1-MCP结合自发气调包装对‘空心李’果实软化和细胞壁代谢的影响

探讨果实软化与细胞壁代谢之间的关系及1-甲基环丙烯(1-MCP)结合自发气调包装(MAP)对果实软化的调控机制,为生产中李果实软化问题提供理论依据和技术参考。笔者以贵州省特色果品‘空心李’为试材,通过测定果实的硬度、细胞壁代谢成分和细胞壁代谢酶活性的变化,研究1-MCP、MAP及两者结合(1-MCP+MAP)对(20±1)℃下果实软化的抑制效应。结果表明：（1）与对照（直接放于纸箱内）相比,1-MCP、MAP及1-MCP+MAP处理抑制了果实硬度下降,原果胶和纤维素降解,抑制了多聚半乳糖醛酸酶(PG)、果胶甲脂酶(PME)和纤维素酶(Cx)活性增加,抑制效果为1-MCP+MAP>1-MCP>MAP。（2）果实硬度的下降与原果胶和纤维素含量呈显著正相关,与可溶性果胶含量关系表现不一,1-MCP和1-MCP+MAP处理与可溶性果胶含量呈显著负相关,而对照和MAP处理与可溶性果胶含量没有表现出明显的相关性。1-MCP、MAP、1-MCP+MAP处理和对照果实硬度的下降与PG和PME活性存在显著负相关,对照和MAP处理的果实硬度与Cx活性表现显著负相关,1-MCP和1-MCP+MAP处理果实硬度与Cx活性没有表现相关性。1-MCP结合MAP对沿河‘空心李’果实硬度下降、细胞壁物质降解及其相关酶活性有显著抑制作用,能够抑制‘空心李’果实软化,延长保鲜时间,减少采后损失。     

湿冷贮藏对冬枣软化水解酶活性影响的研究

软化是冬枣贮藏中存在的主要问题之一。研究了湿冷贮藏对冬枣不溶性果胶含量和果胶甲酯酶(PM E)活性、可溶性果胶含量和多聚半乳糖醛酸酶(PG)活性、纤维素含量和纤维素酶(Cx-cellulases)活性、淀粉含量和淀粉酶活性的影响。结果表明,湿冷贮藏可以延缓冬枣不溶性果胶含量、淀粉含量和PG活性的下降速度,降低可溶性果胶含量、PM E活性、Cx-cellulases活性、淀粉酶活性的上升速度,而纤维素含量则表现为先慢后快的增长规律。     

辣椒果实成熟过程中硬度及相关生理生化指标的变化

选用2个不同硬度的辣椒品系,在果实成熟的不同时期测定其果肉硬度变化,并测定了与硬度相关的原果胶、果胶和纤维素的含量以及促进细胞壁物质分解的PME,PG,纤维素酶和β_半乳糖苷酶等水解酶的活性。结果表明:果实硬度在转色期最大,随着果实成熟,可溶性果胶含量增加,纤维素含量从转色期开始基本呈下降趋势,从幼果期到转色期PME酶的活性呈上升趋势,529品系酶活性在转色期达到最大,585品系在绿熟期酶活性达到最大值。2个品系的PG酶活性不断上升并在红熟期达到最大值。纤维素酶的活性也呈上升趋势并在转色期达到最大值。2个品系的半乳糖苷酶活性在红熟期达到最大值。辣椒果实成熟软化过程中,其硬度的变化与果胶、纤维素等物质的变化有显著相关性,而这些物质的变化又与促进这些物质水解的细胞壁水解酶活性的变化相一致。在果实成熟的不同时期,这些硬度的相关生理生化指标可以反映出果实的硬度特点,在耐贮运辣椒育种过程中有一定参考价值。     

