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Ryanodine receptors (RyRs) are the targets of novel diamide insecticides. The cotton bollworm, Helicoverpa armigera, is one of the most important cotton pests in the world. In this study, we report the full-length RyR cDNA sequence (named as HaRyR) of H. armigera. The 16,083-bp contiguous sequence encoded 5, 142 amino acid residues, which shares 80% and 78% overall identities with its homologues in Nilaparvata lugens (NlRyR) and Drosophila melanogaster (DmRyR), respectively. All hallmarks of RyR proteins are conserved in the HaRyR, including the GXRXGGGXGD motif conserved in the Ca2+ release channels and four copies of RyR domain unique to RyR channels. The previously identified seven lepidopteran-specific RyR residues were also found in HaRyR (N4977, N4979, N4990, L5005, L5036, N5068 and T5119). An amino acid sequence alignment showed that the N-terminal region of HaRyR (residues 188–295) shared high sequence identity with NlRyR (94%) and DmRyR (92%), and moderate sequence identity (47–50%) with three rabbit RyR isoforms, while the short segment of the C-terminal transmembrane region of HaRyR (residues 4632–4676) exhibited moderate sequence identity with NlRyR (69%) and DmRyR (67%), and low sequence identity (19–28%) with three rabbit RyR isoforms. In addition, expression analysis of HaRyR revealed that the mRNA expression level in eggs was significantly lower than in third instar larvae, pupae and adults, and anatomical regulation of HaRyR expression was also observed with the highest expression level in head compared with thorax and abdomen. Our results lay a foundation for comprehensive structural and functional characterization of HaRyR and for understanding of the molecular mechanisms of toxicity selectivity of diamide insecticides among different species.  相似文献   

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温度是影响昆虫生长发育的重要生态因素之一,高温逆境作为一种绿色防控手段可以有效控制温室害虫种群发展。为了探究高温处理西花蓟马若虫对其种群发展的影响,本试验用41℃和43℃两个温度分别处理西花蓟马初孵若虫2、6、12、24和36h后,观察并记录其雌成虫寿命、繁殖力及后代发育指标的变化情况。结果表明,随着处理时间的延长,两个高温处理后西花蓟马雌成虫寿命,子代若虫总数、成虫总数和总存活率(若虫发育到成虫的存活率)均显著下降,后代雌雄性比呈总体下降趋势。41℃处理后,性比从2.30∶1降低到2.13∶1;43℃处理后从2.25∶1降低到2.07∶1,均明显低于对照的2.69∶1。另外,两性生殖种群相比于孤雌生殖种群更易遭受高温处理的影响。  相似文献   

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Although many Pseudomonas syringae strains have already been determined, only a few genomes of strains belonging to pathovar lachrymans have been sequenced so far. In this study we report the genome sequence of P. syringae pv. lachrymans strain 814/98, which is highly virulent to cucumber. The genome size was estimated to be 6.58 Mb, with 57.97% GC content. In total, 6024 genes encoding proteins and 92 genes encoding RNAs were identified in this genome. Comparisons with the available sequenced genomes of pathovar lachrymans as well as with other P. syringae pathovars were conducted, revealing the presence of three unique plasmids and 24 type III effector proteins (TTEs) in strain 814/98. The phylogenetic analyses of MLST loci and TTEs clearly showed the existence of two distinct clusters of strains within pathovar lachrymans, which were grouped into either phylogroup 1 or 3, supporting non-monophyly within this pathovar.  相似文献   

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Specific primers targeting Penicillium digitatum were developed based on fungal genes RPB1 and cmd, which are conserved among the genomes of Penicillium spp. The specific primers were designed based on the mutational sites in the homologous regions of the conserved genes. The results indicated that primer pairs RPB1–1 and cmd-3 were specific enough to distinguish Penicillium digitatum (N1) from Penicillium chrysogenum (Q), Penicillium italicum (A10) and Penicillium expansum (L) when the DNA samples were diluted 100-fold. To further verify the effectiveness and specificity of the two primer pairs RPB1–1 and cmd-3, 38 strains of fungal isolates from sources related to citrus were detected using both primer pairs, and 14 candidate P. digitatum strains were identified. Then, the fourteen candidate P. digitatum strains were further identified as P. digitatum by morphological and molecular methods, which confirmed the detection accuracy and reliability of the specific primer pairs RPB1–1 and cmd-3 as molecular markers of P. digitatum. This work may significantly facilitate the rapid identification of P. digitatum in the citrus industry.  相似文献   

