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1.
ABSTRACT Since 1995, lettuce in coastal California, where more than half of the crop in North America is grown, has consistently suffered from severe outbreaks of Verticillium wilt. The disease is confined to this region, although the pathogen (Verticillium dahliae) and the host are present in other crop production regions in California. Migration of the pathogen with infested spinach seed was previously documented, but the geographic sources of the pathogen, as well as the impact of lettuce seed sparsely infested with V. dahliae produced outside coastal California on the pathogen population in coastal California remain unclear. Population analyses of V. dahliae were completed using 16 microsatellite markers on isolates from lettuce plants in coastal California, infested lettuce seed produced in the neighboring Santa Clara Valley of California, and spinach seed produced in four major spinach seed production regions: Chile, Denmark, the Netherlands, and the United States (Washington State). California produces 80% of spinach in the United States and all seed planted with the majority infested by V. dahliae comes from the above four sources. Three globally distributed genetic populations were identified, indicating sustained migration among these distinct geographic regions with multiple spinach crops produced each year and repeated every year in coastal California. The population structure of V. dahliae from coastal California lettuce plants was heavily influenced by migration from spinach seed imported from Denmark and Washington. Conversely, the sparsely infested lettuce seed had limited or no contribution to the Verticillium wilt epidemic in coastal California. The global trade in plant and seed material is likely contributing to sustained shifts in the population structure of V. dahliae, affecting the equilibrium of native populations, and likely affecting disease epidemiology. 相似文献
2.
土壤大丽轮枝菌微菌核的快速定量检测 总被引：4，自引：0，他引：4
微菌核是大丽轮枝菌在土壤中的主要存活结构和黄萎病的初侵染来源。对土壤中大丽轮枝菌微菌核进行定量是黄萎病监测和预警的基础。本研究以大丽轮枝菌Internal Transcribed Spacer (ITS)区特异性引物对P1/P2扩增产物的重组质粒为标准品,构建SYBR Green I实时荧光定量PCR反应的标准曲线,结合土样水筛法建立了土壤大丽轮枝菌微菌核定量检测体系。同时,建立了土壤中微菌核数量与棉花黄萎病发病率的关系模型。结果表明,实时定量PCR检测灵敏度比常规PCR高10倍,检测下限为1个微菌核/克土,在5.54×102～5.54×107copies范围内,DNA拷贝数的对数值与Ct值具有良好的线性关系。建立的土壤中微菌核个数n与Ct值之间的关系为n=e7.3-Ct/3.905。温室人工接种微菌核数量与棉花黄萎病发病率间的线性关系为y=2.710n+0.251。 相似文献
3.
ABSTRACT Verticillium dahliae is responsible for Verticillium wilt on a wide range of hosts, including strawberry, on which low soil inoculum densities can cause significant crop loss. Determination of inoculum density is currently done by soil plating but this can take 6 to 8 weeks to complete and delay the grower's ability to make planting decisions. To provide a faster means for estimating pathogen populations in the soil, a multiplexed TaqMan real-time polymerase chain reaction (PCR) assay based on the ribosomal DNA (rDNA) intergenic spacer (IGS) was developed for V. dahliae. The assay was specific for V. dahliae and included an internal control for evaluation of inhibition due to the presence of PCR inhibitors in DNA extracted from soil samples. An excellent correlation was observed in regression analysis (R(2) = 0.96) between real-time PCR results and inoculum densities determined by soil plating in a range of field soils with pathogen densities as low as 1 to 2 microsclerotia/g of soil. Variation in copy number of the rDNA was also evaluated among isolates by SYBR Green real-time PCR amplification of the V. dahliae-specific amplicon compared with amplification of several single-copy genes and was estimated to range from ≈24 to 73 copies per haploid genome, which translated into possible differences in results among isolates of ≈1.8 cycle thresholds. Analysis of the variation in results of V. dahliae quantification among extractions of the same soil sample indicated that assaying four replicate DNA extractions for each field sample would provide accurate results. A TaqMan assay also was developed to help identify colonies of V. tricorpus on soil plates. 相似文献
4.
