Effect of Juglone on Active Oxygen Species and Antioxidant Enzymes in Susceptible and Partially Resistant Banana Cultivars to Black Leaf Streak Disease

The black leaf streak disease (BLSD), caused by Mycosphaerella fijiensis, is the most destructive disease of bananas and plantains around the world. Breeding for resistance is the most promising strategy to fight this disease especially in small farmer plantations. Mycosphaerella fijiensis produces many phytotoxins such as juglone, which can be used, jointly with field and inoculations under controlled conditions, for screening banana cultivars for BLSD-resistance. This non-host specific phytotoxin has been shown to act on chloroplasts and disturbs the proton electrochemical gradient across the plasmalemma membrane. Moreover, an involvement of the oxidative burst during the interaction has been suggested. The present study was carried out using two cultivars that differed for either their juglone-responses or their resistance to BLSD (cv. Grande Naine susceptible to BLSD and juglone and cv. Fougamou partially resistant to BLSD and highly tolerant to juglone). The production of active oxygen species (AOS) and the enhancement of the enzymatic and/or non-enzymatic AOS-scavenging systems were investigated after treatment of the two cultivars with juglone. The time-course of AOS-production and AOS-scavenging was shown to be the key difference between these two tested cultivars after treatment with juglone. Thus, an early release of AOS (O₂⁻ radical and H₂O₂) and a quick stimulation of a preferment anti-oxidant system (superoxide dismutases, catalases, and peroxidases) was observed for cv. Fougamou as compared to cv. Grande Naine for which a late and weak generation of AOS accompanied by a late stimulation of the anti-oxidant systems were detected.     

核桃青皮中胡桃醌对朱砂叶螨触杀毒性的研究

为了解核桃青皮提取物对朱砂叶螨触杀毒性的物质基础,采用系统溶剂萃取法分别获得石油醚、二氯甲烷、乙酸乙酯、正丁醇萃取物;利用色谱技术从二氯甲烷萃取物中分离得到1个化合物,经核磁共振(1 H、13 C NMR)技术鉴定为胡桃醌(1);采用玻片法测定了化合物1对朱砂叶螨的触杀活性。结果显示:在处理24、48、72h后,化合物1处理朱砂叶螨的半数致死浓度(LC50)分别为6.96、3.73、1.90 mg/mL;当浓度为1mg/mL时,24、48和72h的校正死亡率分别为24.32%、35.14%和48.65%,触杀毒性研究表明,胡桃醌对朱砂叶螨具有触杀毒性,作用强度中等偏弱。这是首次发现蒽醌类化合物胡桃醌对朱砂叶螨一定的触杀毒性,其作用机理有待进一步研究。     

Juglone (5-hydroxy-1,4 napthoquinone) and soil nitrogen transformation interactions under a walnut plantation in southern Ontario, Canada

Juglone (5-hydroxy-1,4-naphthoquinone), a chemical substance produced by black walnut (Juglans nigra L.), inhibits the growth and existence of some beneficial soil microorganisms, especially Frankia spp. isolate ArI3 and Rhizobium japonicum. However, no studies to date have reported on the effect of juglone on soil ammonification and nitrification. A field study and laboratory incubation study to investigate this were conducted. In the field, in situ soil ammonification and nitrification were measured within and outside of a 60-year-old black walnut plantation and a eight-year-old poplar (Populus spp. clone DN 177) plantation. In the lab, soil (Sandy Fox Loam), collected in the absence of black walnut trees, was incubated for periods of one to six weeks in the presence of varying concentrations of juglone. In the field, peak summer mean nitrate accumulation rates in soils within the black walnut and poplar plantation were 163 and 95 μg 100 g^-1 dry soil day^-1 respectively and in soils outside the plantations, 104 (black walnut) and 78 (poplar) μg 100 g^-1 dry soil day^-1 respectively. No accumulation of ammonium at the end of the incubation period was noted. Therefore, no inhibition effect of juglone on nitrification in the field was observed, and laboratory incubation results confirmed the results of the field study. Results from these studies should address concerns about nitrification inhibition under walnut based intercropping systems. This revised version was published online in June 2006 with corrections to the Cover Date.     

酚类物质对核桃嫁接成活的影响

以富士苹果为对照,通过对嫁接成活率有显著差别的上宋6号、元丰和薄壳香三个核桃品种接穗中营养物质和酚类物质(包括酚类物质总量、酚酸类物质和核桃醌)的定量分析测定表明,酚类物质总量不是核桃嫁接成活困难的主要原因。其中,某些对愈合起抑制作用的酚类物质的存在,或对愈合起促进作用的酚类物质的缺少,可能是影响核桃嫁接成活的主要原因。     

核桃醌对黄芩种子萌发和幼苗生长的影响

为探讨核桃和黄芩复合种植的可行性,本文通过室内盆栽试验的方法研究了核桃主要化感物质核桃醌溶液对黄芩种子萌发及幼苗生长的影响。试验结果表明：核桃醌对黄芩种子的萌发主要表现出抑制作用,随着浓度的升高,抑制作用逐渐增强;对幼苗生长的影响则受到核桃醌浓度和黄芩幼苗密度双因素的影响,在高浓度或高密度下表现出较强的抑制作用,在低浓度高密度下则表现出一定程度的促进作用,但此促进作用主要针对地上部分生物量,对具有较高药用价值的根部则表现出强烈的抑制作用,因此本文认为核桃和黄芩并不适宜采用林药复合种植模式。     

核桃青皮活性物质提取方法及其抑菌作用研究进展

核桃青皮作为核桃生产中的副产物,一直被视为废料而弃之,不仅造成了环境污染,同时也浪费了自然资源。随着核桃青皮的利用价值逐渐被发现,国内外学者对其进行了深入研究和探索,并取得了一定的成果。就核桃青皮中活性物质的有效成分、提取方法及其抑菌作用方面的研究进展进行了综述,并对核桃青皮研究的前景进行展望,为核桃青皮的农业开发利用提供一定参考。     

减压蒸馏法提取核桃楸树皮中的胡桃醌

胡桃醌(5-羟基-1,4-萘醌)是从核桃楸中提取分离出来的一种萘醌类活性物质.研究采用超声波辅助浸提和减压蒸馏等方法,从核桃楸树皮中提取制得胡桃醌产品,产品得率 0.09%.分别用FT-IR表征了产品的有机官能团、用GC-MS分析了产品的化学组成和产品中胡桃醌的相对含量(GC含量达 96.42%)、通过 1 H NMR确认了产品的胡桃醌结构.本研究提供了一种从核桃楸树皮中简便快捷地提取制得高纯度的胡桃醌产品的方法.     

胡桃醌及其衍生物5,8-二羟基-1,4-萘醌抑菌活性研究

以红景天立枯病菌(Rhizoctonia solani Kühn)等12种病原真菌为供试靶标,测试了胡桃醌(5-羟基-1,4-萘醌)及其衍生物5,8-二羟基-1,4-萘醌的抑菌活性。结果表明:两者对丝核菌属病原真菌菌丝生长的抑制作用大于镰刀属,对3种丝核菌属病原真菌的EC₅₀分别为10.63～15.88mg/L、9.79～14.69mg/L;两者对玉米小斑病菌孢子萌发的抑制作用最高,在12.5mg/L时,抑制率均达到60%以上;在50mg/L时,对镰刀属4种病原真菌孢子萌发抑制率均达到60%。