Characteristics and oleocellosis sensitivity of citrus fruits

The effects of variety, growth phase, and water loss on development of oleocellosis, and relationships between chromatism and Vis/NIR spectra were studied in ‘EarlyGold’ sweet orange (Citrus sinensis Osbeck), ‘Fukumoto’ navel (Citrus sinensis Osbeck), and ‘Cara Cara’ navel (Citrus sinensis Osbeck) oranges. The varieties showed significant differences in the rate (RO) and degree (DO) of oleocellosis development. The sensitivity of varieties (from most to least sensitive) was ‘EarlyGold’ > ‘Fukumoto’ > ‘Cara Cara.’ Growth phase and water loss had a significant influence on fruit sensitivity to oleocellosis. The order of sensitivity to oleocellosis was dependent on harvest time (i.e., at normal period > at delayed period > at uncolored period), and RO and DO decreased significantly with water loss. The RO and DO models for fruit water loss were established as y = 0.75 − 3.94x − 271.33x² (R² = 0.77) and y = 1.70 − 7.29x − 1025.83x² (R² = 0.583). The sensitivity of ‘EarlyGold’ to oleocellosis was significantly correlated with dL and dC of fruit chromatism. At the same time, there were significant differences at 480–575 nm, 650–720 nm, and 925–965 nm between varieties with low and high sensitivity to oleocellosis, and ‘EarlyGolds’ with a low RO and DO had a higher reflectance than those with a high RO and DO.     

柑橘衰退病毒侵染对寄主植物同工酶及酸性病程相关蛋白表达的影响

以柑橘衰退病毒(Citrus tristeza virus,CTV)不同致病力株系接种寄主植物,比较分析了寄主植物体内过氧化物酶(peroxidase,POD)和多酚氧化酶(polyphenol oxidase,PPO)活性变化特点。结果表明,该病毒侵染对这2种酶活性的影响因寄主品种和CTV株系而异,CTV强毒和弱毒株系侵染均导致墨西哥莱檬植株中POD活性明显降低;在甜橙上,CTV强毒株系接种植株中POD活性则显著性提高,而弱毒株系接种对POD的活性无明显影响;在对该病毒具有较高抗性的枳壳中,接种CTV不同株系对POD活性均无明显影响。而在接种强毒株系N25的墨西哥莱檬中PPO活性有所增强,在枳壳上则表现为接种植株的PPO活性降低,在甜橙上PPO活性无明显的变化。POD、PPO和酯酶(esterase,EST)同工酶酶谱分析的结果显示,CTV弱毒株系接种枳壳后诱导产生了2条新的EST同工酶谱带,而在其他CTV接种植株上均未诱导表达新的POD、PPO及EST酶谱。酸性病程相关蛋白分析结果显示,CTV强毒株系在甜橙上诱导产生有6条明显的酸性病程相关蛋白条带。     

Expression of PPO and POD genes and contents of polyphenolic compounds in harvested mango fruits in relation to Benzothiadiazole-induced defense against anthracnose

Mango is susceptible to decay caused by pathogen infection during storage and transport. Chemical fungicides have been the major weapons against postharvest fungal diseases, but they have caused increasing public resistance. BTH does not have anti-microbial properties, but it induces systemic acquired resistance in plants. Here the relationship between BTH-induced disease resistance in harvested mango fruits and expression of PPO and POD genes, together with contents of total phenolic compounds (TPC), were investigated. BTH treatment reduced disease indices and lesion diameter. Compared with the control, BTH increased TPC, up-regulated gene expression and enhanced enzymes activities of PPO and POD during the latter period of storage life, suggesting that enhanced gene expression of PPO and POD played an important role in BTH-activated defense response of mango fruits and that the up-regulation of the two genes were related to the accumulation of TPC. This study also showed that BTH-induced resistance in harvested mango fruits could differ with varieties.     

