欧李果实发育期糖和酸组分及其含量的动态变化特性

以农大3号、农大4号、农大5号3个欧李品种为材料,测定果实发育过程中各组分糖、酸及总糖、总酸的含量,以明确欧李果实糖酸积累的动态变化特性.结果显示:(1)3个欧李品种果实成熟期糖含量、酸含量及糖酸比存在明显差异,其中农大3号品种的总糖含量最高,总酸含量最低,糖酸比值最高.(2)成熟期3品种各糖组分中均以果糖含量较高,葡萄糖和蔗糖含量较低,山梨醇含量微量;酸组分中均以苹果酸为主,柠檬酸少量.(3)3个品种果糖、蔗糖、葡萄糖、山梨醇含量在整个果实发育期均呈持续增加态势,并以果糖积累为主;农大3号果糖含量在8周后增幅明显高于另2个品种,且一直保持到果实成熟;3个品种蔗糖含量的变化趋势相近,在前期和中期增加缓慢,接近成熟的2～3周则迅速增加并占整个发育期积累量的70%以上.(4)3个品种酸含量的变化趋势较为相似,苹果酸和柠檬酸在果实发育的前期和中期含量均较低,在果实发育后期迅速增加,但接近果实成熟时又大幅下降.研究表明,果糖与苹果酸的含量及其动态变化是影响欧李果实糖酸比、决定果实风味的主要因素.     

果实成熟的味感变化及其生理生化基础

果实成熟是指果实在生长末期经过一系列生理生化变化而达到食用品质的最佳状态的过程。在此过程中 ,果皮的颜色、果实的味感和硬度等均产生变化。其中 ,味感变化尤为明显和重要。1　甜度增加许多果实未成熟时 ,往往没有甜味或甜味较淡。随着成熟过程的进展 ,甜度才逐渐增加。果实中所含的糖类主要包括贮藏性糖和结构性糖两大类。贮藏性糖主要是可溶性糖 (如蔗糖、葡萄糖和果糖 )和淀粉。结构性糖主要是构成果实细胞壁的果胶类物质。在果实成熟中 ,淀粉可转化为可溶性糖 ,从而使甜度增加。例如香蕉 ,未成熟时淀粉含量占果实重量的 2 0 %～ 2 …     

苹果果实发育期间细胞壁组分变化特性

以 '富士'、'国光'、'红星'、'金冠'和'嘎拉'5个苹果品种为试材,分析了果实发育成熟过程细胞壁物质(CWM)、水溶性果胶(WSP)、共价结合果胶(CSP)、离子结合果胶(ISP)、纤维素及半纤维素各组分变化.结果表明:在苹果果实发育过程中,5个品种果实CWM含量变化均呈先升后降的变化规律,均以果实膨大期为其含量下降的转折点;果实总果胶含量均呈不断降低的趋势,其中CSP为主导成分,'富士'和'国光'果实CSP含量最高,WSP含量最低,'嘎拉'与'红星'果实3种果胶含量变化居中,'金冠'果实总果胶含量最低且变化小,但在近成熟期'红星'和'金冠'果实WSP呈明显的上升趋势.果实半纤维素含量也具相似的变化规律,'国光'、'富士'和'金冠'等3个品种的高峰值显著高于'嘎拉'和'红星';比较5个品种纤维素含量,'国光'果实在成熟期之前显著高于其他4品种,而其他4品种的纤维素含量变化比较平稳.     

