外源一氧化氮对棉花种子吸胀期间耐冷性和发芽能力的影响

 选用对温度敏感性不同的棉花品种为试验材料,研究外源一氧化氮供体硝普钠（SNP）对棉花种子吸胀期间的耐冷性及发芽力的影响。结果表明,一氧化氮引发处理棉花种子,能提高低温胁迫期间胚内过氧化物酶（POD）、过氧化氢酶（CAT）、超氧化物歧化酶（SOD）和抗坏血酸过氧化酶（APX）活性,以及可溶性蛋白质和脯氨酸（Pro）含量,降低了相对电导率及丙二醛（MDA）含量,同时显著提高发芽率,并显著缩短发芽时间。低温吸胀48 h后,与对照相比,SNP处理后种子的发芽率平均提高29.85%,发芽时间平均缩短3 d。因此,一氧化氮处理能提高棉花种子吸胀期间的耐冷性,提高低温胁迫下种子发芽能力。     

H2O2对黄瓜种子发芽及幼苗抗冷性的影响

以津春四号黄瓜种子为试材,用不同浓度的H2O2溶液对黄瓜种子进行浸种处理,研究其对黄瓜种子发芽及幼苗对低温胁迫的影响.研究结果表明:适宜浓度的H2O2溶液能显著提高黄瓜种子发芽率,提高黄瓜幼苗在低温胁迫后叶片内叶绿素的含量,提高脯氨酸、过氧化氢酶的含量,降低丙二醛的含量,从而提高幼苗的抗冷性.     

多胺对玉米种子吸胀期间耐冷性和种子发芽能力的影响

以玉米耐寒自交系黄C和低温敏感自交系Mo17为材料, 研究了亚精胺(Spd)和精胺(Spm)引发对玉米种子吸胀中的耐冷性和种子发芽能力的影响。种子经0.25 mmol L^-1的Spd和Spm引发72 h后, 在5℃下低温吸胀不同时间(12、24、36和48 h)。结果表明, Spd和Spm引发提高了胁迫期间两自交系胚内过氧化物酶(POD)、过氧化氢酶(CAT)、超氧化物歧化酶(SOD)和抗坏血酸过氧化物酶(APX)活性, 以及可溶性蛋白质和脯氨酸(Pro)含量, 降低了胚渗出液的核苷酸含量, 同时显著提高发芽率, 并显著缩短平均发芽时间。低温吸胀48 h后, 与对照相比, Spd和Spm处理分别提高两自交系种子的平均发芽率18.5%和14.0%, 分别缩短平均发芽时间1.21 d和1.14 d。黄C在种子吸胀期间的耐冷性强于Mo17。总之, Spd和Spm处理能提高玉米种子吸胀期间的耐冷性, 提高低温胁迫下种子发芽能力。     

聚乙二醇对低温胁迫下黄瓜种子萌发及幼苗生理特性的影响

以黄瓜(津春4号)种子为材料,研究了不同浓度的聚乙二醇溶液(10%、20%、30%)浸种后在不同温度下对黄瓜种子萌发和幼苗抗冷性的影响。结果表明:本试验条件下,3种浓度的聚乙二醇浸种处理能促进黄瓜种子的萌发,尤其是在低温条件下的萌发,降低黄瓜幼苗的相对电导率、丙二醛和脯氨酸的含量,提高了黄瓜幼苗的过氧化物酶活性;综合比较表明,以20%的聚乙二醇浸种对黄瓜种子萌发和幼苗抗冷性的效果最好。     

低温下玉米幼苗叶片某些细胞器可溶性蛋白质的变化

抗冷性不同的玉米自交系在4～5℃低温处理 0、24、48、72小时后,三叶期幼苗叶片各细胞器中可溶性蛋白质的变化存在着明显的差异.不抗冷自交系各细胞器可溶性蛋白质含量显著降低,凝胶电泳有新蛋白质带出现;抗冷自交系可溶性蛋白质含量降低不显著,仅有细胞质部分出现一条新带.蛋白酶活性在低温处理初期降低,24小时后升高,且不抗冷自交系比抗冷自交系升高的速度快.试验证明,可溶性蛋白质含量的变化是鉴定植物抗冷性的重要指标,并发现有新蛋白质的适应谱带,是抗冷蛋白研究的重要基础.     

