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1.
Wim J.M. Koopman 《Euphytica》2000,116(2):151-159
The wild lettuce species L. serriola, L. saligna, and L. virosa are important genitors in lettuce (L. sativa) breeding. Identifying these wild species can be problematic because in some cases they look very similar. Flow cytometry was tested for its reliability and general applicability as a tool to distinguish them. Three series of tests were conducted: (1) Tests with three accessions of L. sativa and one accession of each of the wild species, repeated three times throughout the year. In each repeat, the mean relative DNA amount of L. serriola was significantly higher than that of L. saligna, but significantly lower than that of L. virosa. The mean relative DNA amount of L. sativa did not differ from that of L. serriola.(2) Tests with each wild species represented by 10 accessions. Significant differences between the accessions within each species demonstrated the presence of intraspecific variation. Notwithstanding this intraspecific variation, the relative DNA amounts of all accessions of L. serriola were significantly higher than that of all L. saligna accessions, and significantly lower than that of all L. virosa accessions. Therefore, all accessions could be assigned to the appropriate species on the basis of their DNA amounts. (3) Tests with single plants from 10 accessions of each of the wild species. These test revealed that individual plants of L. serriola, L. saligna, and L. virosa can be reliably identified with flow cytometry, when aL. serriola sample of established identity is used as internal reference. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

2.
Summary A total of 1789 accessions of several lettuce collections was screened to find new major gene resistance to the downy mildew fungus Bremia lactucae Regel. The accessions belonged to the species Lactuca sativa (N=1288), L. serriola (N=399), L. saligna (N=52) and L. virosa (N=50). A total of 20 races of B. lactucae were used, 14 of which were NL-races, isolated from cultivated lettuce in the Netherlands. The other six races were isolated from wild L. serriola in Czechoslovakia. The accessions were initially screened with two races: NL1 and NL3. Accessions with resistance to one or both of these races were tested with the other races. Phenotypes with new resistance were found in accessions of all four Lactuca species. Of L. sativa, four accessions were found with resistance phenotypes that could not be explained by combinations of known major genes. Many accessions of L. serriola had resistance phenotypes that indicated the presence of unknown resistance genes. All interactions between accessions of L. saligna and races of B. lactucae were incompatible in leaf disc tests, except for four accessions, which showed some sporulation with race NL6. Several accessions of L. virosa were resistant to all races used. Other accessions of L. virosa gave a race-specific interaction with B. lactucae.  相似文献   

3.
In a series of glasshouse and laboratory experiments, lettuce varieties and wild Lactuca species were screened for resistance to the lettuce root aphid, Pemphigus bursarius (Ron.). Several new sources of resistance to P. bursarius development and survival were identified. Extremely high levels of resistance were found in the wild species L. saligna, L. perennis and L. virosa. Resistance was also identified in the lettuce variety Grand Rapids. This resistance is controlled by one or two genes. At least one of these genes is not allelic to the existing Lra gene. Grand Rapids therefore represents a new source of resistance to P. bursarius. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   

4.
Summary Various genes for disease resistance identified in wild Lactuca are difficult, even impossible to exploit in lettuce breeding, due to sexual incompatibility between L. sativa and wild Lactuca sp. We adapted two cellular biology techniques to overcome these interspecific barriers: in vitro embryo rescue and protoplast fusion. In vitro rescue of immature embryos was used successfully for sexual hybridization between L. sativa and L. virosa. Vigorous hybrid plants were produced between L. sativa and seven accessions of L. virosa. Protoplast fusion permitted the regeneration of somatic hybrids between L. sativa and either L. tatarica or L. perennis. Hybrids between L. sativa and L. tatarica were backcrossed to L. sativa.  相似文献   