香蕉果实成熟软化过程中细胞壁物质的变化

系统研究了香蕉果实软化过程中细胞壁物质―醇不溶性固形物(AIS)以及3种不同性质的果胶物质:水溶性果胶(WSP)、酸溶性果胶(HP)和碱溶性果胶(OHP)含量的变化。结果表明:随果实的成熟软化,AIS的含量不断降低,且在呼吸跃变时急剧降低;WSP的含量不断增加,HP和OHP的含量不断减少,且均表现出在早期变化量少,在果实硬度迅速降低时变化明显。该研究进一步证明细胞壁物质的变化是导致香蕉果实软化的主要原因。     

杨梅果实发育进程中的碳水化合物代谢

以‘乌紫’和‘荸荠’两个杨梅品种为试材,测定了干鲜重、糖含量、可滴定酸含量、蔗糖和己糖代谢相关酶活性的动态变化。结果表明,杨梅果实的干鲜重、含糖量的快速增长和可滴定酸含量的快速下降均发生在果实发育后期。成熟‘乌紫’杨梅果实的蔗糖含量约占总糖的2／3以上,而‘荸荠’杨梅仅为总糖的49％。‘荸荠’杨梅的转化酶和蔗糖合酶分解活性随着果实发育呈上升趋势,‘乌紫’杨梅的则变化不大。两个品种的蔗糖磷酸合酶活性随着果实发育呈上升趋势,但蔗糖合酶合成活性到果实发育中期后下降。两个品种的己糖激酶活性变化相似,但果糖激酶活性的变化趋势不同。     

刺梨果实膳食纤维积累动态及其对遮光的反应

刺梨果实是优质膳食纤维的良好来源。该研究以‘贵农5号’刺梨果实为材料,测定了果实发育过程中膳食纤维的含量、组分变化及其对光照的响应特征。结果表明:(1)在刺梨果实的整个发育过程中,总膳食纤维和不溶性膳食纤维含量在花后40 d之前的幼果期更高,并随着果实的快速发育持续下降,至成熟时分别约占果实干重的24%和16%,而可溶性膳食纤维含量在果实发育过程中变化平稳,一直维持在干重的8%左右。(2)果胶在花后20 d之前有一快速积累过程,至果实成熟时纤维素和半纤维素为膳食纤维主要组分,约占总膳食纤维的60%;花后60 d之前是刺梨果实膳食纤维积累的主要时期。(3)刺梨果实总膳食纤维、不溶性膳食纤维中单糖组分主要以半乳糖、葡萄糖为主,而可溶性膳食纤维中单糖组分主要为甘露糖,两类膳食纤维间表现出较大差异。(4)果实套袋遮光不同程度促进了刺梨果实总膳食纤维、可溶性膳食纤维、总果胶、原果胶的积累,尤其是100%遮光的效应更明显,但对果实中不溶性膳食纤维、纤维素、木质素、可溶性果胶的积累影响并不显著。     

膨大期果面喷施IAA对桃成熟期果实性状和相关基因表达的影响北大核心CSCD

为明确桃果实发育后期外源生长素对果实成熟的影响及更深入的认识生长素调控果实发育与成熟的机制,本研究以桃品种‘小白凤’为试材,采用不同浓度的外源IAA(200,10,0.1μmol/L)喷施第2次快速膨大期的桃果实,在处理后10,20,30 d分别取样,分析桃果实的硬度,糖组分(蔗糖、葡萄糖、果糖、山梨醇),果胶,纤维素含量以及乙烯释放量的变化,并对200μmol/LIAA处理后30 d及对照组的果实进行了转录组测序分析,深入认识生长素调控桃果实成熟的作用和机理。结果表明,(1)IAA处理后30 d时,200μmol/L处理组桃果实果肉硬度与对照组相比显著增加,成熟期平均延迟5 d,而10,0.1μmol/LIAA处理组与同期对照组间无显著差异。(2)果肉蔗糖含量在0.1,200μmol/LIAA处理后30 d显著低于同期对照组,在10μmol/LIAA处理后30 d时与对照组无显著差异;葡萄糖、果糖和山梨醇含量在各浓度IAA处理后30 d时多与对照组间无明显差异。(3)在处理30 d时,果肉中可溶性果胶含量在0.1μmol/L IAA处理组与对照组无显著差异,在10,200μmol/LIAA处理组均显著低于对照组,此时不同浓度IAA处理桃果肉中不可溶果胶和纤维素含量均与对照组之间无显著差异。(4)在IAA处理后10,20,30 d时,果实乙烯释放量均表现为0.1,10μmol/L处理与对照组无显著差异,200μmol/L处理组显著低于对照组。(5)转录组数据显示,200μmol/L IAA处理与对照组中共存在86个差异表达基因,KEGG分析发现其中有6个与果实发育成熟密切相关的代谢途径中多个基因的表达谱发生显著变化,且变化趋势与已测定的生理指标数据吻合。综合分析表明200μmol/L的外源IAA处理第2次快速膨大期的桃果实能够延缓果实成熟的进程。     

