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1.
The distribution of hybrid necrosis genes in aboriginal wheats of Middle Asia (Tadzhikistan, Kyrghyzstan, Uzbekistan, and Turkmenistan) was studied. Necrotic genotypes were identified in 154 samples including 147 samples of Triticum aestivum, six samples of T. compactum, and one T. antiquorum sample. The absence of the Ne2 gene in this region was shown. About 43.5% of the samples examined were of the Ne1ne2 genotype, while 56.5% of samples had the genotype ne1ne2. The frequency of the Ne1 gene in T. aestivum from Uzbekistan and Turkmenistan was higher than in Tadzhikistan and Kyrghyzstan (χ 2 = 13.9; d.f. = 1). The height above sea level had no impact on Ne1 frequencies in cultivated wheats. No correlation between the frequencies of Ne1 and lg genes was revealed. It was suggested that the Middle Asia is a secondary route of wheat distribution from its primary center of origin.  相似文献   

2.
In diploid rye, two genes were detected which cause hybrid necrosis by complementary action if both are present in dominant condition. Moreover, these genes cause hybrid necrosis in triticale complementing with cither one of the two genes, Ne1 and Ne2 which are known to cause hybrid necrosis in wheat. It is suggested, that the two genes in rye are named Ner1 and Ner2 corresponding to the wheat gene with which they complement in triticale. The consequences of the presence of necrosis genes in rye populations for breeding of rye are discussed.  相似文献   

3.
In the presented study, the existing AFLP and SSR maps of barley were used to find chromosomal position of four genes controlling different stages of root hair development. Four barley mutants were used in the analysis: the root hairless mutant rhl1.b, mutant rhp1.b with root hair development blocked at the initial bulge formation, mutant rhi1.a with irregular pattern of sparsely located root hairs and mutant rhs1.a with very short root hairs. Each mutant was crossed with parents of ‘Steptoe’/‘Morex’ mapping population and F2 progenies of crosses: mutant × ‘Steptoe’ and mutant × ‘Morex’ were analyzed for segregation of root hair phenotype and polymorphic AFLP and SSR markers. It was possible to map all the analyzed genes on barley chromosomes: rhl1 gene on the short arm of chromosome 7H, rhp1 gene on chromosome 1H, rhs1 locus in the pericentromeric region of chromosome 5H and rhi1 gene on the long arm of chromosome 6H. Subsequently, the Bulk Segregant Analysis and AFLP technique were used for saturation of the identified regions with new markers. The joint maps were constructed using as common points the SSR markers located in the target regions. Linkage maps of the regions around the four genes involved in the root hair formation in barley were composed of 8–11 markers and spanned over 16.1–49.0 cM. The distances between localized genes and the closest markers ranged from 1.0 to 3.8 cM. The identified chromosomal locations of genes can be used for their fine mapping and future map-based cloning.  相似文献   

4.
Brassica napus L. is an important oilseed and fodder crop with significant heterosis for seed yield and other agronomic traits, but very little is known about the molecular basis of heterosis. As an initial step towards understanding the molecular events associated with this phenomenon, a molecular functional map of rapeseed was constructed using differentially expressed genes in hybrid identified by microarrays. Single-strand conformational polymorphism (SSCP) analysis was applied for genetic mapping in an F 2 population of 184 individuals resulting from crossing ‘`SI-1300 × Eagle’'. A total of 162 markers including 154 loci corresponding to 98 differentially expressed genes assigned to 17 functional categories and 8 SSR markers were grouped into 21 linkage groups (LGs), covering a total map distance of 2267.3 cM. Subsequently, this map was aligned with Arabidopsis thaliana in silico. Comparative mapping shows that genes localized on each Arabidopsis chromosome have orthologs dispreading in different B. napus LGs. Similarly, a majority of LGs were made of homologous genes from different Arabidopsis chromosomes. In addition, a total of 25 syntenic regions were identified in B. napus, in most of which the gene order was not consistent between the two species, and each of the conserved regions in the A. thaliana genome was homologous to 1--5 distinct regions in the B. napus genome. These results indicate that it is not easy to exploit A. thaliana information for B. napus based on synteny.  相似文献   