5.
Host plant resistance is an effective protection strategy to control aphids in many crops. However, the evolution of insensitive aphid biotypes necessitates the search for new resistance sources. Wild relatives of crop plants can be important sources for resistance genes to be introgressed into new cultivars. Nasonovia ribisnigri (Mosely) (Homoptera: Aphididae) is an important pest of cultivated lettuce, Lactuca sativa. Since 1982, resistance introduced into lettuce cultivars has relied on the Nr-gene, originating from a wild relative, Lactuca virosa. In 2007 first reports appeared that Nr-based resistance had become ineffective against certain populations of N. ribisnigri. The objective of this study was to establish if the original donor of the Nr-gene L. virosa accession, IVT 280, is resistant against recently emerged virulent (Nr:1) N. ribisnigri biotypes. To this end we investigated feeding and penetration behaviour of virulent and avirulent (Nr:0) aphids on the resistant L. virosa, IVT 280, and two susceptible L. virosa accessions, using the electrical penetration graph method. Additionally, aphid performance was analysed in terms of survival, development time and reproduction on these accessions. L. virosa accession IVT 280 was resistant against all populations of N. ribisnigri tested. The ingestion of phloem was strongly reduced on the resistant accession compared to the susceptible L. virosa accessions. Additionally, none of the aphids survived on the resistant accession that, therefore, constitutes a good source of resistance in lettuce against both biotypes of N. ribisnigri.  相似文献   

6.
Summary Interspecific crosses were carried out between the three Lactuca species L. virosa, L. serriola and L. sativa to transfer resistance to the leaf aphid Nasonovia ribis nigri from L. virosa to the cultivated lettuce. L. sativa, L. serriola was used as an intermediate parent between the other two species. Many irregularities were observed in the interspecific hybrids, ranging from premature dying of F1 plants resulting from a kind of bastard necrosis till complete male and female sterility and deviating microsporogenesis. Using in vitro culture and after several backcrosses male and female fertile plants were obtained with a L. sativa habit and with resistance to the leaf aphid.  相似文献   

7.
Summary Tomato spotted wilt virus (TSWV) was obtained from infected tomatoes in commercial fields in Arkansas in 1985. A greenhouse screening procedure for identifying tomatoes resistant to TSWV was established using an enzyme-linked immunosorbent assay (ELISA) to detect infected plants. Symptom expression was variable and symptom expression was not reliable for identifying infected plants. Germplasm evaluated for resistance to one typical Arkansas isolate (85–9) of TSWV included: twenty cultivars and breeding lines of Lycopersicon esculentum Mill, 52 accessions of L. pimpinellifolium (Jusl.) Mill and 8 accessions of L. peruvianum (L.) Mill. All cultivated accessions and breeding lines evaluated were susceptible. Some individual plants in several accessions of L. pimpinellifolium were resistant and nearly all plants of the L. peruvianum accessions that were evaluated were resistant to isolate 85–9.Dept. of Plant Pathology  相似文献   

8.
Summary Sources of resistance to tomato-yellow-leaf-curl-virus (TYLCV) were investigated in 16 accessions of three Lycopersicon species and 55 commercial tomato hybrids and cultivars. All commercial hybrids and cultivars were highly susceptible. Accessions of L. hirsutum, L. hirsutum f. glabaratum and L. pimpinellifolium showed a wide range of reactions. Those of L. peruvianum, LA 385 of L. peruvianum f. humifusum exhibited very high levels of resistance indicating their potential use in local breeding programs. In contrast to earlier findings, back indexing showed that all symptomless genotypes in this investigation were carriers of the TYLCV.  相似文献   

9.
Summary None of the tested cultivars of lettuce was found resistant to Stemphylium leaf spot, a common disease in Israel. Within a Lactuca saligna population collected in wild lettuce in Israel, resistance was traced. Interspecific crosses of L. saligna x L. sativa were made and the mode of inheritance of resistance to this disease was studied. Resistance is apparently controlled by two genes: one dominant (Sm1) and one recessive (sm2).Contribution No. 1176-E 1984 series, from the ARO.  相似文献   

10.
I. R. Crute  J. A. Dunn 《Euphytica》1980,29(2):483-488
Summary Many lettuce cultivars (Lactuca sativa L.) with high resistance to lettuce root aphid (Pemphigus bursarius L.) also carried the gene Dm-6 for specific resistance to downy mildew (Bremia lactucae Regel). This suggests the possibility of linkage between this gene and root aphid resistance. The origin of this association is discussed.  相似文献   

