【作者】 李英；

【导师】 陈劲枫；

【作者基本信息】 南京农业大学 ， 蔬菜学， 2007， 硕士

【摘要】 瓜类蔓枯病是一种严重危害葫芦科作物后期产量的病害，广泛分布在世界各地，包括美国、加拿大、荷兰、印度等国家。在中国，浙江、上海、甘肃、新疆等地的瓜类产区均有蔓枯病的报道，而且有着逐年加重的趋势。但是，有关瓜类蔓枯病茵的系统报道却很少，本文主要对从南京和海南分离到的A型与Ba-1型菌株进行生物学特性的研究；由于A型菌株分布广泛并且不能直接产孢，为了得到大量可用于接种的分生孢子，对该菌株的产孢条件进行了初步的探讨；为提供可利用的抗病品种和抗源育种材料，从26份材料中，通过不同时期人工接种鉴定筛选出4个具有较高抗性的材料。1瓜类蔓枯病菌A型菌株鉴定及生物学特性的研究依据裘维藩等的分类方法，在南京分离到的蔓枯病菌株经鉴定属于Didymella bryoniae A型茵株。本文研究了培养基、碳氮源、酸碱度、光照和温度对该菌株的影响。10种被试培养基中，病菌菌落直径在马铃薯蔗糖培养基上最大，菌丝干重在酵母浸膏培养基中最高。碳氮源对菌丝生长的影响较大，麦芽糖和磷酸二氢铵有利于菌落直径增大，蔗糖和L-半胱氨酸有利于菌丝干重提高。菌丝生长的最适pH值为4.0。紫外光有助于菌丝的生长。菌丝生长和分生孢子萌发的最适温度为25℃，分生孢子致死温度为50℃10min。2瓜类蔓枯病的分离及A型菌株的产孢条件研究挑取单个子实体的分离方法易于获得纯化的甜瓜蔓枯病菌。A型菌株12h荧光／12h黑暗的常规光照条件下，不能形成分生孢子器，但经过一定时间的暗处理和间歇紫外灯（12h紫外灯／12h黑暗）照射后则能够产生大量分生孢子。本文从光照、温度、pH值、培养基、碳源、氮源几个方面对产孢量的影响进行了研究。综合各种因素，A型菌株产生分生孢子的最佳条件为：7d暗培养和4d间歇紫外灯处理的光照条件下，只含有磷酸二氢氨的马铃薯平板培养基，25℃时产生的分生孢子量最多。3瓜类蔓枯病菌B-la型菌株生物学特性的研究研究了培养基、碳氮源、酸碱度、温度和光照对瓜类蔓枯病菌（D．bryoniae）B-la型菌株菌丝生长、产孢和孢子萌发的影响。该菌株在10种不同的固体和液体培养基上均能生长。菌丝生长以马铃薯蔗糖培养基为最大；产孢量以半组合培养基最高。被试的12种碳源中，以麦芽糖的利用率和产孢量最高；被试的11种氮源中，菌丝生长以酵母提取物为最好，菌丝干重以DL-天门冬酰胺为最好，产孢量以硝酸钾为最好。病菌在pH值3.0-10.0均能生长和产孢，最适pH值为4。光照对菌丝的生长速率影响不大，但紫外光有助于菌丝干物质的积累和孢子量的增加。菌丝生长、产孢和孢子萌发的最适温度均为25℃；分生孢子的致死温度为55℃10min。4黄瓜品种（品系）对蔓枯病抗性的鉴定和筛选本文报道了黄瓜对蔓枯病（D．bryoniae）抗性的苗期鉴定方法和抗病品种（株系）的筛选结果。在1片真叶期以1×10⁶个·mL^-1或在3片真叶期以2×10⁶个·mL^-1的分生孢子悬浮液喷雾接种。25℃左右，RH100％，黑暗条件下保湿72h，可快速地将不同抗性的品种（株系）鉴别出来。苗期接种与成株期（8片真叶）接种抗性鉴定结果基本一致。将该方法与田间抗性鉴定相结合。从26个品种（品系）中选出4个（病情指数＜30％）较高抗性的材料。更多还原

