H2S位于H2O2下游介导葡萄抗霜霉病过程

 以霜霉病抗性葡萄品种左优红和感病品种霞多丽为材料,研究硫化氢(H₂S)在葡萄应答霜霉病过程中的作用及其与过氧化氢(H₂O₂)的相互关系。结果表明,接种霜霉病菌后,抗性品种左优红和感病品种霞多丽叶片均出现H₂S含量的猝发、H₂S合成酶基因表达量增加、抗病相关蛋白多酚氧化酶(PPO)和β-1,3葡聚糖酶(Glu)活性显著升高现象;且H₂S清除剂次牛磺酸(HT)可以显著抑制霜霉病菌诱导的PPO和Glu活性升高,并导致葡萄的感病率和病情指数显著升高;同时外源H₂S可降低两个葡萄品种的感病率和病情指数。说明,H₂S是参与葡萄抗霜霉病过程的新的信号物质。受霜霉病菌侵染后,葡萄叶片H₂O₂含量猝发早于H₂S,并且H₂O₂清除剂抗坏血酸(AsA)可显著抑制霜霉病菌所诱导的H₂S含量的上升,而H₂S清除剂HT对霜霉病菌诱导的H₂O₂含量变化影响不显著,推测,H₂S作用于H₂O₂的下游参与葡萄抵御霜霉病过程。     

H2O2、NO和Ca2+参与疫病菌激发子PB90诱导烟草气孔的关闭

 本文研究了过氧化氢(H₂O₂)、一氧化氮(NO)和Ca²⁺在棉疫病菌激发子PB90诱导烟草气孔运动中的作用。1 nmol/L激发子PB90可诱导野生型烟草Bel-W3气孔关闭,且在相同条件下该激发子诱导反义抑制抗坏血酸过氧化物酶anti-APX烟草气孔关闭的孔径比野生型的更小;进一步药理学证明,抗氧化剂DTT和NADPH氧化酶抑制剂DPI(diphenylene iodonium)、一氧化氮合酶(NOS)抑制剂L-NAME、Ca²⁺螯合剂EGTA和Ca²⁺信号途径中CaMPK Ⅱ的竞争抑制剂KN93与磷脂酶C抑制剂U73122都能抵消PB90诱导气孔关闭的效应。推测该激发子PB90通过NADPH氧化酶途径形成H₂O₂、NOS途径形成NO和Ca²⁺信号途径进而诱导气孔关闭。表明H₂O₂、NO、Ca²⁺在激发子PB90诱导气孔关闭信号传递中作为第二信使起着重要的作用。     

HarpinXoo诱发烟草过敏反应早期H2O2变化及有关基因表达

 Harpin_Xoo是水稻黄单胞细菌(Xanthomonas oryzae pv.oryzae)产生的蛋白类激发子,用harpin_Xoo注射烟草最早在处理后20h出现肉眼可见的细胞死亡(macro-HR),分别经埃文斯蓝(Evans blue)和台盼兰(Trypan blue)染色观察,发现诱导后4-8h即开始有少量细胞死亡,表明在macro-HR发生前烟草细胞已陆续发生微细胞死亡(micro-HR);对二氨基联苯胺(diamino benzidine,DAB)染色显示,在烟草细胞死亡早期,伴有H₂O₂的明显积累;定量RT-PCR法对H₂O₂代谢相关基因的表达进行了分析,发现harpin_Xoo诱导后1h编码NADPH氧化酶的基因rboh即开始表达,3~7h表达较强,10h开始减弱,表达趋势与H₂O₂积累趋势一致;编码交替氧化酶的基因aoxl表达较迟,sodA基因则在诱导后表达减弱。这些基因的不同表达模式说明,它们在harpin_Xoo诱导的H₂O₂代谢过程中可能具有不同的作用。     

H2O2对水稻白叶枯病菌过氧化氢酶相关基因crg表达的诱导作用

 为了阐明H₂O₂对水稻白叶枯病菌(Xanthomonas oryzae pv. oryzae,Xoo)过氧化氢酶(CAT)相关基因(crg)表达的诱导作用,本研究定量分析了在水稻细胞-Xoo互作体系及其加入H₂O₂清除剂CAT后H₂O₂产量和crg表达;外源添加H₂O₂后的病菌生长和crg表达。结果表明:在互作条件下,H₂O₂含量稳定增加,10 h可达到峰值;在互作6 h时crg显著地被诱导表达;加入CAT显著地降低了H₂O₂含量和crg表达;在外源H₂O₂胁迫条件下,H₂O₂以浓度效应的方式影响病菌增殖,显著地诱导了catB和srpA表达。因此,Xoo-水稻互作导致了H₂O₂的发生。无论是互作产生的还是外源的H₂O₂均显著地诱导了Xoocrg表达,从而活化了H₂O₂降解途径。     

