李属植物果实成熟软化研究进展

李属植物果实营养丰富,为人类提供了大量的营养物质,但是其果实采后迅速软化,导致果实品质下降、不耐贮藏及货架期短。为了解李属植物果实成熟软化的研究概况,本研究归纳总结了李属植物果实成熟过程中包括呼吸作用、乙烯释放、品质相关物质变化在内的生理变化,细胞壁结构、物质成分变化、细胞壁降解相关酶在内的细胞壁变化,果实成熟软化相关的基因及果实成熟软化蛋白质组学研究进展,并提出了存在的问题及未来研究趋势。指出目前李属植物果实成熟软化研究集中于果实采收后或贮藏期间细胞壁物质成分、结构变化及细胞壁降解相关酶,如多聚半乳糖醛酸酶、β-半乳糖苷酶等的活性变化,及这些酶的基因克隆、功能分析,指出结合转录组学、蛋白质组学、代谢组学和基因组学等几种组学将是李属植物果实成熟软化研究的发展方向。     

细胞壁分解酶与果实软化的关系研究进展

软化是影响果实采后寿命的重要因素,是果实成熟过程一系列细胞壁酶有序作用的结果。各种酶在不同种类果实成熟与软化过程的表现各有特点。本文针对细胞壁分解相关的各种酶,综述果实成熟与软化过程酶活性变化、酶基因表达的最新研究进展,并推测果实软化的分子机理。     

番茄果实成熟关键调控因子MADS-RIN的研究进展

果实的成熟过程涉及一系列的生理生化变化,如色素的积累,果实的软化、香气和风味物质的形成等。这一过程在分子层面上受到多基因形成的复杂网络的调控,由许多转录因子单独或协同调控实现。为了清晰表述LeMADS-RIN的研究进展,首先对MADS-RIN做了简要介绍,然后论证了LeMADS-RIN是番茄果实成熟过程中关键调控因子,再对LeMADS-RIN影响果实成熟过程的许多生理生化过程和代谢途径进行了详细的归纳分析,如乙烯的生物合成、糖代谢、脂类代谢、色素形成、细胞壁代谢等。之后对LeMADS-RIN的调控模式的相关研究做了系统的回顾总结,随着RIN调控因子以及调控模式研究的深入,依赖于RIN调控而影响果实成熟的网络得到了进一步完善。笔者通过约60篇文献论证了果实成熟关键调控因子LeMADS-RIN对果实成熟调控的重要意义及相关的研究进展,最后对其研究前景提出了展望。     

不同耐贮性粉果番茄贮藏期间果实软化相关酶活性的研究

以不同耐贮性的粉果番茄品种"欧盾"、"津粉207"为试材,研究在低温(10±0.2)℃贮藏期间果实硬度、乙烯释放量、细胞壁降解酶活、膜脂过氧化以及抗氧化酶活性的变化。结果表明:随着贮藏时间的延长,耐贮性强的"欧盾"品种番茄果实硬度下降较慢,乙烯释放量低,细胞壁降解酶活性、丙二醛含量、脂氧合酶(LOX)和抗氧化相关酶活性偏低;而"津粉207"品种番茄比"欧盾"品种番茄硬度下降快,乙烯释放量和丙二醛含量高,细胞壁降解酶活性、LOX和抗氧化相关酶的活性较高。     

黄果柑果实粒化与细胞壁物质及多胺的关系

为了探讨黄果柑果实粒化与细胞壁物质、多胺和果实品质的关系,以黄果柑果实为材料,研究果实粒化对果皮细胞膜透性、细胞壁物质等生理生化指标的影响。结果表明：随着黄果柑果实的成熟,粒化指数逐渐增大;果实粒化增大了果皮细胞膜透性和细胞壁物质含量,降低了（ Spm＋Spd）／Put的比值,降低了果实TSS、Vc、糖含量和可食率,对可滴定酸含量影响较小,增加了果皮厚度。研究认为：果实粒化导致果实木质化,增强了细胞壁物质的相关代谢,降低了果实品质。     

