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1.
Summary Seven wild diploid potato species, Series Tuberosa, representing 1023 clones were screened for resistance to the potato cyst nematode, Globodera pallida. Over 25% of the clones were resistant to pathotype P4A and almost 30% were resistant to pathotype P5A. The resistance in hybrid progenies of these and other resistant species with cultivated potatoes was evaluated, and over 2200 seedlings were screened. High frequencies of resistance (>50%) to P4A were found in progenies with Solanum leptophyes, S. vernei, S. gourlayi and S. capsicibaccatum, whereas resistance to P5A was found in these species as well as S. sparsipilum. The importance of nematode resistant wild species for potato breeding is discussed.  相似文献   

2.
Summary Over 2400 pollinations were made to investigate the crossability relationships between cultivated potatoes, and wild diploid species from Series Tuberosa and Circaeifolia, as well as wild polyploid species in Series Tuberosa and Longipedicellata resistant to potato cyst nematode, Globodera pallida pathotypes P4A and P5A. Wild diploids in Series Tuberosa crossed easily with cultivated diploid species, except with Solanum lignicaule where most pollinations failed, and seed set was extremely low (0.2 seeds per pollination or less). It is suggested that this species is 1EBN. S. capsicibaccatum is clearly isolated from Series Tuberosa, but can form hybrids with S. lignicaule, which can act as a bridging species to S. tuberosum haploids. S. gourlayi and S. oplocense can be crossed with both subspecies of S. tuberosum, but S. papita, Series Longipedicellata is reproductively isolated from the tetraploid cultigens. The crossability data are discussed in the light of germplasm utilisation for breeding potato varieties resistant to potato cyst nematode.  相似文献   

3.
Screening for resistance to powdery mildew of Solanum melongena and wild related species was made in the field under natural infection conditions. A total of 172 accessions originating from several geographical parts of the world were tested. Single plant selection for resistance was carried out and open-pollination was used. Most S. melongena accessions were susceptible or highly susceptible to the disease. By S0 to S3 selection, an increase in the overall powdery mildew resistance level of S. melongena population was obtained and four S. melongena lines possessing a high level of resistance were obtained. Among the wild Solanum species, S. laciniatum and S. nigrum showed to be non-host plants of L. taurica. S. quinquangolare showed no symptoms of powdery mildew, S. linnaeanum, S. aculeatissimum, S. aviculare, S. pseudocapsicum were highly resistant, S. spinosissimum was resistant, S. gilo, S. capsicoides were susceptible or highly susceptible, and plants of S. sisymbriifolium showed a widely variable disease reaction. Four S. melongena resistant lines were obtained: PAVEG 10187 S3, PAVEG 10196 S3, P.I. 230279 S3 and P.I. 419198 S3. These S. melongena lines together with the resistant wild species could be used for genetic studies, classical breeding programs and biotechnological applications.  相似文献   

4.
Summary The past 25 years, 1686 potato accessions, representing 100 species in the genus Solanum L., subgenus Potatoe, section Petota, were evaluated for field resistance to one or more of the following insect pests: green peach aphid, Myzus persicae (Sulzer); potato aphid, Macrosiphum euphorbiae (Thomas); Colorado potato beetle, Leptinotarsa decemlineata (Say); potato flea beetle, Epitrix cucumeris (Harris); and potato leafhopper, Empoasca fabae (Harris). Accessions highly resistant to green peach aphid were identified within 36 species, to potato aphid within 24 species, to Colorado potato beetle within 10 species, to potato flea beetle within 25 species, and to potato leafhopper within 39 species. Resistance levels were characteristic within Solanum species. Insect resistance appears to be a primitive trait in wild potatoes. Susceptibility was most common in the primitive and cultivated Tuberosa. Insect resistance was also characteristic of the most advanced species. The glycoalkaloid tomatine was associated with field resistance to Colorado potato beetle and potato leafhopper. Other glycoalkaloids were not associated with field resistance at the species level. Dense hairs were associated with resistance to green peach aphid, potato flea beetle, and potato leafhopper. Glandular trichomes were associated with field resistance to Colorado potato beetle, potato flea beetle, and potato leafhopper. Significant correlations between insect score and altitude of original collection were observed in six of thirteen species. Species from hot and arid areas were associated with resistance to Colorado potato beetle, potato flea beetle, and potato leafhopper. Species from cool or moist areas tended to be resistant to potato aphid.Abbreviations EBN Endosperm Balance Number  相似文献   