5.
Summary The current powdery mildew (Sphaerotheca fuligninea) resistant cucumber varieties suffer from leaf chlorosis during autumn, winter and early spring cultivation in the Netherlands. Therefore screening was carried out for novel powdery mildew resistance genes. From 177 accessions, derived from different sources, 108 accessions proved to be partially resistant to S. fuliginea. Crosses were made with 53 resistant accessions to distinguish the presence of novel genes. It is likely that the accessions C. sativus 2145, C. sativus LV 41, PI 188807, Vladivostokij, White and Yellow 1 have one or more recessive powdery mildew resistance genes, different from powdery mildew resistance genes of the line NPI, which was used for variety breeding. Powdery mildew resistance tests with S. fuliginea give similar results in different regions of the world.Abbreviations pmr powdery mildew resistance  相似文献   

6.
For breeding potato varieties resistant to late blight, identification of resistance genes to Phytophthora infestans (Rpi genes) is essential. Introduction of Rpi genes from wild Solanum species into cultivated potato is likely to be a good method to achieve durable resistance to P. infestans. In this study, we identified two Rpi genes (Rpi-ber1 and Rpi-ber2) derived from two different accessions of Solanum berthaultii. These two genes are closely linked on the long arm of chromosome 10. There are similarities between the predicted genetic locations of the previously identified Rpi-ber and Rpi-ber1, which given the common origin of these genes, may indicate that they are the same. However, the genetic positions of Rpi-ber1 and Rpi-ber2 are different. Rpi-ber1 is positioned between CT214 and TG63, whereas Rpi-ber2 is located below both of these two markers. In addition, the sequences of four linked markers to both R genes showed different polymorphisms indicating the two Rpi genes could be transmitted from different haplotypes (chromosomes).  相似文献   

7.
K. Tsunewaki  T. Koba 《Euphytica》1979,28(3):579-592
Summary Co-isogenic lines of a common wheat, Triticum aestivum, cv. S-615 with each of the following ten major genes were produced by repeated backcrosses; The gene C on 2D chromosome for the compactum character, s on 3D for the sphaerococcum character, Hd on 4B, B1 on 5A, and B2 on 6B for awn suppression, Hg on 1A for glume hairiness, Hp on 4A for peduncle hairiness, Ne1 on 5B and Ne2 on 2B for hybrid necrosis, and v1 on 3B for virescence. Seven of them showed the typical mendelian fashion of inheritance, while three others (C, s and v1) were transmitted at lower frequencies than their corresponding normal alleles.The effects of those major genes on 24 characters of cv. S-615 were investigated, which are summarized as follows: C: Increased node diameter, number of spikelets per ear and spike density, but decreased lengths of all ear rachis, awn, anther, empty and outer glumes, and grain, and grain index. s: Increased culm diameter and thickness, and spike density, reduced lengths of all 1st and 2nd internodes, culm, flag leaf, rachis, awn, anther, empty and outer glumes, and grain, and grain index, and accelerated heading. Hd: Increased number of spikelets per ear and anther length, while decreased length of awn, and empty and outer glumes. B1: Increased 1st internode, rachis, and anther lengths, and grain index, but decreased spike density, awn length and grain thickness. B2: Increased rachis length, number of spikelets per ear, empty and outer glume lengths and grain index, but reduced awn length and grain thickness. Hg: No effects. Hp: Increased number of spikelets per ear. Ne1: Accelerated heading, and increased empty glume length. Ne2: Increased node and culm diameters. v1: No effects.Two species-specific genes, C and s, affected a large number of characters expressed in various developmental stages. These genes were found to have pleiotropic effects, namely, they influenced, at least, two groups of interdependent characters. Three awn suppressors influenced a limited number of characters, but no evidence of their pleiotropic effects was obtained.Contribution from the Laboratory of Genetics, Faculty of Agriculture, Kyoto University, Japan, No. 422. The work was supported in part by a Grant-in-Aid (No. 148,004) from the Ministry of Education, Japan.  相似文献   