ABSTRACT Broccoli is resistant to Verticillium dahliae infection and does not express wilt symptoms. Incorporation of broccoli residues reduces soil populations of V. dahliae. The effects of broccoli residue were tested on the colonization of roots by V. dahliae, plant growth response, and disease incidence of both broccoli and cauliflower in soils with different levels of V. dahliae inoculum and with or without fresh broccoli residue amendments. The three soils included a low-Verticillium soil, a high-Verticillium soil, and a broccoli-rotation soil (soil from a field after two broccoli crops) with an average of 13, 38, and below-detectable levels of microsclerotia per g of soil, respectively. Cauliflower plants in broccoli-amended high-Verticillium soil had significantly (P 相似文献
5.
ABSTRACT Potato early dying (PED), also known as Verticillium wilt, caused by Verticillium dahliae, is a seasonal yield-limiting disease of potato worldwide, and PED-resistant cultivars currently represent only a small percentage of potato production. In this study, we developed a real-time quantitative polymerase chain reaction (Q-PCR) approach to detect and quantify V. dahliae. The efficiency of the designed primer pair VertBt-F/VertBt-R, derived from the sequence of the beta-tubulin gene, was greater than 95% in monoplex Q-PCR and duplex (using Plexor technology) procedures with primers PotAct-F/PotAct-R, obtained from the sequence of the actin gene, designed for potato. As few as 148 fg of V. dahliae DNA were detected and quantified, which is equivalent to five nuclei. Q-PCR detected V. dahliae in naturally infected air-dried potato stems and fresh stems of inoculated plants. Spearman correlations indicated a high correlation (upward of 80%) between V. dahliae quantifications using Q-PCR and the currently used plating assays. Moreover, Q-PCR substantially reduced the variability compared with that observed in the plating assay, and allowed for the detection of V. dahliae in 10% of stem samples found to be pathogen free on the culture medium. The described Q-PCR approach should provide breeders with a more sensitive and less variable alternative to time-consuming plating assays to distinguish response of breeding lines to colonization by V. dahliae. 相似文献
6.
Effects of Crop Rotation and Irrigation on Verticillium dahliae Microsclerotia in Soil and Wilt in Cauliflower 总被引：1，自引：0，他引：1
ABSTRACT Experiments were conducted in field plots to evaluate the effects of broccoli residue on population dynamics of Verticillium dahliae in soil and on Verticillium wilt development on cauliflower under furrow and subsurface-drip irrigation and three irrigation regimes in 1994 and 1995. Treatments were a factorial combination of three main plots (broccoli crop grown, harvested, and residue incorporated in V.dahliae-infested plots; no broccoli crop or residue in infested plots; and fumigated control plots), two subplots (furrow and subsurface-drip irrigation), and three sub-subplots (deficit, moderate, and excessive irrigation regimes) arranged in a split-split-plot design with three replications. Soil samples collected at various times were assayed for V. dahliae propagules using the modified Anderson sampler technique. Incidence and severity of Verticillium wilt on cauliflower were assessed at 7- to 10-day intervals beginning a month after cauliflower transplanting and continuing until harvest. Number of propagules in all broccoli plots declined significantly (P < 0.05) after residue incorporation and continued to decline throughout the cauliflower season. The overall reduction in the number of propagules after two broccoli crops was approximately 94%, in contrast to the fivefold increase in the number of propagules in infested main plots without broccoli after two cauliflower crops. Disease incidence and severity were both reduced approximately 50% (P < 0.05) in broccoli treatments compared with no broccoli treatments. Differences between furrow and subsurface-drip irrigation were not significant, but incidence and severity were significantly (P < 0.05) lower in the deficit irrigation regime compared with the other two regimes. Abundance of microsclerotia of V. dahliae on cauliflower roots about 8 weeks after cauliflower harvest was significantly (P < 0.05) lower in treatments with broccoli compared with treatments without broccoli. Rotating broccoli with cauliflower and incorporating broccoli residues into the soils is a novel means of managing Verticillium wilt on cauliflower and perhaps on other susceptible crops. This practice would be successful regardless of the irrigation methods or regimes followed on the susceptible crops. 相似文献
7.
