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1.
Six male sterile sunflower lines were crossed with seven restorers in a factorial mating design. The 13 inbred lines and their 42 F1 hybrids were planted in a randomized block design with three replicates. Each replicate consisted of two rows, 5 m long (30–35 plants per replicate). Resistance to natural Phomopsis infection, presented as the percentage of plants with no encircling necrosis lesions of the fungus on the main stem, was determined at physiological maturity. Analysis of variance showed that female and male general combining abilities (GCA) and specific combining abilities (SCA) of F1 hybrids were significant. The ratio of additive variance to total variance was 0.662, a high value which indicates prevailing additive effects. The additive variance due to females was more important than that of males, probably because of the existence of maternal effects or more effective genes for resistance in the female lines used in this experiment. The estimates of GCA were significant and positive for LC1004A, KO549A, 50KD8 and LC1064C inbred lines. These lines should be considered in developing hybrids with improved resistance to Phomopsis in sunflower breeding programmes.  相似文献   

2.
Resistance in the leaf blades of rice plants against a virulent race of the rice blast fungus Magnaporthe oryzae was quantitatively examined using a modified spot inoculation method. Numbers of conidia produced in the lesions were affected by plant age and paralleled the frequency of resistance infection types, which is indicative of whole-plant-specific resistance (WPSR), in the inoculated leaf sheaths of the corresponding plants. Exogenous abscisic acid treatment, which suppresses WPSR, also increased the susceptibility of the leaf blades. These results indicate a correlation between the resistance of the leaf blades and the WPSR in the leaf sheaths.  相似文献   

3.
为明确玉米和甘蔗间作对亚洲玉米螟产卵行为的影响,在尼龙网室研究了亚洲玉米螟在玉米和甘蔗不同种植模式下的产卵时间、产卵部位及产卵量的差异。结果表明,不同种植模式下亚洲玉米螟均于23∶00开始产卵,02∶00~03∶00达产卵高峰。单作甘蔗、单作玉米和间作甘蔗叶背的玉米螟卵块和卵粒数均高于叶面,而间作玉米叶背与叶面的玉米螟卵块数无显著差异,叶背的卵粒数高于叶面。单作玉米叶脉的玉米螟卵块和卵粒数均显著高于叶缘;间作玉米和单作甘蔗叶脉与叶缘卵块数间无差异,但叶脉处卵粒数高于叶缘,间作甘蔗叶脉的卵块数高于叶缘,叶缘卵粒数高于叶脉。单作甘蔗叶背的亚洲玉米螟卵块主要分布在距叶鞘69.14 cm处,而叶面的卵块主要分布在距叶鞘21.09 cm处;间作甘蔗叶背和叶面卵块分布于距叶鞘35.17 cm和12.34 cm处,二者差异显著。单作玉米上亚洲玉米螟卵块仅分布于叶背沿叶脉远离叶鞘处,而间作玉米叶背和叶面卵块分布于近叶鞘。表明玉米和甘蔗间作对亚洲玉米螟雌蛾产卵选择性具有明显的影响。  相似文献   

4.
为探索具有高杀菌活性的新型喹唑啉酮类先导化合物,以4-氯-2-氨基苯甲酸为起始原料,经重氮化、叠氮化、酯化等系列反应,得到17个未见文献报道的喹唑啉-4(3H)-酮Schiff碱类化合物。所有目标化合物的结构均经IR、1H NMR、MS及元素分析确证。初步生物活性测定结果表明,目标化合物表现出一定的杀菌活性,特别是对芒果褐色蒂腐病菌Phomopsis mangiferae Ahmad活性较好。化合物7-氯-3-(2,4-二氯-苯基)亚氨乙基-2-苯氨基喹唑啉-4(3H)-酮 (7e) 在 100 μg/mL 时,对橡胶棒孢霉叶斑病菌Corynespora cassiicola Wei和芒果褐色蒂腐病菌Phomopsis mangiferae Ahmad的抑制率分别为26.21%±1.11%和98.18%±1.07%,与对照药剂百菌清(25.64%±1.31%和100%)相当。初步的构效关系表明,吸电子基团有利于提高目标化合物的杀菌活性。  相似文献   

