甘薯兼抗薯瘟病和蔓割病种质筛选鉴定

用甘薯瘟2个致病型菌株对557份甘薯品种(系)分菌系做盆苗和田间接种鉴定,并用蔓割病菌接种鉴定.结果表明,筛选出兼抗薯瘟病2个菌系的品种(系)31份,兼抗甘薯瘟和蔓割病的品种(系)有16份,其中泉薯860、泉薯854、金山93、榕选416、金山908、广薯88-70和泉薯853等7份与我省主栽抗病品种湘薯75-55(CK)相比,具有类似的双抗性能力,而其抗瘟能力更强.福薯87、林泗2号、金山57和湛93-16等4份对照品种只抗单个病害或兼抗单个菌系.     

抗蔓割病优质甘薯种质C180在育种中的应用

从河北351×莆薯76-16杂交后代中选育出的甘薯种质C180,具高抗蔓割病兼抗甘薯瘟Ⅰ型菌系、品质优良、抗病基因遗传力高、配合力好等特点,是抗病育种上已成功利用的核心亲本。福建省利用C180亲本材料直接或间接育成20多个甘薯新品系,其中通过国家或省级审定的品种8个。这些衍生品种主要用于我国南方薯区,多数分布在福建,推广面积较大的有金山57、福薯3282和泉薯723等品种。     

小麦纹枯病菌侵染过程的组织学研究

本文报道了小麦纹枯病菌侵染小麦的过程,病菌在穿透寄主之前产生侵染热 丝圈以及形态简单的单附着胞等侵染结构,由染垫基部丝或附产丰胞产生的侵染菌丝直接或通过气孔侵入寄主,也可见菌丝直接侵入寄主;菌丝侵入寄主表皮后,迅速在受侵细胞内呈网状产扩展,并直接穿透毗邻细胞壁,向其它细胞纵横扩展,受病组织出现细胞变形,变空;接近菌丝的质膜发生质壁分离,质膜断裂,叶绿体有,变小或接近消失,类本被破坏,叶绿体内嗜颗粒     

苜蓿假盘菌侵染苜蓿叶片的细胞学研究

采用微分干涉相差显微镜、扫描和透射电镜技术系统研究了苜蓿假盘菌Pseudopeziza medicaginis在苜蓿叶片的侵染过程及超微结构特征。结果表明,接种4h后,子囊孢子萌发产生芽管;12h后,芽管以直接侵入的方式进入表皮细胞形成侵染菌丝;24h后,表皮细胞中侵染菌丝向相邻表皮细胞扩展,同时侵入到叶肉细胞以胞内生长方式扩展;接种72h后,侵染菌丝在表皮细胞下的叶肉组织中形成初始菌落;第5d后,菌丝扩展至整个叶片组织,大量菌丝聚集形成子座组织,并进一步形成子囊盘与子囊。病菌菌丝在侵入寄主细胞初期,并不     

甘薯茎线虫病抗侵入和抗扩展资源评价

对69份创新种质和具有200个单株的RAPD分析分离群体进行甘薯茎线虫病抗侵入和抗扩展鉴定,结果表明:可作为抗性亲本的材料仅占创新种质的23.2%,福薯13为高抗侵入和高抗扩展特异资源,泉紫薯1号、烟紫薯176、徐01-2-5、徐01-25-8具有高抗侵入、抗扩展特性,可作为双抗亲本加以利用.另对甘薯茎线虫病抗扩展性鉴定方法的研究表明:采用室内接种200条线虫,25℃室温下培养45d,以薯块的横切和纵切面的平均防效进行评价最为有效.     

