表达与乙烯的关系，实验用RT-PCR方法扩增了乙烯受体基因LeETR1和LeETR4片段，用两片段作探针进行Northern 杂交。结果表明：两受体基因的表达在番茄果实成熟进程中变化不明显，LeETR4在同一时期的果实外果皮中表达水平低于其在辐射壁和中柱的表达。转反义ACS番茄果实中LeETR1和LeETR4的表达水平显著低于野生型番茄果实，外源乙烯处理转反义ACS番茄果实，促进两个受体基因的表达。可见果实中LeETR1和LeETR4的表达受乙烯调控的影响。     

静电场处理对贮藏番茄品质及生理变化的影响

为探讨静电场对番茄贮藏品质的影响,以“朝研219”绿熟番茄为试材,从控制软化和转红出发,筛选了适宜的静电场处理条件为：场强-200 kV/m,频度2 h/d。研究静电场处理对贮藏番茄品质和生理变化的影响,结果表明：静电场处理能显著延缓番茄果实硬度的下降,抑制由绿转红的过程;可以延缓果实可溶性糖含量的下降和可滴定酸含量的上升;经负高压静电场处理的番茄,呼吸跃变推迟6 d出现,乙烯峰的出现也延迟了3 d,相对电导率与丙二醛含量较对照明显降低,说明静电场处理可调控果实细胞膜透性的变化。     

乙烯受体基因LeFTR1和LeFTR4的克隆及在番茄果实中的表达

为研究野生型番茄(Lycopersicon esculentum Mill．cv．Lichun)和转反义ACS番茄果实中乙烯受体基因上eETR1和LeETR4的表达与乙烯的关系，实验用RT-PCR方法扩增了乙烯受体基因LeETR1和LeETR4片段，用两片段作探针进行Northern杂交。结果表明：两受体基因的表达在番茄果实成熟进程中变化不明显，LeETR4在同一时期的果实外果皮中表达水平低于其在辐射壁和中柱的表达。转反义ACS番茄果实中LeETR1和LeETR4的表达水平显著低于野生型番茄果实，外源乙烯处理转反义ACS番茄果实，促进两个受体基因的表达。可见果实中LeETR1和LeETR4的表达受乙烯调控的影响。     

1-甲基环丙烯处理对西洋梨常温贮藏的保鲜效果

为了探索西洋梨采后的常温保鲜方法,以“早红考密斯”为试材,研究了1-甲基环丙烯处理对西洋梨果实在20℃条件下生理代谢的影响。结果表明,在20℃贮藏条件下,1-MCP处理能明显延缓果实硬度的下降和色度的改变;抑制果实乙烯的合成,降低果实的呼吸速率,推迟乙烯、呼吸峰出现,并降低峰值。1-MCP处理与对照相比,乙烯释放高峰和呼吸高峰推迟6 d出现,同时降低了峰值,乙烯释放高峰和呼吸高峰分别仅为对照的69.6%和79.8%;1-MCP处理抑制了可溶性固形物含量和丙二醛含量的快速上升;在贮藏12 d时,果实的过氧化物酶、超氧化物歧化酶、过氧化氢酶活性分别为对照的 144.7%、113.5%、141.4%;另外,1-MCP还可以抑制果实的腐烂,降低果实腐烂率。因此,1-MCP处理可抑制西洋梨货架期的后熟衰老进程,有利于保持果实品质,提高贮藏效果。     

不同处理对海沃德猕猴桃内源ABA相关代谢基因表达的影响

为在分子水平阐明外源乙烯利、1-MCP和ABA处理对海沃德猕猴桃内源ABA合成代谢的影响,并揭示ABA调控果实后熟机理。本研究以海沃德猕猴桃果实为试验材料,利用外源乙烯利、1-MCP和ABA处理猕猴桃果实,分别运用高相液相色谱(HPLC)和RT-qPCR分析20℃贮存条件下对猕猴桃内源ABA合成、信号通路相关基因XanDH、PYR/PYL、PP2C、ABF的表达量影响。结果表明,乙烯利处理下PP2C和ABF基因表达量在DAH17~DAH58都显著低于对照组,XanDH和PYR/PYL在DAH17均显著高于对照组,而后迅速回落。在ABA处理下XanDH基因表达量呈先下降后上升再下降的趋势,在DAH17表达量最高。PP2C和PYR/PYL在DAH17经历高峰后逐渐回落至低水平,与对照组差异显著。ABF在采后前期有较高的表达量,经历峰值后急速回落,在后熟中后期表达水平较低。1-MCP处理下,在整个后熟阶段,XanDH的表达量均显著高于对照组,在DAH17达到最大值,随后逐渐降落。与对照组相比,PP2C基因表达量持续上升,ABF基因持续下调;PYR/PYL在DAH17表达量最高而后下调,但仍显著高于对照组。表明乙烯利、1-MCP、ABA处理对海沃德猕猴桃内源ABA合成、信号传导有较大影响,本试验结果为进一步探究外源乙烯利、1-MCP和ABA对猕猴桃果实采后衰老的调控作用及机理提供了一定的理论依据。     