不同施肥处理对“东红”猕猴桃贮藏期间果实硬度及细胞壁降解的影响

为研究不同施肥处理对猕猴桃采后软化的影响,以“东红”猕猴桃为材料,对不同施肥处理的猕猴桃果实在生理成熟期采摘,于室温贮藏,定期取样分析果实硬度、软化率、淀粉质量分数、原果胶质量分数、可溶性果胶质量分数、纤维素质量分数及多聚半乳糖醛酸酶（Polygalacturonase,PG）、果胶甲酯酶 （Pectin methylesterase,PME）、纤维素酶（Cellulase,Cx）、β-半乳糖苷酶（β-D-galaetosidase,β-Gal）、淀粉酶活性的变化。结果表明,合理的施肥处理可延缓果实硬度的下降,减缓果实中淀粉、原果胶、纤维素质量分数的下降,延缓可溶性果胶质量分数及PG、PME、Cx、β-Gal、淀粉酶活性的升高,并推迟峰值出现的时间。不同施肥处理组的果实在贮藏期间其硬度与可溶性果胶质量分数、PG、Cx、β-Gal、淀粉酶活性呈极显著负相关（P＜0.01）,与原果胶、纤维素、淀粉质量分数呈极显著正相关（P＜0.01）。在猕猴桃生产中采用复合化肥+有机肥+生物菌肥相结合的施肥方式可显著延缓贮藏期间果实的软化,延长果实的贮藏期。     

富士苹果在减压贮藏过程中相关品质指标与硬度的相关性分析

研究了富士苹果在减压贮藏过程中环境中的乙烯含量、多聚半乳糖醛酸酶(PG)活性、β-半乳糖苷酶(β-Gal)活性、果胶质含量与果实硬度的相关性。结果表明,苹果在减压贮藏条件下,贮藏环境中的乙烯含量、 PG活性、β-Gal活性值及最高值均较常压条件下的低,随着贮藏时间的延长,环境中的乙烯含量、PG活性、β-Gal活性增大,引起原果胶水解成水溶性果胶,细胞壁松弛,果实硬度下降,整个贮藏期果实硬度下降了21.7%,常压贮藏条件下硬度下降了35.9%。因此,可判断减压贮藏通过抑制PG活性及β-Gal活性,从而延缓了原果胶的水解速度,抑制了软化速率,延长果实的保质期。     

1-MCP对外源乙烯诱导油桃果实软化的影响

以秦光油桃为试材,研究了1-MCP处理对外源乙烯诱导果实软化的影响.结果表明,1-MCP处理可抑制外源乙烯诱导果实硬度的下降,将乙烯诱导果实的淀粉、纤维素和果胶类物质的降解延迟2天,对引起这些物质降解的相关酶类如淀粉酶、纤维素酶和多聚半乳糖醛酸酶(PG)等酶活性高峰的到来推迟2天,同时降低了多聚半乳糖醛酸酶(PG)活性高峰值.     

密集烘烤过程中烤烟细胞生理和质地变化

采用河南农业大学设计的电热式温湿自控密集烤烟箱,以中烟100上部叶为材料,研究了烘烤过程中烟叶细胞生理和质地变化的规律。结果表明,烘烤中烟叶的呼吸强度在38℃时达到高峰,箱内CO₂含量为1.80%,48℃以后烟叶的呼吸作用减弱。烘烤中果胶酯酶和纤维素酶在38~54℃活性较高,其中果胶甲酯酶(PME)和纤维素酶活性42℃最高,多聚半乳糖醛酸酶(PG)活性48℃最高,PG与PME共同促进了原果胶的水解进程,烘烤中原果胶、总果胶和纤维素含量不断降低。烟叶质地(除黏聚性)在38~48℃之间发生显著变化,其中42℃硬度和咀嚼性值最大,38℃拉力和剪切力值最大,48℃黏聚性、拉力和剪切力值最小。相关分析表明,可溶性果胶与回复性呈显著负相关(P<0.05);原果胶、总果胶及纤维素与回复性、拉力均呈显著或极显著正相关(P<0.05)。这些结果说明烘烤过程中烟叶质地的绵软在某种程度上是细胞壁物质不断降解的结果。研究表明,烘烤中烟叶剪切力的动态变化较为直观,回复性和拉力可以作为探讨烟叶细胞生理变化的参数,而烟叶细胞生理变化是导致质地差异显著的主要因素。     

