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1.
Host-plant resistance is the preferred strategy for management of Asian rice gall midge (Orseolia oryzae), a serious pest in many rice-growing countries. The deployment of molecular markers linked to gall midge resistance genes in breeding programmes can accelerate the development of resistant cultivars. In the present study, we have tagged and mapped a dominant gall midge resistance gene, Gm1, from the Oryza sativa cv. W1263 on chromosome 9, using SSR markers. A progeny-tested F2 mapping population derived from the cross W1263/TN1 was used for analysis. To map the gene locus, initially a subset of the F2 mapping population consisting of 20 homozygous resistant and susceptible lines each was screened with 63 parental polymorphic SSR markers. The SSR markers RM316, RM444 and RM219, located on chromosome 9, are linked to Gm1 at genetic distances of 8.0, 4.9 and 5.9 cM, respectively, and flank the gene locus. Further, gene/marker order was also determined. The utility of the co-segregating SSR markers was tested in a backcross population derived from the cross Swarna/W1263//Swarna, and allelic profiles of these markers were analysed in a set of donor rice genotypes possessing Gm1 and in a few gall midge-susceptible, elite rice varieties.  相似文献   

2.
The increasing number of expressed sequence tag (EST) projects dedicated to ectomycorrhizal fungi is translating into the release of large sets of ESTs. The aim of this study was to develop and test simple sequence repeat (SSR) markers from EST databases of the model ectomycorrhizal fungus Hebeloma cylindrosporum. Six SSR markers were found to be both unambiguously scorable and polymorphic among 12 H. cylindrosporum isolates. Two SSR markers were transferable to other Hebeloma species and one marker was interestingly found to be polymorphic among seven H. crustuliniforme isolates.  相似文献   

3.
Laccaria amethystina is a major early successional ectomycorrhizal fungus. We isolated 10 polymorphic loci from L. amethystina using a dual‐suppression‐PCR (polymerase chain reaction) technique. These loci provided microsatellite markers with polymorphism of two to 10 alleles per locus. The observed and expected heterozygosities ranged from 0.136 to 0.545 and 0.206 to 0.877, respectively.  相似文献   

4.
Twenty‐six polymorphic microsatellite markers were isolated from (AC)n and (AG)n microsatellite‐enhanced genomic libraries of the gray, short‐tailed opossum Monodelphis domestica. All 26 loci showed high allelic diversity, with allele numbers ranging from five to 11 in a subset of 35 animals. Normal Mendelian inheritance was confirmed for 24 loci by analysing allelic segregation in 10, two‐generation, families. Non‐amplifying (null) alleles were detected at two loci, which we recommend be used only if pedigree data are available. We conclude that all of these microsatellite markers would be useful for quantitative trait locus mapping and population genetic studies.  相似文献   

5.
Carya illinoinensis (pecan) belongs to the Juglandaceae (walnut family) and is a major economic nut crop in the southern USA. Although evidence suggests that some species in the Juglandaceae are ectomycorrhizal, investigations on their ectomycorrhizal fungal symbionts are quite limited. Here we assessed the ectomycorrhizal fungal diversity in cultivated orchards of C. illinoinensis. Five pecan orchards in southern Georgia, USA, were studied, three of which were known to fruit the native edible truffle species Tuber lyonii. We sequenced rDNA from single ectomycorrhizal root tips sampled from a total of 50 individual trees. Mycorrhizae were identified by ITS and LSU rDNA sequence-based methods. Forty-four distinct ectomycorrhizal taxa were detected. Sequestrate taxa including Tuber and Scleroderma were particularly abundant. The two most abundant sequence types belonged to T. lyonii (17%) and an undescribed Tuber species (~20%). Because of our interest in the ecology of T. lyonii, we also conducted greenhouse studies to determine whether this species would colonize and form ectomycorrhizae on roots of pecan, oak, or pine species endemic to the region. T. lyonii ectomycorrhizae were formed on pecan and oak seedlings, but not pine, when these were inoculated with spores. That oak and pecan seedling roots were receptive to truffle spores indicates that spore slurry inoculation could be a suitable method for commercial use and that, ecologically, T. lyonii may function as a pioneer ectomycorrhizal species for these hosts.  相似文献   