生长调节剂处理对高州矮香蕉贮藏品质的影响

以高州矮香蕉为试材,研究了1-甲基环丙烯(1-MCP)和外源乙烯处理对香蕉贮藏品质的影响。结果表明,200nl/L 1-MCP处理可显著抑制香蕉可溶性糖和可溶性固形物含量上升,延缓果实硬度下降,从而延缓香蕉后熟进程;20μl/L外源乙烯对1-MCP处理果实的后熟进程影响不明显。     

1-MCP对冷藏花牛苹果生理活性及香气合成相关酶活性的影响

以花牛苹果为试材,研究了1-甲基环丙烯(1-MCP)处理对花牛苹果冷藏期间果实呼吸强度、乙烯释放速率及香气成分相关酶活性的影响。结果表明,1-MCP能够显著抑制冷藏期间花牛苹果果实呼吸强度和乙烯生成,推迟呼吸和乙烯释放高峰的出现,同时能够抑制花牛苹果香气合成的相关酶活性,从而延缓果实的后熟与衰老,有效保持花牛苹果贮藏期间的生理品质。冷藏120 d,果实LOX酶活性峰值较同期对照降低了21.6%;PDC酶活性于冷藏180 d时达到最大,较同期对照低了51.5%。1-MCP 处理降低了AAT酶活性峰值,但并未推迟峰值的来临。     

Abscisic acid improves tomato fruit quality by increasing soluble sugar concentrations

Abscisic acid (ABA) is crucial in fruit maturation and senescence and is considered as the other ripening control factor other than ethylene. Important components in ripening fruit are soluble sugars, which make the fruit sweeter and carotenoids, important flavor compounds in ripened fruit. The purpose of this study was to examine the effects of foliar ABA and calcium (Ca) fertilizer treatments (individually and in combination) on determinate beef-steak greenhouse tomato (Solanum lycopersicum) leaf chlorophylls and carotenoids, fruit carotenoids, and soluble sugar concentrations. Foliar spray treatment of 500 mg L^?1 ABA increased zeaxanthin (ZEA) and β-carotene (BC) in tomato leaf tissue. Increases in Ca fertilizer treatments significantly decreased tomato leaf violaxanthin (VIO), but no effect on other carotenoids. The application of 500 mg L^?1 ABA foliar spray significantly increased glucose and fructose concentrations in tomato fruit tissue. Foliar application of ABA treatments can increase overall chlorophyll, carotenoid content, and fruit quality.     

高压电场处理对贮藏番茄活性氧代谢的调节

为探讨高压电场调控采后果实成熟衰老的作用机理,研究了交变电场和稳恒电场处理对采后番茄活性氧代谢的影响。试验结果表明：交变电场处理可诱导贮藏前期番茄超氧化物歧化酶（SOD）和过氧化氢酶（CAT）活性,延缓贮藏后期SOD活性上升和CAT活性下降;稳恒电场处理对酶活性的诱导不显著。两种电场处理均延缓了过氧化物酶（POD）活性高峰出现的时间。稳恒电场处理果实整个贮藏过程中保持了高水平的抗坏血酸（AsA）以及还原型谷胱甘肽（GSH）含量。整个贮藏期间高压电场处理均显著抑制了番茄过氧化氢含量以及超氧阴离子的产生。     

Impact of UV-C irradiation on the cell wall-degrading enzymes during ripening of tomato (Lycopersicon esculentum L.) fruit

The effect of a hormic dose of UV-C (254 nm) on changes in fruit firmness and cell wall-degrading enzyme (CWDE) activity was determined using tomato fruit. Throughout the storage period, a decrease in firmness was jointly observed with an increase of the CWDE (polygalacturonase, pectin methyl esterase, cellulase, xylanase, beta-D-galactosidase, and protease) activity for all treatments, suggesting the involvement of these enzymes in the ripening process. However, the enhancement in the activity of the CWDE was significantly less in fruit subjected to the hormic dose of UV-C. This reduction may explain why irradiated fruit were firmer than control and consequently may explain how UV-C could delay the ripening and senescence process. We suggest that the CWDE are one of the targets of the UV-C, and by this action, irradiation contributed to a delay of the cell wall degradation and consequently retarded softening of the tomato fruit tissues.     

