Respiratory control: loss in mitochondria from diseased plants

Mitochondria from healthy oat seedlings oxidized succinate with good respiratory control and high ratios of adenosine diphosphate to oxygen. After treatment with victorin, the pathotoxin responsible for symptoms of Victoria blight of oats, susceptible seedlings yielded mitochondria with little respiratory control and lower ratios of adenosine diphosphate to oxygen. No such effects were obtained with victorin-treated resistant seedlings or when victorin was added directly to mitochondria from healthy susceptible or resistant plants. These data indicate that victorin-induced disease results in a reduction in efficiency of the energy-generating system of isolated mitochondria.     

大豆疫霉根腐病菌毒素对抗感不同大豆品种根部超微结构的影响

用不同浓度的毒素处理抗感不同的大豆品种的根部,研究毒素对大豆细胞根部超微结构的影响。结果表明,较高浓度大豆疫霉根腐病菌毒素(稀释50倍,浓度为0.1794mg·mL-1)处理抗感不同大豆品种的根部后,抗病品种和感病品种根部细胞内部结构均遭到了明显的破坏。适宜浓度的毒素(稀释100倍,浓度为0.0897mg·mL-1)处理抗感品种根部后,抗病品种细胞内部结构基本上比较完整,而感病品种细胞内部结构已经发生了较大的变化,线粒体绝大多数都出现了空泡化。这说明只有在适宜浓度毒素处理下,才能在细胞超微结构上区分出抗感品种在抗性上的差异。本研究为揭示毒素在细胞水平的致病机理及寄主抗毒素的机理奠定了一定的理论基础。     

玉米大斑菌致病毒素及其应用的初步研究

用大斑菌接种玉米幼苗和用大斑菌的培养滤液处理玉米根冠细胞的试验证明,大斑菌无论在体内或体外均能产生致病毒素。大斑菌不同菌株,1号和2号生理小种所产生的毒素作用强弱不同。在不含Ht_1基因的玉米1号小种(真16号菌株)的毒力明显强于2号小种(260号菌株)。大斑菌毒素制剂以病叶提取液的毒素作用最强。毒素的生物测定以根冠细胞测定法精确度高。用大斑菌接种玉米幼苗后形成的病斑大小和其毒素处理玉米离体根冠细胞的死亡率呈正相关,接种和处理含Ht_1基因的RB37Ht_1自交系的结果也相同。可见,应用大斑菌毒素可以代替大斑菌分生孢子接种玉米鉴别1号和2号生理小种和自交系的抗病性。     

玉米单倍体胚性细胞无性系抗大、小斑病性与过氧化物酶活性关系的初步研究

本研究在亚致死浓度的选择压力下,分别用玉米大、小斑菌毒素筛选玉米单倍体胚性细胞无性系,获得了抗性细胞团。然后用毒素及病菌孢子处理,初步阐明了抗病性与过氧化物酶活性的关系,为玉米单倍体愈伤组织抗病性鉴定提供了生化依据。     

外源硅和辅酶Q10对盐胁迫下黄瓜根系线粒体的保护作用

【目的】探明外源Si和辅酶Ｑ10(CoQ10)对NaCl胁迫下黄瓜(Cucumis sativus L.)幼苗根系离体线粒体膜生物物理特性和呼吸功能的保护作用。【方法】试验设置3个处理：CK; 加50 mmol·L-1 NaCl; 加1.0 mmol·L-1 K2SiO3 + 50 mmol·L-1 NaCl。处理10 d后取各处理植株根系提取线粒体，在离体线粒体中加入10 mmol·L-1 CoQ10。【结果】Si能显著降低盐胁迫下黄瓜线粒体的H2O2含量，抑制线粒体的脂质过氧化，增加线粒体膜的流动性和膜电位(ΔΦM)，降低膜的肿胀度，使线粒体呼吸控制比(RCR)和氧化磷酸化效率(P/O)显著升高，提高线粒体的呼吸速率。CoQ10也有降低线粒体膜膨胀度，增加线粒体膜流动性和膜电位的作用，同时可以降低线粒体的H2O2和MDA含量，缓解盐胁迫的伤害作用。【结论】外源Si和CoQ10能有效缓解盐胁迫对黄瓜根系线粒体膜的损伤，增强线粒体抗膜脂质过氧化能力和膜完整性，提高线粒体的呼吸作用。     

