黄瓜感染白粉病菌后的生理变化

抗性不同的黄瓜品种接种白粉病菌后,对与抗性有关的光合作用、呼吸强度及叶绿素、可溶性糖、可溶性蛋白质的含量进行了测定。结果表明:抗病品种呼吸强度比对照明显升高,感病品种则低于对照;抗、中抗品种光合速率先升高,5~6 d后开始下降,而感病品种的光合速率基本上低于对照,这与呼吸强度的变化相一致;无论抗病品种还是感病品种叶绿素含量均有增加,抗病品种增加幅度更大,说明黄瓜抗白粉病的能力与叶绿素含量呈正相关;接种后各品种糖含量的变化趋势基本一致,即降低-升高-再降低-再提高,而且均在第5 d出现第1个峰值,第7 d则出现最大幅度下降,可溶性糖含量明显低于对照,说明病菌的侵染消耗植株体内的糖,但并不能说明糖含量的降低与品种的抗病性密切相关;各黄瓜品种叶片可溶性蛋白质含量均高于对照,但感病品种比抗、中抗品种的峰值出现的要早,说明感病品种对病菌的侵染更敏感,品种的抗病性与对病菌侵染的反应呈负相关。     

不同抗性花生品种接种疮痂病菌后其生理特性及产量的变化

为了研究不同抗性花生品种对疮痂病的抗性差异,在田间试验条件下,采用喷雾法研究抗病品种‘贺油13’、感病品种‘泉花10号’接种疮痂病菌后其叶片生理特性及产量的变化。结果表明：可溶性糖含量在接种后呈先升高后降低的趋势,抗病品种其可溶性糖含量均高于其对照,而感病品种与其对照相比均有所下降,说明花生叶片中可溶性糖含量与植株抗病性有一定的相关性。抗感花生品种接菌后叶片可溶性蛋白质含量均高于其对照,但感病品种比抗病品种的峰值出现的要早,表明感病品种对病菌的侵染较敏感,品种的抗病性与对病菌侵染的反应呈负相关。接菌后抗感品种叶片超氧化物歧化酶(SOD)活性均呈先升高后降低的变化趋势,与其相应的对照相比,抗病品种比感病品种降低的幅度相对较小;花生叶片过氧化氢酶(CAT)和过氧化物酶(POD)活性随生育进程的推进整体呈现先下降后升高再降低的变化趋势,其相应的对照相比,接种后抗病品种的CAT和POD活性表现相对较高,由此说明保护酶在花生对疮痂病的抗性机制中起了重要作用。接种后2个品种叶片丙二醛(MDA)含量有所增加,表明其质膜受到不同程度的伤害。产量结果研究表明,接菌后抗、感品种均有所减产,但感病品种‘泉花10号’减产幅度较大。     

黄瓜感染黑星病菌后的生理变化及抗病性的产生

对抗性不同黄瓜品种接种前后与抗性有关的酶活性、木质素含量、酚类物质含量进行测定，结果表明：接种前各品种的POD，PPO，PAL活性、木质素及酚类物质含量与品种的抗病性之间无相关性，接种后则与品种抗病性密切相关。抗病品种PAL活性峰在接种后24h出现，POD和PPO活性峰在接种后48～72h出现，酶活性提高幅度大；感病品种酶活性峰则在接种后72～96h出现，提高幅度小于抗病品种。抗病品种木质素含量的最大值出现在接种后24h，较未接种对照提高幅度大；感病品种木质素含量的最大值出现在接种后96h，较对照提高幅度小于抗病品种。接种后抗病品种比感病品种合成更多的酚类物质，而且酚类物质含量的变化与POD、PPO活性变化之间呈负相关性。     

水杨酸诱导辣椒抗疫病生化机制的研究

对水杨酸（SA）处理及其挑战接种辣椒疫霉菌的4个抗性不同的辣椒品系体内木质素含量和多酚氧化酶（PPO）、过氧化物酶（POD）、苯丙氨酸解氨酶（PAL）活性的测定结果表明：SA诱导的供试品系与未经诱导的相同品系相比,木质素含量增高,PPO、POD、PAL活性增强,其中木质素的含量与抗病性呈显著正相关;挑战接种后两者相比,SA处理的供试材料的木质素含量和PPO、POD、PAL活性的增强幅度更大,其中抗、耐病品系的增加早且增加幅度高于感病、高感品系。值得注意的是,经SA诱导的各供试品系接种后木质素含量与抗病性也呈显著相关。木质素含量与相关酶活性的上述变化趋势与SA对各品系的诱抗效果完全吻合。     

