钙处理对采后猕猴桃果实生理生化的影响

对采收后的猕猴桃果实采用不同的钙处理,然后测定其软化衰老过程中糖类含量的动态变化情况,结果表明:猕猴桃果实成熟时,其果糖含量由采后第20天的15.5μg.mg-1增加到第80天的26.5μg.mg-1;而经过浸钙处理的猕猴桃果实,其果糖含量比对照的低,这说明浸钙处理能够抑制其果实的软化衰老,从而能延长果实的贮藏期。     

猕猴桃园套种蕺菜对土壤养分、酶活性及果实品质的影响

为了提高猕猴桃果实产量与品质,在猕猴桃园以套种蕺菜、清耕和对照作为试验处理,测定不同时期猕猴桃根际土壤养分含量、微生物数量、酶活性和果实产量及品质,分析其相关性。结果表明:套种蕺菜后猕猴桃根际土壤碱解氮、速效磷、速效钾含量分别比对照处理提高13.95%、7.92%和3.94%,土壤细菌、真菌、放线菌数量分别提高19.01%、28.89%和16.32%,土壤过氧化氢酶、脲酶、蔗糖酶、磷酸酶活性分别提高17.02%、12.63%、17.57%和7.98%,单果质量和单位面积产量分别提高7.14%和7.68%,维生素C、干物质、可溶性固形物、可溶性总糖和可滴定酸含量分别提高7.97%、18.29%、2.09%、12.37%和14.18%。相关性分析结果表明,套种蕺菜后猕猴桃根际土壤速效钾含量与土壤中细菌数量、真菌数量、放线菌数量、脲酶活性、蔗糖酶活性、磷酸酶活性极显著正相关。土壤细菌数量与蔗糖酶活性显著正相关,与磷酸酶活性极显著正相关。土壤真菌数量与蔗糖酶活性极显著正相关。土壤放线菌数量与蔗糖酶活性、磷酸酶活性显著正相关。土壤速效磷含量与维生素C含量、可滴定酸含量极显著负相关,与干物质含量、可溶性固形物含量和可溶性总糖含量极显著正相关。土壤细菌数量、放线菌数量与维生素C含量极显著负相关。土壤真菌数量与维生素C含量显著负相关。土壤脲酶活性与干物质含量显著正相关,与可滴定酸含量显著负相关。维生素C含量与土壤蔗糖酶活性极显著负相关,与土壤磷酸酶活性显著负相关。套种蕺菜有利于提高猕猴桃根际土壤养分含量、微生物数量和酶活性,增加猕猴桃果实产量,改善猕猴桃果实品质。     

同果实软化有关的酶类研究进展

果实软化一直是采后生理研究的重要内容,果实软化同纤维素酶、多半乳糖醛酸酶、果胶甲酯酶和β-半乳糖苷酶的活性变化密切相关。该文综述了同果实软化有关的酶类在果实成熟衰老和软化过程中的变化规律,为控制果实采后软化提供理论依据。     

软枣猕猴桃果实软化特性研究

为了探讨软枣猕猴桃[Actinidia arguta(Sieb.et Zucc.)Planch.Ex Miquel]果实软化特性,以软枣猕猴桃果实为试材,测定了果实软化各个阶段的品质、呼吸率、乙烯发生量、淀粉含量、细胞壁成分变化以及果实软化阶段果胶和半纤维素分子大小变化。结果表明,软枣猕猴桃果实软化过程中硬度迅速下降、可溶性固形物含量迅速增加和可滴定酸含量下降明显。在果实软化前期淀粉降解迅速,呼吸高峰出现,乙烯发生量增加,半纤维素降解明显;而果实软化后期果胶和纤维素降解明显。初步认为软枣猕猴桃果实软化是淀粉降解、乙烯和果胶酶等多种因素共同作用的结果。     