玉米圆斑病菌（Helminthosporium Carbonum）致病毒素研究初报

玉米圆斑病菌1号和2号生理小种均能产生对寄主具有选择性的致病毒素(HC—毒素)。根据HC—毒素处理玉米根冠细胞后细胞的死亡情况,能较确切地反映如同分生孢子接种结果一样的抗感反应。HC—毒素的生物测定以根冠细胞测定法较精确。测定不受光照影响。培养基中性偏酸有利于活体外培养获得毒素作用较强的滤液。     

玉米圆斑病菌致病毒素的研究进展

玉米圆斑病菌(Helminthosporium carbonum)和寄主玉米作用过程中所产生的致病毒素(简称HC-毒素)是圓斑病菌诱发玉米发生圆斑病的主要因素。国外在HC-毒素的特性、致病机理以及毒素的应用等方面已有大量研究报导。本文就HC-毒素的特性、致病机理、生物测定及应用等方面作了比较全面的评述。     

玉米愈伤抗病性的快速鉴定技术

研究以玉米单倍体胚性细胞无性系和玉米小斑病菌致病毒素为试材，首先测定了ｐＨ值、温度和光照等因素对愈伤组织的离散细胞自然存活率的影响，在此基础上，进一步明确了致病毒素的最佳处理条件，从而建立了一套玉米愈伤组织抗病性的鉴定体系──离散细胞染色法。试验证明，该技术体系可操作性强、快速简便、灵敏可靠，可在其他许多植物细胞和组织培养的抗病突变体筛选中引用。     

A 13-kilodalton maize mitochondrial protein in E. coli confers sensitivity to Bipolaris maydis toxin

The Texas male-sterile cytoplasm (cms-T) of maize carries the cytoplasmically inherited trait of male sterility. Mitochondria isolated from cms-T maize are specifically sensitive to a toxin (BmT-toxin) produced by the fungal pathogen Bipolaris maydis, race T, and the carbamate insecticide methomyl. A mitochondrial gene unique to cms-T maize, which produces a 13-kilodalton polypeptide associated with cytoplasmic male sterility, was expressed in Escherichia coli. After addition of BmT-toxin or methomyl, inhibition of whole cell respiration and swelling of spheroplasts were observed in Escherichia coli cultures producing the novel mitochondrial protein; these effects are similar to those observed with isolated cms-T mitochondria. The amino-terminal region of the 13-kilodalton polypeptide appears to be essential for proper interaction with the BmT-toxin and methomyl. These results implicate the 13-kilodalton polypeptide in conferring toxin sensitivity to mitochondria of cms-T maize.     

大豆疫霉根腐病菌毒素的提取及生物活性测定

对大豆疫霉根腐病原菌的主要致病因子之一—毒素的提取方法进行了探讨,并用抗感不同大豆品种的切根苗进行了毒素生物活性及最佳浓度的测定、筛选。结果表明:毒素的提取采取弱极性的有机溶剂萃取的方法比较理想,尤其是用乙醚萃取;用稀释100×浓度的毒素处理抗感不同的大豆品种的切根苗可以产生与病原菌下胚轴接种法相同的症状,同时也证明该毒素是一种非寄主专化性毒素     

小麦叶片线粒体的分离

用差速离心法分离绿色小麦叶片线粒体。结果表明,经两次低速离心和两次高速离心,分离所得线粒体具有较高的呼吸活性和ADP/O比值,线粒体完整率达70％左右。本文对影响线粒体分离效果的因素亦进行了讨论。     