6.
Using ectomycorrhizal root tip morphotyping (anatomical and morphological identification) and molecular analysis (internal transcribed spacer region amplification and sequencing), we assessed diversity and composition of the ectomycorrhizal fungal community colonizing P. densiflora seedlings (from 1 to 5 years ) in a naturally regenerating area of a mature forest, in Dongning County of Hei Longjiang Province, China. A total of 22 ectomycorrhizal taxa were determined on the roots of 100 seedlings. The most frequent species was Cenococcum geophilum, which colonized 31.2% of the root tips and occurred in 93.8% of the all samples. It was followed by Clavulina cinerea, Thelephora sp.2, and Russula albidula. They colonized in 22.7%, 17.5%, 13.4% of the root tips and occurred in 63.4%, 42.6%, 29.3% of the samples respectively. These results suggested that ectomycorrhizal diversity increased in P. densiflora seedlings with increasing age.  相似文献   

7.
Liming (Ca–Mg soil amendment) is a forestry practice used to correct soil acidification and restore health and productivity in declining stands. Liming is known to modify tree mineral nutrition beyond the sole Ca and Mg. We hypothesized that liming also modifies the very functioning of the tree absorbing system (that is the ectomycorrhizal fine roots) in a way that facilitates the mobilization of mineral nutrients, particularly those entrapped in soil organic matter. This hypothesis has been tested here in beech and Norway spruce stands in North-Eastern France. In autumn, we compared the ectomycorrhizal community structure and the enzymatic profiles of ectomycorrhizal root tips in limed and untreated plots by measuring the activities of eight enzymes related to the degradation of soil organic matter. The results show that the ectomycorrhizal community responds to the Ca–Mg amendment and to the resulting soil modifications by modified enzyme activity profiles and ability to mobilize nutrients from soil organic matter. The effects of liming on the belowground functioning of the tree stands result essentially from specialized ECM fungal species such as Clavulina cristata (with strong glucuronidase activity), Lactarius subdulcis (with strong laccase activity) or Xerocomus pruinatus (with strong leucine aminopeptidase activity).  相似文献   

8.
Kantartzi SK  Ulloa M  Sacks E  Stewart JM 《Genetica》2009,136(1):141-147
The cultivated diploid, Gossypium arboreum L., (A genome) is an invaluable genetic resource for improving modern tetraploid cotton (G. hirsutum L. and G. barbadense L.) cultivars. The objective of this research is to select a set of informative and robust microsatellites for studying genetic relationships among accessions of geographically diverse G. arboreum cultivars. From more than 1,500 previously developed simple sequence repeat (SSR) markers, 115 genomic (BNL) and EST-derived (MUCS and MUSS) markers were used to evaluate the allelic diversity of a core panel of G. arboreum accessions. These SSR data enabled advanced genome analyses. A set of 25 SSRs were selected based both upon their high level of informativeness (PIC ≥ 0.50) and the production of clear PCR bands on agarose gels. Subsequently, 96 accessions representing a wide spectrum of diversity of G. arboreum cultivars were analyzed with these markers. The 25 SSR loci revealed 75 allelic variants (polymorphisms) ranging from 2 to 4 alleles per locus. The Neighborjoining (NJ) method, based on genetic dissimilarities, revealed that cultivars from geographically adjacent countries tend to cluster together. Outcomes of this research should be useful in decreasing redundancy of effort and in constructing a core collection of G. arboreum, important for efficient use of this genetic resource in cotton breeding.  相似文献   