蓝莓果实同化物韧皮部卸载路径与糖代谢酶活性

【目的】韧皮部卸载和韧皮部后运输在调节蔗糖在库器官间的分配、维持果实的库强方面起着至关重要的作用,而且很大程度上决定着果实的产量和质量。本文研究目的是明确蓝莓同化物韧皮部卸载的机制与糖代谢机制。【方法】以5年生高丛蓝莓品种‘喜来’(‘Sierra’)为研究对象,对各个发育时期的蓝莓果实韧皮部的超微结构进行观察,并综合运用荧光染料活细胞示踪与激光共聚焦扫描显微镜技术实时观察果实内韧皮部同化物卸载路径,运用高效液相色谱等技术,测定分析蓝莓果实可溶性糖含量及相关代谢酶的活性变化等。【结果】对韧皮部细胞进行的超微结构观察显示,在蓝莓果实整个发育期,果实韧皮部SE/CC(筛管伴胞复合体)与周围薄壁细胞之间均未发现胞间连丝,从而形成了共质体隔离,但在薄壁细胞之间、薄壁细胞与果肉细胞之间存在大量胞间连丝。荧光染料CF[5(6)-羧基荧光素]的活细胞示踪试验表明,果实发育过程中,CF均被严格限制在韧皮部中,没有扩散到周围的薄壁细胞。这些结果证实蓝莓果实同化物以质外体卸载途径为主,韧皮部后运输存在着活跃的共质体途径,大量胞间连丝的存在有利于薄壁细胞之间以及薄壁细胞与果肉细胞之间的物质交换。进一步酶活性测定结果显示,在蓝莓果实的整个发育期,转化酶活性保持在较高水平,为证实蓝莓果实同化物以质外体卸载为主提供了证据。对糖代谢相关酶活性分析显示,在果实发育的各个阶段,蓝莓果实的可溶性糖主要以积累果糖和葡萄糖为主,蔗糖酶的分解活性始终大于合成活性;在果实发育中后期,可溶性酸性转化酶和中性转化酶活性进一步升高,显示果实发育后期果肉细胞内进行着活跃的蔗糖分解、转化及贮藏过程,且糖积累与转化酶、蔗糖合酶和蔗糖磷酸合酶等酶活性成正相关。在蓝莓果实发育过程中,蔗糖代谢相关酶的综合作用是影响蓝莓果实中可溶性糖积累的重要因子。【结论】蓝莓果实同化物以质外体卸载途径为主,韧皮部后运输存在着活跃的共质体途径。蓝莓果实主要以积累果糖和葡萄糖为主,且糖积累与转化酶、蔗糖合酶和蔗糖磷酸合酶等酶活性成正相关。     

浅析猕猴桃果实贮藏条件及方法

一、猕猴桃贮藏保鲜的条件 （一）对果实质量的要求。用于长期贮藏的猕猴桃一定要在生理成熟阶段采收,过早或过晚都不利于贮藏。关键是要做到适时采收,且不造成任何机械伤。受伤的果实呼吸增加,淀粉酶、乙烯形成酶、多聚半乳糖醛酸酶和纤维素酶活性也明显增加,则加速多糖类物质的水解,导致果实迅速软化。而且,受伤部位易引起微生物侵染。此外,采后的果实要及时运往贮藏场所,尽快进入适宜温度贮藏。     

李果实发育过程中糖含量变化与糖代谢相关酶的关系

以‘龙园蜜李’为研究对象,运用分光光度计法,研究李子生长过程中糖含量和糖代谢相关酶含量的变化,通过对其相关性分析,发现：李子在坐果初期,转化酶活性旺盛,蔗糖含量较低,随着果实生长发育,转化酶活性逐渐下降,蔗糖合成酶和蔗糖磷酸合成酶活性升高,蔗糖含量逐渐上升。相关性分析得出,蔗糖含量与蔗糖合成酶和蔗糖磷酸合成酶活性呈现极显著和显著正相关性,而与转化酶活性呈现显著负相关性。     

果实软化过程中细胞壁结构和组分及细胞壁酶的变化

概述了果实软化过程中细胞壁结构和组分及细胞壁酶的变化。多数果实软化是由于多聚半乳糖醛酸酶、纤维素酶、果胶甲酯酶和β-半乳糖苷酶等细胞壁酶降解细胞壁物质,使细胞壁结构和组分发生变化,进而引起果实软化。不同的研究结果提示果实软化也有其他因子参与,加强果实生理生化基础研究尤为重要。     

油柿果实成熟过程中生理指标的变化规律

[目的]探讨油柿果实成熟过程中生理指标的变化规律,为油柿资源的深入开发利用提供理论依据.[方法]以不同时期油柿果实为试材,测定成熟过程中单宁、总酚、黄酮、可溶性糖、果糖、葡萄糖、蔗糖、果胶含量以及半乳糖醛酸酶(PG)、果胶裂解酶(PL)和果胶甲酯酶(PME)活性的变化规律,并分析其相关性.[结果]油柿果实成熟软化过程中...     