5.
Bananas cultivated for export all belong to Cavendish cultivars and are all recognized as very susceptible to nematodes, particularly to the burrowing nematode Radopholus similis and the lesion nematode Pratylenchus coffeae. Even if there have been many changes in the management of banana nematodes in large commercial banana plantations, chemical control still remains most often the last resort method to manage the nematodes, although the number of registered products is definitely declining. Therefore, nematode control though genetic improvement is gaining new interest worldwide. In this study, 55 banana accessions mostly diploids from the Musa acuminata genome group (AA) but including some triploid accessions (AAA), some diploids of the Musa balbisiana genome group (BB) and some interspecific hybrids (AAB, AB) were evaluated for resistance to four nematode species R. similis, P. coffeae, Meloidogyne incognita and M. arenaria. These experiments were conducted in a growth chamber under controlled conditions. All banana accessions were susceptible to nematode species, although many different levels of susceptibility were detected. This study confirmed the good resistance status to R. similis of some cultivars from the Pisang jari buaya and Pisang batuau subgroups and the partial resistance of 17 diploid accessions significantly different from the susceptible reference cv. Grande Naine. This study also showed that 12 diploid accessions exhibited a partial resistance to P. coffeae, including some usual or potential genitors belonging to the wild diploids subspecies burmannica (cvs. Long Tavoy 1 and 2) and burmannicoides (cv. Calcutta 4). No source of resistance to Meloidogyne spp. was found. These screening results, combining for the first time four nematode species, are discussed within the scope of banana breeding in order to produce parental diploid lines with single or combined nematode resistances and further develop triploids that can substitute existing susceptible commercial cultivars.  相似文献   

6.
The peach root‐knot nematode, Meloidogyne floridensis (MF), infects majority of available nematode‐resistant peach rootstocks which are mostly derived from peach (Prunus persica) and Chinese wild peach (P. davidiana). Interspecific hybridization of peach with its wild relative, Kansu peach (P. kansuensis), offers potential for broadening the resistance spectrum in standard peach rootstocks. We investigated the inheritance of resistance to MF in segregating populations of peach (‘Okinawa’ or ‘Flordaguard’) × P. kansuensis. A total of 379 individuals from 13 F2 and BC1F1 families were challenged with a pathogenic MF isolate “MFGnv14” and were classified as resistant (R) or susceptible (S) based on root galling intensity. Segregation analyses in F2 progeny revealed the involvement of a major locus with a dominant or recessive allele determining resistance in progeny segregating 3R:1S and 1R:3S, respectively. Testcrosses with a homozygous‐susceptible peach genotype (‘Flordaguard’ or ‘UFSharp’) confirmed P. kansuensis as a source of new resistance and the heterozygous allelic status of P. kansuensis at the locus conferring resistance to MF. We propose a single‐locus dominant/recessive model for the inheritance of resistance.  相似文献   

7.
Spodoptera litura (Fabr.), the tobacco caterpillar, is a major defoliator on sunflower in the tropics. Genetic variability for resistance to S. litura is limited in the cultivar germplasm of sunflower. In the present investigation, 43 accessions of 17 wild Helianthus species of the annual and perennial habit groups were evaluated along with cultivated sunflower under field and no-choice conditions in the laboratory for resistance to this pest. Under field conditions, H. occidentalis and H. argophyllus were found to be immune with no leaf damage and few accessions of the species belonging to section Divaricati were found to be resistant. Laboratory bioassays against neonate, two and 4-day-old larvae confirmed resistance both in terms of high larval mortality and low larval weight gain in eight species viz., H. occidentalis, H. argophyllus, H. tuberosus, H. maximiliani, H. mollis, H. simulans, H. divaricatus and H. hirsutus. Intra-accessional variability was observed and accessions of few species showed varied reaction (resistant, partially resistant to susceptible) to the target pest. Field evaluation of 224 backcross derived inbred lines from five cross combinations involving diploid species under high natural pest incidence revealed low damage in plants derived from crosses involving H. argophyllus and H. petiolaris.  相似文献   