Changes in Cell Ultrastructure in Maize Leaves Infected by Maize Dwarf Mosaic Virus

Ultrastructural alterations in foliar cells were studied in leaves of resistant maize varietyLuyu16 and susceptible maize inbred line Luyuan92 infected by maize dwarf mosaic virus Shandong isolate(MDMV-SD), respectively. The results showed that marked cytopathological alterations were observed both inresistant plants and in susceptible plants, compared with that in healthy plants. However, some ultrastructur-al alterations, which observed in resistant plants, were different from those in susceptible plants. In resistantplants, which infected with the virus, the main organelles, including chloroplasts and mitochondria, wereslightly destroyed, the amount of mitochondria and peroxisome were increased. A few or no plasmodesmatawere observed. There were three kinds of inclusions including pinwheel, bundle and laminated aggregate, andthe virus particles in the cytoplasm. In susceptible plants, which infected with the virus, the chloroplasts wereheavily disrupted, including thylakoid swelling and envelope broking. The virus particles were more than thosein the resistant variety. Four kinds of inclusions including pinwheel, bundle, laminated aggregate and highelecton-dense body appeared in cytoplasm. Plasmodesmata and plasma membrane were abundant, and therewere frequent invaginations of the plasma membrane that led to the formation of vesicles and myelin-likestructures.     

感染玉米矮花叶病毒后玉米叶片细胞超微结构的变化

 利用透射电镜对感染玉米矮花叶病毒山东分离物 (MDMV SD)的不同抗性玉米叶片细胞超微结构进行了观察。结果表明 ,与健康植株相比 ,无论是在抗病品种鲁玉 16还是在感病的自交系鲁原 92细胞中 ,MDMV SD与玉米植株之间的互作都可以导致寄主发生明显的细胞病理学变化。但是 ,在抗病和感病植株中叶片细胞超微结构的变化存在明显差异。在抗病植株细胞中 ,虽然叶绿体、线粒体等主要细胞器的结构损伤较轻 ,但线粒体和过氧化物酶体的数量明显增多 ,细胞质中有风轮体、束状体和片层聚集体 3种内含体 ,存在于细胞质中的病     

氯化钾对玉米木质素代谢的影响及其与茎腐病抗性的关系

 【目的】阐明氯化钾（KCl）对玉米木质素代谢的影响，探讨和揭示KCl对提高玉米茎腐病抗性的机制。【方法】通过田间试验与室内分析相结合，研究了KCl对玉米不同抗性品种在接种禾谷镰刀菌（Fursarium graminearum）前后茎基部髓组织木质素含量的影响以及相关酶活性的变化。【结果】抗病品种吉单180茎基部髓组织原生木质素含量低于感病品种吉单327，但诱导木质素高于感病品种；而施用KCl则可降低原生木质素含量，增加诱导木质素含量。抗病品种茎基部髓组织苯丙氨酸解氨酶（PAL）和酪氨酸解氨酶（TAL）活性高峰出现时间均早于感病品种。虽然KCl降低了接种前玉米茎基部PAL、TAL和过氧化物酶（POD）活性的本底值，却提高了接种后PAL、TAL和POD的活性，尤其是高峰值。而且在接种前后，KCl处理的玉米茎基部髓组织肉桂醇脱氢酶（CAD）活性均保持较高水平。【结论】诱导玉米在接种后PAL、TAL、POD和CAD酶系的快速反应，提高诱导木质素含量，进而增强植株对病原菌的抗性，是KCl增强玉米茎腐病抗性的机制之一。     