9.
Hobbie EA  Jumpponen A  Trappe J 《Oecologia》2005,146(2):258-268
Nitrogen isotopes (15N/14N ratios, expressed as δ15N values) are useful markers of the mycorrhizal role in plant nitrogen supply because discrimination against 15N during creation of transfer compounds within mycorrhizal fungi decreases the 15N/14N in plants (low δ15N) and increases the 15N/14N of the fungi (high δ15N). Analytical models of 15N distribution would be helpful in interpreting δ15N patterns in fungi and plants. To compare different analytical models, we measured nitrogen isotope patterns in soils, saprotrophic fungi, ectomycorrhizal fungi, and plants with different mycorrhizal habits on a glacier foreland exposed during the last 100 years of glacial retreat and on adjacent non-glaciated terrain. Since plants during early primary succession may have only limited access to propagules of mycorrhizal fungi, we hypothesized that mycorrhizal plants would initially be similar to nonmycorrhizal plants in δ15N and then decrease, if mycorrhizal colonization were an important factor influencing plant δ15N. As hypothesized, plants with different mycorrhizal habits initially showed similar δ15N values (−4 to −6‰ relative to the standard of atmospheric N2 at 0‰), corresponding to low mycorrhizal colonization in all plant species and an absence of ectomycorrhizal sporocarps. In later successional stages where ectomycorrhizal sporocarps were present, most ectomycorrhizal and ericoid mycorrhizal plants declined by 5–6‰ in δ15N, suggesting transfer of 15N-depleted N from fungi to plants. The values recorded (−8 to −11‰) are among the lowest yet observed in vascular plants. In contrast, the δ15N of nonmycorrhizal plants and arbuscular mycorrhizal plants declined only slightly or not at all. On the forefront, most ectomycorrhizal and saprotrophic fungi were similar in δ15N (−1 to −3‰), but the host-specific ectomycorrhizal fungus Cortinarius tenebricus had values of up to 7‰. Plants, fungi and soil were at least 4‰ higher in δ15N from the mature site than in recently exposed sites. On both the forefront and the mature site, host-specific ectomycorrhizal fungi had higher δ15N values than ectomycorrhizal fungi with a broad host range. From these isotopic patterns, we conclude:(1) large enrichments in 15N of many ectomycorrhizal fungi relative to co-occurring ectomycorrhizal plants are best explained by treating the plant-fungal-soil system as a closed system with a discrimination against 15N of 8–10‰ during transfer from fungi to plants, (2) based on models of 15N mass balance, ericoid and ectomycorrhizal fungi retain up to two-thirds of the N in the plant-mycorrhizal system under the N-limited conditions at forefront sites, (3) sporocarps are probably enriched in 15N by an additional 3‰ relative to available nitrogen, and (4) host-specific ectomycorrhizal fungi may transfer more N to plant hosts than non-host-specific ectomycorrhizal fungi. Our study confirms that nitrogen isotopes are a powerful tool for probing nitrogen dynamics between mycorrhizal fungi and associated plants.  相似文献   

10.
Seven microsatellite loci were isolated and characterized from ectomycorrhizal basidiomycete Suillus pictus associated with soft pine species (Pinus subgenus Strobus) using a dual‐suppression‐PCR technique. Microsatellite variation was assessed using 38 isolates of S. pictus sampled from three different local populations in Japan. The number of alleles per locus ranged from three to 12 within populations. These microsatellite loci can be used for studying the allelic variation and genetic structure in/among local populations of S. pictus.  相似文献   

11.
The ecology and physiology of ectomycorrhizal (EcM) symbiosis with conifer trees are well documented. In comparison, however, very little is known about the molecular regulation of these associations. In an earlier study, we identified three EcM-regulated Pinus expressed sequence tags (EST), two of which were identified as homologous to the Medicago truncatula nodulin MtN21. The third EST was a homologue to the receptor-like kinase Clavata1. We have characterized the expression patterns of these genes and of auxin- and mycorrhiza-regulated genes after induction with indole-3-butyric acid in Pinus sylvestris and in a time course experiment during ectomycorrhizal initiation with the co-inoculation of 2,3,5-triiodobenzoic acid, an auxin transport inhibitor. Our results suggest that different P. sylvestris nodulin homologues are associated with diverse processes in the root. The results also suggest a potential role of the Clv1-like gene in lateral root initiation by the ectomycorrhizal fungus.  相似文献   