陆地棉植株组织结构和生化代谢与黄萎病抗性的关系

通过对8个陆地棉品种的植株组织结构、酶活性和根系分泌物的比较分析,研究陆地棉黄萎病抗性机制。研究结果表明,陆地棉抗病品种根和茎的导管细胞壁厚、直径小、数目多,髓射线数目多、单位面积薄壁细胞数多,有助于抵御棉花黄萎病菌的侵入与扩展。过氧化物酶（POD）活性与棉花抗黄萎病的关系不明显,但苯丙氨酸解氨酶（PAL     

Screening for Resistance to Bacterial Blight in Upland Cotton (Gossypium hirsatum L.)

Fifty four varieties of upland cotton (Gossypium hirsutum L.) were screened for resistance to bacterial blight caused by Xanthomonas malvacearum E. F. Smith, (Dowson) under natural field conditions and artificial Inoculation. In general, moderately high levels of field infection provided useful information on susceptibility of varieties but 11 needed to be1 supplemented with artificial inoculation to confirm resistance. Hypocotyl regions of one week-old seedlings were subjected to artificial inoculation with bacterial blight crude isolate using hypodermic needles. None of the fifty lour varieties tested was immune to disease 18.5 % showed a high level of resistance, 29.6 % were recorded as resistant while 20.4 % were susceptible. Another 18.5 % were highly susceptible and 13.0 % showed inconsistent disease reaction under natural field conditions. However, under artificial inoculation the seedlings showed lesions of varied sizes but none of the varieties was found to be resistant. Statistical analysis showed non-significant (P = 0.05) disease interaction indicating susceptibility to disease at the seedling stage. This may be due to lower levels of resistance in seedlings than in mature cotton plants. The resistant varieties were mainly of African origin and well adapted to local conditions. They are therefore potentially useful as commercial varieties in their own right or as donor parents for blight resistance.     

棉花黄萎病不同抗性品种接菌前后体内酶活性及酚类物质含量的变化

研究了对黄萎病不同抗性棉花品种在接菌前后酶活性与酚类物质含量的变化。结果表明 :棉花对黄萎病的抗性与棉株组织中的过氧化物酶 (POD)、多酚氧化酶 (PPO)、苯丙氨酸解氨酶(PAL)活性及酚类物质 (主要为二元酚 )含量密切相关。不同抗感黄萎病棉花品种接种病原菌后 ,4个指标都有不同程度地提高 ,并于接种后 3～ 5d内出现峰值 ,峰值高低与抗性程度呈正相关     

马铃薯种质资源室内接种晚疫病的抗性鉴定

为了获得具有抗马铃薯晚疫病的品种,本研究以100份马铃薯种质资源为试材,采用室内离体叶片接种法和室内成株接种法进行晚疫病抗性评价,用高感品种Favorita接种后的症状为对照。室内离体接种鉴定结果为:‘CIP09-2’、‘CIP09-13’、‘DR-6’、‘DR-9’、‘花云’、‘R1R3’、‘云薯501’、‘R2’、‘BE13-3’等9份材料表现为高抗,占供试材料的9%;其它的15份表现中抗、44份表现抗病、23份表现感病和9份表现高感。欧氏距离类平均法聚类分析表明,聚为抗性品种的种质最多,其来源与马铃薯晚疫病的抗性没有太大关系。本研究对其中4份材料进行室内成株接种,结果表明:‘青薯10号’的抗病性高于离体叶片接种的抗性,为高抗品种;‘青薯9号’、‘2017ch-6’和‘费乌瑞它’抗性表现与离体叶片接种抗性鉴定结果一致。本研究发现所有供试马铃薯种质资源的抗性材料较丰富,可为抗病育种提供优质的亲本材料。     