Shinpei Banno Hidenari Saito Hiroshi Sakai Toshihiko Urushibara Kentaro Ikeda Takeshi Kabe Isao Kemmochi Makoto Fujimura 《Journal of General Plant Pathology》2011,77(5):282-291
Verticillium longisporum and V. dahliae, causal agents of Verticillium wilt, are spreading through the cabbage fields of Gunma Prefecture. Using the V. longisporum-specific intron within the 18S rDNA and differences between ITS 5.8S rDNA sequences in Japanese isolates of V. longisporum and V. dahliae, we developed three quantitative nested real-time (QNRT) PCR assays. The QNRT-PCR quantification of V. longisporum or V. dahliae in cabbage field soil was consistent with the severity of Verticillium wilt disease in those fields. In field trials of resistant
cultivar YR Ranpo grown for three seasons in soil infested with the pathogen, disease severity and pathogen density in the
soil were significantly reduced in a field moderately contaminated by V. dahliae, but only slightly reduced in a highly contaminated field. These results suggest that continuous cultivation of a resistant
cultivar is an effective way to reduce the pathogen population. QNRT-PCR assays provide a powerful analytical tool to evaluate
the soil population dynamics of V. longisporum and V. dahliae for disease management. 相似文献
8.
The incidence of wilt was recorded in runner and fruiting crops of 13 strawberry cultivars at 72 locations in southern England in 1989 and 1990, and soil samples from the sites were analysed for Verticillium dahliae . Linear regressions of wilt incidence on inoculum concentration in soil for runner crops of the susceptible cv. Elsanta in both years were significant whilst that for runner crops of the susceptible cv. Hapil in 1989 approached significance; the regression for cv. Elsanta fruiting crops in 1990 was not significant. The inclusion of sand content of soil in the regression model improved the fit for the cv. Hapil data but not for the cv. Elsanta data; neither clay nor silt content of soil significantly improved the fit of the models for any data set. There were insufficient data in either year for regression analysis for other cultivars, but the levels of wilt generally corresponded with the degree of soil infestation and broadly reflected known field resistance. The data were used to estimate an inoculum concentration which corresponds to 5% wilt incidence (IC5 ) for cv. Elsanta. It is suggested that this could be used as a yardstick for determining the risk of unacceptable levels of wilt in susceptible cultivars on the basis of pre-planting soil analysis. For the 44 sites where the cropping history over the 15 years prior to soil analysis was available there was no clear association between any crop and soil infestation levels at or above the IC5 . However, V. dahliae was more common at sites with a history of vegetatively propagated crops than at sites which had only supported crops grown from true seed. 相似文献
9.
ABSTRACT Six potato cultivars were grown with or without the addition of Verticillium dahliae inoculum and were watered at 50, 75, or 100% estimated consumptive use. The applied water x cultivar interaction was significant (P = 0.009 and P = 0.001 for 1996 and 1997, respectively) for the relative area under the senescence progress curve (RAUSPC). With a decrease in water, there was an increase in RAUSPC. A significant interaction of inoculum density x cultivar also was found, based on RAUSPC (P = 0.0194 and P = 0.0033 for 1996 and 1997, respectively). In V. dahliae-infested plots, 'Katahdin' and 'Ranger Russet' were resistant to Verticillium wilt. Population size of V. dahliae in stem apices was significantly lower in 'Katahdin' in both 1996 and 1997 (P = 0.0001) and in 'Ranger Russet' in 1997 (P = 0.0001) than in the other cultivars. 'Russet Burbank' and 'Shepody' had large apical stem populations of V. dahliae and higher RAUSPC values associated with both V. dahliae inoculum and decreased amount of applied water. Marketable tuber yield was unaffected by V. dahliae in both years. Cultivar resistance to Verticillium wilt was related to cultivar tolerance to moisture deficit stress. Results suggest that moisture deficit stress response has the potential to be a useful tool in protocols for screening potato for Verticillium resistance. 相似文献
10.
