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1.
Summary Sequence characterized amplified regions (SCARs) were derived from eight random amplified polymorphic DNA (RAPD) markers linked to disease resistance genes in lettuce. SCARs are PCR-based markers that represent single, genetically defined loci that are identified by PCR amplification of genomic DNA with pairs of specific oligonucleotide primers; they may contain high-copy, dispersed genomic sequences within the amplified region. Amplified RAPD products were cloned and sequenced. The sequence was used to design 24-mer oligonucleotide primers for each end. All pairs of SCAR primers resulted in the amplification of single major bands the same size as the RAPD fragment cloned. Polymorphism was either retained as the presence or absence of amplification of the band or appeared as length polymorphisms that converted dominant RAPD loci into codominant SCAR markers. This study provided information on the molecular basis of RAPD markers. The amplified fragment contained no obvious repeated sequences beyond the primer sequence. Five out of eight pairs of SCAR primers amplified an alternate allele from both parents of the mapping population; therefore, the original RAPD polymorphism was likely due to mismatch at the primer sites.  相似文献
2.
水杨酸诱导植物抗病性的新进展   总被引:43,自引:0,他引:43       下载免费PDF全文
水杨酸是一种重要的能激活一系列植物抗病防卫反应的内源信号分子.首先介绍了水杨酸在植物抗病性中的作用,并从水杨酸与过氧化氢及其代谢酶类相互作用的角度初步探讨了水杨酸诱导植物抗病性的分子机理,最后概述了目前这一领域中需要进一步研究的若干问题.  相似文献
3.
The majority of plant disease resistance genes are members of very large multigene families. They encode structurally related proteins containing nucleotide binding site domains (NBS) and C-terminal leucine rich repeats (LRR). The N-terminal region of some resistance genes contain a short sequence called TIR with homology to the animal innate immunity factors, Toll and interleukin receptor-like genes. Only a few plant resistance genes have been functionally analyzed and the origin and evolution of plant resistance genes remain obscure. We have reconstructed gene phylogeny by exhaustive analysis of available genome and amplified NBS domain sequences. Our study shows that NBS domains faithfully predict whole gene structure and can be divided into two major groups. Group I NBS domains contain group-specific motifs that are always linked with the TIR sequence in the N terminus. Significantly, Group I NBS domains and their associated TIR domains are widely distributed in dicot species but were not detected in cereal databases. Furthermore, Group I specific NBS sequences were readily amplified from dicot genomic DNA but could not be amplified from cereal genomic DNA. In contrast, Group II NBS domains are always associated with putative coiled-coil domains in their N terminus and appear to be present throughout the angiosperms. These results suggest that the two main groups of resistance genes underwent divergent evolution in cereal and dicot genomes and imply that their cognate signaling pathways have diverged as well. Received: 17 May 1999 / Accepted: 25 September 1999  相似文献
4.
5.
Polyamines and plant disease   总被引:31,自引:0,他引:31  
Walters DR 《Phytochemistry》2003,64(1):97-107
The diamine putrescine and the polyamines spermidine and spermine are found in a wide range of organisms from bacteria to plants and animals. They are basic, small molecules implicated in the promotion of plant growth and development by activating the synthesis of nucleic acids. Polyamine metabolism has long been known to be altered in plants responding to abiotic environmental stress and to undergo profound changes in plants interacting with fungal and viral pathogens. Polyamines conjugated to phenolic compounds, hydroxycinnamic acid amides (HCAAs), have been shown to accumulate in incompatible interactions between plants and a variety of pathogens, while changes in the diamine catabolic enzyme diamine oxidase suggest a role for this enzyme in the production of hydrogen peroxide during plant defence responses. More recent work has suggested a role for the free polyamine spermine in the hypersensitive response of barley to powdery mildew and particularly in tobacco to TMV. The prospects for the genetic manipulation of HCAA levels in plants as a means of both defining their role in plant defence and in the generation of disease resistant plants is discussed briefly.  相似文献
6.
 Genes cloned from diverse plants for resistance to different pathogens have sequence similarities in domains presumably involved in pathogen recognition and signal transduction in triggering the defense response. Primers based on the conserved regions of resistance genes often amplify multiple fragments that may not be separable in an agarose gel. We used denaturing polyacrylamide-gel electrophoresis to detect PCR products of plant genomic DNA amplified with primers based on conserved regions of resistance genes. Depending upon the primer pairs used, 30–130 bands were detected in wheat, rice, and barley. As high as 47%, 40%, and 27% of the polymorphic bands were detected in rice, barley, and wheat, respectively, and as high as 12.5% of the polymorphic bands were detected by certain primers in progeny from a cross of the wheat cultivars ‘Stephens’ and ‘Michigan Amber’. Using F6 recombinant inbred lines from the ‘Stephens’בMichigan Amber’ cross, we demonstrated that polymorphic bands amplified with primers based on leucine-rich repeats, nucleotide-binding sites and protein kinase genes, were inherited as single loci. Linkages between molecular markers and stripe rust resistance genes were detected. This technique provides a new way to develop molecular markers for assessing the genetic diversity of germplasm based upon potential candidate resistance genes in diverse species. Received : 5 September 1997 / Accepted : 6 November 1997  相似文献
7.