人工脱涩处理对广西野生柿种质果实贮藏性的影响

为研究广西野生柿种质资源果实采后软化机制,该研究以广西特有的野生柿种质‘油柿''(YS)、‘农家栽培柿''(ZP)和主栽品种‘恭城月柿''为材料,分析了人工脱涩乙烯利处理的果实采后贮藏中可滴定酸含量、可溶性糖含量、硬度、乙烯生物合成量、色差、可溶性单宁含量、果胶及细胞壁降解酶活性的变化。结果表明:(1)与‘恭城月柿''相比,‘油柿''可滴定酸含量高,可溶性糖含量低,转色缓慢,果实易软化。其中,YS-4最不耐贮藏,乙烯利处理后,贮藏第4天硬度降至1.620 N,第6天可溶性单宁含量下降至2.398 mg·g^-1,整个贮藏期原果胶含量下降最慢,末期可溶性果胶值最低,为0.832%; YS-2最耐贮藏,乙烯利处理第8天硬度为YS-4的3.6倍,贮藏末期硬度在所有‘油柿''中最高。(2)‘农家栽培柿''中乙烯利处理贮藏末期ZP-2可滴定酸含量最高,可溶性糖含量低,转色最缓慢,原果胶降幅最小,可溶性果胶含量最高; 相反ZP-3果实转色快且易软化,可滴定酸含量最低,可溶性糖含量低,原果胶降幅最大,可溶性果胶含量低。(3)‘恭城月柿''PG酶活性和Cx酶活性远远高于‘油柿'',各‘油柿''种质的果实软化程度与细胞壁降解酶活性的相关性不同,β-D-Gal酶和Cx酶在‘农家栽培柿''贮藏前期起作用,PG酶在贮藏前期和后期对果实软化起作用,说明不同柿种质品种在软化过程中起主导作用的酶不同。综上认为,与‘恭城月柿''相比,‘油柿''耐贮性差,其中YS-4极不耐贮藏,而‘农家栽培柿''ZP-2极耐贮藏,这为研究柿果实软化机制提供了基础的种质材料。     

宁夏枸杞果实发育过程中淀粉代谢和质体超微结构研究h

该研究以宁夏枸杞为材料,对其果实发育过程中果实淀粉含量、淀粉代谢相关酶活性进行测定,并对果实发育过程中果皮细胞内质体超微结构和淀粉组织化学定位进行了系统观察。结果表明:(1)枸杞果实内淀粉含量随果实的发育呈现先增加后降低的变化趋势,在果实花后14d其含量达到最高(13.85mg·g-1)。(2)果实内α淀粉酶活性和β淀粉酶活性随果实发育成熟呈现逐渐增加的趋势,且α淀粉酶活性始终明显高于β淀粉酶活性。(3)组织化学和超微结构研究表明,在果实转色(花后24d)以前果实的造粉体内有大量淀粉粒的存在,但在果实第二次快速生长期,果实内的淀粉粒分解、消失,而叶绿体内没有观察到淀粉粒。研究认为,淀粉是宁夏枸杞果实发育过程中碳水化合物的一种暂时贮存形式,对维持果实早期的库强起到了重要作用,但随着第二次快速生长期果实库强的增加,淀粉体内的淀粉被淀粉酶分解转化为还原糖贮藏在果肉细胞中。     