果实成熟衰老过程中软化机理研究进展

介绍了果实成熟衰老过程中呼吸作用、乙烯释放量、细胞壁超微结构和组分变化,以及与果实软化有关的细胞壁酶的活性变化。多数果实软化是由于细胞壁的破坏,细胞中的果胶溶液化,纤维素解体等。与果实软化相关较为密切的4种细胞壁酶:多聚半乳糖醛酸酶(PG)、β-半乳糖苷酶(β-Gal)、纤维素酶(Cx)和果胶甲酯酶(PME)。为深入研究果实软化机理提供参考。     

耐贮性不同番茄果实成熟过程中生理特性差异的研究

为了从普通番茄中筛选耐贮的优良育种材料,以番茄(Lycopersicon esculentum)07g-31(红果)、07g-32(粉果、F1)、07g-33(粉果、父本)、07g-34(粉果、母本)为试验材料,研究耐贮性不同的番茄果实成熟软化过程中呼吸、乙烯生理、硬度、多聚半乳糖醛酸酶及果实细胞壁超微结构的变化差异.结果表明:在耐贮性方面表现出明显优势的07g-31、07g-33果实成熟软化过程中,呼吸峰来临时间晚、强度弱,乙烯释放量低,ACC含量、ACC合成酶和ACC氧化酶的活性偏低,硬度下降较慢,多聚半乳糖醛酸酶活性较低,细胞壁及胞间层分裂缓慢、程度轻,07g-34的表现恰好相反,而07g-33、07g-34的杂交一代07g-32在以上各方面的表现介于双亲之间.     

调控果实成熟的基因工程研究进展

阐述了在果实成熟过程中与乙烯生物合成和细胞壁降解相关的酶（ACC合酶、ACC氧化酶、多聚半乳糖醛酸酶和果胶甲基酯酶）及其调控果实成熟的基因工程研究进展。     

果实软化过程中果胶降解酶及相关基因研究进展

果实软化发生在储运过程中的后熟阶段,果实中不溶性原果胶降解为可溶性果胶和果胶酸是引发该阶段果实软化的主要原因。本文介绍了果实成熟软化过程中细胞壁结构的变化,以果胶为重点描述细胞壁组分的变化;由于果胶降解过程中参与的酶种类较多,因此,重点从起关键作用的三种果胶降解酶(多聚半乳糖醛酸酶、果胶酯酶、β-半乳糖苷酶)以及相关基因表达对果实成熟软化过程的影响方面进行综述。     

番茄N-聚糖酶基因SlaPNGase1的功能分析

番茄(Solanum lycopersicum)作为新疆红色产业,对当地经济发展有重要意义。由于新疆气候特点,无霜期较短,导致番茄被集中采收。加工能力不足,番茄采摘后被搁置数天,伴随高温天气,番茄成熟过度,导致软化变质,造成严重的经济损失和资源浪费。本试验为研究N-聚糖酶基因SlaPNGase1在番茄果实成熟软化过程中的潜在生物学功能,以加工番茄‘里格87-5’为材料,克隆到番茄N-聚糖酶基因SlaPNGase1(Solyc06g051020)及其上游2 220 bp的启动子序列。通过生物信息学初步分析,发现SlaPNGase1含有信号肽序列,不含有跨膜结构域,该启动子中含有多个与果实成熟应答相关的顺式作用元件。通过实时定量PCR检测SlaPNGase1在番茄幼苗根、茎、叶,开花后5 d幼果(DPA5),成熟绿果(DPA33),成熟红果(DPA52)中的转录表达水平(day post-anthesis, DPA)。结果显示,SlaPNGase1在番茄成熟红果中的表达水平最高。构建启动子活性分析载体prPNG1::GUS,对T1代转基因番茄果实进行GUS染色,结果表明,SlaPNGase...     