5.
为明确小豆白粉病病原菌的种类以及小豆种质资源对白粉病的抗性,采用形态学和系统发育学方法对近年来在北京市发生的小豆白粉病病原菌种类进行鉴定,并采用室内苗期人工接种法评价小豆常见栽培品种（系）对白粉病的抗性。结果表明,从北京市采集的感白粉病小豆病样中培养获得病原菌BJ1,该菌能在小豆叶片和茎上产生明显的白色粉斑,分生孢子梗直立,不分枝,分生孢子单细胞,成链状着生于分生孢子梗上,呈椭圆形或卵圆形。通过rDNA-ITS序列系统发育分析,小豆白粉病菌BJ1被鉴定为白粉菌目白粉菌科的苍耳叉丝单囊壳Podosphaera xanthii。室内苗期人工接种条件下,19个供试小豆品种（系）接种小豆白粉病菌BJ1后均可发病,其中9个审定品种均表现为中度感病或高度感病,10个优良品系发病略轻。  相似文献   

6.
The main fungi affecting black locust(Robinia pseudoacacia L.) were recorded during a survey which took place in northern Greece in 1997. It was found thatPhomopsis oncostoma (Thüm.) v. Höhn,Aglaospora profusa (Fr.) de Not. andCucurbitaria elongata (@#@ Fr.) Grev. cause necroses of twigs, branches and even entire trees. The pathogenicity of these fungi was confirmed by inoculation experiments in which typical disease symptoms appeared with re-isolation of the respective fungi from the inoculated plants.  相似文献   

7.
This study aimed to evaluate the effect of silicon (Si) rates on some components of sorghum resistance to anthracnose. Two 2×5 factorial experiments, consisting of two sorghum lines (BR005 and BR009, resistant and susceptible, respectively) and five Si application rates (0, 0.06, 0.12, 0.24 and 0.30 g Si kg−1 of soil) were arranged in a completely randomised design with three replications. Plants from both lines were inoculated with a conidial suspension of Colletotrichum sublineolum (1×106 conidia ml−1) 30 days after emergence. The incubation period (IP), latent period (LP60), area under relative infection efficiency progress curve (AURIEPC), area under anthracnose index progress curve (AUAIPC), final disease severity (FDS), percentage of pigmented leaf area (PLA), and percentage of necrotic leaf area (NLA) were evaluated. Silicon and calcium (Ca) content in leaf tissue of both lines was also determined. The content of Si in leaf tissue increased relative to the control by 55 and 58%, respectively, for the susceptible and resistant lines. There was no significant change in Ca content in leaf tissue for either of the lines; therefore the variations in Si accounted for differences in the level of disease response. The IP for the resistant line was not affected by Si application rates. The LP60 was not evaluated in the resistant line due to the absence of acervuli. For the resistant line, Si application rates had no significant effect on AUAIPC, FDS, percentage of PLA, and percentage of NLA. On the susceptible line, a quadratic regression model best described the effect of Si application rates on IP, LP60, AURIEPC, AUAIPC, FDS, percentage of PLA, and percentage of NLA. The correlation between Si content in leaf tissue of the susceptible line and the AURIEPC, AUAIPC, FDS, PLA, and NLA was negatively significant (r = −0.57, −0.37, −0.40, −0.67, and −0.77, respectively). There was no correlation between Si content and IP or LP60. The correlation between the percentage of PLA with the percentage of NLA was negatively significant (r = −0.74). In conclusion, the results from this study underscore the importance of Si in sorghum resistance to anthracnose particularly for the susceptible line.  相似文献   

8.
Four carnation cultivars, Novada (resistant to races 1 and 2 ofFusarium oxysporum f.sp.dianthi), Elsy (susceptible to race 1), Lena (susceptible to race 2) and Sam's Pride (susceptible to both races), were selfed and crossed. When three months old, the seedlings were inoculated via the roots or via the stems, after which wilting was recorded weekly according to a 5-point ordinal scale.Analyses were carried out on the proportions of diseased plants. For race 1 variation between the progenies could be described by means of general combining abilities only; GCA values were not affected by the inoculation method used. Also for race 2 GCAs were most important but the GCA values appeared different for the two inoculation methods. It is concluded that resistance to both races is inherited in an additive way.Indications for independently inherited root-specific resistance components (extravascular resistance) were only found with race 2. With both races, the ability to confine the pathogen at the infection site appeared the most important resistance component. Resistant progenies were also characterized by longer latent periods and lower wilting rates.Both race 1 and race 2 induced the accumulation of the phytoalexins dianthalexin and methoxydianthramide S, but race 2 induced higher amounts than race 1. The accumulation of phytoalexins was positively correlated to the resistance level of the progenies against the respective races. The progenies of the double-resistant cultivar Novada appeared to produce particularly high levels of phytoalexins.  相似文献   