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。     

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。     

冰温保鲜对新疆鲜枣贮藏品质的影响

为探讨冰温贮藏条件对鲜枣品质的影响,以新疆若羌冬枣为试材,将其分别置于0℃冷藏(CK)、-1.5～-1.0℃冰温贮藏,分别测定了贮藏过程中冬枣的失重率、腐烂率、硬度、色差、可溶性固形物含量、果胶含量、多聚半乳糖醛酸酶(PG)、果胶甲酯酶(PME)、β-半乳糖苷酶(β-Gal)活性。结果表明:随着贮藏时间的延长,冰温贮藏枣果失重率的上升、色差的变化程度及可溶性固形物含量的下降均得以延缓;对0℃冷藏的枣果来说,其硬度的下降更快,PG、PME、β-Gal活性也随之升高,而冰温贮藏则抑制酶活性的升高速率,降低枣果实腐烂变质和衰老软化的进程,有效延长若羌冬枣的贮藏期。     

我国主要储粮害虫抗性调查研究

通过对全国范围内23个省、市和自治区的55个地区粮库中的主要储粮害虫进行取样，用FAO抗性测定方法对92个虫样进行磷化氢抗性测定，得出无抗性虫样占调查虫样总数的54．3％、低抗性虫样占9．8％、中等抗性虫样占7．6％、高抗性虫样占13．0％、极高抗性虫样占15．2％。在调查的几种主要储粮害虫中，高抗性虫样主要为锈赤扁谷盗、谷蠹和米象，其中锈赤扁谷盗的抗性普遍比较严重，谷蠹和米象通过与1995年抗性调查所取的样品进行比较，在最近的8年内米象的抗性倍数增加了10．7％、谷蠹增加了71．2％。磷化氢抗性较高的区域主要是我国西南、华中和华南地区。     

Durability of resistance against fungal, bacterial and viral pathogens; present situation

In evolutionary sense no resistance lasts forever. The durability of a resistance can be seen as a quantitative trait; resistances may range from not durable at all (ephemeral, or transient) to highly durable. Ephemeral resistance occurs against fungi and bacteria with a narrow host range, specialists. It is characterised by a hypersensitive reaction (HR), major gene inheritance and many resistance genes, which often occur in multiple allelic series and/or complex loci. These resistance genes (alleles) interact in a gene-for-gene way with a virulence genes (alleles) in the pathogen to give an incompatible reaction. The pathogen neutralises the effect of the resistance gene by a loss mutation in the corresponding avirulence allele. The incompatible reaction is not elicited any more and the pathogenicity is restored. The pathogens can afford the loss of many avirulences without loss of fitness. Durable resistance against specialised fungi and bacteria is often quantitative and based upon the additive effects of some to several genes, the resulting resistance being of another nature than the hypersensitive reaction. This quantitative resistance is present to nearly all pathogens at low to fair levels in most commercial cultivars. Durable resistance of a monogenic nature occurs too and is usually of a non-HR type. Resistance against fungi and bacteria with a wide host range, generalists, is usually quantitative and durable. Resistances against viruses are often fairly durable, even if these are based on monogenic, race-specific, HR resistances. The level of specialisation does not seem to be associated with the durability of resistance. This revised version was published online in August 2006 with corrections to the Cover Date.     

The integrated concept of disease resistance: A new view including horizontal and vertical resistance in plants