8.
Worldwide, cyst nematode (SCN) Heterodera glycines is the most destructive pathogen on cultivated soybean (Glycine max (L.) Merr.). In the USA yield losses in 2001 were estimated to be nearly 60 million dollars. Crop losses are primarily reduced by the use of resistant cultivars. Nematode populations are variable and have adapted to reproduce on resistant cultivars overtime because resistance primarily traces to two soybean accessions. Recently cv. Hartwig was released which has comprehensive resistance to most SCN populations. A virulent nematode population LY1 was recently selected for its reproduction on Hartwig. LY1 population originated from a mass mating of Race 2 (HG Type 1.2.5-) females with Race 5 (HG Type 1.2-) males. LY1 nematode population infects currently known sources of resistance except PI 567516C. The female indices obtained on PI 567516C and Hartwig were 7% (resistant) and 155% (susceptible), respectively. However, the genetic basis of LY1 resistance in soybean PI 567516C is not known. Resistant PI line 567516C was crossed to susceptible cultivar Hartwig to generate 105 F2:5 families. These families together with parents, seven indicator lines and a susceptible control cv. Lee-74 were evaluated for response to LY1 nematode population in the greenhouse. Chi-square analysis showed resistance in PI567516C to LY1 was conditioned by one dominant and two recessive genes (Rhg, rhg, rhg). Chi-square value was 0.15 and P = 0.70. This information will be useful to soybean researchers for developing resistant cultivars to nematode population that infects Hartwig.  相似文献   

9.
The genetic base for soybean cultivars is narrow compared to most other crop species. Twenty-seven wild perennial Glycine species comprise the tertiary gene pool to soybean that may contain many genes of economic importance for soybean improvement. We evaluated 16 accessions of G. argyrea, G. clandestina, G. dolichocarpa, and G. tomentella for resistance to Heterodera glycines (HG), also known as the soybean cyst nematode, and to multiple isolates of Phakopsora pachyrhizi, the causal fungus of soybean rust. All 16 accessions were classified as resistant to H. glycines HG Type 2.5.7, based on number of cysts per root mass with plant introductions (PIs) 483227, 509501, 563892, and 573064 (all G. tomentella) void of any cysts indicating no reproduction by this pest. All 16 accessions had an immune reaction to one isolate of P. pachyrhizi. Regardless of isolate, no sporulating uredinia were observed on G. argyrea (PI 505151) and G. tomentella (PIs 483227, 509501, and 573064). These results demonstrate that some accessions within the perennial Glycine species harbour resistance to both H. glycines and P. pachyrhizi and would be good candidates for wide hybridization programs seeking to transfer potentially unique multiple resistance genes into soybean.  相似文献   

10.
Breeding for reniform nematode (Rotylenchulus reniformis) resistance is hindered by the lack of resistance in upland cotton (Gossypium hirsutum) cultivars. Resistance has been frequently identified in accessions from the Gossypium arboreum germplasm collection with accession PI 529740 rated as highly resistant. Accession PI 529740 was crossed with the susceptible G. arboreum accession PI 529729 to develop an F2 population for genetic characterization. The population showed quantitative variation suggesting multiple genes conferred the resistant phenotype. Thirteen of the 216 F2 plants showed resistance similar to the resistant parent and these data supported a two recessive gene model. Sixty plants were classified as resistant or moderately resistant, indicating a single recessive gene conferred the moderately resistant phenotype. The classification of 24 F2:3 families for nematode resistance generally supported the classification of the corresponding F2 plants; however, most families were highly variable for infection with no families rated as resistant. This information will aid in the introgression of resistance into upland cotton as larger populations will be required to successfully recover resistance conferred by multiple recessive genes.  相似文献   

11.
Potato leafroll virus (PLRV; Genus Polerovirus; Family Luteoviridae) is one of the most important virus pathogens of potato worldwide and breeders are looking for new sources of resistance. Solanum etuberosum Lindl., a wild potato species native to Chile, was identified as having resistances to PLRV, potato virus Y, potato virus X, and green peach aphid. Barriers to sexual hybridization between S. etuberosum and cultivated potato were overcome through somatic hybridization. Resistance to PLRV has been identified in the BC1, BC2 and BC3 progeny of the somatic hybrids of S. etuberosum (+) S. tuberosum haploid × S. berthaultii Hawkes. In this study, RFLP markers previously mapped in potato, tomato or populations derived from S. palustre (syn S. brevidens) × S. etuberosum and simple sequence repeat (SSR) markers developed from tomato and potato EST sequences were used to characterize S. etuberosum genomic regions associated with resistance to PLRV. The RFLP marker TG443 from tomato linkage group 4 was found to segregate with PLRV resistance. This chromosome region has not previously been associated with PLRV resistance and therefore suggests a unique source of resistance. Synteny groups of molecular markers were constructed using information from published genetic linkage maps of potato, tomato and S. palustre (syn. S. brevidens) × S. etuberosum. Analysis of synteny group transmission over generations confirmed the sequential loss of S. etuberosum chromosomes with each backcross to potato. Marker analyses provided evidence of recombination between the potato and S. etuberosum genomes and/or fragmentation of the S. etuberosum chromosomes.  相似文献   