Accumulation of soluble phenolic compounds in sunflower capitula correlates with resistance to Sclerotinia sclerotiorum

Disease symptoms and total soluble phenolics content have been analysed in four sunflower (Helianthus annuus L.)lines with different resistance levels(from highly susceptible to resistant) to head rot caused by Sclerotinia sclerotiorum (Lib.) de Bary. At the beginning of the flowering stage, capitula were inoculated by spraying with a water suspension of ascospores, and disease symptoms were evaluated from day 6 to day14 after inoculation. The most susceptible genotypes showed all their ovaries to be necrosed and abundant lesions in corollas, bracts and receptacle. In the resistant line, the ovary and corolla were only partially necrosed with no symptoms in the bracts or the receptacle. Total soluble phenolics were extracted and quantified from different parts of the capitulum in both inoculated and non-inoculated plants. The amount of phenolic compounds depended on the sunflower line, the time after inoculation, and the tissue. Higher constitutive and induced phenolic content as well as phenylalanine ammonia-lyase activity were present in the most resistant line, these differences correlated with the absence/presence of disease symptoms. This revised version was published online in July 2006 with corrections to the Cover Date.     

Standardizing resistance screening to Pseudomonas fuscovaginae and evaluation of rice germplasm at seedling and adult plant growth stages

Sheath lesions, grain sterility and grain discolouration of rice caused by Pseudomonas fuscovaginae can cause yield losses of up to 100 %. The most sustainable method of managing this disease is the use of host plant resistance. To identify sources of resistance an inoculation method that is practical, rapid and reliable is needed. We compare three different inoculation methods. Results showed that the pin-prick method is appropriate for identifying sources of resistance to P. fuscovaginae, while the spray method could be useful for mass screening of rice genotypes. The seed-soaking method was also evaluated and has showed potential in detection of early disease resistance. A total of 16 Multiparent Advanced Generation Inter-Crosses and 20 OryzaSNP set varieties from the International Rice Research Institute were evaluated using the pin-prick and seed-soaking methods. All growth stages were susceptible to the pathogen and the 10⁷ cfu mL^?1 inoculum concentration was optimal for discriminating between resistant and susceptible genotypes. For the pin-prick method, a single point assessment of disease severity at 14 days post-inoculation could be used instead of the AUDPC values to classify genotypes. An index of reduction in seedling height 10 days after seed soaking was established for the classification of the genotypes reaction to the disease. Resistant varieties identified using both the pin-prick and seed-soaking methods could be verified for use in disease resistance breeding programs. Of the 36 genotypes evaluated 22 were found to be resistant at the late booting or early panicle exsertion stage by pin-prick method, while 25 were resistant at the seed to germination stage. No correlation was found between the resistance classification of varieties between the two inoculation methods, indicating that there could be different mechanisms of resistance to P. fuscovaginae in rice.     

过氧化物酶同工酶与棉花黄萎病抗性的相关研究

对20个来源及抗性不同的海岛棉和陆地棉品种和2个陆地棉(S)/海岛棉(R)杂交组合 的亲本、 F1、 F2世代的POX同工酶研究表明, 接种黄萎病菌前后, 棉花叶片中的 POX同工酶酶谱发生明显变化, 抗病品种与感病品种的阴性POX同工酶谱带均由原来的3 条 增 至6条, 但两者之间不存在明显差异; 阳性POX同工酶谱带接种前后均只有1条(     

烟蚜取食对抗、感烟草品种信号分子和CAT活性的影响

为研究烟草品种抗蚜机制，选用6个不同烟蚜抗性的烟草品种，采用盆栽试验接种蚜虫，研究烟蚜侵袭后第0、3、6、9 h烟草叶片茉莉酸(JA)、一氧化氮(NO)含量以及CAT活性的变化。结果表明，受到蚜虫为害后，叶片JA含量均表现为先增加后降低的趋势，烟蚜取食6 h后叶片JA含量达到峰值，且抗蚜品种JA增量大于感蚜品种。受到蚜虫为害后，抗蚜品种叶片NO含量表现为先增加后减少的趋势，烟蚜取食3 h后NO含量达到峰值，感蚜品种烟蚜取食3 h后的NO含量与取食前差异不显著，但6 h和9 h后显著低于0 h。受到烟蚜侵袭9 h后，参试品种CAT活性均表现为增加趋势，烟蚜取食9 h后，抗蚜品种‘竖把老母鸡2113’的CAT活性增量最多，增幅最大。JA和NO含量以及CAT活性均可以作为烟草品种蚜虫抗性鉴定的生理指标，烟蚜取食5~6 h叶片茉莉酸含量的增幅可以用于鉴定烟草品种抗蚜性。     