小麦叶锈菌侵染过程的显微和超微结构

采用光学显微技术和电子显微技术对小麦叶锈菌的侵染过程进行了研究。发现叶锈菌从气孔侵入后在气孔腔内形成气孔下泡囊,然后分化出圆形的膨大体,由膨大体产生1—2初生菌丝,初生菌丝在寄主细胞间隙延伸扩展,与叶肉细胞壁接触后分化形成吸器母细胞,吸器母细胞进入寄主细胞后形成吸器。初生菌丝在吸器母细胞处产生分枝,形成次生菌丝在叶肉细胞间蔓延。在病原菌侵染早期(接种后8—24h),寄主细胞的超微结构变化并不明显。侵染中、后期(接种48—72h),被侵染叶肉细胞发生严重质壁分离,叶绿体膨胀变形,基粒片层排列疏松。线粒体嵴突退化。     

棉花黄萎病病叶解剖

棉花黄萎病是一种维管束病。中脉的不同部位(基部、中部和顶部)病菌侵染的程度有明显不同。一般由基部向顶部,病菌侵染导管的百分率,由小到大。同时在某些导管中尚可见到胶状物质或侵填体。侵染导管的菌丝形状有二种,一种较粗,黄褐色;另一种较细,暗褐色,后一种比较普遍。黄萎病可以根据病叶感病的状况分为四级。在基部菌丝侵染的导管数量与外部症状之间,没有一定的相关关系。不过,如果把被菌丝侵染的导管与被胶状物质充塞的导管,以及含有侵填体的导管合并计算时,似可看到一些关系。     

高淀粉多抗甘薯新品种徐薯25的选育及特性评价

高淀粉多抗甘薯新品种徐薯25利用高产综合性状较好的徐薯18为母本,高干高抗优异材料徐781为父本,通过人工控制授粉杂交、多点综合鉴定筛选育成;2007年通过国家甘薯新品种鉴定,鉴定编号为国品鉴甘薯200702;2008年通过山东省品种审定,审定编号为鲁农审2008040.通过对徐薯25特征特性、生产力、抗病性、品质性状以及产量形成的生理特点进行深入研究表明:鲜薯产量与高产兼用品种徐薯18持平,薯干产量比徐薯18增产15%以上,薯块干物质含量则比徐薯18高4.24%;徐薯25在总光合势、净同化率等方面与徐薯18相似,其获得高产主要依赖于光合产物合理的分配,物质生产属"经济系数型";徐薯25高抗茎线虫病、根腐病、蔓割病;薯块粗蛋白、薯块还原糖、薯块可溶性糖和叶片粗蛋白均高于徐薯18.     

基于发根培养体系的甘薯品种抗线虫特性鉴定研究

利用发根农杆菌诱导的甘薯发根体系,鉴定甘薯品种抗线虫的特性。试验在甘薯品种徐薯18、栗子香和鲁78066诱导的发根体系上,接种马铃薯腐烂线虫,六周后调查发根繁殖线虫情况及线虫侵染发根情况,然后评价它们的抗线虫特性。结果表明:培养六周后,线虫在徐薯18、栗子香和鲁78066发根上繁殖倍数分别为8.82,0.76和0.70;在徐薯18发根上观察到多处线虫侵入位点,在栗子香和鲁78066发根上只观察到一处线虫侵入位点;基于以上结果,鉴定徐薯18为易感线虫病品种,栗子香和鲁78066为抗线虫病品种,徐薯18和鲁78066的鉴定结果和发病地自然诱发鉴定结果相一致,栗子香不同于发病地自然诱发鉴定结果。鉴定结果表明:用不同品种的甘薯发根作鉴定其抗线虫特性,具有体系简单、直观方便、重复性好以及不受自然环境影响等优点,进一步完善可以作为植物对线虫病抗性鉴定新的体系。     

尖角突脐孢菌侵染过程及稗草反应超微结构观察*

为了解尖角突脐孢菌侵染稗草植株的致病机理,应用电镜观察了该菌侵染稗草植株过程和寄主细胞的超显微结构变化。结果表明：尖角突脐孢菌分生孢子于接种8h后从突脐孢的基部开始萌发菌丝,接种13h后菌丝直接穿透稗草叶表面细胞连接处或经气孔侵入,接种后24～26h完成侵染过程。被侵染的寄主,膜结构发生变形,同时细胞线粒体的嵴变形膨大,叶绿体内的淀粉粒消失,寄主细胞内有大量酚物质出现。     