Summary Horizontal, uniform, race-non-specific or stable resistance can be discerned according to Van der Plank, from vertical, differential, race-specific or unstable resistance by a test in which a number of host genotypes (cultivars or clones) are tested against a number of pathogen genetypes traces of isolatest. If the total non-environmental variance in levels of resistance is due to main effects only differences between cultivars and differences between isolates) the resistance and the pathogen many (in the broad sense) are horizontal in nature. Vertical resistance and pathogenicity are characterized by the interaction between host and pathogen showing up as a variance compenent in this test due to interaction between cultivars and isolates.A host and pathogen model was made in which resistance and pathogenicity are governed by live polygenic loci. Within the host the resistance genes show additivity. Two models were investigated in model I resistance and pathogenicity genes operate in an additive way as envisaged by Van der Plank in his horizontal resistance. Model II is characterized by a gene-for-gene action between the polygenes of the host and those of the pathogen.The cultivar isolate test in model I showed only main effect variance. Surprisingly, the variance in model II was also largely due to main effects. The contribution of the interaction to the variance uppeared so small, that it would be difficult to discern it from a normal error variance.So-called horizontal resistance can therefore be explained by a polygenic resistance, where the individual genes are vertical and operating on a gene-for-gene basis with virulence genes in the pathogen. The data reported so far support the idea that model II rather than model I is the realistic one.The two models also revealed that populations with a polygenic resistance based on the gene-for-gene action have an increased level of resistance compared with the addition model, while its stability as far as mutability of the pathogen is concerned, is higher compared to those with an additive gene action. Mathematical studies of Mode too support the gene-for-gene concept.The operation of all resistance and virulence genes in a natural population is therefore seen as one integrated system. All genes for true resistance in the host population, whether they are major or minor genes are considered to interact in a gene-for-gene way with virulence genes either major or minor, in the pathogen population.The models revealed other important aspects. Populations with a polygenic resistance based on a gene-for-gene action have an increased level of resistance compared to populations following the addition model. The stability, as far as mutability of the pathogen is concerned, is higher in the interaction model than in the addition model.The effect of a resistance gene on the level of resistance of the population consists of its effect on a single plant times its gene frequency in the population. Due to the adaptive forces in both the host and the pathogen population and the gene-for-gene nature of the gene action an equilibrium develops that allows all resistance genes to remain effective although their corresponding virulence genes are present. The frequencies of the resistance and virulence genes are such that the effective frequencies of resistance genes tend to be negatively related to the magnitude of the gene effect. This explains why major genes often occur at low frequencies, while minor genes appear to be frequent. It is in this way that the host and the pathogen, both as extremely variable and vigorous populations, can co-exist.Horizontal and vertical resistance as meant by Van der Plank therefore do not represent different kinds of resistances, they represent merely polygenic and oligogenic resistances resp. In both situations the individual host genes interact specifically with virulence genes in the pathogen. Van der Plank's test for horizontal resistance appears to be a simple and sound way to test for polygenic inheritance of resistance.The practical considerations have been discussed. The agro-ecosystems should be made as diverse as possible. Multilines, polygenic resistance, tolerance, gene deployment and other measures should be employed, if possible in combination.     

Plant pathosystems: An attempt to elucidate horizontal resistance

Summary Resistance to parasites can be distinguished into true resistance and pseudo or escape resistance. In the former resistance mechanisms operate after intimate contact between the host tissue and the parasite has been established. The resistance is expressed by a reduced growth of the parasite in or on the host tissue. Escape resistances operate before the parasite has made contact with the host tissue and is expressed by a reduced chance of such contacts. True resistance genes are assumed to act in a gene-for-gene way with virulence genes in the parasite. Genes governing escape resistances are supposed to function independently from genes in the parasite (no gene-for-gene action). It is deduced, that escape resistances and polygenic true resistances both are of a horizontal nature. Vertical resistance is to be found in the category of monogenic true resistances.     

Quantitative resistance to downy mildew (Plasmopara halstedii) in sunflower (Helianthus annuus)

Downy mildew of sunflower, caused by the Oomycete, Plasmopara halstedii is at present controlled by major resistance genes. However, the pathogen has shown a considerable capacity for changes in virulence and these resistance genes are overcome only a few years after they have been introduced into new sunflower varieties. This paper presents research for quantitative, non-race-specific resistance independent of major genes. The reaction of cultivated sunflower genotypes to field attack by downy mildew was studied over 4 years in several environments and in the presence of the two most common races in France: 703 and 710. An experimental protocol with pre-emergence irrigation was developed, making it possible to observe downy mildew reaction whatever the weather conditions. Significant levels of partial resistance were observed in about 50 inbred sunflower lines among the 800 observed. These results suggest that it should be possible to select for non-race-specific downy mildew resistance and to include it in modern varieties. However, since this non-specific resistance is partial, it may be necessary to combine it with major gene resistance. Possible strategies are discussed to obtain durable resistance to downy mildew.     

