The Effect of Post Inoculation Treatment with Mineral Oil on TMV Multiplication in Tobacco Leaves and Protoplasts

Half leaves of N. tabacum dipped into a 0.2 % emulsion of meneral oil 15min after inoculation with tabacco masaic virus (TMV) developed significantly fewer lesion than when not dipped Dipping reduced lesion numbers when applied up to 2½ h after inoculation and multiple dippings were more effective than one. The effect of oil was the same whether the inoculum was whole virus or RNA. Tobacco protoplasts treated with mineral oil contained less virus than untreated protoplasts. The oil probably acted by killing the protoplasts and was effective only when protoplasts were centrifuged through the oil emulsion, When water-treated leaves were dipped into a TMV solution there was an effect on TMV infection similar to that caused by dipping in oil after TMV inoculation.     

Acquired Resistance in Hypersensitive Tobacco Operates by Limiting Cell-to-Cell Spread of Virus Infection without Affecting Virus Multiplication

Localized and systemic acquired resistance against tobacco mosaic virus (TMV) or tobacco necrosis virus was induced when local lesions were produced in leaves of Xanthi-nc tobacco by mechanical inoculation with TMV. Both types of resistance were characterized by reduction in the size of lesions produced by the challenging viruses, whereas accumulation of viral antigen in lesions was slightly increased. These results, confirming previous findings relative to other hypersensitive plant virus combinations, do not support the view that an inhibitor of virus replication operates in the resistant tissues, but indicate that both types of resistance operate only against cell-to-cell spread of virus.     

The Effects of Polyacrylic Acid, Acetylsalicylic Acid and Salicylic Acid on Resistance of Cucumber to Colletotrichum lagenarium

Injection of cucumber cotyledons with polyacrylic acid (PA), acetylsalicylic acid (ASA) and salicylic acid (SA) induced resistance to inoculations with Colletrichum Iagenarium when inoculation followed injection by 96 h but not by 24 h. Size and number of lesions were greatly decreased. Resistance was greatest in injected cotyledons but was also pronounced in non-injected halves of cotyledons and occasionally in first or second leaves.
Incorporation of PA, ASA and SA into liquid shake cultures did not significantly affect growth of the pathogen.
Gel electrophoresis of soluble proteins extracted from cotyledons showed that induction of resistance was not accompanied by the appearance of novel soluble proteins.     

Effects of Light and Inhibitors of Photosynthesis and Respiration on the Multiplication of Tobacco Mosaic Virus in Tobacco Protoplasts

The multiplication rate of tobacco mosaic virus (TMV) in tobaccoprotoplasts in light was several times than in the dark. 3-(3,4-Dichlorophenyl)-1,1-dimethylurea(DCMU) at 10^–5M completely antagonized this illuminationeffect. KCN at 10^–4 M and antimycin A at 10^–5 M,which prevented the protoplasts from surviving in the dark,did not block TMV multiplication in light. Inhibitor experimentsshowed that photosynthesis and respiration were indirectly associatedwith the TMV multiplication. Either of them was found to benecessary for TMV multiplication but neither was indispensable.They play complementary roles in the supply of energy and materialsrequired for virus production. (Received August 2, 1984; Accepted July 9, 1985)     

The Effects of Salicylic Acid and Tobacco Mosaic Virus Infection on the Alternative Oxidase of Tobacco

Salicylic acid (SA) is a signal in systemic acquired resistance and an inducer of the alternative oxidase protein in tobacco (Nicotiana tabacum cv Xanthi nc) cell suspensions and during thermogenesis in aroid spadices. The effects of SA on the levels of alternative oxidase protein and the pathogenesis-related 1a mRNA (a marker for systemic acquired resistance), and on the partitioning of electrons between the Cyt and alternative pathways were investigated in tobacco. Leaves were treated with 1.0 mM SA and mitochondria isolated at times between 1 h and 3 d after treatment. Alternative oxidase protein increased 2.5-fold within 5 h, reached a maximum (9-fold) after 12 h, and remained at twice the level of control plants after 3 d. Measurements of isotope fractionation of 18O by intact leaf tissue gave a value of 23% at all times, identical to that of control plants, indicating a constant 27 to 30% of electron-flow partitioning to the alternative oxidase independent of treatment with SA. Transgenic NahG tobacco plants that express bacterial salicylate hydroxylase and possess very low levels of SA gave a fractionation of 23% and showed control levels of alternative oxidase protein, suggesting that steady-state alternative oxidase accumulates in an SA-independent manner. Infection of plants with tobacco mosaic virus resulted in an increase in alternative oxidase protein in both infected and systemic leaves, but no increase was observed in comparably infected NahG plants. Total respiration rate and partitioning of electrons to the alternative pathway in virus-infected plants was comparable to that in uninfected controls.     