Although extensive data has described the key role of salicylic acid (SA) in signaling pathogen-induced disease resistance, its function in physiological processes related to cell death is still poorly understood. Recent studies have explored the requirement of SA for mounting the hypersensitive response (HR) against an invading pathogen, where a particular cell death process is activated at the site of attempted infection causing a confined lesion. Biochemical data suggest that SA potentiates the signal pathway for HR by affecting an early phosphorylation-sensitive step preceding the generation of pro-death signals, including those derived from the oxidative burst. Accordingly, the epistatic relationship between cell death and SA accumulation, analyzed in crosses between lesion-mimic mutants (spontaneous lesion formation) and the transgenic nahG line (depleted in SA) places the SA activity in a feedback loop downstream and upstream of cell death. Exciting advances have been made in the identification of cellular protective functions and cell death suppressors that might operate in HR. Moreover, the spatio-temporal patterns of the SA accumulation (non-homogeneous distribution, biphasic kinetics) described in some HR lesions, may also reveal important clues for unraveling the complex cellular network that tightly balances pro- and anti-death functions in the hypersensitive cell death.  相似文献
8.
水杨酸在植物抗病中的作用   总被引:27,自引:0,他引:27  
水杨酸是一种重要的能激活植物抗病防卫反应的内源信号分子,本文首先介绍了水杨酸的基本性质及水杨酸在植物抗病中的作用,然后从水杨酸与水杨酸结合蛋白的相互作用以及水杨酸介导的信号传导途径与非水杨酸介导的信号途径等方面初步探讨了水杨酸诱导植物抗病性的作用机制,最后总结了研究水杨酸作用机制对植物抗性生理和抗性分子生物学发展的意义。  相似文献
9.
Transposon tagging in rice   总被引:27,自引:0,他引:27  
To develop an efficient gene isolation method for rice we introduced the maize Ac/Ds system into rice. Extensive analysis of their behavior in rice for several generations indicated that Ac and Ds in the presence of Ac transposase gene actively transpose in rice. A wide spectrum of mutations affecting growth, morphogenesis, flowering time and disease resistance have been obtained in the population carrying Ac/Ds and some of them were genetically analyzed. Main efforts are currently being made to isolate genes responsible these mutations. In addition, a number of Ac/Ds were mapped on chromosomes and mapped elements will be used in the future for directed tagging of genes with known chromosomal positions.  相似文献
10.
Brassinolide (BL), considered to be the most important brassinosteroid (BR) and playing pivotal roles in the hormonal regulation of plant growth and development, was found to induce disease resistance in plants. To study the potentialities of BL activity on stress responding systems, we analyzed its ability to induce disease resistance in tobacco and rice plants. Wild-type tobacco treated with BL exhibited enhanced resistance to the viral pathogen tobacco mosaic virus (TMV), the bacterial pathogen Pseudomonas syringae pv. tabaci (Pst), and the fungal pathogen Oidium sp. The measurement of salicylic acid (SA) in wild-type plants treated with BL and the pathogen infection assays using NahG transgenic plants indicate that BL-induced resistance does not require SA biosynthesis. BL treatment did not induce either acidic or basic pathogenesis-related (PR) gene expression, suggesting that BL-induced resistance is distinct from systemic acquired resistance (SAR) and wound-inducible disease resistance. Analysis using brassinazole 2001, a specific inhibitor for BR biosynthesis, and the measurement of BRs in TMV-infected tobacco leaves indicate that steroid hormone-mediated disease resistance (BDR) plays part in defense response in tobacco. Simultaneous activation of SAR and BDR by SAR inducers and BL, respectively, exhibited additive protective effects against TMV and Pst, indicating that there is no cross-talk between SAR- and BDR-signaling pathway downstream of BL. In addition to the enhanced resistance to a broad range of diseases in tobacco, BL induced resistance in rice to rice blast and bacterial blight diseases caused by Magnaporthe grisea and Xanthomonas oryzae pv. oryzae, respectively. Our data suggest that BDR functions in the innate immunity system of higher plants including dicotyledonous and monocotyledonous species.  相似文献
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