柑橘果实有机酸代谢研究进展

柑橘果实中有机酸含量是决定果实品质好坏的重要指标之一,降低果实中有机酸含量提高果实品质一直是人们研究的一个热点及难点。综述了柑橘果实中柠檬酸的合成与降解、柑橘果实中有机酸代谢相关酶、柑橘果实柠檬酸的跨膜运输及柑橘果实有机酸的调控等方面内容。尤其是柠檬酸新的降解途径、柠檬酸跨膜运输时液泡内外柠檬酸盐的动静态平衡和分子方面给出了国内外最新研究进展,推测柑橘果实发育后期柠檬酸的急剧下降可能是由于其参与了GABA途径并最终代谢成氨基酸而导致的;详细介绍了柠檬酸离子与氢离子在液泡内外转运的模型。最后总结讨论了柑橘果实有机酸调控的思路,提出了今后的研究方向、思路和需要解决的问题。     

红星苹果多酚氧化酶某些特性及其抑制剂的研究

用硫酸铵分级盐析及透析法提取红星苹果ＰＰＯ,并分别测定了该酶的最适ｐＨ、最适温度及酶促动力学参数Ｋｍ值和Ｖｍａｘ值,比较分析了常见几种ＰＰＯ抑制剂的抑制作用,结果表明：以邻苯二酚为底物,苹果ＰＰＯ的最适ｐＨ为６．２,最适温度为２８℃,Ｋｍ值为４１ｍｍｏｌ／Ｌ,Ｖｍａｘ值为２３５．３ｕｎｉｔ／ｍｉｎ。在所测５种抑制剂（Ｌ－半胱氨酸、偏二亚硫酸钠、硫脲、谷胱甘肽、抗坏血酸）中,Ｌ－半胱氨酸、偏二亚硫酸钠和抗坏血酸对苹果ＰＰＯ表现出较强的抑制作用,并以Ｌ－半胱氨酸最强。     

Cellular wall metabolism in citrus fruit pericarp and its relation to creasing fruit rate

Citrus creasing results in serious economic loss in many citrus orchards. Based on the different incidence of creasing, two sweet orange cultivars ‘Hong Jiang’ (grafting chimaera of which flesh is mostly from Citrus reticulata Blanco and peel is from Citrus sinensis Osbeck in) and ‘An Liu’ (Citrus sinensis Osbeck) were used to investigate the creasing rate. The ultrastructure in cellular wall, cellular wall component, cellular wall degradation-related enzymes and expansin (Ct-Exp1) of sweet orange during fruit ripening in field were comparatively analyzed. ‘Hong Jiang’ sweet orange had a higher creasing rate than ‘An Liu’ during ripening. The activities of polygalacturonase, cellulase and pectinesterase in cellular wall of ‘Hong Jiang’ increased more markedly compared with ‘An Liu’. The increases in the content of soluble pectin, ionically associated pectin, covalently bound pectin, hemicellulose and cellulose of ‘Hong Jiang’ were higher than those of ‘An Liu’. Furthermore, the enhanced degradation of the ultrastructure in the albedo cellular walls was observed in ‘Hong Jiang’. Moreover, the northern blot analysis indicated that the Ct-Exp1 gene expressed more strongly in peel of ‘Hong Jiang’ than ‘An Liu’ during fruit ripening. These data suggest that enhanced loss of pectin and cellulose in the cellular walls of peel tissue of sweet orange could result in fruit creasing.     

苹果梨中多酚氧化酶酶学特性的研究

 以苹果梨中的多酚氧化酶为研究对象, 对其酶的活性变化及其特性的研究表明, 苹果梨中的多酚氧化酶的最适pH 值是4. 6 , 最适温度是40 ℃; 亚硫酸氢钠、维生素C、柠檬酸对苹果梨中多酚氧化酶的抑制作用依次减弱, 硫酸钠几乎无抑制作用。不同底物和同底物不同浓度影响多酚氧化酶特性。     

宽皮柑桔果实贮藏期间汁胞粒化与某些生理特性的关系

对Ｐｅｎｇ柑、温州蜜柑贮藏果汁胞粒化发生过程的若干生理研究表明，Ｐｅｎｇ柑和温州蜜柑在果实发生汁胞粒化前，其乙醇含量均出现一个明显的高峰，以后随着粒化程度的加重乙醇含量趋于下降。果皮电导率在整个贮藏过程中持续上升，汁胞粒化程度越重，电导率越高。果实呼吸强度与失重率也随粒化程度加重而有所上升。     

柑橘果实生物活性物质与糖尿病防治研究进展

柑橘果实含丰富的营养和生物活性物质,具有重要的营养、医药和保健价值.现有报道表明,柑橘果实的类黄酮、香豆素类、单萜类、果胶等生物活性物质均有防治糖尿病的功效.系统地回顾了近年来柑橘果实生物活性物质与糖尿病防治的有关研究报道,总结了有关物质防治糖尿病的机理及取得的进展,旨在为进一步开发利用我国丰富的柑橘资源提供新信息.     