由大丽轮枝菌引起的棉花黄萎病是一种难以防治的土传病害,西兰花残体还对其有一定的防治作用,防效为62.82%。为解析西兰花残体对棉花黄萎病的防治机制,本研究通过土壤杆菌转化的方法构建了大丽轮枝菌的绿色荧光标记菌株,采用共聚焦显微镜观察标记菌株在添加西兰花残体营养基质中和空白对照营养基质种植的棉花体内的侵染和扩展情况。结果表明构建的标记菌株gfp-wx-1与野生菌株wx-1的生物学特性无显著性差异。同时发现大丽轮枝菌在添加西兰花残体营养基质中棉花体内扩展较慢,具体表现为:在空白营养基质种植的棉花体内,大丽轮枝菌在接种第2 d时就可侵染根尖表层及根内部,第3 d到达茎部维管束,第5 d叶片可观察到少量病原菌,第7 d第一片子叶呈现大量病原菌,后期迅速扩展,叶片出现黄萎病斑;而在营养基质中添加西兰花残体种植的棉花体内,大丽轮枝菌在接种第2 d时就可侵染根尖表层,第3 d侵染根尖内部,第5 d侵染茎部维管束,直到第7 d第一片子叶才出现少量病原菌,后期扩展慢,叶片病斑较少。本研究通过荧光定量PCR方法检测了大丽轮枝菌在两个处理棉花根部定殖情况,结果表明西兰花残体能够显著降低大丽轮枝菌在棉花根部定殖的量。该研究初步明确了西兰花残体对棉花黄萎病的防治机制,为棉花黄萎病的绿色防治提供了一条新的途径。 相似文献
11.
由大丽轮枝菌引起的棉花黄萎病是一种难以防治的土传病害,西兰花残体还对其有一定的防治作用,防效为62.82%。为解析西兰花残体对棉花黄萎病的防治机制,本研究通过土壤杆菌转化的方法构建了大丽轮枝菌的绿色荧光标记菌株,采用共聚焦显微镜观察标记菌株在添加西兰花残体营养基质中和空白对照营养基质种植的棉花体内的侵染和扩展情况。结果表明构建的标记菌株gfp-wx-1与野生菌株wx-1的生物学特性无显著性差异。同时发现大丽轮枝菌在添加西兰花残体营养基质中棉花体内扩展较慢,具体表现为:在空白营养基质种植的棉花体内,大丽轮枝菌在接种第2 d时就可侵染根尖表层及根内部,第3 d到达茎部维管束,第5 d叶片可观察到少量病原菌,第7 d第一片子叶呈现大量病原菌,后期迅速扩展,叶片出现黄萎病斑;而在营养基质中添加西兰花残体种植的棉花体内,大丽轮枝菌在接种第2 d时就可侵染根尖表层,第3 d侵染根尖内部,第5 d侵染茎部维管束,直到第7 d第一片子叶才出现少量病原菌,后期扩展慢,叶片病斑较少。本研究通过荧光定量PCR方法检测了大丽轮枝菌在两个处理棉花根部定殖情况,结果表明西兰花残体能够显著降低大丽轮枝菌在棉花根部定殖的量。该研究初步明确了西兰花残体对棉花黄萎病的防治机制,为棉花黄萎病的绿色防治提供了一条新的途径。 相似文献
12.