小麦赤霉病与DON积累的抗性及其相关SSR位点差异

以禾谷镰刀菌(Fusarium graminearum Schwabe)菌株进行穗部喷雾和单花滴注接种,评价了10个小麦抗源的赤霉病和脱氧雪腐镰刀菌烯醇(DON)积累抗性。结果表明,望水白、苏麦3号、延岗坊主、繁60096属于高抗品种,Frontana表现感病,其余品种表现中抗。除Frontata外,所有抗源DON含量在3 mg/kg以下。不同接种方法间、不同致病菌株间的病小穗率和DON含量以及同一处理内的病小穗率和DON含量间呈极显著相关。利用与已报道的赤霉病抗性QTL相关SSR引物对供试材料进行PCR扩增,比较扩增产物等位位点的差异,除4B染色体的GWM113标记外,其余标记在品种间具有2~8个等位位点,多态信息含量为0.14~0.85。单倍型分析表明,延岗坊主具有与望水白一致的3B主效QTL的SSR标记位点,扬麦158和新中长分别在2D和4B上具有多个与武汉1号一致的抗性QTL相关SSR位点,翻山小麦在3B和6B上具有多个与苏麦3号或望水白一致的抗性QTL相关SSR位点,繁60096在2D上有多个与武汉1号一致的QTL相关SSR标记,而镇麦7459和温州红和尚与已报道的小麦赤霉病抗性多数SSR位点不一致,可能具有不同的抗性基因。     

Greenhouse and field techniques for testing sugar beet for resistance to Rhizoctonia root and crown rot

Rhizoctonia‐resistant sugar beet varieties are the key to an integrated control strategy for Rhizoctonia root rot. Because of the unpredictable occurrence of Rhizoctonia solani in the field testing of sugar beet for resistance to Rhizoctonia root rot is difficult. The aim of the study was to develop advanced greenhouse and field techniques which allow a reliable assessment of sugar beet for resistance to R. solani. A highly infectious liquid inoculum was used for the first time in this study. It can be produced in large quantities of a standardized quality, sterile, and exactly quantified according to its carbon content. In a greenhouse trial, sugar beet grown in the same way as field grown beet was inoculated by applying a suspension of Rhizoctonia mycelium (equivalent to 10 mg carbon per plant) to the beet crown. After 3 weeks, inoculation had led to uniform and severe root rot. Disease symptoms were similar to those found under natural conditions in the field. No ‘escapes’, i.e. susceptible plants apparently expressing resistance were observed in the test. A new nine‐class disease scale was established and a Rhizoctonia index (RI) was calculated. Reliability of disease assessment was demonstrated on progeny of plants, selected from segregating populations, showing Rhizoctonia resistance more closely related to the resistant parent lines than to the susceptible ones. Sugar beet varieties could be assessed in the greenhouse within only 11 weeks. All varieties were affected by the pathogen but partially resistant varieties could be clearly recognized by a significantly lower Rhizoctonia index. Significant differences in susceptibility were also found within the group of new resistant genotypes. Infection studies performed in the field showed the superiority of the new liquid inoculum compared with a solid form and revealed the influence of inoculation date and inoculum level on the development of Rhizoctonia root rot. In field tests performed at different sites under different environmental conditions, susceptible and partially resistant sugar beet varieties could be reproducibly rated according to their susceptibility to R. solani. On average, susceptible varieties showed a Rhizoctonia index of 8 while resistant genotypes ranged from 5 to 6. The newly developed techniques allow fast and reliable evaluation of sugar beet for resistance to R. solani.     