8.
A synthetic winter rye population was produced with two race-specific powdery mildew resistance genes, one dominant (Rm1) and the other (rm2) recessive, each at a frequency of about 0.50. The population was advanced by open-pollination in an isolated plot under mildew-free conditions for eight years. Samples of generations Syn-0 through Syn-7 were inoculated in the laboratory with two mildew isolates, one avirulent to either resistance gene, the other virulent to Rm1 and avirulent to rm2, to discriminate resistant and susceptible phenotypes. From the proportions of resistant plants, frequencies of Rm1 and rm2 were calculated and the fitness of carriers of resistance alleles was estimated in relation to carriers of susceptibility alleles at the two loci using continuous models and linear regression analyses. Frequencies of the two resistance genes oscillated only weakly over the eight generations. Coefficients of selection against Rm1-and rm2rm2 genotypes were –0.04 and –0.02, respectively, and not significantly different from zero. Thus the two resistance genes were selectively neutral. It is concluded that pyramiding of major powdery mildew resistance genes in rye varieties should not reduce their yield potential in the absence of mildew.  相似文献   

9.
Fourteen accessions of rye when crossed to Triticum aestivum cv. C 306 (Ne1ne2ch1Ch2) yielded chlorotic F1 hybrids and six accessions involved in hybrid combination with the same tester produced normal F1 hybrid plants. Two rye accessions, namely, EC 179188 and EC 143825 when crossed to the wheat lines HD 2329 (ne1Ne2ch1Ch2) and NI 5439 (ne1ne2ch1Ch2) also produced chlorosis. The hybrids between T. macha and two rye accessions produced normal plants. Variable degrees of chlorosis were observed among different wheat × rye F1 hybrids. It is suggested that the rye accessions producing chlorosis in combination with wheat cvs. C 306, HD 2329 and NI 5439 (all Ch2-carriers) carry one of the complementary genes for chlorosis. Gene symbol Chr1 is proposed for the chlorosis gene of rye.  相似文献   

10.
A single dominant blast resistance gene conferring resistance to a Korean rice blast isolate was identified in rice variety `Suweon 365'. We report the chromosomal localization and molecular mapping of this blast resistance gene designated as Pi-18, which confers resistance to Korean isolate `KI-313' of the blast pathogen. To know whether there is a relationship among genes conditioning resistance to location-specific isolates of the blast pathogen and thereby to identify linked markers to resistance gene for isolate KI-313 collected in Korea, RFLP markers previously reported to be linked to major blast resistance genes in different rice germplasm and other markers mapped to nearby regions were surveyed for polymorphism between a resistant (`Suweon 365') and a susceptible (`Chucheongbyeo') parent. Linkage associations of the RFLP markers with the resistance gene were verified using an F2 and F3 segregating population of known blast reaction. RFLP analysis showed that Pi-18 was located near the end of chromosome 11, linked to a single copy clone RZ536 at a distance of 5.4 centiMorgans (cM) and that this gene was different from Pi-1(t). An allelism test revealed that this gene was also different from Pi-k. Currently, a combination of RAPD and microsatellite primers is being employed to find additional markers in this region. Tightly linked DNA markers will facilitate selection for resistant genotypes in breeding programs and provide the basis for map based cloning of this new blast resistance gene. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