In a survey of verticillium wilt of cultivated and weed hosts in Crete in 1988–89, Verticillium dahliae was the only species isolated. The pathogen was found in 84 out of 231 vegetable crops, and six out of 14 olive orchards. It was also found in two locations on the weed Solanum nigrum. Hosts belonged to 12 plant species in six different botanical families. Natural infection of Vicia faba by V. dahliae is reported for the first time. The physiological races of 92 isolates of V. dahliae were identified using two differential tomato cultivars. Of these isolates, 89 were race 1, one was race 2, and the remaining two were non-pathogenic. Virulence of the various isolates to tomato varied from slightly to highly pathogenic and was independent of the hosts from which they originated. 相似文献
13.
ABSTRACT In a field trial in soil infested with Verticillium dahliae, we compared the yield, growth, incidence of symptoms of Verticillium wilt, and mortality of two interspecific hybrid pistachio tree rootstocks (UCBI and PGII) with the standard rootstocks: the V. dahliae-resistant and susceptible Pistacia integerrima and P. atlantica, respectively. After 10 years, the trees were destructively sampled for V. dahliae in the xylem at the graft union. The results indicate that trees on the (P. atlantica 'KAC' x P. integerrima) hybrid UCBI rootstock grew and yielded as well as those on P. integerrima. Trees on the hybrid PGII yielded the least. Analysis of variance and log-linear models indicate that in soil infested with V. dahliae, three associations significantly affect pistachio nut yield. Rootstock affects scion vigor and extent of infection. Third, the extent of infection and scion vigor are inversely associated. Although trees on the P. integerrima rootstock had the highest ratings in a visual assessment of vigor, 65% were infected with V. dahliae in the trunk in the graft region compared with 73% in P. atlantica and 25% in UCBI. Thus, P. integerrima and UCBI have at least one different mechanism for resistance to V. dahliae. 相似文献
14.
为了解北疆棉花黄萎病的发生情况及发病与土壤中黄萎病菌微菌核数量的关系和病原菌种群类型, 2021年对北疆石河子?奎屯?博乐等8市(县)棉田棉花黄萎病发病率?土壤中黄萎病菌的微菌核数量?菌株种群类型进行了抽样调查?结果表明, 北疆未发生棉花黄萎病的棉田占49.2%, 0%<发病率<5.0%的棉田占32.7%, 发病率≥5.0%的棉田占18%?与2013年?2015年相比, 2021年无病田率分别增加17.7和12.7百分点, 发病率≥5%的棉田分别减少15.7和21.6百分点?从棉田黄萎病发病率与土壤中微菌核数量的关系来看, 整体上北疆棉田棉花黄萎病发病率与微菌核数量相关性不显著(r=0.119 1); 分区域看, 石河子-沙湾片区?奎屯-乌苏片区?精河-博乐片区棉田黄萎病发病率与微菌核数量的相关系数分别为0.033 2?0.007 6?0.062 3, 均无显著相关性; 而呼图壁-玛纳斯片区棉田黄萎病发病率与微菌核数量的相关系数为0.635 7, 呈中度正相关?土壤中的黄萎病菌菌株以菌核型为主, 占57.9%, 菌丝型占23.2%, 中间型占18.9%?用特异性引物进行PCR检测表明, 土壤中黄萎病菌落叶型菌株占97.6%, 占绝对优势?本研究将为北疆棉区棉花黄萎病的综合防控提供理论依据? 相似文献
15.
Verticillium wilt of oilseed rape ( Brassica napus ) is caused primarily by Verticillium longisporum and has become a serious problem in northern Europe. In order to evaluate whether V. longisporum and V. dahliae differ in their interaction with oilseed rape, phenotypical and molecular assessments were made. Oilseed rape plants for fungal assessments were inoculated with V. longisporum and V. dahliae via root-dipping and samples were taken from roots, stems, leaves, flowers, pods and seeds during plant development. The infection by V. longisporum was found to start mainly in lateral roots and root-hairs, followed by colonization of the xylem vessels and extensive spread in stems and leaves, whereas V. dahliae infected the main roots and remained in the region below the cotyledon node of the plants. Re-isolation studies, together with PCR analysis of samples taken from early growth stages through to fully ripe plants, showed that the onset of flowering was a critical phase for V . longisporum to colonize plants. No seeds infected with V. longisporum were found. Mycelial growth from V. dahliae but not V. longisporum was significantly reduced on media containing tissue from a low glucosinolate B. napus genotype compared with growth on media containing tissue from a high glucosinolate cultivar. The results of this study suggest that V. longisporum favours B. napus as host and that the transition from the vegetative to the generative phase is of importance for the spread of the fungus in oilseed rape plants. 相似文献
16.