11.
Summary Twenty-one accessions of 3 wild Lactuca species which could be hybridised with L. sativa, the cultivated lettuce, were inoculated at different stages of plant development with 3 multivirulent isolates of Bremia lactucae. Nineteen sources of resistance to B. lactucae, not attributable to the previously recognised resistance factors 1–11 were identified. Two lines of L. serriola showed similar resistance patterns as lines carrying R11. The resistance of some accession was incomplete particularly at the seedling stage and this phenomenon may be race specific.Tests on segregating F2 populations of crosses between 2 different L. serriola accessions and L. sativa cultivars showed that the resistance in one line (LSE/18) appears to be inherited as a single dominant gene, which is sometimes incomplete in expression and allelic to either Dm6 or R7. The segregation patterns for resistance in PI 281876 did not give readily interpretable ratios.To assess the frequency of occurrence in B. lactucae populations of virulence factors to overcome this novel resistance, 11 of the novel sources of resistance were inoculated with numerous collections of the pathogen from the UK, Czechoslovakia and elsewhere and found to show a high level of resistance.  相似文献   

12.
Summary Eighty-one accessions of three Lactuca species which showed no recognisable race specific resistance to Bremia lactucae when tested in the laboratory as seedlings, exhibited different degrees of susceptibility when exposed to natural field infection. As a group, crisp genotypes had less mildew and a slower rate of disease development than other types of lettuce. Wild forms of Lactuca sativa and Lactuca serriola were particularly susceptible. In a further trial, the low field susceptibility of three lettuce cultivars (Iceberg, Batavia blonde de Paris and Grand Rapids) was confirmed. Disease development on cv. Iceberg was compared to that on the highly susceptible cv. Hilde in experiments where the two cultivars were grown either in close proximity or in isolation. The absolute level of attack on cv. Iceberg depended upon disease pressure and differences between the two types only became apparent approximately 8 wk after sowing.  相似文献   

13.
Summary The genetics of partial resistance of lettuce to Myzus persicae was studied using F1 and F2 generations of two crosses between a susceptible and partially resistant accession (Norden x Batacer and Liba x Norden) and three crosses in which both parents were partially resistant (Batavia la Brillante x Batacer, Batacer x Liba and CGN4741 x Batacer). Partial resistance to M. persicae inherited quantitatively, without important dominance effects. Only in the cross Batacer x Liba were significant departures of the F1 and F2 from the midparent found, which were probably caused by epistatic effects. Reciprocal F1s had similar resistance levels, indicating the absence of cytoplasmic or other maternal effects. Estimates of broad-sense heritability ranged from 0.34 to 0.61. The results indicated that lines with an improved resistance level can be obtained from crosses between partially resistant accessions, preferably by line selection or the application of indirect marker aided selection.Abbreviations PR partial resistance, partially resistant - S susceptibility, susceptible  相似文献   

14.
A. Lebeda 《Euphytica》1985,34(2):521-523
Summary The natural infection of Erysiphe cichoracearum on 29 accessions of five wild Lactuca species (L. serriola, L. saligna. L. virosa, L. aculeata and L. dentata) and on one hybrid of L. serriola x L. sativa has been investigated for two and three years, respectively. No infection was observed on L. serriola (PI 255665), L. saligna (LSA/92/1 and LSA/92/2), L. virosa (LVIR/26 and LVIR/57/1) and L. dentata (PI 234204). The level of susceptibility of the control cultivars of L. sativa was found to be moderate (Fila) to fairly high (Hilde).  相似文献   

