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121.
122.
The pathogenicity of Alternaria spp. isolated from wheat leaves collected in regions where alternaria leaf blight has been reported was compared with that of IMI reference isolates of A. triticina and A. alternata using two durum and two bread wheat genotypes. To identify isolates putatively corresponding to A. triticina , morphological and DNA sequence analyses based on ribosomal DNA from the internal transcribed spacer (ITS) region (ITS1, 5·8S rRNA gene, ITS2) and toxicity bioassays of culture filtrate were combined. Glasshouse inoculations provided reliable information to assess the pathogenicity of A. triticina isolates on wheat. Alternaria leaf blight symptoms were produced by the A. triticina isolates only on durum wheat cv. Bansi, while A. alternata , A. tenuissima and A. arborescens isolates were found to be nonpathogenic on the wheat cultivars tested. Alternaria triticina isolates were distinguished from other Alternaria species by Simmons and Roberts' sporulation pattern 6 and two to three conidia per sporulation unit associated with primary conidia bearing long (> 7 µ m) apical secondary conidiophores. Phylogenetic analysis also proved effective at discriminating wheat-pathogenic A. triticina from other nonpathogenic Alternaria species. Alternaria triticina isolates yielded longer ITS sequences than A. alternata , A. tenuissima and A. arborescens isolates, leading to clear-cut differences as visualized with agarose gel electrophoresis. Additionally, only culture filtrates of A. triticina isolates caused nonspecific necrotic lesions on leaves of 3-week-old wheat plants. 相似文献
123.
Peter S. Solomon T. J. Greer Wilson Kasia Rybak Kerrie Parker Rohan G. T. Lowe Richard P. Oliver 《European journal of plant pathology / European Foundation for Plant Pathology》2006,114(3):275-282
The interaction between Stagonospora nodorum and a susceptible wheat cultivar was investigated using a range of microscopic techniques. Germination of pycnidiospores
occurred approximately 3 h after making contact with the leaf surface and was followed by attempted penetration 8–12 h later.
Penetration was observed through stomata and also directly through periclinal and anticlinal epidermal cell walls. Penetration
down the anticlinal cell walls appeared to occur without a differentiated penetrating structure whilst structures identified
as either lateral appressoria or hyphopodia were typically present when penetrating over a periclinal cell wall. Once inside
the leaf, the fungus continued to grow for the next 4–5 days colonising all parts of the leaf except the vascular bundles.
Only in the later phase of the infection was total host cell collapse apparent. Evidence of polyphenolic compounds was observed.
The infection cycle was completed within 7 days as indicated by sporulation on the leaf surface. These results have allowed
us to understand how the fungus physically interacts with the leaf and will help the overall understanding of the infection
process. 相似文献
124.
Two trials were conducted in 2002 with 14-day-old spring canola (Brassica napus L.) seedlings to evaluate the effects of previous leaf injuries of different cultivars on subsequent injury by western black
flea beetle (WBFB),Phyllotreta pusilla Horn (Coleoptera: Chrysomelidae), under greenhouse conditions in Colorado (USA). Previous leaf cutting was found to have
only minor effects on subsequent infestation and injury by WBFB, and such effects may be cultivar-specific. Only IMC205 showed
significant differences by more than one parameter during these studies; cultivars Excel and 46A65 showed no responses in
injury or infestation between previously cut and uncut plants.
http://www.phytoparasitica.org posting Nov. 14, 2005. 相似文献
125.
条斑型玉米圆斑病病原鉴定及其生物学特性研究 总被引:5,自引:0,他引:5
本研究通过致病性测定、形态学和分子生物学鉴定方法,首次明确陕西省发生的玉米条斑型叶斑病是玉米圆斑病的一种症状类型,由玉米生离蠕孢(Bipolaris zeicola)3号生理小种引起。供试品种豫玉22、农大108、农大3138、东单7号、沈单10号、沈单16号、户单4号、新陕资1号、高农1号和陕单9号都对3号生理小种表现感病,品种间抗病性差异不显著。此菌在PDA、PSA、OMA、CMA、WA和Czapek上均可生长,最适生长培养基为PDA。菌落生长温度为5~35℃,最适菌落生长温度为25℃。分生孢子在5~40℃均可萌发,低于5℃高于40℃萌发率极低,萌发的最适温度为28℃。孢子在pH 3~11均可萌发,萌发最适pH为5。在自来水中分生孢子可以萌发,蔗糖和葡萄糖溶液可以明显促进孢子萌发。 相似文献
126.
127.