DNA微阵列技术在柑橘研究中的应用

DNA微阵列技术是一项能够分析基因组、基因表达特征性图谱的新技术,使研究人员能同时对成千上万的相互作用的基因展开研究。随着Affymetrix公司生产的世界上第一个商品化的柑橘基因组阵列(Citrus Genome Array)的诞生,该技术在柑橘基因组学和相关科学研究中扮演着越来越重要的角色。综述了运用DNA微阵列技术在柑橘研究中的现状,重点说明了该技术在柑橘重要功能基因的检测及基因差异表达研究中的应用,介绍了柑桔研究中DNA微阵列的种类,及其在代谢途径分析、突变检测和突变机理分析等其他领域的研究现状,并对其在病原检测方面的可能应用也进行了探讨。     

Allelopathy in citrus orchards

The involvement of allelopathy in citrus orchards is indicated by the discovery of a phenolic phytotoxin in soils and partly decomposed citrus root residues. The phytotoxin, which was tentatively identified as homovanillic acid, is produced by the anaerobic decomposition of citrus roots in the deeper soil horizons. It caused an arrest in rough lemon (Citrus jambhiri) radicle elongation and a severe swelling of the root tip.     

双孢蘑菇易褐变菌株的多酚氧化酶特征

采用凝胶电泳等生化技术探讨了蘑菇易褐变菌株的酚酶特征。发现易褐变菌株具有特异的同工酶表型,子实体阶段表达的酚酶位点多,且酶活性高;其整个生活史的胞内酚酶活性曲线变化与优质菌株不同;所表达的酚酶对亚硫酸盐类酚酶抑制剂的敏感性低;所表达的酚酶较耐热,在加热的初始阶段(35～40℃)就能迅速催化褐变反应;所含的潜伏型酚酶含量大,且随着鲜菇贮藏期延长而大量活化,继续催化褐变。本文还就如何防止褐变进行了探讨。     

柑橘密码子用法分析

采用高频密码子分析法,对柑橘的177个蛋白质编码基因序列(codingDNAsequence,CDS)进行了分析,计算出同义密码子相对使用频率(relativefrequencyofsynonymouscodon,RFSC),确定了TAA、GCT、GAT、CTT、AGG、AGA和GTT等7个高频密码子。将柑橘的密码子使用频率与人、果蝇、酵母和大肠杆菌等不同种类模式生物比较后发现,柑橘密码子的偏爱性与不同种类生物有不同程度的差异;但将柑橘的密码子使用频率与拟南芥、番茄、水稻和尖叶蕉等不同种类的植物相比,发现柑橘密码子的偏爱性与同为双子叶植物的拟南芥、番茄完全一样,而与水稻、尖叶蕉这2种单子叶植物均有较大的差异。分析结果对动物或微生物的基因在柑橘中的表达或柑橘基因在微生物中的表达以及基因克隆时设计引物具有一定指导意义。     

几种防褐变剂对去皮切片马铃薯贮藏的影响

几种防褐变剂对去皮切片马铃薯的贮藏试验表明,采用３００ｍｇ／Ｌ的亚硫酸钠液处理,能有效抑制马铃薯组织中多酚氧化酶的活性,防褐变效果佳,维生素Ｃ损失少。     

平阴玫瑰组培苗多酚含量及多酚氧化酶活性与其生根的关系

对平阴玫瑰(Rosa rugosa) 多酚含量及多酚氧化酶( Polyphenol oxidase, PPO) 活性与组培苗生根的关系进行了研究, 对多酚含量、PPO活性与生根指数进行了相关性分析。结果表明: 平阴玫瑰不同品种间的多酚含量、PPO活性及生根指数存在极显著差异。多酚含量与生根指数显著负相关, PPO活性与生根指数极显著负相关。对不同pH条件下‘紫枝玫瑰’组培苗的PPO活性和生根指数的研究表明, ‘紫枝玫瑰’组培苗的PPO活性及生根指数与pH均有密切联系, pH为6.5时PPO活性最高, 而生根指数最低, pH 5.5最适宜生根。     

Susceptibility of citrus species to Alternaria alternata, the causal agent of the Alternaria brown spot