菘蓝根腐病菌毒素最适浓度的筛选及其对菘蓝幼苗可溶性蛋白的影响

［目的］为深入研究菘蓝对根腐病的抗性机制提供理论依据。［方法］采用不同浓度菘蓝根腐病菌毒素处理菘蓝幼苗，筛选最适处理浓度；对最适浓度毒素处理过的菘蓝幼苗的外部形态进行鉴定，并测定其可溶性蛋白的含量。［结果］稀释10、20倍毒素处理过的菘蓝幼苗在试验期间全部萎蔫死亡，稀释40、50倍毒素处理过的菘蓝幼苗在试验期间大部分无病变现象，稀释30倍毒素处理过的菘蓝幼苗病变现象明显，处理72 h后50%幼苗萎蔫死亡。经稀释30倍毒素处理的菘蓝幼苗可溶性蛋白的谱带大体相同，但也出现了个别特异性条带；经毒素处理的样品蛋白条带数多于对照，且染色较深。［结论］菘蓝根腐病菌毒素的筛选压力以稀释30倍最好。     

海带岩藻黄素对小鼠脂质过氧化抑制作用的影响

用硫代巴比妥酸法测定小鼠肝组织及线粒体中丙二醛的含量,用分光光度法测定小鼠红细胞溶血和肝线粒体的肿胀程度,从而考察海带Laminaria japonica岩藻黄素对小鼠脂质体系的抗氧化能力。结果表明：岩藻黄素能在自发和诱导条件下抑制肝匀浆液及线粒体中丙二醛的产生,降低红细胞的溶血程度,并能减轻肝线粒体的肿胀程度,且其抑制作用均呈明显的剂量效应关系。这说明海带岩藻黄素具有明显的抗氧化作用。     

蔗糖含量与玉米对镰刀菌茎腐病的抗病性的关系

就玉米茎秆蔗糖含量与玉米对由禾谷镰刀菌 ( Fusarium graminearum)引起的茎腐病 ( cornstalk rot)的抗性间的关系进行了研究。结果表明 ,在玉米生理成熟期地上第二茎间髓部组织内蔗糖的含量与玉米对茎腐病的抗性密切相关 ,抗病的玉米杂交种的蔗糖含量明显高于感病的玉米杂交种。蔗糖含量与茎腐病的发病率呈显著的负相关关系。研究结果表明 ,在生理成熟期地上第二茎间髓部组织内蔗糖含量可作为选育抗镰刀菌茎腐病玉米杂交种的生化指标。     

Pathotoxin-induced disease resistance in plants

Primary leaves of bean plants treated with nonphytotoxic concentrations of the pathotoxin victorin were rendered highly resistant to two plant viruses. Leaves treated with higher concentrations of victorin became necrotic. These effects on plants that are resistant to victorin and to the fungus that produces it lend support to the hypothesis that activation of a defensive self-repair mechanism may account for resistance to this highly selective pathotoxin.     

C型雄不育玉米组培筛选专一性抗病株体

在培养2个C型胞质雄不育玉米杂交种的胚性愈伤组织时,加入玉米小斑病菌专化侵染性C小种两个菌株C7和C87-200的混合毒素,筛选出抗毒愈伤组织,经继代分化,获得抗病雄性不育再生植株。发现花粉育性和抗病基因不连锁,其下一代R#-1穗行仍表达抗病及雄性不育性状。     

Puromycin: action on neuronal mitochondria

Puromycin, in dosages that inhibit cerebral protein synthesis and expression of memory in mice, produces swelling of neuronal mitochondria. Acetoxycycloheximide, which inhibits cerebral protein synthesis to the same extent as puromycin, fails to produce swelling of neuronal mitochondria. Puromycin and heximide mixtures produce severe inhibition of protein synthesis, but result in a minimal swelling of neuronal mitochondria and in a decrease of peptidylpuromycin complexes to a level of 30 percent of that following the injection of puromycin alone. It is concluded that swelling of neuronal mitochondria in the presence of puromycin is not due to inhibition of cerebral protein synthesis per se, but is related to a specific action of puromycin on ribosomal protein synthesis. The findings are consistent with the hypothesis that peptidyl-puromycin complexes are responsible for mitochondrial swelling.