9.
Three artificial infection tests measuring the rate of mycelial growth of 7 Phomopsis/Diaporthe helianthi isolates were used on leaves, stems and capitula of 6 sunflower hybrids. Isolates and hybrids were chosen to cover the range of variability and resistance levels known at the present time. Significant genotype and isolate effects and isolate×genotype interactions were shown in all the tests, with some changes in order of hybrids according to the isolate used for infection. Consequences of interactions in breeding for stable resistance to P./D. helianthi are discussed.  相似文献   

10.
Barley leaf rust resistance gene Rph7, derived from barley accession Cebada Capa, is the most effective R-gene for resistance to Puccinia hordei. Virulence for this gene was known in the USA, Israel and Morocco but not yet in Europe. We found an unexpected leaf rust infection in the field at Córdoba, Spain in 2004 on Rph7 carrying lines. This virulence for Rph7 was confirmed in growth chamber experiments, being the first report of Rph7 virulence in European populations of P. hordei. A collection of 680 barley accessions was screened for resistance against this new isolate. Twelve accessions showed segregation with individual plants showing resistance based on hypersensitivity (low infection type). These individual resistant plants were selected and grown in the greenhouse to obtain seeds.  相似文献   

11.
Screening of 51 promising safflower germplasm lines in Fusarium wilt-infested plots resulted in identification of highly wilt-resistant selections viz., 86-93-36A, 237550, VI-92-4-2 and II-13-2A, with some moderate resistance in HUS-305. Progenies from crosses made using these resistant lines were tested for their reaction to wilt. F1 progenies from 86-93-36A × 237550 and 86-93-36A × II-13-2A recorded zero wilt incidence, while 237550 × 86-93-36A was highly resistant to the Rajendranagar geographical isolate. The reaction for the three progenies showed stability for wilt resistance with no segregation until the F7 generation. Geographical isolates of Fusarium oxysporum f. sp. carthami (Foc) were collected from different safflower growing regions and tested for their pathogenic variability on six host differentials under glasshouse conditions. Based on the reaction of the differentials, the Foc isolates were grouped into four biotypes. The three resistant progenies were tested for their reaction to the four biotypes. The progeny of cross 86-93-36A × 237550 showed an immune reaction to all the biotypes, except for a highly resistant reaction to biotype 3. The progenies of the two other crosses (86-93-36A × II-13-2A and 237550 × 86-93-36A) exhibited immune reactions to biotypes 2,3 and 1,3, respectively, and were highly to moderately resistant to biotypes 1,4 and 2,4, respectively.  相似文献   

12.
Twelve selected cowpea cultivars were screened for resistance to Cercospora leaf spot (CLS) disease caused by Pseudocercospora cruenta and Cercospora apii s. lat. under artificial epiphytotic conditions in a replicated field trial, with the objective of developing a quantitative measure of disease resistance. CLS incidence, leaf spotting score, lesion density, lesion size, proportion of nodes infected, diseased leaf area, conidia number mg−1 and fascicle density were assessed in 12 cowpea genotypes at crop maturity. Proportion of nodes infected and leaf spotting score were best able to quantitatively differentiate between the levels of resistance, and allow the exploitation of quantitative resistance to the disease. Both lesion density and lesion size were important in determining the final leaf spotting score but the former was epidemiologically more important than the latter, indicated by its correlation to most of the CLS symptom measures. There was differential resistance to the P. cruenta and C. apii s. lat. among the cowpea varieties screened. Among the cowpea lines screened, resistance to P. cruenta was more common than resistance to C. apii s. lat. Nevertheless, P. cruenta was considered the more aggressive and epidemiologically more important than C. apii s. lat. on the varieties tested evidenced by the strong correlation of P. cruenta incidence with acropetal spread of CLS, intensity of leaf spotting, conidia number mg−1 and fascicle density. The highly susceptible varieties namely VRB7, Los Banos Bush Sitao no.1 and CB27 were susceptible to both Cercospora pathogens. The cowpea variety VRB-10 was completely resistant to both pathogens and is a useful source of resistance in CLS breeding programmes.  相似文献   