Relationships Between Verticillium dahliae Inoculum Density and Wilt Incidence, Severity, and Growth of Cauliflower 总被引：1，自引：0，他引：1
ABSTRACT Microplot and field experiments were conducted to evaluate the effects of inoculum density on Verticillium wilt and cauliflower growth. Soil containing Verticillium dahliae microsclerotia was mixed with various proportions of fumigated soil to establish different inoculum densities (fumigated soil was used as the noninfested control). Seven inoculum density treatments replicated four times were established, and the treatments were arranged in a randomized complete block design. Soil was collected from each microplot immediately after soil infestation for V. dahliae assay by plating onto sodium polypectate agar (NP-10) selective medium using the Anderson sampler technique. Five-week-old cauliflower was transplanted into two beds within each 1.2- by 1.2-m microplot. At the same time, several extra plants were also transplanted at the edge of each bed for destructive sampling to examine the disease onset (vascular discoloration) after planting. Cauliflower plants were monitored for Verticillium wilt development. Stomatal resistance in two visually healthy upper and two lower, diseased leaves in each microplot was measured three times at weekly intervals after initial wilt symptoms occurred. At maturity, all plants were uprooted, washed free of soil, and wilt incidence and severity, plant height, number of leaves, and dry weights of leaves and roots were determined. The higher the inoculum density, the earlier was disease onset. A density of 4 microsclerotia per g of dry soil caused 16% wilt incidence, but about 10 microsclerotia per g of soil caused 50% wilt incidence. Both wilt incidence and severity increased with increasing inoculum density up to about 20 microsclerotia per g of soil, and additional inoculum did not result in significantly higher disease incidence and severity. A negative exponential model described the disease relationships to inoculum levels under both microplot and field conditions. Stomatal resistance of diseased leaves was significantly higher at higher inoculum densities; in healthy leaves, however, no treatment differences occurred. The height, number of leaves, and dry weights of leaves and roots of plants in the fumigated control were significantly higher than in infested treatments, but the effects of inoculum density treatments were variable between years. Timing of cauliflower infection, crop physiological processes related to hydraulic conductance, and wilt intensity (incidence and severity) were thus affected by the inoculum density. Verticillium wilt management methods used in cauliflower should reduce inoculum density to less than four micro-sclerotia per g of soil to produce crops with the fewest number of infected plants. 相似文献
17.
大丽轮枝菌是引起棉花、马铃薯等重要作物黄萎病的土传病原真菌,其分泌的胞外蛋白是侵染寄主的重要毒力因子,因此研究胞外蛋白与寄主的相互作用具有重要意义。本研究旨在构建高效的棉花酵母双杂交cDNA文库,并通过已知大丽轮枝菌效应子VCR1互作蛋白的筛选来评价构建文库的质量。分别采用大丽轮枝菌及茉莉酸甲酯、水杨酸和乙烯处理海岛棉‘海7124’以诱导其抗病基因表达,混合RNA样品构建酵母双杂交cDNA文库,文库滴度达1.18×108 cfu/mL,检测重组率100%,插入片段在300~2000 bp之间。以效应子VCR1为诱饵筛选获得27个潜在互作蛋白,并进一步确证了1个与VCR1互作的靶标蛋白。本研究构建的酵母双杂交文库将为筛选与大丽轮枝菌效应子互作的蛋白及后续互作机理研究提供重要的研究基础。 相似文献
18.