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Phytophthora infestans is the causal agent of potato late blight. Genotypes of Japanese populations of P. infestans have been classified as US-1, JP-1, JP-2, JP-3, and JP-4 based on analyses of DNA polymorphisms. These populations may have been introduced to Japan by the migration of P. infestans from other countries and by domestic changes produced through sexual and asexual propagation. Resistance to late blight has been an ongoing desire of potato farmers in Japan and elsewhere. Recurrent backcrossing of Solanum demissum to varieties of S. tuberosum has been used to transfer late blight resistance. Many varieties carry the R1 gene, whereas others carry R2, R3, and/or R4. However, R genes provided only transient resistance to late blight. New races rapidly overcome R-gene-mediated resistance. The R genes of potato generally encode receptors that recognize secretory effector (Avr) proteins produced by P. infestans. These effector proteins induce robust resistance in potato varieties containing R genes, while they suppress resistance in potato varieties lacking R genes. Conserved molecules from Phytophthora species such as fatty acids, glucans, and elicitins also act as elicitors in Solanaceae species. These P. infestans-derived elicitors induce defensive reactions, including the accumulation of phytoalexins and hypersensitive cell death. A future challenge will be to combine our accumulated knowledge with that from other scientific fields to develop a disease management approach for late blight.  相似文献   

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病原真菌通常分泌效应子到寄主组织中调控寄主的生理过程,从而有利于其侵染。CFEM(common in several fungal extracellular membrane)蛋白是真菌所独有的,且与致病性密切相关。本研究利用Pfam数据库对草莓胶孢炭疽菌全基因组进行搜索,鉴定获得22个CFEM蛋白。对CFEM蛋白的信号肽、跨膜结构域和亚细胞定位进行分析,结果表明仅有8个CFEM蛋白为分泌蛋白。对CFEM分泌蛋白在不同侵染阶段的转录情况进行转录组学及RT-PCR分析,结果显示8个CFEM蛋白在侵染后不同时期均有表达。其中,1个CFEM分泌蛋白于附着胞形成期特异表达,2个于活体寄生阶段特异表达,2个于死体寄生阶段特异表达。综合上述分析结果,预测这8个分泌蛋白可能为草莓胶孢炭疽菌的效应子。本研究为深入解析植物病原真菌CFEM效应子提供了理论依据。  相似文献   

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Filamentous fungi produce hydrophobins, small proteins localized on the outer surface of their cell walls and involved in growth and development. Hydrophobin gene expression depends on nutrient availability, light, and the activity of conserved signal-transduction pathways. We found four hydrophobins, one class I and three class II family members, in the Cochliobolus heterostrophus genome with high homology to other ascomycete hydrophobins, which present a typical conserved array of cysteines. The expression profile of a selected gene from each class was determined in a series of signaling-deficient mutants. Loss of either of two mitogen-activated protein kinase (MAPK) genes, CHK1 and MPS1, led to decreased hydrophobin class I (CHYD1) gene expression. Mutants in both MAPK genes had easily wettable colonies, but decreased CHYD1 expression was not the sole explanation for this phenotype. A significant elevation of hydrophobin class II (CHYD3) gene expression was measured in the chk1 mutant, suggesting a complex role for MAPK in controlling the expression of these hydrophobins. Similar but less marked tendencies were observed in G-protein α and β subunit loss-of-function mutants; however these showed no alteration in colony hydrophobicity. Overexpression of CHYD1 in the wild-type background caused a change in colony morphology and a small but significant increase in aerial growth. Thus G-protein and MAPK signal transduction influence hydrophobin gene expression and colony hydrophobicity. The connection between colony hydrophobicity and expression of the hydrophobin genes CHYD1 and CHYD3, however, is not one-to-one, indicating that additional factors determine colony-surface properties. The approach of using hydrophobin-overexpression mutants to investigate their role may be generalized to other hydrophobins and small secreted proteins.  相似文献   

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RNA silencing is one of the conserved antiviral mechanisms in plants, and viruses encode RNA silencing suppressors (RSS) to overcome host RNA silencing and facilitate virus infection. Sugarcane streak mosaic virus (SCSMV; species Sugarcane streak mosaic virus, genus Poacevirus, family Potyviridae) is a major causal agent of sugarcane mosaic disease in many countries in Asia, including China. In this study, we used Agrobacterium co-infiltration to show that the SCSMV P1 protein, rather than the helper component-proteinase (HC-Pro), functions as a strong RSS to suppress local RNA silencing in Nicotiana benthamiana. Mutational analysis indicated that the 15 amino acids (aa; aa 1–15) of the SCSMV P1 N-terminus were not important for RNA silencing suppression, but rather another 15 aa domain (aa 108–122) containing a conserved motif (LFR/KNKQAYIST) was essential for efficient silencing suppression by P1. In addition to the 15 aa (aa 344–358) domain in the P1 N-terminus, another 15 aa domain (aa 65–79) of P1, containing the LXKA motif and one conserved aa (D78), were associated with P1 protein stability. Furthermore, substituting the histidine (H263) residue in P1 with threonine (H263T) or alanine (H263A) also affected P1 protein stability. Notably, the H263 residue is both a positively selected site and part of the serine protease catalytic triad (HDS). Taken together, our data demonstrate that SCSMV P1, and not HC-Pro, plays a functional role in suppressing RNA silencing, and also show that some conserved motifs and a positivelyselected site in the P1 protein are associated with RSS activity and protein stability.  相似文献   