铜胺氧化酶基因PpCuAO4在桃成熟中的功能鉴定

为明确铜胺氧化酶(CuAO)在桃果实成熟过程中的作用,分别采用1.0、5.0和10.0 mmol·L^-1的CuAO抑制剂氨基胍(AG)对黄水蜜桃果实进行喷施处理,并于桃果实成熟后测定果实硬度。结果表明,5 mmol·L^-1 AG处理组桃果实的硬度保持效果最好。进一步采用5.0 mmol·L^-1 AG处理黄水蜜桃果实,并测定果实成熟相关生理指标。结果表明,AG处理下桃果实在采后7 d内果实硬度均显著高于对照水平,乙烯释放量和呼吸强度均显著低于对照水平,表明抑制CuAO介导的多胺分解可显著延缓桃果实成熟。AG处理显著抑制乙烯合成、生长素转运和细胞壁降解相关基因PpACO1、PpACS、PpPIN1、PpGH3.3、PpPG和PpPME1的表达水平。为进一步明确CuAO在桃成熟中的功能,利用病毒诱导的基因沉默(VIGS)技术沉默腐胺(Put)分解关键基因PpCuAO4。结果显示,转基因桃果实PpCuAO4表达水平仅为对照的18%,Put含量和果实硬度显著高于对照水平,而乙烯释放量和呼吸强度均显著低于对照水平。上述结果表明,PpCuAO4介导的Put分解可以促进桃果实成熟。本研究为进一步深入解析多胺(polyamine)调控桃果实成熟的机制提供了重要的理论依据。     

水氮耦合供应对温室番茄果实硝酸盐累积的影响

采用2水平灌水量(W1:4541.0、W2:2270.6 m3/hm2)×3水平氮肥追施量(N1:747.4、N2:373.7及N3:0 kg/hm2),研究了不同灌溉、施氮量对日光温室番茄果实硝酸盐累积的影响。结果表明,番茄果实硝酸盐含量随果实成熟度的提高而降低、随结果部位的提高而提高。水氮耦合供应可以显著影响番茄果实中硝酸盐含量。在施氮量相同的情况下,果实硝酸盐含量随着灌水量的增加而降低;而在灌水量相同的情况下,果实硝酸盐含量随施氮量的增加而增加。     

Influence of 1-methylcyclopropene on ripening,storage life,and volatile production by d'Anjou cv. pear fruit

d'Anjou cv. pear fruit (Pyrus communis L.) exposed at harvest to 0, 0.42, 4.2, or 42 micromol m(-)(3) 1-methylcyclopropene (1-MCP) for 12 h at 20 degrees C were stored at 1 degrees C for up to 8 months. After storage, half of the fruit was continuously exposed to ethylene (0.45 or 4-18 mmol m(-)(3)) for 7 days at 20 degrees C. All fruit treated with 1-MCP had lower respiration and ethylene production compared to untreated controls. Fruit quality changes were delayed following 1-MCP treatment, as was development of superficial scald and peel yellowing. The duration of 1-MCP-induced responses was dependent on 1-MCP treatment concentration. When 1-MCP-treated fruit began to ripen, softening and production of volatile compounds proceeded similar to that of untreated fruit. Post-storage ethylene exposure did not consistently stimulate ripening of fruit previously treated with 1-MCP. Efficacy of ethylene treatment depended on 1-MCP concentration and storage duration.     

Effect of dips in a 1-methylcyclopropene-generating solution on 'Harrow Sun' plums stored under different temperature regimes

The effect of postharvest dips in a 1-methylcyclopropene-generating solution of the formulation AFxRD-038 (Rohm & Haas) on plum fruit (Prunus salicina Lindell cv. 'Harrow Sun') quality and ripening during storage was determined. Fruit weight loss, tissue firmness, soluble solids content (SSC), titratable acidity (TA), ethylene production, respiration, and the activities of the cell wall modifying enzymes polygalacturonase (PG), 1,4-beta-D-glucanase/glucosidase (EGase), beta-galactosidase (beta-gal), and pectin methylesterase (PME) were measured. Fruit reddening, anthocyanin content, and phenylalanine ammonia-lyase (PAL) activity were also analyzed. The 1-MCP-treated fruit showed reduced ethylene production and respiration rate and delayed softening, which was associated with the reduction in the activity of PG, EGase, and beta-gal. The immersion in 1-MCP-generating solutions also decreased weight and acidity loss without modifying the fruit SSC. The immersion treatment was particularly effective in the fruit stored at 5 degrees C, keeping higher overall quality, maintaining lower levels of anthocyanins and PAL activity, and preventing flesh reddening. The present data show that beneficial effects in delaying plum fruit ripening and controlling chilling injury can be obtained by dipping the fruits in a solution of this novel 1-MCP-generating formulation.