Effects of Oxyamylose and Polyacrylic Acid on Foot-and-Mouth Disease and Hog Cholera Virus Infections

Two interferon-inducing polycarboxylates were tested for antiviral activity on foot-and-mouth disease (FMD) virus infections in mice, guinea pigs, and swine. Polyacrylic acid, given intraperitoneally, had a protective effect on infection by FMD virus administered in the peritoneal cavity of mice and in the foot pad of guinea pigs. Chlorite-oxidized oxyamylose (COAM) was effective in mice at a dosage of 2 mg/kg. Swine were not protected against naturally transmitted FMD by 120 mg/kg of COAM nor by polyacrylic acid. Swine were not totally unresponsive to COAM since it delayed symptoms of hog cholera. Interferon was not detected in the serum of COAM-treated swine. With FMD virus, an example was found of activity of interferon inducers in experimental hosts and lack of activity in a natural host.     

两个缺陷型TMV粒子在烟草中的互补表达

根据对ＴＭＶ高效复制和基因表达的顺式作用元件的分析,在体外重组包装了２个缺失型ＴＭＶ粒子：ＴＭＶＲＰ和ＴＭＶＣＰ。前者缺失了ＴＭＶ外壳蛋白ＣＰ基因的３′端及后序区域,后者缺失了大部分复制酶基因。把两者分别或共同电击感染烟草原生质体：１．用ＣＰ抗体进行免疫印渍检测,单独感染的原生质体内的ＣＰ在１６小时内无增加,而在共同感染的原生质体内,ＣＰ在感染２小时后就开始明显增加。２．用ＲＴ一两次ＰＣＲ法专一地检测新生负链ＲＮＡ的合成情况,在单独感染的原生质体内没有检测到,但在混合感染的原生质体内在感染１小时后就检测到ＣＰ基因特异的负链ＲＮＡ的形成,并用Ｓｏｕｔｈｅｒｎ杂交得到进一步验证。这些结果表明,复制酶缺失型ＴＭＶＣＰ内的ＣＰ基因不能表达,但可以在ＴＭＶＲＰ存在时,通过其所表达的复制酶互补作用得到复制从而有效表达．     

Cross-Protection and Multiplication of Mild and Severe Strains of TMV in Tomato Plants

The presence of virus having mixed coats has been demonstrated serologically in tomato plants cross-protected with a mild strain (M 11–16) against the severe (UI) strain of tobacco mosaic virus (TMV). The proportion of virus having mixed coats remained constant throughout at ca. 40% even in top leaves where severe symptoms caused by the challenge virus (U1) first appeared. The symptoms caused by the U1 in doubly-inoculated plants occurred in the leaves where:

• (a) the amout of total virus (irrespective of the type of coat) protein was 52% that of U1 strain in singly inoculated plants,
• (b) the multiplication of the severe U1 strain was reduced to only 9% as compared with the leaves singly inoculated with U1,
• (c) the ratio of severe to mild strain was increased to near equality although there was a significant reduction in the multiplication of U1in these leaves,
• (d) the amount of infective U1RNA started to increase.

     

The Effect of Light on Tobacco Mosaic Virus (TMV) Formation

Discs were punched from TMV-inoculated tobacco leaves (Nicotiana tabacum L.) and illuminated while floating on half strength Vickery's solution maintained at 24°C. After 48 hours some discs were placed in the dark for 24 hours and the amount of TMV formed in the light and dark compared. Discs from young leaves formed more virus in the light than in the dark. Discs from older leaves produced less virus, but as much in the dark as in the light.     