壳聚糖对黄瓜种子萌发及幼苗抗冷性的效应

以黄瓜（津春4号）为试材，研究了不同浓度的壳聚糖溶液在不同温度下浸种，时黄瓜种子萌发及幼苗抗冷性相关生理生化指标的影响。结果表明：3种浓度的壳聚糖溶液浸种均能不同程度的提高黄瓜种子的发芽率、发芽势、发芽指数、活力指数，提高黄瓜幼苗过氧化物酶（POD）、过氧化氢酶（CAT）的活性；降低细胞膜透性、丙二醛（MDA）；对幼苗脯氨酸含量的影响不明显。其中以0．3％壳聚糖溶液浸种效果最好。     

贮藏在海藻酸钙胶丸中的荔枝种子活力

从健康果实中取出的荔枝种子分别放入加有0．1％代森锌的海藻酸钙溶液中，然后在2％氯化钙溶液中胶丸化，形成胶丸种子。胶丸种子和非胶丸种子在10℃下贮存80天，非胶丸种子在10℃中贮藏40天发芽率是11．7％，胶丸种子（4％海藻酸钙）在贮藏80天后仍有53．3％的发芽率。结果表明用海藻酸钙制成的胶丸可延长荔枝这样的“顽拗型”种子的贮藏寿命。     

玉米自交系芽期耐冷性鉴定

低温冷害是北方春玉米区主要的气象灾害之一。通过种子低温发芽试验对8个东北地区生产上主要利用的玉米自交系进行芽期耐冷性鉴定。在常温（25℃）和低温（10℃）条件下分别测定了发芽势、发芽率、平均发芽时间、发芽指数、幼苗干重和活力指数等,并以各性状低温与常温下测定值的比值（相对值）作为耐冷性鉴定指标。通过聚类分析将自交系分为耐冷性强中弱3类,其中PH4CV、吉419和吉495耐冷性强,H21耐冷性中等,W9706、黄早四、丹黄02和四279耐冷性弱。相关性分析表明,相对发芽率、相对发芽指数、相对幼苗干重与相对活力指数呈极显著相关,可以作为玉米自交系芽期耐冷性鉴定指标。本试验为大规模鉴定和筛选芽期耐冷玉米种质奠定了基础。     

棉花幼苗对低温胁迫的响应及抗冷机制初步研究

【目的】探讨棉花不同组织对低温胁迫的响应,初步探讨研究抗冷的生理生化和分子机制。【方法】测定了4个抗冷性差异显著的材料在低温处理后的生物量、抗氧化酶活力和可溶性蛋白含量,同时分析了抗冷相关基因在豫2067根、茎、叶的表达情况。【结果】4℃低温处理24 h对冷敏感材料生长抑制最大,对根系生长的抑制大于地上部分;细胞膜透性测定结果表明,受低温胁迫后4个材料根系细胞膜能保持相对稳定的结构,而叶片细胞膜对低温胁迫敏感,抗冷材料叶片细胞膜稳定性大于冷敏感材料,低温胁迫后叶片细胞膜透性与棉花的抗冷性呈负相关,可以作为棉花抗冷性的鉴定指标;棉花在受到低温胁迫24 h后,抗冷材料根中SOD的活力基本不变,冷敏感材料根中SOD的活力却极显著下降,2个材料的根系中POD、CAT的活力均下降,但抗冷材料豫2067下降的幅度小于冷敏感材料,可溶性蛋白含量在抗冷材料叶茎中基本不变,在冷敏材料的叶片和茎中均下降。低温胁迫后5个与抗冷相关的基因在豫2067叶片中上调表达的多于下调表达的,上调表达的基因分别是脂肪酸脱氢酶基因、胁迫诱导蛋白基因、假定R2R3-MYB转录因子基因、b HLH1转录因子基因;在根中下调表达的多于上调表达的,下调的基因分别为b HLH1转录因子基因、胁迫诱导蛋白基因、伸展蛋白基因2,这与根系的生长受抑制的结果是一致的。【结论】推测这些抗冷相关基因在叶片中的上调表达与叶片生长受低温抑制程度低有一定的关系。     

不同物理方法处理对武陵假俭草种子萌发影响的研究

本实验采用摩擦处理、划破种皮处理、热水浸种处理、低温处理和浸泡处理5种物理方法处理武陵假俭草种子,比较了不同物理处理方法对种子发芽率的影响。结果表明:摩擦处理效果最好,发芽率、发芽势和发芽指数分别为93.30%、91.33%和68.03,分别比对照高50.71%、98.54%和86.34%;其次为划破种皮处理,该处理的发芽率可达88.67%;60℃热水浸种10min处理的发芽率为80.67%,比对照提高42.97%;-18℃处理50min和浸种处理12h也能显著提高种子的萌发效果(p<0.05),种子的发芽率分别为78.67%和75.33%。综上所述,如需小面积建植武陵假俭草草坪,建议采用摩擦处理,提高种子萌发效果最好;如需大面积建植武陵假俭草草坪,建议采用60℃热水浸种10min,以提高种子的发芽率。     

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。     

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).     

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。     

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。