猕猴桃塑料棚播芽育苗试验

<正> 猕猴桃,又名糖子,是多年生攀缘性藤本植物。其果实酸甜适口,含有糖类、维生素类、蛋白质及无机盐类,营养丰富,是延年益寿的佳品。近年来研究还发现其果和根有抗癌作用。据此,引起了国内外有关人员的高度重视。 猕猴桃一般多采用种子育苗,为了加快猕猴桃资源的开发利用,近年来有关单位也     

铁皮石斛可溶性糖含量与蔗糖代谢酶活性的相关性研究

通过对F型及H型铁皮石斛不同时期可溶性糖含量与蔗糖代谢酶活性的测定,并对其相关性进行分析,分析了可溶性糖的合成与蔗糖代谢酶活性间的关系。结果表明,移栽后F型和H型铁皮石斛叶片中蔗糖磷酸合成酶的活性与季节性变化趋势一致,但F型较H型高;蔗糖降解酶与可溶性糖含量及其还原糖间存在相关关系,达到显著水平。对可溶性糖和相关因子进行偏相关分析和通径分析可知,还原糖的直接通径系数最大为1.015,酸性转化酶的直接通径系数为负值(-0.356),与可溶性糖呈负相关关系,4个因子对可溶性糖含量的直接作用大小顺序为还原糖>酸性转化酶>中性转化酶>蔗糖。     

Sucrose metabolic pathways in sweetgum and pecan seedlings

Sucrose metabolism and glycolysis were studied in one- to two-year-old seedlings of sweetgum (Liquidambar styraciflua L.) and pecan (Curya illinoinensis (Wangenh.) C. Koch). The sucrose synthase pathway was identified as the dominant sucrose metabolic activity in sucrose sink tissues such as terminal buds and the root cambial zone. The sucrose synthase pathway was completely dependent on uridine diphosphate and pyrophosphate and it was activated by fructose 2,6-bisphosphate. Both acid and neutral invertases were less active than sucrose synthase in sucrose sink tissues. According to the magnitude of seasonal changes in activity, sucrose synthase, the pyrophosphate-dependent phosphofructokinase, and fructokinase were identified as adaptive enzymes, whereas neutral invertase, uridine diphosphate-glucopyrophosphorylase, phosphoglucomutase, and the nonspecific, nucleotide triphosphate-dependent phosphofructokinase were identified as maintenance enzymes. The periodically high activities of pyrophosphate-dependent phosphofructokinase indicate that pyrophosphate can serve as an energy source in trees. The observations support the hypothesis that sucrose glycolysis and gluconeogenesis in plants proceed by a network of alternative enzymes and substrates.     

Carbohydrate metabolism of vegetative and reproductive sinks in the late-maturing peach cultivar 'Encore'

Activities of NAD(+)-dependent sorbitol dehydrogenase (SDH), sorbitol oxidase (SOX), sucrose synthase (SS), acid invertase (AI), and neutral invertase (NI) in 'Encore' peach (Prunus persica L.) fruits and developing shoot tips were assayed during the growing season to determine whether carbohydrate metabolizing enzymes could serve as indicators of sink strength. In fruit flesh, SS activity was detected during Stage I of growth, when cells were actively dividing, and SDH activity was detected during Stage III, when cells were actively enlarging. Acid invertase activity was detected during Stage I and showed a closer correlation with relative increase in fruit weight during the growing season than SS activity. During seed filling and pit hardening (Stage II), when relative fruit growth rate was slowest, activities of carbohydrate metabolizing enzymes in fruit flesh were not detectable. No SOX activity was detected during Stages I and II. The highest sucrose content occurred near the end of fruit development when the activities of sucrose metabolizing enzymes were low. In developing shoot tips, the sorbitol:sucrose ratio was 2:1 (w/w) and SDH activity was low at the beginning and end of the season when vegetative growth was slowest. The sorbitol:sucrose ratio changed to 1:1 (w/w) along with an increase in SDH activity in shoot tips during the mid-growing season. In 'Nemaguard' peach, SDH exhibited higher activity in root tips than in other organs. Among the sorbitol- and sucrose-metabolizing enzyme activities, only SDH activity was positively correlated with shoot growth in 'Nemaguard' plants.     