果实成熟软化机理研究进展

果实在采收后仍然是活的有机体，在贮藏过程中会发生不断的软化现象。果实的成熟软化是一个非常复杂的发育调控过程，其间经历了一系列生理生化的变化，包括细胞壁的降解、内含物的变化、呼吸速率以及其他的代谢变化。本文就果实成熟软化方面的进展进行了综述，介绍了与果实成熟软化过程相关的胞壁酶(多聚半乳糖醛酸酶、果胶酯酶、木葡聚糖内糖基转移酶、纤维素酶、糖苷酶等)、胞膜酶(脂氧合酶)、胞内酶(淀粉酶和蔗糖酶)以及植物激素(乙烯、生长素、细胞分裂素、赤霉素、脱落酸)等在果实成熟软化过程中含量的变化和作用，并对软化机理进行了探讨。综合表明，果实的成熟软化过程受多种酶、植物激素等因素的影响，各种酶活性的变化情况及植物激素的作用在不同种类、不同品种果实中表现不同。果实成熟软化机理的探讨为果实的贮藏、保鲜及加工提供了理论依据，具有现实的意义。     

番茄果实成熟相关基因SlPEL和SlAPL的表达特性

分析27个代表番茄不同发育阶段和生物反应的组织特异性、含有152 635个独立EST数据库的数码表达,发现果胶裂解酶基因 (pectate lyase, SlPEL) 和番茄AP2 Like (SlAPL)的转录受果实成熟的调节。以授粉后不同发育时期的番茄(品种为美味樱桃)果实为试材, 用半定量PCR和荧光实时定量PCR分析SlPEL的表达模式,结果表明,授粉后12 d,其表达水平明显上升;授粉后16~18 d,达到第一个小高峰;28 d到最高峰;从28 d到完全成熟逐步下降到第一个小高峰的水平。SlAPL的表达模式与SlPEL类似,但其表达启动的时期迟于SlPEL。从授粉后25 d,SlAPL转录启动;授粉后28~32 d,其转录水平上升到第一个小高峰;39 d达到最高峰,以后到完全成熟略有下降。该研究也印证利用EST的数据库进行基因数码表达分析的可行性。     

含迟熟基因rin的番茄果实货架寿命相关性状的研究

分析比较了贮藏过程中的番茄成熟突变体rin材料L2与正常成熟番茄品种L5及其杂种一代L20果实的果实硬度、呼吸强度、番茄红素、贮藏指数及各种商品品质的差异。结果表明:番茄果实贮藏过程中果实硬度呈下降趋势;而果实的可溶性固形物、可溶性糖、Vc、番茄红素含量变化呈上升趋势,但是有机酸含量变化总体上呈现下降趋势,因此果实的糖酸比呈上升趋势;呼吸高峰的出现有很大的差异,L2的波动较小,且呼吸强度一直处于最低状态;rin番茄果实的贮藏指数最高,达到75%以上,而正常成熟的番茄贮藏指数最低,仅60%左右,含迟熟基因的品种与正常品种杂交后贮藏性显著下降,但比正常成熟番茄耐贮,贮藏指数比正常成熟的高约15%。     

Cell wall disassembly during papaya softening: Role of ethylene in changes in composition,pectin-derived oligomers (PDOs) production and wall hydrolases

Cell wall disassembly in ripening climacteric fruit is a highly complex process where ethylene plays a crucial role. Ethylene inhibitors can be used to explore the changes in the cell wall matrix and cross-linked polysaccharides in ethylene-regulated processes. The results of applying the ethylene receptor blocking inhibitor 1-methylcyclopropene (1-MCP) and the ethylene-releasing compound ethephon (2-chloroethylphosphonic acid) indicate that softening of ‘Maradol’ papaya fruit is dependent on ethylene. When fruit were induced to ripen extensively by exposure to a high dose of ethephon, 1-MCP inhibited the subsequent softening dramatically, but when inhibition of the ethylene response was caused by application of 1-MCP, subsequent fruit treatment with ethephon promoted extensive loss of galactose from the water-soluble polysaccharides, but this was not accompanied by fruit softening. The cell wall changes accompanying normal fruit softening were pectin solubilization and polyuronide depolymerization and these processes occurred simultaneously. Polygalacturonase likely is responsible for the ripening-associated changes in ‘Maradol’ papaya fruit texture and pectin polymer integrity. An increase in extractable fruit polygalacturonase follows the increased presence of pectin-derived oligosaccharides.     