糯米糍荔枝裂果的生理机理与防裂效果研究

以果实易裂品种糯米糍荔枝为材料,对果皮内与裂果有关的一些生理指标以及两种处理硝酸钙(Ca(NO3)2)和赤霉素(GA)的防裂效果进行了探索性研究。结果表明:在果实发育初期,果皮内的水溶性果胶和原果胶的含量均升高,且原果胶含量的增长幅度大于水溶性果胶。除果实成熟期外,果胶脂酶(PE)和多聚半乳糖醛酸酶(PG)的活性一直呈上升趋势,且水溶性果胶的含量与PG的活性有显著正相关关系。纤维素酶(CX)在整个果实发育期都表现出较高的活性且有两次明显的活性高峰。同时还发现除果实成熟期外,Ca(NO3)2处理能增强PE和PG活性,但对CX则有抑制作用。此外,Ca(NO3)2处理和GA处理均能明显地改善糯米糍荔枝果皮质地的组成,使果实的裂果率明显降低,且GA处理的效果要明显好于Ca(NO3)2处理。     

Regulation of ascorbate oxidase expression in pumpkin by auxin and copper

Ascorbate oxidase expression in pumpkin (Cucurbita spp.) tissues was studied. Specific ascorbate oxidase activities in pumpkin leaf and stem tissues were about 2 and 1.5 times that in the fruit tissues, respectively. In seeds, little ascorbate oxidase activity was detected. Northern blot analyses showed an abundant ascorbate oxidase mRNA in leaf and stem tissues. Fruit tissues had lower levels of ascorbate oxidase mRNA than leaf and stem tissues. Ascorbate oxidase mRNA was not detected in seeds. Specific ascorbate oxidase activity gradually increased during early seedling growth of pumpkin seeds. The increase was accompanied by an increase in ascorbate oxidase mRNA. When ascorbate oxidase activity in developing pumpkin fruits was investigated, the activities in immature fruits that are rapidly growing at 0, 2, 4, and 7 d after anthesis were much higher than those in mature fruits at 14 and 30 d after anthesis. The specific activity and mRNA of ascorbate oxidase markedly increased after inoculation of pumpkin fruit tissues into Murashige and Skoog's culture medium in the presence of an auxin such as 2,4-dichlorophenoxyacetic acid (2,4-D) but not in the absence of 2,4-D. In the presence of 10 mg/L of 2,4-D, ascorbate oxidase mRNA was the most abundant. Thus, ascorbate oxidase is induced by 2,4-D. These results indicate that ascorbate oxidase is involved in cell growth. In pumpkin callus, ascorbate oxidase activity could be markedly increased by adding copper. Furthermore, immunological blotting showed that the amount of ascorbate oxidase protein was also increased by adding copper. However, northern blot analyses showed that ascorbate oxidase mRNA was not increased by adding copper. We suggest that copper may control ascorbate oxidase expression at translation or at a site after translation.     

绞股蓝正常茎转变为根状茎的形态结构和内源激素含量变化

绞股蓝(Gynostemma pentaphyllum)茎端具有在秋季钻入土中发育为根状茎以越冬和增殖的现象。观察绞股蓝根状茎的形成过程及其组织结构特点,并检测根状茎不同发育阶段和不同节段的内源激素含量。结果表明,正常茎端首先发育为膨大的变态茎并钻入土中,在土中发育成根状茎并进行增殖,腋芽或侧枝的增殖倍数为2.28,来春可萌发出多株新苗。正常芽、变态茎和根状茎的基本结构相似,但后两个阶段的淀粉鞘细胞、髓和髓射线细胞中含有丰富的淀粉粒。生长素、赤霉素和茉莉酸的含量在正常茎端中最高,变态茎端次之,根状茎最低。三种激素在各茎端从芽尖段、弯曲段、膨大段至稳定段的含量总体表现为先升后降趋势。三种激素在变态茎的弯曲段含量明显升高,并在膨大段达到最高值,而生长素在根状茎的弯曲段含量最高,反映它们对相应节段发育的促进作用。     