模拟CO2浓度升高对宁夏枸杞营养生长与果实品质的影响

【目的】研究宁夏枸杞对大气CO2浓度升高的生理生态响应机制,为探究枸杞及其他木本经济林植物在气候变化背景下优质高效栽培与育种提供理论依据。【方法】以‘宁杞1号’扦插苗为材料,采用开顶气室(open-top chamber,OTC)及自动监控系统模拟控制CO2浓度,测定宁夏枸杞在升高CO2浓度环境下植株营养生长指标与果实糖分含量、主要活性物质含量和蔗糖代谢相关酶活性的变化。【结果】 1) CO2浓度升高,促进宁夏枸杞植株生长发育,苗高增长量较对照分别高11.67%和18.65%,地径分别高55.09%和62.58%,新梢加长和加粗生长均呈增加趋势。2) 2种CO2浓度升高处理下,宁夏枸杞果实横径较对照分别增加4.56%和7.71%,单果质量分别增加15.05%和34.53%,果实更加饱满。3) CO2浓度升高处理下,夏果(处理90天左右)果实中果糖含量较对照略高,秋果(处理120天后)含量比对照分别低1.39%和3.98%。试验处理期间,果实中葡萄糖和总糖含量均低于对照,且CO2浓度升高1倍[(760±20)μmol·mol^-1 ]处理下降最为明显。夏果果实蔗糖含量均低于对照,秋果在CO2浓度升高1倍[(760±20)μmol·mol^-1 ]下较对照略高。4)果实中枸杞多糖含量低于对照,黄酮含量在秋果期比对照分别低16.62%和18.35%,且CO2浓度升高1倍[(760±20)μmol·mol^-1 ]处理对果实活性物质含量影响较大。5) CO2浓度升高增加了酸性转化酶和中性转化酶活性;夏果蔗糖磷酸合成酶较对照明显增加,但秋果酶活性低于对照;蔗糖合成酶分解方向与合成方向酶活性变化趋势相同,夏果均高于对照,秋果酶活性低于对照,CO2浓度升高1倍[(760±20)μmol·mol^-1 ]处理下差异极显著。【结论】长期高CO2浓度处理促进宁夏枸杞植株营养生长,果实单果质量与纵横径增大,有利于改善果实外观品质;但果实中糖分含量和枸杞多糖、黄酮等生物活性物质的含量明显降低,相关酶活性发生变化,影响果实营养品质。     

Vascular cambial sucrose metabolism and growth in loblolly pine (Pinus taeda L.) in relation to transplanting stress

Sucrose synthase (SS) was the dominant enzyme of sucrose metabolism in both stem and root vascular cambial zone tissues of nursery-grown loblolly pine (Pinus taeda L.) seedlings. Acid invertase (AI) and neutral invertase (NT) activities were generally less than 10% of the SS activity in both tissues. In both cambial tissues, seasonal patterns of enzyme activity were observed for SS but not for AI or NI. The seasonal patterns of SS activity in stem and root cambia paralleled the periodic growth of stems and roots. Stems had high SS activity and growth during summer and early fall. Roots had substantial SS activity and growth during summer and fall, but SS activity and growth were even higher in winter. When seedlings were transplanted, about eight months elapsed before stem and root cambia resumed rates of growth and sucrose metabolism similar to those in control nontransplanted seedlings. Two months after transplanting, root SS was at its lowest, whereas AI activity in transplants was 50% higher than in control nontransplanted seedlings. In stems, SS activity decreased in response to transplanting, whereas AI and NI activities did not change appreciably. In loblolly pine tissues, SS was specific for uridylates, whereas the nucleotide triphosphate-dependent phosphofructokinase (NTP-PFK) had similar activity with either UTP or ATP. Except in winter, the NTP-PFK was less active than the pyrophosphate-dependent phosphofructokinase (PPi-PFK) during all seasons. The PPi-dependent PFK activity in nontransplanted seedlings followed similar seasonal and spatial patterns to those of SS activity. In actively growing tissues, such as stem cambial tissues in summer and root cambial tissues in winter, the measured total PFK to SS ratio ranged between 1.5/1 and 3/1. In contrast, in less actively growing tissues or transplanted seedlings, a greater decrease occurred in SS than in PFK activity, hence the ratio rose to as high as 12/1. It was concluded that: (1) SS was the dominant enzyme for sucrose metabolism in root and stem cambial tissues of loblolly pine seedlings; (2) both SS and PPi-PFK in the cambial tissues can be used as biochemical indicators of growth sink strength in stems and roots; and (3) both enzymes can be used as indicators of seedling stress caused by events such as transplanting and winter freezing.     

Formation of callose from sucrose in cotton fiber microsomal membranes

Callose is formed from exogenous sucrose by cotton fiber microsomal membranes that contain both sucrose synthase and callose synthase activity. Although the coupled reaction between sucrose and callose synthases occurs predominantly to channel glucose from sucrosederived uridine diphosphate (UDP)-glucose into callose in the membranes, there is no difference in the UDP-glucose-forming/sucrose-forming activity ratios between the soluble and membrane-bound forms of sucrose synthase. The consumption of UDP-glucose from sucrose into callose probably leads to UDP-glucose formation rather than sucrose formation despite the lower affinity of sucrose synthase for sucrose than for UDP-glucose. Callose formation is markedly stimulated by the addition of either recombinant Glu¹¹ (S11E) or in vitro phosphorylated Ser¹¹ mung bean sucrose synthase but not by the wild-type nonphosphorylated Ser¹¹ enzyme. We propose that a negative charge (by phosphorylation or mutagenesis) at Ser¹¹ in sucrose synthase causes the enzyme to promote a coupled callose-forming reaction.Part of this paper was presented at the 8th International Cell Wall Meeting, Norwich, UK, September 1998     