12.
Cytoplasmic male sterility (CMS), one of the most important traits in crop breeding, is used for commercial F1-hybrid seed production in peppers (Capsicum annuum L.). A nuclear gene, Restorer-of-fertility (Rf), can induce normal pollen production in CMS plants resulting in fertility. Since the first report of fertility restoration in peppers, various inheritance modes have been suggested, including the presence of a third haplotype of the locus. The pepper Rf gene has not been cloned, and calculated genetic distances of linked markers have varied between research groups. A more precise allelic test and additional genetic mapping are needed to accurately select recombinants for use in marker-assisted backcrossing (MAB). Therefore, the reliability and application of these markers for allelic selection of the Rf gene was tested. Two different F2 populations, Buja and Tamna, were used for the construction of a linkage map. From these linkage groups, a new closely linked flanking marker of the Rf gene were identified. Previous allelic testing revealed the existence of a third haplotype, Rfls 7701 , which can function as dominant (Rf) or recessive (rf). In a previous report, Rfls 7701 was considered to be linked to unstable male sterility (MS). However, our results suggest that unstable MS was induced by a gene residing at another locus rather than by Rfls 7701 haplotype-linked allele.  相似文献   

13.
In this study, the genotype distribution and allelic frequencies of CAPN1 (Calcium activated neutral protease) single nucleotide polymorphisms (SNPs) were analyzed taking advantage of the different genetic backgrounds provided by Hereford, Brahman and Braford cattle. We report a new insertion/deletion (InDel) polymorphism, consisting of a change of seven nucleotides for only one nucleotide (TCTGGGT → C) within intron 17 of the CAPN1 gene. The segregation pattern of this polymorphism was analyzed together with the markers CAPN316, CAPN530 and CAPN4751 already described. The allele distribution of CAPN1 markers in the Braford crossbreed (3/8 Brahman 5/8 Hereford) is described for the first time. Four assays of allelic discrimination were designed: the tetra primer ARMS-PCR technique for genotyping the new InDel and the CAPN4751 marker, and a PCR-RFLP method for genotyping the markers CAPN316 and CAPN530. The genotypic and minor allele frequencies (MAFs) obtained showed that the InDel polymorphism does not provide redundant information to that already provided by the other CAPN1 markers and segregates differently between breeds, being a common SNP (MAF ≥ 0.05) in the herds with a high percentage of Bos indicus background. The high percentage of heterozygous individuals found in the Braford crossbreed for the markers assessed reveals enough genetic variation that could help to solve the tenderness problem of tropical-adapted cattle.  相似文献   

14.
In terrestrial ecosystems, plant roots are colonized by various clades of mycorrhizal and endophytic fungi. Focused on the root systems of an oak‐dominated temperate forest in Japan, we used 454 pyrosequencing to explore how phylogenetically diverse fungi constitute an ecological community of multiple ecotypes. In total, 345 operational taxonomic units (OTUs) of fungi were found from 159 terminal‐root samples from 12 plant species occurring in the forest. Due to the dominance of an oak species (Quercus serrata), diverse ectomycorrhizal clades such as Russula, Lactarius, Cortinarius, Tomentella, Amanita, Boletus, and Cenococcum were observed. Unexpectedly, the root‐associated fungal community was dominated by root‐endophytic ascomycetes in Helotiales, Chaetothyriales, and Rhytismatales. Overall, 55.3% of root samples were colonized by both the commonly observed ascomycetes and ectomycorrhizal fungi; 75.0% of the root samples of the dominant Q. serrata were so cocolonized. Overall, this study revealed that root‐associated fungal communities of oak‐dominated temperate forests were dominated not only by ectomycorrhizal fungi but also by diverse root endophytes and that potential ecological interactions between the two ecotypes may be important to understand the complex assembly processes of belowground fungal communities.  相似文献   

15.
Nine polymorphic microsatellite loci were identified in the tropical plant Vasconcellea ×heilbornii and used to estimate allelic diversity in two populations of southern Ecuador. Allelic richness ranged from two to five alleles, observed heterozygosity ranged from 0.150 to 0.947 and expected heterozygosity ranged from 0.186 to 0.701. Most of these markers also amplified microsatellite loci in two other Vasconcellea species (Vasconcellea stipulata and Vasconcellea cundinamarcensis). Hence, these markers will be useful for population genetic analysis and the evaluation of genetic diversity and gene flow in these species.  相似文献   