低温胁迫对不同西葫芦品种幼苗生长与生理特性的影响

在昼/夜温度为10℃/5℃的低温胁迫下,对‘特早’、‘早青’、‘冬宝’3个西葫芦(Cucurbit pepoL.)品种的幼苗生长和生理生化指标的变化规律进行研究。结果表明,随着低温处理时间的延长,幼苗单株叶面积、单株干重均有一定程度下降,叶绿素总含量也呈下降趋势;各品种的根系活力显著下降,电导伤害率均明显升高;丙二醛含量在处理9 d时有所下降但整体呈现缓慢上升的趋势,脯氨酸含量呈现逐渐上升的趋势,且处理6 d是脯氨酸和丙二醛两指标测定的理想时期;处理幼苗的POD活性呈"V"字形变化趋势,抗寒性强的品种酶活性也较高,CAT和SOD活性则呈现出先上升后下降的趋势,三者活性均显著高于相应对照,且以处理6 d时酶活性受影响最大。各测定指标间表现出一定的交叉适应和协调性。研究发现,西葫芦耐冷性强弱可根据幼苗电解质渗透率结合根系活力或干物质积累来综合评判,品种‘冬宝’对低温具较强耐受性。     

The influence of proximal stem geometry and surface finish on the fixation of a double-tapered cemented femoral stem

In this study, the in vitro fixation of four otherwise identical double-tapered stem-types, varying only in surface finish (polished or matte) and proximal stem geometry (with or without flanges) were compared under two conditions. First, four specimens of each stem type were tested with initially bonded stem–cement interfaces, representing early post-operative conditions. Then, simulating conditions a few weeks to months later, stems were implanted in unused synthetic femurs, with a thin layer coating the stem to prevent stem–cement adhesion. Per-cycle motions were measured at both cement interfaces throughout loading. Overall, surface finish had the smallest relative effect on fixation compared to flanges. Flanges increased axial fixation by 22 μm per-cycle, regardless of surface finish (P=0.01). Further, all stems moved under dynamic load at the stem–cement interface during the first few cycles of loading, even without a thin film. The results indicate that flanges have a greater effect on fixation than surface finish, and therefore adverse findings about matte surfaces should not necessarily apply to all double-tapered stems. Specifically, dorsal flanges enhance the stability of a tapered cemented femoral stem, regardless of surface finish.     

Influence of Sink-Source Interaction on Dry Matter Production in Tomato

Sink-source ratio in tomato was manipulated, in six glasshouseexperiments, by fruit pruning (trusses pruned to two to sevenfruits immediately after fruit set of each truss), truss pruning(removal of every other truss at anthesis) and truss pruningin plants with two shoots. Periodic destructive harvest wereconducted for about 100 d after flowering of the first truss.Dry matter production was not influenced by sink-source ratio,whereas dry matter distribution between fruits and vegetativeparts was greatly affected. The fraction of dry matter distributedto the fruits at the end of the fruit pruning experiments (F_fruits)could be described accurately as a saturation-type functionof number of fruits retained per truss (N_f): F_fruits = 0.660(l-e^-0.341N_f). Specific leaf area and internode length decreasedand plant leaf area increased when sink-source ratio was reduced.Removal of every other truss at anthesis did reduce dry matterpartitioning into the fruits, but it did not influence internodelength. Plant development (number of visible leaves at the endof the experiments) was not influenced by sink-source ratio.In four experiments some plants were pruned to one fruit pertruss. Final dry matter production was 8-24% lower for theseplants, compared with plants with more than one fruit per truss.This was, at least party, the result of less light interceptionby these plants, which had strongly curled leaves pointing downwards. Results indicate that effects of sink demand on dry matter productionper unit of intercepted radiation and probably on leaf photosyntheticrate in commercial tomato production can be ignored.Copyright1995, 1999 Academic Press Dry matter production, feedback control, glasshouse, growth analysis, Lycopersicon esculentum, pruning, sink demand, sink-source ratio, tomato     