Alternaria alternata, the causal agent of Alternaria brown spot (ABS), causes necrosis on leaves, twigs, and fruit, reducing the productivity and quality of fruits. Tangerines and their hybrids are highly susceptible to the disease. Species, hybrids, and cultivars of Citrus from the germplasm bank of the Estação Experimental de Citricultura de Bebedouro, São Paulo, Brazil, were evaluated in 2004 and 2005 with respect to their resistance to A. alternata, both through natural infection and by inoculation. Detached leaves were also used to demonstrate susceptibility or resistance to the disease. Ten cultivars of Satsumas (Citrus unshiu), and 14 cultivars of Clementine mandarin (C. clementina) did not show any symptoms of the disease in their leaves, either through natural infection or when inoculated in the field. The Burguess SRA-412, Wallent SRA-438, Carvalhais, Ampefy SRA-459, Ananas SRA, and Macaque SRA-426 mandarin hybrids (C. reticulata) did not show symptoms of the disease under natural or artificial infection in the field. Some cultivars of C. deliciosa, C. tangerina, C. erythrosa, and C. temple showed symptoms of the disease, even though no previous record of their susceptibility to Alternaria brown spot had been previously reported. The hybrids Fairchild, Nova, Page, Fortune, and Sunburst were susceptible to the disease. However, Fremont mandarin (a crossing between C. clementina and C. reticulata), Encore (C. nobilis × C. deliciosa), and Fallglo (C. reticulata × C. paradisi) did not show symptoms in field, and few symptoms were verified in detached leaves. These materials are promising for the cultivation of tangerines, and will enable genetic improvement for the development of cultivars resistant to Alternaria brown spot.     

姬松茸加工过程中防褐变的研究

根据姬松茸酶促褐变的机理,研究了姬松茸加工过程中防褐变的有效方法。以处理后菇片中多酚氧化酶的残存活性及视觉观察菇片放置8h不褐变为指标,确定每种方法的最适参数。结果表明,防止姬松茸褐变有四种方法:沸水热烫10min,0.7％亚硫酸钠溶液浸泡,直接添加0.7％VC或添加0.5％亚硫酸钠与0.3％VC。     

Asymmetric growth of citrus fruit peel induced by localized application of gibberellins in lanolin pastes

Lanolin pastes containing 0.02–1.0% gibberellin A₄₊₇(GA₄₊₇) were applied to one side of developing citrus fruitlets and caused thickening of the peel in the proximity of the treated zone. Enlargement of albedo (= the white portion of citrus peel) cells was involved, as revealed by scanning electron microscopy. The flavedo (= the coloured portion of the peel) and the pulp were not affected by the hormone. Gibberellin A₃ was slightly less active than GA₄₊₇. Cultivars with a naturally thick peel, such as ‘Marsh’ grapefruit (Citrus paradisi Macf.) and ‘Shamouti’ orange (Citrus sinensis (L.) Osbeck) responded more strongly than thin-peel cultivars. The role of gibberellins in the differential growth of citrus fruit tissues is discussed.     

利用AFLP鉴定柑橘变异

利用AFLP分析鉴定了7个柑橘变异类型,从64对引物组合中筛选了8对引物组合,共得到334个扩增位点2099条带数据。7个变异类型与亲本品种之间多态性带为36至92条,变异类型的多态性带数与亲本品种总带数的比例为0.1721至0.4182。说明变异类型的遗传基础已经发生了不同程度的改变,7个柑橘变异类型应是芽变,具备了成为新品种的遗传基础,特别是红皮冰糖脐橙选育成功将填补高糖脐橙空白。研究同时表明,AFLP具有扩增谱带多,谱带清晰,扩增信息量大的特点。根据谱带位点差异即可鉴定柑橘变异是否遗传,多态性位点数也反映了性状变异程度。AFLP方法1次可同时鉴定多个变异类型,是柑橘新品种选育早期鉴定灵敏、可靠、有效的方法。     

柑橘轮斑病抗性鉴定方法的建立

【目的】探究柑橘轮斑病最适宜接种条件,建立一种快速鉴定柑橘轮斑病抗性的方法。【方法】以柑橘轮斑病菌为接种体,运用离体叶片接种法,在室内不同温度下对离体柠檬叶片的不同部位进行接种,探讨柑橘轮斑病的最适宜接种条件。随后采用前期确立的接种体系对27个主栽柑橘品种进行轮斑病抗性评价。【结果】针刺接种易发病,最适宜的接种温度为10℃,最适宜接种部位为叶片背部。27个柑橘品种中沙田柚为免疫品种,091无核沃柑最易感病。【结论】研究建立了叶片背面针刺、10℃条件下保湿培养28 d的抗性鉴定体系。并利用此技术体系鉴定出柚类抗病力最强,杂柑类相对最感病,而橙类、柑类与橘类抗性处于柚类与杂柑类中间。