Fusarium Head Blight of Common Polish Winter Wheat Cultivars – Comparison of Effects of Fusarium avenaceum and Fusarium culmorum on Yield Components

The effects of Fusarium avenaceum and Fusarium culmorum on the reduction in yield components, after independent inoculation of 14 winter wheat cultivars, were investigated. Single isolates of F. avenaceum and F. culmorum were independently used in inoculations of winter wheat heads. Reductions in the following yield traits: 1000‐kernel weight (TKW), the weight (WKH) and number (NKH) of kernels per head after inoculation were analysed statistically. The results indicate differences between both pathogens in their effects on yield traits. The statistical calculations were performed using analysis of variance (a three‐factor experiment) for particular yield trait reductions and multivariate analysis of variance for the yield trait reductions jointly. Almost all of the univariate and multivariate hypotheses concerning no differences between pathogens (F. culmorum, F. avenaceum), climatic conditions (years) and cultivars as well as hypotheses concerning no interactions between factors (pathogens, years, cultivars) were rejected at least at P= 0.05 significance level. The reduction of yield traits indicated individual reactions of the tested winter wheat cultivars to different pathogens. Among the tested traits the highest influence on the rejection of the hypothesis concerning the equivalence of F. avenaceum and F. culmorum was observed for TKW and WKH. The effect of the pathogen on yield reduction was greater for F. avenaceum than for F. culmorum during 1996 and 1997. A comparison of the cultivars indicated that the Begra cultivar showed the highest tolerance to inoculation with both Fusarium pathogens. Moreover, this genotype as well as several others showed lower tolerance to F. avenaceum rather than to F. culmorum, whereas Elena was the only cultivar with the opposite tendency.     

大麦赤霉病抗扩展性鉴定与评价

利用禾谷镰刀菌单花滴注接种研究了245份大麦品种对赤霉病抗扩展性。结果表明,大麦赤霉病抗性除了抗初侵染外还存在抗扩展类型。比较了接种后7d、14d和21d的病小穗数和病小穗率以覆由不同期病小穗率获得的病程曲线面积等7个指标性状,并对其进行遗传参数分析,发现21d病小穗率指标在品种间具帔大的变幅、遗传变异系数和遗传率,21d病小穗数和病程曲线面积与病小穗率呈极显著正相关。不同大麦品种抗扩展性表现不一,供试品种中以Suyin21、乌金一号、莆846193、盐97001、96AC20-30五个品种21d病小穗率最低,为高抗品种,占全部供试品种的2．04％。     

Hydrolytic Activities of Fusarium solani and Fusarium solani f. sp. eumartii Associated with the Infection Process of Potato Tubers

The development of dry rot caused by Fusarium solani f. sp. eumartii was evaluated in susceptible (Huinkul) and resistant (Spunta) potato cultivars. Fungal proteolytic and polygalacturanase activities were measured at different days postinoculation either with the pathogenic F. solani f. sp. eumartii, isolate 3122 or with the non‐pathogenic F. solani, isolate 1042. After inoculation with the pathogenic fungus, proteolytic and polygalaturonase activities were higher in the susceptible than in the resistant cultivar. In addition, we found a correlation between the levels of proteolytic activity detected in the intercellular washing fluids with the size of the lesion area caused by F. solani f. sp. eumartii in Huinkul tubers. The action of the proteolytic activity over cell wall proteins of both potato cultivars was assayed. An extracellular potato protein with homology to proteinase inhibitors of the Kunitz family was identified as a substrate of the proteolytic activity in the susceptible cultivar. A microscopic study revealed differences between the potato genotypes in the rate of response to infection by F. solani f. sp. eumartii. In addition, the cell wall alteration caused by F. solani f. sp. eumartii in cortical cells of susceptible tubers was evaluated. The data with respect to the correlation between the course of cyto‐ and biochemical events of the two host–pathogen interactions were discussed.     