katExoo基因缺失突变对水稻白叶枯病菌H2O2抗性和致病性的影响

 为了揭示过氧化氢酶基因katExoo在水稻白叶枯病菌(Xanthomonasoryzaepv.oryzae,Xoo)过氧化氢(H₂O₂)抗性和致病性中的功能,本研究构建了基因缺失突变体ΔkatExoo,测定了突变体的H₂O₂抗性、过氧化氢酶(CAT)活性、在离体培养条件下的生长速率以及对水稻的致病性。用标记基因置换法获得了ΔkatExoo突变体,其保守的CAT结构域(GATase1_catalase和catalase_clade_2)被Gm^R片段所替换。katExoo基因缺失突变并不导致病菌的H₂O₂抗性和CAT活性降低或丧失,反而在一定程度上使之增强和升高。ΔkatExoo离体生长量显著降低,水稻接种叶片病斑明显缩短、在叶组织内的种群量下降。表明基因缺失突变显著地影响了病菌的生长、定殖和致病性。本研究结果为“KatExoo可能是Xoo的一个毒性因子”的假设提供了遗传学证据。     

欧亚种葡萄自交F1代对白粉病和霜霉病的抗性遗传

采用田间自然鉴定、田间接种鉴定及室内离体叶圆片接种鉴定三种方法,研究了10个欧亚种葡萄品种(系)、一个欧山杂种及其493株自交后代幼苗对葡萄霜霉病及白粉病的抗性及遗传关系,同时对其自交后代抗白粉病和霜霉病的遗传趋势进行了分析.结果表明,供试品种(系)及其自交后代对霜霉病与白粉病的抗性存在极显著相关,自交后代对两病表现伴随遗传现象,初步推断这可能是由葡萄抗病基因的多效性引起.在欧亚种葡萄品种自交后代群体中,虽然90%以上都是感病性中等或高的类型,但仍能够得到一定比例(10%以下)抗病性强的类型,这为利用欧亚种葡萄品种进行自交或品种间杂交选育优质抗病新品种提供了依据.     

外源Ca2＋和H2O2对NaCl 胁迫下枸杞离体叶片叶绿体中活性氧代谢的影响研究

以枸杞离体叶片为材料,研究NaCl胁迫下外源Ca2+和H2O2对枸杞离体叶片叶绿体中O2·产生速率、丙二醛(MDA)含量及抗坏血酸过氧化物酶(APX)、过氧化物酶(POD)和过氧化氢酶(CAT)活性的影响.结果表明:在NaCl胁迫下O2·产生速率呈上升趋势,丙二醛含量增大,保护酶APX、CAT、POD活性较对照升高.在NaCl胁迫下,加入外源Ca2+和H2O2时丙二醛(MDA)含量和O2·产生速率较单纯NaCl胁迫下降低;保护酶APX、CAT、POD活性较单纯NaCl胁迫下升高.表明外源Ca2+和H2O2在一定程度上可以缓解NaCl胁迫对植物体造成的伤害.     

葡萄应答霜霉病过程中多磷酸肌醇激酶基因与过氧化氢的作用机制

以对霜霉病不同抗性的葡萄品种左优红和霞多丽为材料,利用分子生物学和植物生理学试验手段,结合药理学试验,探讨葡萄在应答霜霉病过程中葡萄多磷酸肌醇激酶基因（VvIPK2）和H2O2的作用机制。接种霜霉病菌后15 h葡萄叶片VvIPK2表达量是正常水平的12倍,接种后3 hH2O2含量达最大值,同时苯丙氨酸解氨酶和几丁质酶活性升高;多磷酸肌醇激酶（IPK2）抑制剂、外源H2O2及H2O2清除剂均能改变霜霉病菌所引起的抗性葡萄品种左优红叶片PAL和几丁质酶活性的变化,同时可以影响不同抗性品种叶片的感病情况;IPK2抑制剂对葡萄霜霉病菌引起的H2O2水平变化没有影响;清除H2O2可减弱葡萄霜霉病菌对VvIPK2表达量的诱导效应。研究表明H2O2位于IPK2的上游,通过调控PAL和几丁质酶活性参与葡萄应答霜霉病过程。     

草酸和BTH对黄瓜幼苗霜霉病抗性和胞间隙病程相关蛋白的诱导

 本文研究了草酸和BTH(苯并噻二唑)溶液对黄瓜幼苗霜霉病的抗性诱导及病程相关蛋白的积累。结果表明:10mmol/L草酸或0.5mmol/LBTH均能诱导黄瓜对霜霉病产生局部和系统抗性,且抗性的持久期均在15d以上。BTH处理或接种霜霉菌都可系统诱导黄瓜叶片胞间隙液产生分子量分别为33、27和22kD的蛋白,而草酸没有诱导这3种蛋白的表达。BTH或草酸处理均可引起POD活性的升高,但和对照相比并没有新的POD同工酶表达,POD活性升高与黄瓜对霜霉病的抗性有关。     