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TIR-NBS-LRR (TNL) genes greatly affect plant growth and development. Ninety TNL-type genes were identified and characterized in Chinese cabbage (Brassica rapa ssp. pekinensis). Tissue-expression profiling revealed different expression levels in different tissues. qRT-PCR analysis revealed the expression patterns of 69 genes challenged by Turnip mosaic virus (TuMV): 42 genes were up-regulated, and 11 genes down-regulated; genes were grouped according to their different expression patterns. Sixteen candidate genes were identified as responding to TuMV infection. This study supplies information on resistance genes involved in Chinese cabbage's response against TuMV, and furthers the understanding of resistance mechanisms in B. rapa crops.  相似文献   

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HrpG, a two-component response regulator-like protein, is a key regulator of the type III secretion system (T3SS) in Xanthomonas spp. In X. campestris pv. vesicatoria, HrpG with a single amino acid substitution (HrpG*) gains the ability to induce the expression of T3SS-related genes even under nutrient-rich conditions. In this study, we investigated the role of HrpG in the synthesis of the secretory protein using HrpG* in strain NA-1 of X. axonopodis pv. citri (Xac NA-1), a causal agent of citrus canker. Eleven proteins secreted via a type II secretion system (T2SS) were induced by HrpG*. In proteomic analyses, six of the 11 proteins were identified as extracellular enzymes, and the others as a fimbrial biogenesis-related protein, a type IV-related protein, two hypothetical proteins, and a conserved hypothetical protein. Further analysis of these proteins revealed that the genes coding all 11 proteins were upregulated by HrpG*, even though they had different expression patterns for HrpXct-dependency. The data indicated that HrpG, a key regulator of T3SS, also acts as a positive regulator of certain proteins secreted via a T2SS in Xac NA-1.  相似文献   

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To identify proteins important for invasion into host plant tissue, Aspergillus flavus was cultured on medium containing cotton carpel tissue as the sole carbon source. We identified several hydrolases suggesting they are important as A. flavus virulence factors for plant colonization. Specifically, Aspergillus flavus AF13 secreted at least two endoxylanase activities and a pectolytic activity when grown on the cotton carpel tissue medium. A concentrated sample derived from the A. flavus growth medium (6-day) was subjected to gel filtration chromatography on a BioGel P-30 column. A major endoxylanase activity was separated from the other fungal-secreted proteins. Additional fungal secreted proteins were partially resolved by gel filtration chromatography on a BioGel P-60 column. Multiple proteins with molecular weights in the 20 to 70 kD range were present in the harvested fungal growth medium. Analysis of these fungal-secreted proteins by liquid chromatography/tandem mass spectrometry identified both endo- and exo-glucanase proteins, α-l-arabinofuranosidase, glucoamylase, α-amylase A, pectate lyase A, xylanase F1, acetylxylan esterase, glutaminase A, as well as conserved hypothetical proteins of unknown function. These proteins likely assist A. flavus in the maceration of plant cell walls, allowing for pathogenic entry and accession of host nutrient resources. Pectolytic and xylanolytic hydrolases, as well as glucanases, appear to be important A. flavus virulence factors.  相似文献   

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The oomycete pathogen, Phytophthora infestans, is the causal agent of potato late blight, which is one of the most destructive and economically important plant diseases. We investigated the interaction between P. infestans and Solanaceous model plant Nicotiana benthamiana. Mature N. benthamiana plants were resistant to 8 isolates of P. infestans, whereas relatively young plants were susceptible to all isolates. Analysis with virus-induced gene silencing (VIGS) indicated that NbSGT1 and NbHSP90, genes essential for the function of R proteins, are required for the resistance of N. benthamiana to P. infestans. NbSGT1 was also required for the production of reactive oxygen species (ROS), hypersensitive cell death and expression of NbEAS, a gene for phytoalexin biosynthesis, induced by INF1, a secretory protein derived from P. infestans. These results suggested that N. benthamiana possibly possesses a broad-spectrum R protein against P. infestans, which requires an SGT1/HSP90-dependent mechanism, for the recognition of a conserved molecular pattern of P. infestans.  相似文献   

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During the growing seasons of 1996 and 1997, samples of potato stems and tubers with symptoms of blackleg and soft rot were collected in different regions in Poland. After growing to pure cultures on crystal violet pectate (CVP) medium, isolates of bacteria were identified as Pectobacterium spp. on the basis of their ability to degrade pectate and with the use of biochemical tests. About 43 % strains isolated from 122 different plant samples were identified as Pectobacterium carotovorum subsp. carotovorum, whereas the rest of the pectinolytic bacteria was identified as Pectobacterium atrosepticum. A recent screening of these isolates with recA PCR-RFLP allowed identification of 18 different RFLP groups within the tested P. c. subsp. carotovorum strains. The third largest group of the tested P. c. subsp. carotovorum strains (14 %), which were assigned to the profile 3 recA PCR-RFLP, was re-identified as Pectobacterium wasabiae (formerly Erwinia carotovora subsp. wasabiae) on the basis of recA and 16S rRNA genes sequences. About 50 % of P. wasabiae isolated from potato, in contrast to horseradish isolates of P. wasabiae, have an ability to grow at 37°C and some of them grow on media containing 5 % of NaCl. In a pathogenicity test with 11 strains of P. wasabiae these strains showed a high capacity to rot potato tubers.  相似文献   

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