A rapid serological test for detecting Fusarium oxysporum f.sp. narcissi in Narcissus

Polyclonal antiserum was elicited against a strain of Fusarium oxysporum f.sp. narcissi (GCRI80/26) and a specific and sensitive enzyme-linked immunosorbent assay developed. Antiserum raised to cell wall fractions gave better recognition than that to cytoplasmic fractions. Recognition was equally good in artificially and naturally infected bulbs. Little cross-reactivity in bulb tissue was shown by three other bulb-rotting fungi. Nine isolates of F. oxysporum f.sp. narcissi from a wide geographic area gave similar results in an indirect ELISA of mycelial extracts, although some cross-reactivity was observed with two other Fusarium spp. Four Fusarium spp. and four other fungi showed little cross-reactivity. Ten days after inoculation the pathogen was readily detected in the base plate area of three Narcissus cultivars and points remote from the inoculation site in the most susceptible cultivar. A direct correlation was observed between positive results in the enzyme-linked immunosorbent assay and recovery of the pathogen on selective medium.     

Somatic Hybrids Between Potato and S. berthaultii Show Partial Resistance to Soil‐Borne Fungi and Potato Virus Y

Three tetraploid somatic hybrid lines produced by protoplast fusion between a dihaploid potato, Solanum tuberosum, cultivar BF15 and the wild potato species Solanum berthaultii were evaluated here for their response to different soil‐borne pathogens, that is Fusarium solani, Pythium aphanidermatum and Rhizoctonia solani as well as to infection by potato virus Y (PVY). Both hybrid and BF15 plants grown in vitro were inoculated with the tested pathogen strains, that is R. solani, P. aphanidermatum, or F. solani. The growth level and disease severity index of these plants were compared to the susceptible commercial cultivar Spunta. A better growth of inoculated hybrid plants and restricted disease symptoms were observed in comparison with the commercial plants. Under glasshouse conditions and after inoculation with R. solani and P. aphanidermatum, improved resistance of the hybrid plants to these pathogens was confirmed. Indeed, these plants showed no significant damage following inoculation and a better development in R. solani‐infected plants. The susceptibility of the hybrid tubers to R. solani, P. aphanidermatum, and to F. solani infection was also determined. A significant reduction of tissue colonisation was observed in all the hybrid lines compared to the cultivated cultivars. The STBc and STBd hybrids also showed improved resistance to the PVY ordinary strain (PVY^o) under glasshouse conditions.     

Common Bean Reaction to Fusarium oxysporum f. sp. Phaseoli, the Cause of Severe Vascular Wilt in Central Africa

During the September‐December season of 1990, severe symptoms of Fusarium wilt were for the first time observed on a popular climbing bean (Phaseolus vulgaris L.) cultivar. G 2333. introduced within the previous 5 years. Seventy‐three bean genotypes were screened for resistance lo the disease, using artificial inoculation. The effect of inoculation density on the reaction of four selected genotypes was also investigated. Of the 29 climbing bean genotypes evaluated, 19 were resistant, including 11 of the 15 pre‐release or released cultivars. Of the 44 bush bean cultivars evaluated, 28 were resistant, five were intermediate and 11 were susceptible. All susceptible cultivars showed vascular discoloration. In both susceptible and resistant genotypes, the fungus spread almost equally from the entry points in inoculated roots to the base of the plants, but colonization and vertical spread within the vascular system were markedly less in resistant than in susceptible cultivars. At 20 and 30 cm above soil level, the fungus was only recovered from susceptible cultivars. Increasing inoculum density from 10² to 10⁷ conidia/ml did not affect the resistance of cultivars RWR 950 and G 685 but. in the susceptible cultivars G 2333 and MLB‐48‐89 A. it resulted in early appearance, high incidence and severity of the disease.     