13.
The relative levels of tolerance of two wild barley lines (Hordeum spontaneum), B19909 and I-17-40, and one cultivated barley (Hordeum vulgare), cv. Prisma, to Blumeria graminis f.sp. hordei were determined by comparing the effects of different levels of infection on the photosynthesis and respiration rates of the third leaf. Infection caused the early onset of senescence in all three lines, and in particular in cv. Prisma, and was accompanied by decreases in gross and net photosynthesis rates, increases in respiration rates, and loss of chlorophyll. The onset of senescence occurred at approximately the same time in infected leaves of the two wild lines, but once triggered, photosynthesis rates and chlorophyll levels declined more rapidly in I-17-40 than in B19909. A burst of respiratory activity accompanied the onset of senescence, and this was greatest in cv. Prisma. Conidial production was higher in B19909, indicating a higher level of tolerance in this line.  相似文献   

14.
多堆柄锈菌侵染玉米的细胞学及超微结构特征   总被引：2，自引：1，他引：1  
为明确玉米对多堆柄锈菌Puccinia polysora侵染后病理反应的细胞学特征,利用扫描和透射电镜技术分析了玉米自交系与多堆柄锈菌互作中二者的细胞变化过程。多堆柄锈菌对玉米的侵染主要以直接穿透叶片表皮侵入为主,少量可从气孔和细胞间隙侵入。接种后,病菌夏孢子在感病自交系叶片上快速并大量萌发,在叶表生长蔓延并侵入表皮组织细胞,7 d后形成夏孢子堆;在抗病自交系上,病菌萌发、菌丝生长均受到明显抑制,少量入侵的病菌也由于寄主细胞死亡而导致菌丝和夏孢子干瘪死亡。侵染早期在感病寄主细胞间隙出现菌丝并穿透细胞壁,在胞内产生分枝菌丝,此时寄主细胞结构正常;随着菌丝进一步扩展,叶绿体等结构发生紊乱,被侵染细胞逐渐死亡。在抗病自交系上,接菌24 h后寄主即出现过敏性坏死反应,侵入位点与周围细胞快速坏死,抑制菌丝生长蔓延;叶绿体中清晰可见深色颗粒状物质;72 h后细胞壁外侧产生大量致密的深色结晶体,应为与抗病反应相关的酚类物质。表明抗多堆柄锈菌的玉米材料可能存在2种抗病途径,即寄主与病菌互作中由分子识别引起的免疫反应和病菌侵入后的系统防卫反应。  相似文献   

15.
Biological control of the western flower thrips (WFT)Frankliniella occidentalis, using the entomopathogenicMetarhizium anisopliae-7 (M. a-7) strain was studied in three consecutive seasons under greenhouse conditions. Cucumber plants infested with WFT were sprayed with spore suspension of the fungusM. a-7 (0.5 g m-2), or the soil was treated with dry powder of the fungus (0.5 g m-2); the control was without fungus application. In the 1997 spring experiment, when the cucumber plants were initially infested with only three or four insects per leaf, the spore suspension spray caused a significant reduction in growth of the thrips population compared with the other treatments and the control. However, in the 1997 summer experiment, when the plants were initially heavily infested with WFT (10–15 insects per leaf), the spray treatment caused only a modest reduction in WFT population growth, and only after 4 weeks of treatment was the reduction significant. In the 1999 experiment, with a low initial WFT population of three or four insects per leaf, the spray treatment was effective in reducing the population growth to a lower level than in the other treatments or control. TheM. a-7 strain was found to be effective in reducing the population growth of WFT under greenhouse conditions, particularly when the initial thrips population was low to moderate. http://www.phytoparasitica.org posting Nov. 4, 2001.  相似文献   

16.
Inoculation experiments with 14 genotypes of oats (10 cultivars and 4 lines) were performed during 1996, 1997 and 1998 in Sitaniec, South-Eastern Poland. Panicles of oats were inoculated with a conidial suspension of Fusarium avenaceum, which caused a reduction in yield by 33% and in 1000 kernel weight (TKW) by 21%. During the period between inoculation and harvest, F. avenaceum was able to accumulate moniliformin (MON) in kernels at an average level of 0.13mgkg–1 (gg–1). The highest reduction of yield components caused by the F. avenaceum inoculation was found for cv. Santor, followed by lines CHD 1171, STH 2795 and cvs: Kwant and Farys, while cvs Slawko, Dukat, Borys and Komes exhibited the highest resistance to the disease in terms of TKW and yield reductions after inoculation.  相似文献   