16.
The Bang's leaf‐nose bat, Hipposideros turpis, is an endangered cave‐dwelling species inhabiting the southwesternmost islands of Japan. We isolated six dinucleotide microsatellite markers from the partial genomic library of the bat, and examined their allelic variation using a sample (N = 33) from the largest colony in Japan. All the loci showed a moderate allelic variation ranging from two to eight alleles, with the observed heterozygosities from 0.33 to 0.73, and conformed to Hardy–Weinberg expectations. The present microsatellite markers will be useful in assessing population genetic structure and gene flow among populations of this species.  相似文献   

17.
Ten Fusarium sporotrichioides strains from different geographic regions were analyzed by RAPD in order to detect DNA loci potentially suitable as new markers for taxonomic characterization and identification of toxigenic Fusarium fungi. Three monomorphic fragments were selected from PCR amplificates obtained with one of the standard RAPD primers and sequenced. Analysis of the sequences enabled the development of specific SCAR markers for identification of Fusarium fungi at the level of species groups characterized by similar profiles of produced mycotoxins.  相似文献   

18.
This study reports the isolation and characterization of eight microsatellite markers for the study of Philippine tarsiers (Tarsius syrichta), small primates endemic to this Southeast Asian archipelago. The markers were used to screen 14 Tarsius syrichta for allelic diversity. This suite of highly polymorphic microsatellites provides the first chance to genetically study parentage and dispersal patterns in Philippine tarsiers.  相似文献   

19.
Little information is known on what the magnitude of nitrogen (N) processed by ectomycorrhizal (ECM) fungal species in the field. In a common garden experiment performed in a northern California oak woodland, we investigated transfer of nitrogen applied as 15NH4 or 15NO3 from leaves to ectomycorrhizal roots of three oak species, Quercus agrifolia, Q. douglasii, and Q. garryana. Oak seedlings formed five common ectomycorrhizal morphotypes on root tips. Mycorrhizal tips were more enriched in 15N than fine roots. N transfer was greater to the less common morphotypes than to the more common types. 15N transfer from leaves to roots was greater when , not , was supplied. 15N transfer to roots was greater in seedlings of Q. agrifolia than in Q. douglasii and Q. garryana. Differential N transfer to ectomycorrhizal root tips suggests that ectomycorrhizal morphotypes can influence flows of N from leaves to roots and that mycorrhizal diversity may influence the total N requirement of plants.  相似文献   

20.
In the last two centuries, several species of Australian eucalypts (e.g. Eucalyptus camaldulensis and E.␣globulus) were introduced into the Iberian Peninsula for the production of paper pulp. The effects of the introduction of exotic root-symbitotic fungi together with the eucalypts have received little attention. During the past years, we have investigated the biology of ectomycorrhizal fungi in eucalypt plantations in the Iberian Peninsula. In the plantations studied, we found fruit bodies of several Australian ectomycorrhizal fungi and identified their ectomycorrhizas with DNA molecular markers. The most frequent species were Hydnangium carneum, Hymenogaster albus, Hysterangium inflatum, Labyrinthomyces donkii, Laccaria fraterna, Pisolithus albus, P. microcarpus, Rhulandiella berolinensis, Setchelliogaster rheophyllus, and Tricholoma eucalypticum. These fungi were likely brought from Australia together with the eucalypts, and they seem to have facilitated the establishment of eucalypt plantations and their naturalization. The dispersion of Australian fungal propagules may be facilitating the spread of eucalypts along watercourses in semiarid regions increasing the water lost. Because ectomycorrhizal fungi are obligate symbionts, their capacity to persist after eradication of eucalypt stands, and/or to extend beyond forest plantations, would rely on the possibility to find compatible native host trees, and to outcompete the native ectomycorrhizal fungi. Here we illustrate the case of the Australasian species Laccaria fraterna, which fruits in Mediterranean shrublands of ectomycorrhizal species of Cistus (rockroses). We need to know which other Australasian fungi extend to the native ecosystems, if we are to predict environmental␣risks associated with the introduction of Australasian ectomycorrhizal fungi into the Iberian Peninsula. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

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