不同株龄日本落叶松插穗的内源激素含量与生根的关系

研究了日本落叶松母株年龄、插穗内源激素含量与生根之间的关系,以及外源IBA对插穗内源激素含量的影响及其对插穗生根的促进作用。结果表明：不同株龄插穗生根性状及插穗茎和叶中激素含量差异均达极显著水平,叶中激素含量对插穗生根力没有直接影响;插穗茎中生根抑制激素（ABA）含量随株龄增长而增加,生根促进激素与抑制激素的比值（IAA＋GA＋ZR）/ABA却随株龄的增长而递减,与生根力随株龄的变化趋势一致,且该比值与生根性状紧密相关,因此可作为评价母株（无性系）生根力的指标;插后13～32d是插穗愈伤组织形成和不定根诱导的关键期,此期生根促进激素消耗量大,茎中含量大幅度降低,进入根伸长生长阶段,含量上升;外源IBA促进插穗生根的机制在于通过外源激素的刺激,在不定根诱导期,插穗茎中ABA含量大幅度降低,从而有利于不定根的发生和发育。     

Changes in Auxin and Cytokinin Activity in Roots of Red Oak, Quercus rubra, Seedlings during Lateral Root Formation

Quercus rubra L. seedlings were partially root pruned to induce formation of new laterals. Auxins in root extract fractions that cochromatographed with IAA, and cytokinins in root xylem sap fractions that cochromatographed with zeatin and zeatin riboside, were quantified by bioassays at 24 h intervals after pruning. Auxin activity sharply increased in the first 24 h and then decreased to prepruning levels. Cytokinin activity also increased during the first 24 h. New laterals appeared 4 to 5 days after pruning. The possible sources and role of these two hormones in root initiation are discussed.     

Effects of treatments potentially influencing the supply of assimilate on its partitioning in sugarcane.

Two pot experiments and one field experiment were conducted on sugarcane to assess the effects of treatments expected to change total carbon assimilation on the partitioning of assimilate. In the first experiment pots of cultivars CP and N14 were arranged to simulate normal field spacing. At 5 months, plants were partially defoliated or left intact. In the subsequent four months, defoliation resulted in a small (not significant) decrease in total dry mass increment; it increased the proportional partitioning of assimilates to leaves in N14, whilst in CP it increased the proportional partitioning to stems. In both cultivars defoliation increased proportional allocation to non-structural dry matter, and thus sucrose, in the stem. In the second experiment pots of cv. CP were grown at normal spacing for 4 months, then left untreated, shaded, or placed further apart. During the subsequent four months shading decreased total dry matter increment, but increased proportional partitioning to the stems, and within stems to non-structural dry matter, and so sucrose. Widened spacing increased total assimilation, but decreased proportional allocation to stems; partitioning within the stems was not affected. In the field experiment plants of both cultivars were partially defoliated at 6 months, or left intact. Defoliation resulted in only a very small decrease in stem dry mass increment during the subsequent four months (leaves were not measured). Within the stem partial defoliation caused proportionally increased partitioning to non-structural dry matter, hence to sucrose. The results suggest that sucrose storage receives priority in the allocation of assimilate, rather than representing the accumulation of assimilate not required for vegetative growth.     

高温胁迫对菊花电阻抗图谱参数的影响

以菊花(Chrysanthemum morifolium)‘神马’扦插苗茎段和叶片为材料,测定其高温胁迫(25~50℃)下电阻抗图谱参数的变化,通过膜透性(相对电导率)与电阻抗图谱参数间的相关性,来证明电阻抗图谱法研究菊花耐热性的有效性。结果表明:随着温度升高,茎叶的胞外电阻、胞内电阻、弛豫时间呈现先增加,后急剧下降的趋势,而弛豫时间分布系数变化趋势为不规则下降。茎叶相对电导率是随着温度的升高先增加后降低再急剧增加。经过菊花茎叶电阻抗图谱参数拟合菊花的耐热性与相对电导率表示的耐热性温度极为接近。相关分析表明,高温胁迫下菊花茎叶相对电导率与胞外电阻(茎p<0.01,叶p<0.05)、弛豫时间(p<0.05)之间有显著的相关。由此可见,胞外电阻和弛豫时间是测定菊花耐热性的适合参数。