Leaf responses of micropropagated apple plants to water stress: nonstructural carbohydrate composition and regulatory role of metabolic enzymes

We examined changes in nonstructural carbohydrate biosynthesis and activities of related enzymes in leaves of micropropagated apple plants (Malus domestica Borkh. cv. 'NaganoFuji') in response to water stress, with particular emphasis on the enzymes associated with sorbitol, sucrose and starch metabolism. Water stress resulted in the accumulation of photosynthates in leaves, mainly sorbitol, sucrose, glucose and fructose, accompanied by a reduction in starch concentration. Correlation and path analysis indicated that water stress affected the partitioning of newly fixed carbon among terminal products. In response to water stress, ADP-glucose-pyrophosphorylase (ADPGPPase) activity decreased, becoming a critical and limiting step in shifting partitioning of photosynthetically fixed carbon. Amylase and ADPGPPase affected sucrose and sorbitol metabolism, mainly by regulating substrate supply; however, competition for limited substrate had a greater effect on the biosynthesis of sorbitol than of sucrose. Starch metabolism was also strictly regulated by ADPGPPase and amylase, whereas other related enzymes were downstream of the pathway for synthesis and degradation of carbohydrates and thus had relatively little effect on starch metabolism. Sorbitol dehydrogenase and sucrose phosphate synthase were critical regulators of sorbitol and sucrose metabolism, respectively.     

Variations in sucrose and ABA concentrations are concomitant with heteroblastic leaf shape changes in a rhythmically growing species (Quercus robur)

In rhythmically growing woody species such as common oak (Quercus robur L.), stem growth is discontinuous and a bud forms at regular intervals at the shoot apex. These buds are composed of different types of leaves: laminate, aborted lamina and scale. The change in heteroblastic leaf shape from laminate to aborted lamina leaves is regarded as one of the events marking shoot growth arrest. To better understand the determinism of heteroblastic leaf shape change and thus, of rhythmicity, we studied morphogenetic events during the early days of the second flush of growth in oak, as well as changes in sucrose metabolism and abscisic acid (ABA) concentrations in control plants expressing the heteroblastic leaf shape change and in defoliated plants showing no heteroblastic leaf shape change and producing only laminate leaves. In control plants, the leaf shape change was underway on Day 5 of the second flush with the differentiation of the first two aborted lamina leaves. Sucrose concentration in the apices of control plants decreased between Days 3 and 5 during differentiation of the aborted lamina leaves. An inverse pattern was observed in defoliated plants, suggesting that sucrose acts as a signal triggering heteroblastic leaf shape changes. During the same period, acid cell wall invertase activity was high in young stem and laminate leaves of control plants, whereas the activity remained constant and low in the apices. If the laminate leaves were removed, the increase in apical sucrose concentration was proportionally higher than the decrease in apical acid vacuolar invertase activity, suggesting that, in the absence of young leaves, sucrose is imported to the apex. The sucrose concentration in the apex is therefore likely to be affected by trophic competition with the expanding laminate leaves. The decrease in apex sucrose concentration may be one of the mechanisms driving heteroblastic leaf shape change. Differentiation of aborted lamina leaves was followed by a decrease in the organogenic activity of the shoot apical meristem (SAM) between Days 7 and 9. High concentrations of ABA are associated with differentiation of aborted lamina and scale leaves and with low SAM organogenic activity. Shoot apical meristem organogenic activity remained high and ABA concentration in the apex remained low in defoliated plants producing only photosynthetic leaves. These results suggest that (1) ABA is involved in the gradual conversion of embryonic leaves to abnormal leaves, thereby regulating heteroblastic leaf shape changes and (2) changes in ABA concentration influence the intensity of SAM organogenic activity. Heteroblastic development and therefore rhythmic growth could be the result of competition between apices and laminate leaves, with competition first involving sucrose and thereafter ABA.     

桉树人工林与其它林地土壤酶活性的差异分析

研究了桉树萌生林、桉树植苗林、灌草丛和马尾松林地土壤中过氧化氢酶、蔗糖转化酶及脲酶的活性变化。结果表明：桉树萌生林、桉树植苗林与灌草丛、马尾松林地土壤中3种酶活性的差异不显著,说明栽植桉树对林地土壤酶活性没有显著影响。