SO2对灰霉葡萄孢和交链孢的抑制作用

灰霉葡萄孢（Ｂｏｔｒｙｔｉｓｃｉｎｅｒｅａ）和交链孢（Ａｌｔｅｒａｒｉａｓｐ．）是鲜食葡萄采后贮运中的主要病原菌ＳＯ２能有效地控制它们引起的鲜食葡萄的采后腐烂,作者分别设定５０μｌ／Ｌ．１ｈ,１００μｌ／Ｌ．１ｈ,２００μｌ／Ｌ．０．５ｈ,２００μ／Ｌ．１ｈ和对照５个处理,研究了不同剂量的ＳＯ２对灰霉葡萄孢和交链孢的孢子,菌丝及所引起的腐烂的抑制作用,研究了不同剂量的ＳＯ２对灰霉葡萄孢和交链孢的孢     

葡萄感染霜霉病菌后几种信号物质的变化

以3个抗病性不同的酿酒葡萄品种(‘西拉’‘霞多丽’‘赤霞珠’)叶片为材料,检测霜霉病菌侵染后几种病原相关信号物质,如脱落酸(ABA)、过氧化氢(H2O2)、一氧化氮(NO)、茉莉酸(JA)和乙烯(ETH)等的变化,以探讨葡萄抵御霜霉病菌的信号转导机制。结果表明,H2O2和NO是葡萄感应霜霉病菌的早期信号分子,且抗性较强的品种‘西拉’的变化最为明显;JA和ABA是抗性较差品种‘赤霞珠’应答霜霉病的信号组分。而3个抗性不同葡萄品种的乙烯变化无明显差别。推测H2O2、NO、JA和ABA均参与了葡萄对霜霉病菌的防御反应,但不同品种间信号转导组分可能存在差异。     

Inheritance of resistance to carboxylic acid amide (CAA) fungicides in Plasmopara viticola

Mandipropamid is a new mandelic acid amide fungicide expressing high activity against foliar infecting oomycetes, including the grapevine downy mildew, Plasmopara viticola . Because cross-resistance with the valinamide fungicides iprovalicarb and benthiavalicarb and the cinnamic acid amide fungicides dimethomorph and flumorph was postulated, all five compounds are classified as carboxylic acid amide (CAA) fungicides. To support this classification, cross-resistance among these compounds with field isolates and the segregation of resistance in F₁ and F₂ progeny of P. viticola were evaluated. A bimodal distribution of sensitivity in field isolates and cross-resistance among all CAAs for the vast majority of isolates were detected. Crosses between sensitive (s) and CAA-resistant (r) isolates of opposite mating types, P1 and P2, yielded abundant oospores. All F₁-progeny isolates were sensitive to CAAs (s:r segregation 1:0), whereas in F₂ progeny segregation of about 9:1 (s:r) was observed suggesting that resistance to CAA fungicides is controlled by two recessive nuclear genes. Mating type segregated in a ratio P1:P2 of c . 2:1 in F₁ and 1:1 in F₂ progeny. In the same crosses, resistance to the phenylamide fungicide mefenoxam segregated in a ratio of c . 1:3:2 (sensitive:intermediate:resistant), reflecting the monogenic, semidominant nature of resistance. The risk of resistance in P. viticola was classified as high for phenylamide and moderate for CAA fungicides. This is the first report on the inheritance of phenotypic traits in P. viticola .     

Temporal disease dynamics and relative importance of sexual and asexual reproduction of grape downy mildew (Plasmopara viticola) in an isolated vineyard in the North Georgia Mountains,USA

The North Georgia Mountains are the southernmost region along the United States East Coast where European wine grapes (Vitis vinifera) are grown commercially. Epidemics of downy mildew, caused by Plasmopara viticola, are frequent and severe, but little is known about the epidemiology and population biology of the pathogen in this region. Disease monitoring in an experimental vineyard from 2015 to 2017 indicated that times of disease onset and progress rates were highly variable across years and cultivars. Oospores were observed microscopically, and simulation with a process-based model indicated presence of conditions favourable for oospore germination in the spring and early summer each year. A total of 409 P. viticola isolates collected over three  years were genotyped with seven microsatellite markers, revealing very high genotypic diversity, which when combined with the observation of oospores is indicative of a sexually reproducing population. Among the 409 isolates, 225 multilocus genotypes (MLGs) were identified, of which 164 were detected only once and 61 were repeated (clonal). Eight MLGs (represented by 28 isolates) were detected across years, suggesting the possibility of asexual overwintering of P. viticola in this region. Across sampling dates, the percentage of isolates belonging to nonrepeated (unique) MLGs ranged from 27.3% to 63.2%. Even towards the end of the annual epidemic, the percentage of isolates in nonrepeated MLGs was still relatively high, around 30%. These MLGs may have originated from oospores germinating late during the growing season, although incomplete sampling at earlier dates and contribution by immigration cannot be fully excluded.