解磷细菌对7种常见抗生素的抗性研究

摘要：测定8株供试菌株对氨苄青霉素,四环素,链霉素,卡那霉素,利福平,头孢霉素,氯霉素的不同浓度的抗性反应。结果发现抗氨苄青霉素的菌株有PSB3,PSB4,PSB13,PSB26,PSB58,PSB67,PSB77;抗链霉素的菌株PSB4,PSB13,PSB26,抗卡那霉素的菌株PSB4,PSB26,PSB67,PSB77;PSB4,PSB26,PSB77菌株对四环素具有较强的抗性;PSB4,PSB13,PSB15,PSB26,PSB67,PSB77菌株对氯霉素具有较强的抗性;PSB3,PSB4,PSB26,PSB58,PSB77菌株对利福平有抗性,PSB77菌株对头孢霉素有较强抗性。解磷细菌对抗生素的抗性实验结果,可用于研究今后8株解磷细菌在土壤中的定殖状态。     

洛阳市番茄灰霉病菌对嘧霉胺的抗药性检测

为了明确洛阳市番茄灰霉病菌对苯胺基嘧啶类杀菌剂嘧霉胺的抗药性状况,2012—2013年从洛阳市不同保护地中采集番茄灰霉病病果或病叶,经单孢分离共获得番茄灰霉病菌54株。采用菌丝生长速率法测定了其对嘧霉胺的敏感性。结果显示,高抗菌株9株（16.67%）,中抗菌株19株（35.19%）,低抗菌株10株（18.52%）,敏感菌株16株（29.63%）。比较抗性水平不同菌株间的菌丝生长情况,发现菌丝生长速度和抗性水平无相关性。研究表明,洛阳市番茄灰霉病菌已对嘧霉胺产生不同水平的抗药性,且以中抗菌株为主,生产上应合理更换或轮换使用与嘧霉胺无交互抗性的药剂防治番茄灰霉病。     

Resistance of barley genotypes to brown leaf spot

Resistance of 59 barley cultivars to three distinct isolates of Bipolaris sorokiniana, causing brown leaf spot was tested on seedlings and adult plants in a screen house and in a growth room, by determination of disease incidence, disease severity, and rate of lesion expansion. The disease reaction and severity at the seedling stage differed among cultivars. The cultivars MNS Brite, NDB 112, Kindred, Parkland, and Oderbrucke were moderately resistant to brown leaf spot, but the resistance was partial to all three isolates. None genotype with complete resistance was found. The cultivars CI 9539, Svanhals, and Chevron, considered as sources of resistance, were classified as moderately susceptible, and susceptible, respectively. Disease severity, disease reaction, and incidence of B. sorokiniana in grains also differed among the cultivars at the adult plant stage. Nevertheless, none of the genotypes was resistant to B. sorokiniana. The rate of lesion expansion differed among cultivars BR 2, MN 698, Kitchin, Svanhals, and NDB 112, with NDB 112 having the slowest expansion rate (0.194–0.205 mm²/day).     

棉铃虫对甲氨基阿维菌素苯甲酸盐的抗性遗传力

 为了评估棉铃虫对甲氨基阿维菌素苯甲酸盐的抗性风险,在室内进行了棉铃虫对该药剂的抗性选育和现实遗传力分析。连续用甲维盐对棉铃虫选育25代,与同源对照种群相比,获得抗性倍数为2.974倍的汰选种群。采用阈性状分析方法,获得棉铃虫对甲维盐的抗性现实遗传力 (h²)为0.05218。进一步预测其抗性发展速度,假设以90%致死率继代处理棉铃虫,其抗性达到5倍、10倍分别需要18.67代和26.71代。