【Abstract】 Gummy stem blight is a serious disease causing by D. bryoniae that affects the middleand late product of cucurbitaceous crops.This pathogen had been found in most of thecountries and regions, including America, Canada, Northerland, India, and so on. In China,gummy stem blight was becoming worse and worse in Zhejiang, Shanghai, Gansu andXinjiang.But there was a little systemic reports about the pathogen.This paper studied thebiology characteristics of A strain from Nanjing and B-la strain from Hainan.Because Astrain distributed abroad and couldn’t produce spores in the normal incubation, sporulationcondition of this strain was researched elementarily to get abundant conidium spores forinoculation.To provide germplasm resistanct to gummy stem blight, through artificialinoculation at different growth stages,we got 4 materials of cucumber that had high level ofresistance from 26 varieties （lines）.1 Identification and biology characteristics of A strain of D. bryoniae Acooeding to Qiu’s classification, the isolates from Nanjing were identified as A strainof D. bryoniae. The effects of different media, carbon sources, nitrogen sources, pH value,illumination and temperatures on the A strain of D. bryoniae were tested. In the 10 kinds oftested medium, diameter of colony was longest on the potato dextrose agar media and dryweight of mycelial was heaviest on the yeast extract media. It had different mycelialgrowth on different kinds of carbon or nitrogen sources media. Potato solid media withmaltose and NH₄H₂PO₄ was propitious to diameter of colony; and potato liquid media withdextrose and L-Cysteine was best for dry weight of mycelial. The fungus grew best with anoptimum of pH 4.0.The mycelial growth was enhanced by ultraviolet. The optimumtemperature for mycelial growth and conidia germination was 25℃, and the lethaltemperature of conidia was 50℃10min.2 Fruiting-body isolation of D.bryoniae and sporulation condition of its A stainUsing a single fruiting-body of D. bryoniae from infected melon stems could yield purecultures effectively, avoiding contamination with Fusarium oxysporum. Dark and UV light（12h UV and 12h darkness） treatment of the A stain of D. bryoniae yielded abundantconidia. 12h fluorescent and 12h darkness produced sterile mycelia. Media compositionaffected the amount of conidia produced. Among the 11 carbon sources combined withpotato agar, lactose gave the best results while no conidia were produced on potato agarwith fructose. Of the nitrogen sources, NH₄H₂PO₄ generated the most conidia and noconidia were produced on （NH₄）₂SO₄. Conidia could be produced within the pH range5.0-11.0, best results were obtained at pH 6.0 on PDA. Only plus NH₄H₂PO₄ in potato agar,7 d darkness and 4 d UV at 25℃were the ideal conditions for sporulation.3 Biology characteristics of B-la strain of D. bryoniaeThe effects of different media, carbon sources, nitrogen sources, pH value, illuminationand temperatures on the mycelial growth, sporulation and conidial germination of B-laswain of D. bryoniae were tested. The results showed that in the tested 10 media, mycelialgrowth was the fastest on the PDA, and the amount of conidia was the largest onhalf-composition agar. In the tested 12 carbon sources, maltose is an optimum carbon formycelial growth and sporulation. In the tested 11 nitrogen sources, mycelial growth was thefastest on the medium using yeast extract as nitrogen source; mycelial dry weight was thehighest on the medium using DL-asparagine as nitrogen source; and the amount of conidiawas the largest on the medium using niter as nitrogen source. The pH values for themycelial growth and sporulation were 3.0-10.0, with an optimum of pH 4.0.Illuminationhad no effect on the linear growth of mycelium, but contious ultraviolet could increase themycelial growth and the amount of conidia. The optimum temperature is 25℃for mycelialgrowth, sporulation and conidia germination, and the lethal temperature of conidia was55℃10min.4 Identification of cucumber cultivars and lines resistance to D. bryoniaeThe fast and reliable methods for identifying resistance of cucumber to D. bryoniae byartificial inoculation of the plant seedlings and screening of resistant plant seedlings andscreening the resistant plant varieties and lines were reported. The critical technique ofthese methods included inoculation of seedlings at 1 true leaf stage with a spore suspensionof 1×10⁶ spores·mL^-1 or at 3true leaf stage with 2×10⁶ spores·mL^-1, and incubation of the inoculated plants in the controlled condition （25℃, RH100％,darkness） for 72h, respectively,followed by examination of resistance levels. Resistance identify by these methods wasconsistent with mature plants （8 true leaves） in the field. Using these methods, 4matefialsof 26 cultivars and lines were high resistant （disease index＜30％） to D. bryoniae.更多还原