15.
Summary Six lettuce lines, representing two types of resistance to the green peach aphid, Myzus persicae, and a control line with high susceptibility to M. persicae were tested for resistance to six different clones of Myzus persicae and two clones of the potato aphid, Macrosiphum euphorbiae.The clones of M. persicae showed very different levels of aggressiveness on lettuce: two had a high level of reproduction, two had an intermediate level and two were poorly adapted to lettuce as a host. Differences between lettuce lines in aphid reproduction increased with increasing aggressiveness of the aphid clone, which means that aggressive clones are most effective for selection purposes. No evidence was found for clone-specific plant genotype reactions, meaning that lines resistant to one clone will also be resistant to other clones of M. persicae, allthough not neccessarily at the same level. The lettuce lines selected for partial resistance to the aggressive clone WMp1 were completely or almost completely resistant to less aggresive clones.No differences in level of reproduction were found between the two clones of M. euphorbiae and no relation was observed between resistance to M. persicae and M. euphorbiae, indicating the species-specific character of resistance to leaf aphids in lettuce.  相似文献   

16.
Summary More than 200 accessions of three wildLactuca species were screened in the laboratory for race-specific resistance toBremia lactucae. Only a fewLactuca entries showed resistance both as seedlings and in a leaf disc test. Accessions ofL. serriola andL. sativa had a low degree of resistance. The best entries were also compared under field conditions. TheL. saligna entries were totally free from disease in the field test. High resistance was also recorded in a fewL. serriola entries and in lettuce cultivars such as Saffier and Mariska.  相似文献   

17.
Jens Weibull 《Euphytica》1986,35(3):993-999
Summary Thirty-two accessions of Avena species and breeding lines were evaluated for resistance, primarily antibiosis, to the aphid Rhopalosiphum padi (L.) in greenhouse and growth room tests. The highest levels of resistance were found in A. barbata and in the perennial species A. macrostachya. One breeding line, Obee, was also found to have interesting resistance characters. Resistance in A. macrostachya is discussed in relation to perenniality. A different screening method for rapid testing of large collections of varieties is evaluated.  相似文献   

18.
Summary The inheritance of resistance to Nasonovia ribis nigri in L. sativa was investigated. Parents and F1 and F2 populations from crosses between the susceptible cultivar Ravel and two resistant breeding lines were tested. In both breeding lines one dominant gene appeared responsible for resistance.  相似文献   

19.
Since the late 1980s powdery mildew, designated Oidium lycopersicum, frequently invaded the tomato crop in Western Europe. All commercial cultivars are susceptible. To screen for resistance in wild species a reliable and efficient disease test was developed. Young plants with two to three true leaves are inoculated at high relative humidity by spraying with a freshly prepared suspension of 2×104 conidia, ml–1. Symptoms are periodically evaluated according to a scale based on the percentage of leaf area with mycelium.One hundred and twenty seven accessions, representing eight wild Lycopersicon species, were screened for resistance to O. lycopersicum. A large variation in resistance was found between species. L. hirsutum was the most resistant species; L. pennellii was moderately resistant; species of the subgeneric group of L. esculentum and of the peruvianum-complex were all susceptible. L. parviflorum was classified separately due to a large variation between accessions. Except for this species, a low variation was found between accessions within species. High levels of resistance were observed in four accessions of L. hirsutum, in one of L. parviflorum and in one of L. peruvianum. This resistance is characterized by a very low disease incidence and a strongly restricted mycelium growth and lack of sporulation.  相似文献   

20.
A total of 240 kale, 38 cabbage and 126 winter cauliflower French landraces from the B. oleracea genepool of INRA were assessed for resistance to clubroot caused by Plasmodiophora brassicaeWoron. Two French isolates of the pathogen (K and SJ) were used in the experiments under controlled conditions. The reaction of the 126 cauliflower accessions to naturally occurring clubroot was also evaluated in field trials. Kales exhibited considerable variation for expression of disease resistance and high levels of resistance were found in several accessions. In this group, single resistant plants were observed in most of the morphological types and from quite different geographical origins. Cabbage accessions were moderately to highly susceptible to both isolates. All cauliflower populations proved to be highly susceptible to K isolate and moderately susceptible to SJ isolate. In field trials, cauliflowers were also severely infected. Two lines selected from a resistant kale population were highly resistant against a large range of pathotypes of the pathogen. These lines presented a sufficient level of resistance to be directly useful in the breeding program in order to develop cauliflower and broccoli hybrids resistant to clubroot. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

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