11.
Chickpea wilt caused by Fusarium oxysporum f. sp. ciceris is one of the major yield limiting factors in chickpea. The disease causes 10–90% yield losses annually in chickpea. Eight physiological races of the pathogen (0, 1A, 1B/C, 2, 3, 4, 5 and 6) are reported so far whereas additional races are suspected from India. The distribution pattern of these races in different parts of the world indicates regional specificity for their occurrence leading to the perception that F. oxysporum f. sp. ciceris evolved independently in different regions. Pathogen isolates also exhibit differences in disease symptoms. Races 0 and 1B/C cause yellowing syndrome whereas 1A, 2, 3, 4, 5 and 6 lead to wilting syndrome. Genetics of resistance to two races (1B/C and 6) is yet to be determined, however, for other races resistance is governed either by monogenes or oligogenes. The individual genes of oligogenic resistance mechanism delay onset of disease symptoms, a phenomenon called as late wilting. Slow wilting, i.e., slow development of disease after onset of disease symptoms also occurs in reaction to pathogen; however, its genetics are not known. Mapping of wilt resistance genes in chickpea is difficult because of minimal polymorphism; however, it has been facilitated to great extent by the development of sequence tagged microsatellite site (STMS) markers that have revealed significant interspecific and intraspecific polymorphism. Markers linked to six genes governing resistance to six races (0, 1A, 2, 3, 4 and 5) of the pathogen have been identified and their position on chickpea linkage maps elucidated. These genes lie in two separate clusters on two different chickpea linkage groups. While the gene for resistance to race 0 is situated on LG 5 of Winter et al. (Theoretical and Applied Genetics 101:1155–1163, 2000) those governing resistance to races 1A, 2, 3, 4 and 5 spanned a region of 8.2 cM on LG 2. The cluster of five resistance genes was further subdivided into two sub clusters of 2.8 cM and 2.0 cM, respectively. Map-based cloning can be used to isolate the six genes mapped so far; however, the region containing these genes needs additional markers to facilitate their isolation. Cloning of wilt resistance genes is desirable to study their evolution, mechanisms of resistance and their exploitation in wilt resistance breeding and wilt management.  相似文献   

12.
Pathogenicity data from surveys of Puccinia triticina (formerly P. recondita f. sp. tritici) conducted in western Europe in 1995 were analysed to compare the structure of regional populations of the pathogen. Many of the populations differed in phenotypic diversity and pathotypic composition, even though they occurred within a single epidemiological unit, suggesting that local factors may influence the establishment and propagation of individual pathotypes in the regional populations. Neighbouring regions were more similar than distant regions, and all regions shared at least one pathotype, except populations in northern Italy and Scotland. A high degree of similarity was found between populations in northern France and Great Britain, providing strong evidence of free movement of inoculum between these regions. Resistance genes were postulated for a selection of 91 wheat cultivars, representing those most commonly grown in western Europe in 1995. Thirteen cultivars lacked detectable seedling resistance genes and the remaining 78 possessed from one to three resistance genes; those detected were Lr1, Lr3a, Lr10, Lr13, Lr14a, Lr17b, Lr20, Lr26 and Lr37. The most commonly detected resistance gene was Lr13, which was present singly or in combination with other resistance genes in 48 cultivars (53%). The gene Lr14a was detected in 18 cultivars, Lr26 was present in 16 cultivars. The role of host selection in the composition of the regional populations of P. triticina in western Europe in 1995 was difficult to assess on the basis of the results obtained, since virulence data were not available for Lr13 and Lr14a. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   

13.
Jerzy H. Czembor 《Euphytica》2002,125(3):397-409
Seventy-five barley landraces from Morocco were tested for resistance to powdery mildew and a number of different resistance genes were detected. Thirty-five isolates of Blumeria graminis f. sp. hordei and the Pallas isoline differential set were used. Isolates used in the experiment had virulences corresponding to all major resistance genes used in Europe. Forty-four of the tested landraces showed resistant reactions. From each of these landraces, one to five resistant plants were selected and 92 single plant lines were created. Six lines selected from 3landraces were assumed to carry the mlo gene but they were discarded after microscopic investigation. Seventeen lines were tested in the seedling stage with 17isolates and another 69 lines were tested with 23 differential isolates. These lines showed 71 reaction spectra to isolates of powdery mildew. Eight lines (9%), 255-3-3, 282-3-4, 286-1-1, 294-2-3,294-2-4, 295-1-2, 308-1-2 and 327-2-1, selected from 7 landraces showed resistance to all isolates. Seventy-eight lines (90%) showed a resistant infection type 2with more than 50% of the isolates used. In most of the selected lines (86%) unknown genes, alone or in combination with known specific resistance genes, were detected. Four different resistance alleles (Mlat, Mla6, Mla14 and Mla1) were postulated to be present in the tested lines. The most common was Mlat, which was postulated in 35 (41%) lines. The use of newly identified sources of powdery mildew resistance in barley breeding is discussed. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   