梨组织中苹果褪绿叶斑病毒的原位RT-PCR检测 总被引:6,自引:2,他引:6
为了建立梨树苹果褪绿叶斑病毒原位RT-PCR检测技术, 用已知带有苹果褪绿叶斑病毒的库尔勒香梨和无病毒实生苗叶片为材料, 利用D IG标记, 研究了香梨病毒的叶片石蜡切片IS-RT-PCR检测技术。包括AMV逆转录酶、dNTPs、RNasin及互补引物浓度对cDNA合成的影响, 退火温度、Taq DNA聚合酶、Mg2+ 、引物浓度及循环次数对原位PCR效果的影响。结果表明: RNasin的用量大于0.2 U·μL-1时,信号强度随着RNasin量的加大而增强; 只有当dNTPs浓度达1.0 mmol·L-1时才能生成一定量的cDNA;AMV浓度在0.3~0.5 U·μL-1均可进行正常的逆转录, 而且在该范围内产物的量随AMV浓度提高而增多; 引物浓度达到0.9μmol·L-1以上时才能进行有效的逆转录, 并且生成的cDNA的量随引物浓度增大而增加。原位扩增ACLSV的cDNA适合退火温度为56℃。循环20~30次可出现较强的蓝色信号, 引物浓度在0.8~1.2μmol·L-1时显色较好; Taq酶浓度为20 U·mL-1以上, 均显示较深的蓝色; Mg2 +浓度为1.5mmol·L-1就可满足原位PCR所需。获得了苹果褪绿叶斑病毒的原位PCR优化检测体系, 利用建立的优化程序对香梨样品进行了检测验证, 取得了很好效果。 相似文献
128.
129.
Effects of deficit irrigation strategies on cluster microclimate for improving fruit composition of Moscatel field-grown grapevines 总被引:1,自引:0,他引:1
Tiago Pedreira dos Santos Carlos M. Lopes M. Lucília Rodrigues Claudia R. de Souza Jorge M. Ricardo-da-Silva João P. Maroco João S. Pereira M. Manuela Chaves 《Scientia Horticulturae》2007
The grapevine plays a very important role in the economic, social and cultural sectors of many regions; however vineyards are often grown in regions under stressful conditions and thus they are vulnerable to climate change. The objective of this research was to investigate the effect of partial root-zone drying (PRD) irrigation on vine water relations, vegetative growth, plant microclimate, berry composition and yield components, compared to conventional deficit irrigation (DI, 50% ETc), full irrigation (FI, 100% of ETc) and non-irrigated vines (NI). The study was undertaken in mature ‘Moscatel’ grapevines (Vitis vinifera L.) grown in Pegões, South of Portugal. Compared to the other irrigated treatments, PRD vines showed a better microclimate at the cluster zone with higher incident photosynthetic photon flux density (PPFD). Within the more open canopies of NI and PRD treatments, berry temperatures were higher than those of denser ones (DI and FI). Compared to the conventional irrigation technique the better microclimate observed in PRD vines was a consequence of a reduction in vine growth, where lower values of leaf layer number, leaf area, canopy wideness, water shoots and shoot weight were observed. In PRD vines we observed a tendency to a development of a deeper root system, while DI and FI showed a more homogeneous root distribution throughout the different soil layers. PRD showed an improvement in berry quality with higher values of flavour precursors, and total phenols concentration without any significant yield reduction compared to DI and FI. 相似文献
130.
There is little available information on the effects of temperature and CO2 enrichment on stomata anatomical characteristics of plants. Effect of these two microclimates was studied on five rose (Rosa spp.) cultivars, viz. ‘First Red’ (used as check), ‘Arjun’, ‘Raktima’, ‘Raktagandha’ and ‘Pusa Pitamber’. Budded, single-stemmed rose cultivars having five lateral buds were grown in controlled environment growth cabinets under enriched CO2 (1000 μmol mol−1) and optimum (28/18 °C, T0) or high (35/25 °C, T1) temperature for 50 days. All observations were made on the abaxial leaf surface. Significant increases in stomatal density (68.7%), index (29.6%) and epidermal cell density (37.3%) were recorded in plants grown at high temperature over control with CO2 enrichment. The cultivars responded differently in terms of length and width of guard cell and stoma (pore) under high temperature, however, the values averaged over treatments showed a significant reduction in these parameters. Further, number of stomata per leaf was higher (28.3%) in plants grown at high temperature, except First Red. A reduction in mean leaf area (26.7%) and dry mass (32.0%) was recorded at high rather than optimum temperature. The specific leaf area was maximum in Arjun (87%) while in First Red, a 14% reduction was noted at high temperature. 相似文献