Changes in activities of cell wall hydrolases during ethylene-induced ripening in banana: effect of 1-MCP,ABA and IAA

Softening during ripening in climacteric fruit is generally attributed to degradation in cell wall assembly, particularly the solublization of pectin. These changes could involve increased activities of various cell wall hydrolases. Their activity is believed to be regulated by ripening-related hormones and/or other signal molecules. Activities of pectin methyl esterase (PME), polygalacturonase (PG), pectate lyase (PL) and cellulase in banana cv. dwarf cavendish fruit were measured over a period of 7 days after ripening was initiated with ethylene. Effects of treatments with 1-methylcyclopropene (1-MCP), abscisic acid (ABA) and indole acetic acid (IAA) on activities of these hydrolases were measured in order to help elucidate their roles during banana ripening. Ethylene stimulated activities of all four enzymes, at best differentially. 1-MCP and IAA suppressed the ethylene effects. ABA stimulated activities of all hydrolases except polygalacturonase. ABA stimulation was most evident for pectate lyase. Thus ethylene plays a major role in up-regulating the activities of various cell wall hydrolases. In contrast IAA suppresses their activity. ABA can enhance softening with or without ethylene.     

Patterns of enzymatic activity of cell wall-modifying enzymes during growth and ripening of apples

Fruit softening is thought to result from extensive cell wall modifications that occur during ripening. These modifications are the result, at least in part, of the activity of members of cell wall-modifying enzymes from the same families involved in the cell wall loosening which promote tissue extension and growth. In this work, the activities of a set of pectolytic and non-pectolytic cell wall-modifying enzymes, namely polygalacturonase (PG; endo-and exo-acting), pectin methylesterase (PME), pectate lyase (PL), β-galactosidase (β-Gal), α-l-arabinofuranosidase (AFase), endo-1,4-β-glucanase (EGase), xyloglucan endotransglycosylase (XET) and expansin, were monitored during growth and ripening of ‘Mondial Gala’ apple (Malus × domestica Borkh.) fruit. After optimisation of protein extraction protocols and standard activity assays, activity could be detected in all the assays, except for endo-PG. The overall results suggest that fruit growth and ripening are possibly coordinated by members of the same families of cell wall-modifying enzymes, although different isoforms may be involved in distinct developmental processes. Based on the trend of total activity measured in vitro using equal amounts of protein per developmental stage, the role of EGase seems to be more prominent during growth than during ripening, and XET activity is most important only after the fruit stopped growing and is maintained throughout ripening. β-Gal and AFase activities increased after harvest as the fruit became over-ripe. On the other hand, exo-PG, PL and expansin activities increase from that in unripe fruit to fruit at harvest but are maintained at similar levels thereafter, throughout the over-ripe stages. The patterns of activity observed are discussed in relation to published information about ripening of apples and to results reported using other species.     

1-MCP对采后‘红心’番石榴果实软化的影响

为了从细胞壁代谢角度研究1-甲基环丙烯(1-MCP)调控采后番石榴果实软化的机制,用1 μL/L 1-MCP处理‘红心’番石榴果实试材。通过测定果实的硬度、细胞壁代谢相关物质及相关酶活性的变化,研究1-MCP处理对常温(25±1℃)贮藏下番石榴果实软化的抑制作用。结果表明,1 μL/L 1-MCP处理使采后番石榴果实的硬度比对照组果实高0.51倍,并有效抑制多聚半乳糖醛酸酶、果胶甲酯酶、纤维素酶、β-葡萄糖苷酶、α-淀粉酶和β-淀粉酶的活性,减缓可溶性果胶、葡萄糖含量的增加,延缓原果胶、纤维素和淀粉含量在采后贮藏期间的下降。因此,1 μL/L 1-MCP处理能有效延缓采后‘红心’番石榴的软化进程,延长其采后贮运保鲜期。