14.
Z. Eyal  E. Levy 《Euphytica》1987,36(1):237-250
Summary Pathogenicity patterns of 42Mycosphaerella graminicola (Septoria tritici) isolates secured from the major wheat growing regions in Israel, were assessed on seedlings of 16 bread and durum wheats. The spring bread wheat cultivar Titan (CI12615), the winter bread wheats Bezostaya 1, Kavkaz, NE7060 and the durum wheats Nursit 163 and Zenati Bouteille, all exhibited a high level of resistance. Significant cultivar × isolate interactions were recorded for isolates from the different regions in relation to the response of the 16 cultivars organized in 6 reponse classes to the test isolate ISR8036. Number of genes for resistance in the 16 cultivars was estimated, based on the assumption of a gene-for-gene relationship. Twelve complementary genes were hypothesized in the 42M. graminicola isolates × 16 wheat cultivars matrix. There was considerable variation in virulence frequencies between regions and between locations within the same region. The overall frequency of Bezostaya-Kavkaz virulence was low throughout the country (5–7%). The frequency of designated hypothesized virulence genes VST OLAF, VST COLOTANA, VST IAS 20 in Israel, was high in most locations. The reported analytical approach enables the identification of virulence hot-spots and assists in designing breeding for resistance strategies.  相似文献   

15.
In this study, we characterized the genetic resistance of the Andean bean cultivars Kaboon and Perry Marrow and their relation to other sources of anthracnose resistance in common bean. Based on the segregation ratio (3R:1S) observed in two F2 populations we demonstrated that Kaboon carries one major dominant gene conferring resistance to races 7 and 73 of Colletotrichum lindemuthianum. This gene in Kaboon is independent from the Co-2 gene and is an allele of the Co-1 gene present in Michigan Dark Red Kidney (MDRK) cultivar. Therefore, we propose the symbol CO-1 2 for the major dominant gene in Kaboon. The Co-1 is the only gene of Andean origin among the Co anthracnose resistance genes characterized in common bean. When inoculated with the less virulent Andean race 5, the segregation ratio in the F2 progeny of Cardinal and Kaboon was 57R:7S (p = 0.38). These data indicate that Kaboon must possess other weaker dominant resistance genes with a complementary mode of action, since Cardinal is not known to possess genes for anthracnose resistance. Perry Marrow, a second Andean cultivar with resistance to a different group of races, was shown to possess another resistant allele at the Co-1 locus and the gene symbol Co-1 3 was assigned. In R × R crosses between Perry Marrow and MDRK or Kaboon, no susceptible F2 plants were found when inoculated with race 73. These findings support the presence of a multiple allelic series at the Andean Co-1 locus, and have major implications in breeding for durable anthracnose resistance in common bean. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

16.
We examined the effects of heavy-ion bombardment on mutagenesis in sweet pepper (Capsicum annuum L.). Dose–response studies indicated that 10 Gy irradiation of 12C or 20Ne ions on dry seeds is suitable for inducing mutations in plants. From 20Ne-irradiated M1 plants, putative mutants included two dwarf plants and one plant whose pericarp was yellow were isolated. Phenotypes of their M2 progeny were similar to those of the M1 plants and did not segregate. F1 plants resulting from reciprocal crosses between the mutants and wild-type plants showed the wild-type phenotype, but phenotypes of F2 and BC1F1 segregated at 1:3 (mutant:wild) and 1:1, respectively. These crossing experiments indicate that the three mutants have monogenic recessive mutations in nuclear genes. In light of these data, we discuss the effectiveness of using heavy-ion bombardment to mutate sweet peppers.  相似文献   