Fusarium eumartii Growth in Resistant and Susceptible Oak Species

Fusarium eumartii is a fungus associated with declining Quercus robur , in which it is found in the vessels. The response of oak species to infection is known to vary: Q. robur is susceptible , but Quercus cerris and Quercus pubescens are resistant. An experiment was carried out in 1996 and repeated in 1997, to examine how F. eumartii colonization differed in oak species that were susceptible or resistant to the fungus by counting the number of vessels with mycelium at various distances from the inoculation site in infected seedlings and by determining the amount of viable fungus in infected tissue. Infected vessels with mycelium were counted on sections (10  μ m thick) cut at 0, 2, 4, 6, 8 and 10 cm from the inoculation site on 1-year-old inoculated seedlings as well as on sections cut every 2 cm to the seedling tip. The amount of viable fungus was determined by counting the colony forming units (CFUs) in stem segments from the same seedlings. Quercus robur seedlings had the greatest number of infected vessels and the greatest number of CFUs. Forty days after inoculation, the extent of vertical fungal spread was 28.12 cm in Q. robur , 3.15 cm in Q. cerris and 3.00 cm in Q. pubescens . The greatest number of CFUs was found in Q. robur at day 5 after inoculation. Analysis of variance confirmed the results.     

Inheritance of resistance to Fusarium graminearum in wheat

To study the inheritance of resistance in wheat to Fusarium graminearum, six resistant cultivars from China were crossed to two susceptible cultivars. The parents and their progenies were evaluated in the greenhouse for resistance to the spread of scab within a spike. A central floret was inoculated by injecting a droplet of inoculum at the time of anthesis. Inoculated plants were kept in a moist chamber for three subsequent nights. The proportion of scabbed spikelets was recorded six-times from 3-days to 21-days after inoculation, and the area under the disease progress curve (AUDPC) was calculated from these proportions. One to three genes, depending on the cultivar, conditioned resistance to scab as reflected by the AUDPC. A simple additive-dominance effect model fitted the segregation data for 8 of the 11 crosses. Dominance and epistatic effects were significant in a few crosses. These effects increased resistance in some crosses but decreased resistance in others. However, relative to additive effects, dominant and epistatic effects accounted for only a small portion of the genetic effects in the populations evaluated. The importance of additive effects means that it should be possible to accumulate different genes to enhance resistance to scab in wheat. Received: 15 December 1998 / Accepted: 17 June 1999     

Reaction of Melon (Cucumis melo L.) Cultivars to Monosporascus cannonballus (Pollack & Uecker) and their Effect on Total Phenol,Total Protein and Peroxidase Activities

Eighteen melon cultivars were screened for resistance to Monosporascus cannonballus under greenhouse conditions. The melon cultivars were grown in pasteurized sand, which had been inoculated with a high level (60 CFUs/g of soil) of M. cannonballus mycelium from culture. Cultivars Nabijani, Sfidak khatdar, Sfidak bekhat, Ghandak, Mollamosai, Chappat, Hajmashallahi and Shadgan were moderately resistant to M. cannonballus but all other melon cultivars were moderately to highly susceptible (HS) to this pathogen. A second screening was performed for resistance to M. cannonballus under greenhouse conditions. In the second screening, cultivars Nabijani, Sfidak khatdar, Sfidak bekhat, Ghandak, Mollamosai, Chappat, Hajmashallahi and Shadgan were moderately resistant to M. cannonballus. To examine the melon resistance mechanism against M. cannonballus, the activities of total phenol, total protein and peroxidase in two melon cultivars Nabijani (as resistant) and Khaghani (as susceptible) were determined at 0, 24, 48 and 72 h after inoculation. Inoculated resistant cultivar roots had always higher content of total phenol, total protein and peroxidase than the corresponding inoculated susceptible cultivar roots. The results indicated that there was a relationship between resistance in Nabijani and accumulation of total phenol, total protein and peroxidase.