新疆榆树黄萎病病原菌鉴定 总被引：1，自引：0，他引：1
2013年以来,在石河子大学农学院试验站榆树苗上,出现了一种病害,可导致叶片褪绿,变黄,萎蔫,甚至枯死,剖茎检查可见维管束变成褐色。采用常规组织分离法对病茎组织进行分离、纯化获得单孢纯培养菌株;通过常规纸钵撕底蘸根法对其进行致病性测定;用形态学和rDNA-ITS序列分析方法对病原菌进行鉴定。结果表明,分离菌株的菌落形态、分生孢子梗和分生孢子的形态都与大丽轮枝菌(Verticillium dahliae)一致;经分子生物学鉴定,该菌的rDNA-ITS序列与中国棉花黄萎病菌(V.dahliae)的ITS序列(登录号EU 835817.1)相似性达99.0%,故将引起新疆榆树黄萎病的病原菌鉴定为大丽轮枝菌(V.dahliae)。 相似文献
19.
Interactions between lettuce and a green fluorescent protein (GFP)-expressing, race 1 isolate of Verticillium dahliae, were studied to determine infection and colonization of lettuce cultivars resistant and susceptible to Verticillium wilt. The roots of lettuce seedlings were inoculated with a conidial suspension of the GFP-expressing isolate. Colonization was studied with the aid of laser scanning confocal and epi-fluorescence microscopes. Few differences in the initial infection and colonization of lateral roots were observed between resistant and susceptible cultivars. Hyphal colonies formed on root tips and within the root elongation zones by 5 days, leading to the colonization of cortical tissues and penetration of vascular elements regardless of the lettuce cultivar by 2 weeks. By 8 to 10 weeks after inoculation, vascular discoloration developed within the taproot and crown regions of susceptible cultivars well in advance of V. dahliae colonization. Actual foliar wilt coincided with the colonization of the taproot and crown areas and the eruption of mycelia into surrounding cortical tissues. Advance colonization of stems, pedicels, and inflorescence, including developing capitula and mature achenes was observed. Seedborne infection was limited to the maternal tissues of the achene, including the pappus, pericarp, integument, and endosperm; but the embryo was never compromised. Resistant lettuce cultivars remained free of disease symptoms. Furthermore, V. dahliae colonization never progressed beyond infected lateral roots of resistant cultivars. Results indicated that resistance in lettuce may lie with the plant's ability to shed infected lateral roots or to inhibit the systemic progress of the fungus through vascular tissues into the taproot. 相似文献
20.
一种新的棉花黄萎病快速接种技术及其在病原菌致病力和寄主抗病性鉴定上的应用 总被引：6，自引：0，他引：6
棉花品种抗黄萎病鉴定一般在田间病圃中进行,其结果受病圃中病原菌分布均匀程度、气象等因素影响极大,往往导致鉴定结果不准确。为了使鉴定方法简单、科学、可靠,我们在温室条件下比较了3种苗期接种棉花黄萎病的方法,即切根蘸孢子法(接种浓度为106分生孢子/mL);菌培养物土壤接种法(0.5%、1%、2%,w/w);微菌核土壤接种法(103个微菌核/g土)。结果表明,切根蘸孢子法导致棉苗发病均匀、严重、迅速,播种35~45 d后即可得到均匀一致的发病结果。而其它2种接种方法在播种75 d后才得到相对稳定的发病结果。同时,研究还表明接种浓度为104分生孢子/mL所导致的黄萎病显著比105或106的轻。利用切根蘸孢子法在室内鉴定12个棉花品种或品系的抗黄萎病能力,证明该方法是抗黄萎病快速鉴定的有效方法。此外,该鉴定方法还可快速鉴定黄萎病菌不同菌株的致病性,并可应用于作物对其它土传病害的抗病性鉴定上。 相似文献