壳寡糖诱导烟草对TMV长距离移动的影响

采用ELISA-DSM法和半叶枯斑法,测定了壳寡糖(50μg/mL)诱导后普通烟(Nicotiana tabacum)植株体内TMV浓度的变化.ELISA-DSM测定显示,在接种后10 d,仅在接种叶的上位叶和新生叶片中检测到病毒,且病毒浓度仅为不诱导对照的52.7%和38.8%,在下位叶中未检测到病毒;同时,接种叶内病毒增殖严重受抑,接种后10 d,病毒浓度仅为不诱导对照的23.52%.半叶枯斑法检测获得了相同结果,以壳寡糖处理植株的不同叶位的叶片为毒源,产生的枯斑数目都大幅度低于不诱导对照.以上结果证明,壳寡糖处理后TMV的上行和下行长距离移动均明显延迟和减少,下行移动受到的影响更大.透射电镜检查发现,处理植株接种叶的下位叶片韧皮部细胞中没有病毒晶体和病毒粒子,在上位叶片筛管伴胞中仅见少量病毒粒子,两者都未发现任何诱导新生物,也未见其他细胞结构变化.结果表明,壳寡糖处理使烟草对TMV病毒侵染产生了诱导抗病性,系统侵染症状明显减弱;壳寡糖处理对病毒长距离移动的不利影响可能是接种叶片病毒增殖减少所造成的.     

Effects of Gibberellic Acid and Abscisic Acid on Shoot Formation in Tobacco Callus Cultures

Tobacco (Nicotiana tabacum L. cv. W. 38) callus grown on a shoot-forming medium was exposed to gibberellic acid (GA₃) and abscisic acid (ABA) for varying lengths of time and at different periods during culture. The results suggest that if the tissue accumulated sufficient GA₃ prior to the initiation of meristemoids and shoot primordia, repression of shoot formation occurred. This repression was not reversed by increasing the levels of auxin or cytokinin in the medium, but ABA could partially overcome the GA₃ repression of shoot formation.     

L型氨基酸对烟草赤星病菌毒素毒性的影响

为确定不同氨基酸对烟草赤星病菌产生的毒素毒性的影响,作者采用摩擦接种处理法、浇根处理法、种子根处理法三种生物测定方法,确定了以烟草种子根处理法作为烟草赤星病菌的毒性测定方法。用12种氨基酸分别以5种不同浓度与AT毒素混合接种,根长测定结果表明：L-谷氨酰胺,L-天冬酰胺,L-组氨酸所有供试浓度均增强病原菌毒素的毒性,而其余9种L型氨基酸对烟草赤星病菌GL-6产生的毒素有抑制作用,其中L-甲硫氨酸、L-亮氨酸、L-赖氨酸适宜浓度可明显降低供试病原菌毒素对烟草的致病性,与对照差异极显著,其有效浓度分别为0．02mg／ml、0．02mg／ml、0．02～2mg／ml。     

甲基紫精对水稻不同耐冷品种叶绿素荧光参数的影响

研究了不同浓度甲基紫精(MV)对水稻幼苗进行浸根处理,对不同耐冷品种常温和低温下叶绿素荧光参数的影响.结果发现,常温下,低浓度短时间的MV处理引起水稻原初光能转换效率(Fv/Fm)、光合电子传递量子效率(ΦPSⅡ)和光化学猝灭系数(qP)较对照增加,高浓度、长时间的MV处理则使各参数下降并低于对照,耐冷品种可以维持较高的非光化学猝灭系数(NPQ).低温下只有5 μmol/L甲基紫精(简称MV5)短时间处理时两品种的Fv/Fm增加,各处理引起ΦPSⅡ和qP下降,低浓度、短时间MV处理时NPQ增加.这说明轻度氧化胁迫可以刺激水稻的光合能力增加,但氧化胁迫会加剧水稻的低温伤害,耐冷品种也可以通过维持较高的线性电子传递速率和热耗散来避免这种过氧化伤害,表现出强的抗冷性.