海岛棉枯萎病抗性与类黄酮代谢相关基因表达量的相关

枯萎病是危害海岛棉生产的重要因素之一, 研究枯萎病抗性分子机制将为培育抗病海岛棉品种、解决枯萎病对海岛棉的危害问题提供坚实的基础。本研究在前期转录组测序的基础上, 对海岛棉枯萎病抗性差异表达基因进行分析(DEG, Differentially Expressed Gene); 以7个抗病性表现不同的海岛棉品种为材料, 利用qRT-PCR的方法研究抗病差异表达基因在不同接菌时间点的表达量差异, 并分析基因表达量与病情指数的相关性。结果表明, DEG分析得出类黄酮代谢通路相关基因与海岛棉枯萎病抗性有关。qRT-PCR分析显示抗病材料中类黄酮代谢通路关键基因的表达量显著高于感病材料。在接菌后多个时间点, 类黄酮代谢通路中的关键基因TT7、CHI和DFR在抗病材料中的表达量显著或极显著高于感病材料, 其中CHI和DFR基因的表达量与病情指数呈显著负相关。综上所述, 类黄酮代谢通路相关基因对海岛棉枯萎病抗性均有影响, 且CHI、TT7和DFR基因是关键基因。     

感抗油菜近等基因系混播对根肿病发病率的影响

近年来,根肿病的迅速蔓延已对我国油菜生产造成严重威胁。课题组前期多年多点大田试验发现,感病、抗病品种混播可显著降低感病油菜品种根肿病发病率。为进一步探究感病、抗病品种播种间距对根肿病的防控效果,本试验采用穴盘栽培,设置感、抗根肿病油菜近等基因系不同播种间距(0、2、4、6 cm),出苗后7 d接种根肿菌,接种42 d后调查幼苗发病率、病情指数,并测定根系主要成分。结果表明:(1)与单播相比,感病、抗病品种同播时,抗病品种苗期发病率无明显变化,而感病品种苗期发病率显著下降,其发病率与感病、抗病品种播种间距密切相关,二者距离为0 cm时的发病率及病情指数均显著(P0.05)低于其他处理;(2)与单播相比,感病、抗病品种同播时,抗病品种和感病品种根中可溶性糖及可溶性蛋白质含量均显著降低,酸不溶木质素含量在感病品种中显著增加,而在抗病品种中呈现先增加后降低的趋势;(3)发病率和病情指数均与根系可溶性糖和可溶性蛋白质含量显著正相关(P0.01),发病率与可溶性糖和可溶性蛋白质含量的相关系数分别为0.797、0.403,病情指数与可溶性糖和可溶性蛋白质含量的相关系数分别为0.822、0.509。综上,油菜感、抗品种混播可以显著降低感病品种的根肿病发病率,且混播间距在0 cm时效果最好。该技术可以作为油菜根肿病防控的技术措施,在根肿病发病区域油菜生产上有着较好的应用前景。     

Fungitoxic effect of scopolin and related coumarins on Sclerotinia sclerotiorum. A way to overcome sunflower head rot

Summary The content of coumarins, as probable phytoalexins, was analysed in four sunflower genotypes that ranged in responses to head rot from highly susceptible to highly resistant. Low levels of all coumarins (scopolin, scopoletin and ayapin) were detected in the three most susceptible genotypes irrespective of time after inoculation. However, in the resistant genotype there was a clear time-dependent disease-induced increase of all coumarins that reached a maximum after 10–14 days. Detailed comparison of the most susceptible and the resistant genotype showed that in the resistant but not the susceptible, scopoletin peroxidase activity increased during the course of the experiment. Results confirmed a clear negative correlation between coumarin content and disease symptoms and in particular for scopolin. Furthermore we show for the first time that scopolin is inhibitory to Sclerotinia at similar doses to scopoletin. As scopolin is known to be less phytotoxic than ayapin and scopoletin, its accumulation may well confer head rot resistance with minimal plant damage and might be one of the bases for resistance to Sclerotinia.     

Expression of resistance to downy mildew at cotyledon and adult plant stages in Brassica oleracea L.