17.
The greenbug [Schizaphis graminum (Rondani)] is an extremely damaging pest of barley (Hordeum vulgare L), particularly in the southern Great Plains of the USA. Two greenbug resistance genes, Rsg1a (in ‘Post 90’) and Rsg2b (in PI 426756), available for developing resistant barley cultivars, have similar phenotypes when challenged by various greenbug biotypes. This study was conducted to separate these two resistance genes via differential plant reactions to a recently collected field isolate of greenbug. Four barley entries and one wheat germplasm were challenged with two greenbug isolates and damage ratings were recorded for each combination. One greenbug isolate used in this study (TX1) was able to differentiate Rsg1a from Rsg2b through dramatically different plant responses (Rsg2b conferred resistance, Rsg1a did not). The results indicate the potential vulnerability of greenbug resistance genes in barley. Based on these and other reported results, we propose that gene symbol designations for greenbug resistance in barley be changed from Rsg1a to Rsg1 and Rsg2b to Rsg2.  相似文献   

18.
Summary In studies of the inheritance of resistance, pea seedlings of seven lines in which stems and leaves were both resistant to Mycosphaerella pinodes were crossed with a line in which they were both susceptible. With seven of the crosses resistance was dominant to susceptibility. When F2 progenies of five crosses were inoculated on either stems or leaves independently, phenotypes segregated in a ratio of 3 resistant: 1 susceptible indicating that a single dominant gene controlled resistance. F2 progenies of one other cross gave ratios with a better fit to 9 resistant: 7 susceptible indicating that two co-dominant genes controlled resistance. The F2 progeny of another cross segregated in complex ratios indicating multigene resistance.When resistant lines JI 97 and JI 1089 were crossed with a susceptible line and leaves and stems of each F2 plant were inoculated, resistance phenotypes segregated independently demonstrating that leaf and stem resistance were controlled by different genes. In two experiments where the F2 progeny of the cross JI 97×JI 1089 were tested for stem and leaf resistance separately, both characters segregated in a ratio of 15 resistant:1 susceptible indicating that these two resistant lines contain two non-allelic genes for stem resistance (designated Rmp1 and Rmp2) and two for leaf resistance (designated Rmp3 and Rmp4). Evidence that the gene for leaf resistance in JI 1089 is located in linkage group 4 of Pisum sativum is presented.  相似文献   

19.
Tlalnepantla 64 (PI 207262) is an important source of genes for resistance to common bean anthracnose, caused by Colletotrichum lindemuthianum. However, these genes have not been fully characterized. Inheritance studies using crosses involving PI 207262 show that two independent genes confer resistance to anthracnose. Allelism tests showed that the genes are located at distinct loci from the previously identified resistance genes Co-1, Co-2, Co-3, Co-5, Co-6, and Co-10. Also, no segregation was observed in relation to Co-4, Co-4 2, Co-9, and to the gene present in cultivar Widusa, indicating that PI 207262 harbors alleles of these genes. We conclude that PI 207262 harbors two anthracnose resistance genes, Co-4 and Co-9. The Co-4 allele of PI 207262 would be different from Co-4 and Co-4 2 and it is proposed Co-4 3 as the genetic symbol for this resistance allele. As PI 207262 is the parent of BAT 93, the Co-9 symbol represents the gene of both cultivars. Also, one allele of Co-9 gene was detected in cultivar Widusa.  相似文献   

20.
Summary Studies were conducted to determine the inheritance and allelic relationships of genes controlling resistance to the Russian wheat aphid (RWA), Diuraphis noxia (Mordvilko), in seven wheat germplasm lines previously identified as resistant to RWA. The seven resistant lines were crossed to a susceptible wheat cultivar Carson, and three resistant wheats, CORWA1, PI294994 and PI243781, lines carrying the resistance genes Dn4, Dn5 and Dn6, respectively. Seedlings of the parents, F1 and F2 were screened for RWA resistance in the greenhouse by artificial infestation. Seedling reactions were evaluated 21 to 28 days after the infestation using a 1 to 9 scale. All the F1 hybrids had equal or near equal levels of resistance to the resistant parent indicating dominant gene control. Only two distinctive classes were present and no intermediate types were observed in the F2 segregation suggesting major gene actions. The resistance in PI225262 was controlled by two dominant genes. Resistance in all other lines was controlled by a single dominant gene. KS92WGRC24 appeared to have the same resistance gene as PI243781 and STARS-9302W-sib had a common allele with PI294994. The other lines had genes different from the three known genes.  相似文献   

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