17.
To determine whether populations of Phytophthora infestans attacking wild and cultivated potatoes in the highlands of Peru are specialized on their hosts of origin, we characterized isolates using several neutral markers, metalaxyl resistance and for aggressiveness in a detached leaf assay. One hundred and fifty-three isolates were collected from the northern and central highlands of Peru from different potato cultivars (both modern and native cultivars) and from different species of wild, tuber-bearing potatoes. All the isolates analyzed belonged to one of four clonal lineages that had been described previously in Peru: EC-1, US-1, PE-3 and PE-7. The EC-1 lineage (n = 133) was dominant and present in similar frequencies on wild and cultivated potatoes. PE-3 (n = 14) was found primarily on cultivated potatoes, with only one isolate coming from a wild host. US-1 (n = 2) and PE-7 (n = 4) were rare; all but one (PE-7) occurred on wild potatoes. Isolates from the EC-1 lineage from modern cultivars were compared in three separate detached leaf inoculation assays with EC-1 isolates from the wild potato species S. sogarandinum, S. bill-hookerii or S. huancabambense, respectively. No significant interactions between isolate type (from wild or cultivated potato) and host type (wild or cultivated) were measured for any assay. It appears that the pathogen genotypes in the EC-1 lineage indiscriminately attack both wild and cultivated tuber-bearing solanaceous hosts in Peru, and breeders should be able to select for resistance using the common EC-1 lineage.  相似文献   

18.
Brown leaf spot disease caused by Cylindrocladium was found on Howea belmoreana on Hachijojima Island, Tokyo, Japan, in December 2001. Typical symptoms were incited after artificial inoculation. A culture of white mycelia, isolated from leaf spot symptoms, produced reddish perithecia of a nectriaceous fungus. Based on morphological and molecular analyses, this fungus was identified as Calonectria ilicicola (anamorph: Cylindrocladium parasiticum). Pathogenicity of this fungus on five plants cultivated on Hachijojima Island was confirmed by artificial inoculation. This report is the first on Cylindrocladium brown leaf spot of H. belmoreana caused by C. ilicicola (anamorph: Cy. parasiticum).  相似文献   

19.
In maize endosperm, a cytosolic albumin, b-32, with a molecular weight of 32 kDa is synthesised in temporal and quantitative coordination with the deposition of storage proteins. This protein has homology with several previously characterised Ribosome-Inactivating Proteins (RIPs). To verify if the maize plant expressing b-32 in various tissues has an increased tolerance to fungal pathogens, transgenic plants were obtained through genetic transformation using a chimeric gene containing the b-32 coding sequence downstream of a constitutive 35SCaMV promoter. A set of four independent homozygous progenies expressing b-32, were selected for a detailed analysis of b-32 expression in leaves and for pathogenicity tests. A differential b-32 content in leaf protein extracts was recorded in the transgenic progenies. Proteomic investigations on protein leaf extracts were carried out; the overlapping of the two-dimensional electrophoresis maps demonstrated the presence in a transgenic progeny, of additional spots, identified as b-32 and as a protein for herbicide resistance, in comparison to the negative control. Transgenic progenies were tested in bioassays to evaluate the response to Fusarium attack in leaf tissues. Preliminary experiments supported the choice of bioassay parameters for a reliable evaluation of transgenic progenies. The negative control was most susceptible to Fusarium verticillioides attack, compared to transgenic progenies. The data obtained indicate that maize b-32 was an effective antifungal protein by reducing Fusarium infection progression. Additionally, the reduction in Fusarium attack symptoms was related to b-32 concentration in leaf tissues.  相似文献   

20.
The biology ofLixus bardanae (F.) (Coleoptera: Curculionidae) on curly dock (Rumex crispus L.) in northeastern Anatolia (Bayburt, Erzurum and Kars Provinces), Turkey, was studied during the years 2000 and 2001.L. bardanae completes one generation in a year, overwintering as an adult. It feeds on leaves of the host plant. Females lay eggs individually into stems and the young larvae create galleries in stems while feeding. Pupation occurs inside stems in cells fashioned from frass. In late September, adults move into soil and overwinter in an upright position around the roots of the host plant. Infestation levels were found to range between 34% and 84%. Two parasitoids,Exeristes roborator F. andEndromopoda phragmitidis Perve (Hymenoptera: Ichneumonidae), were reared fromL. bardanae. http://www.phytoparasitica.org posting Dec. 21, 2003.  相似文献   

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