This research compared the expression of resistance to downy mildew at cotyledon and adult plant stages in seven Brassica oleracea genotypes against two P. parasitica isolates of different virulence. Seven day old seedlings were dual inoculated under controlled environment by depositing two 10 μl droplets of a spore suspension of a different isolate on each cotyledon and the interaction phenotype (IP) evaluated 7 days later using a 0–5 scale of increasing susceptibility. The seedlings were transplanted to 16 cm pots and grown in the greenhouse for 110 days (15 to 28 leaves). Adult plants were tested using a single leaf inoculation method that allowed the same plant to be simultaneously inoculated with the two P. parasitica isolates. Leaves were scored 10 days after inoculation using a 0–5 scale of increasing susceptibility. The inoculation of the same plant with the two isolates produced different combinations of cotyledon (CT) and adult-plant (AP) interaction-phenotype according to the genotype. CrGC 3.1 was susceptible at CT and AP stages, ‘Algarvia’ resistant at CT and AP stages, and broccoli ‘A’ susceptible at CT and resistant at AP stage against the two isolates. ‘Murciana’ and broccoli ‘B’ were differential at CT and AP stages. Savoy and Shetland cabbages were differential at CT stage and resistant to both isolates as adult plants. Cotyledon resistance could not be used to predict adult-plant resistance since the two types of resistance were very poorly correlated. Resistance can be race specific either at cotyledon or at adult-plant stage. This revised version was published online in July 2006 with corrections to the Cover Date.     

Resistance of nineteen cultivars of subterranean clover to four races of Phytophthora clandestina

Summary The resistance of 19 cultivars of subterranean clover was screened against 4 races of P. clandestina by mycelial inoculation of roots of 10-day-old seedlings growing in water agar and by growing seedlings in pasteurised potting mix containing infested vermiculite in controlled conditions. The cultivars showed differential resistance (vertical resistance) to races of the pathogen and can be divided into 4 resistance groups. Cultivars Clare, Esperance, Green Range, Junee, Mount Barker, Rosedale, Woogenellup and Yarloop were susceptible to all races. Cultivars Bacchus Marsh, Denmark, Enfield, Gosse, Goulburn, Karridale, Larisa, Leura and Trikkala were susceptible to races 1 and 3, but resistant to races 0 and 2. Cultivar Meteora was susceptible to races 2 and 3, but resistant to races 0 and 1. Cultivar Seaton Park (LF) was resistant to all races. Cultivars also varied in their race-non-specific (horizontal) resistance: cultivars that were susceptible to particular races usually varied in their degree of susceptibility to those races. In particular, Junee was more resistant to all four races than the other cultivars within its group. Similarly, cultivars Gosse, Larisa, Denmark and Trikkala were more resistant to races 1 and 3 than the other cultivars in their group. Races of the pathogen varied in their aggressiveness as well as in their virulence, as shown by the variation in aggressiveness of different isolates of race 0.     

甜瓜种质资源对疫病的抗性鉴定研究

旨在通过苗期人工接种鉴定,筛选高抗疫病的甜瓜材料,为甜瓜抗病育种以及抗疫病遗传学研究奠定基础。本研究采用灌根接种法,向植株根茎部土壤注入浓度为1×106个/mL的游动孢子悬浮液,对收集到的166份甜瓜材料进行了抗性鉴定,这些材料中有薄皮类型甜瓜41份,厚皮类型甜瓜104份,野生材料15份,近缘种6份。最终筛选到4份免疫材料,25份高抗材料。在供试的厚皮类型甜瓜中有66%的材料抗性水平在中抗及以上,而薄皮类型中有98%的抗性水平是感病或高感。通过相关性分析,发现厚皮类型甜瓜对疫病的抗性要显著高于薄皮类型甜瓜。通过对不同材料的果实性状进行调查,发现在免疫和高抗材料中有14份单瓜重达到1 kg以上,有8份果实可溶性固形物含量在10%以上。这些兼具高抗、高产和高可溶性固形物的材料,可用于抗病基因的定位、克隆等遗传学研究,也可作为育种亲本将抗病基因转移到农艺性状优良但抗性差的甜瓜品种中。