12.
Sugar beet (Beta vulgaris ssp. vulgaris L.) has a relatively narrow genetic base and several programmes have sought to evaluate the potential for introducing novel traits from wild and cultivated Beta germplasm into the crop. In particular, resistance to important sugar beet diseases has been identified within individual Beta accessions. We report here the successful transfer of resistance to Beet mild yellowing virus (BMYV) from garden beet, fodder beet and leaf beet accessions to progeny populations in initial crosses with sugar beet. Twelve plant populations derived from different Beta accessions were inoculated with viruliferous aphids carrying BMYV and the virus content of individual plants subsequently quantified by an ELISA test. Seven populations were significantly more resistant than a control sugar beet cultivar (P ≤ 0.05). BMYV resistance was successfully inherited in BC1 and BC2 generations, suggesting that resistance could potentially be introgressed from these sources into elite sugar beet lines.  相似文献   

13.
In order to determine genetically diverse parents for the generation of mapping populations segregating for resistance to ascochyta blight in wild Cicer species, the genetic diversity between a selection of resistant and susceptible accessions was assessed using molecular markers. Twenty Cicer accessions — comprising eight C. reticulatum accessions, six C. echinospermum accessions, five C. bijugum accessions, and one C. arietinum accession — were compared using a combination of seven RAPD primers and seven ISSR primers. A total of 231 polymorphic bands were scored and used to determine the genetic distances between accessions using Jaccard similarity coefficients. The most genetically diverse parents for the generation of intraspecific and interspecific populations segregating for resistance to ascochyta blight are reported. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

14.
Cultivating resistant varieties of potato is the most effective and environmentally sound method of protecting potato crops against pests and diseases. Potato cyst nematodes (PCN) are major nematode pests causing severe constraints in potato production worldwide. There are five pathotypes of Globodrea rostochiensis (Ro1–Ro5) and three of G. pallida Pa1–Pa3. Cultivation of potato varieties with broad nematode resistance may influence the growth of the wide spectrum of PCN pathotypes, but there is limited availability of such varieties on the market. The use of molecular markers allows for the effective selection of resistant genotypes at early stages of breeding. However, the impact of early selection for nematode resistance on the agronomic value of the final selected clones is a cause of concern for potato breeders. This study investigates the relationships between the presence of the combined resistance genes H1, Gro1-4 and GpaVvrn, which confer resistance to the nematodes, and certain agricultural traits. Clones with broad nematode resistance conferred by the genes H1, Gro1-4 and GpaVvrn presented yields and tuber morphology traits similar to those of the clones without identified resistance genes.  相似文献   

15.
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   

16.
Late blight (LB), caused by the oomycete Phytophthora infestans, is one of the most destructive diseases of tomato and potato worldwide. Identifying and characterizing new sources of resistance is essential given the emergence of new aggressive and fungicide‐resistant P. infestans isolates. Recently, we reported identification of several new sources of LB resistance within the tomato wild species, Solanum pimpinellifolium. In this study, we examined heritability (h2) of LB resistance conferred by the S. pimpinellifolium accession PI 224710 using a parent–offspring regression (correlation) analysis. F2 and F3 progeny populations, derived from crosses between PI 224710 and a LB‐susceptible tomato breeding line, were evaluated for response to LB infection. To obtain a better estimate of h2, the F3 progeny were evaluated for LB resistance in two separate replicated experiments. The h2 estimates were similar in the two experiments and averaged ~0.87, suggesting that this resistance was highly heritable. Two different methods estimated involvement of one resistance locus. Breeding and mapping efforts are underway to further assess the viability of this newly reported LB resistance.  相似文献   

17.
Resistance to potato viruses was examined in the F1 hybrids (TET) obtained from a cross between a diploid (2n = 24), tuber-bearing interspecific hybrid 87HW13.7 (Solanum tuberosum W231 ×S. multi-dissectum PI 473354) and a diploid (2n = 24), nontuber-bearing wild potato species (S. brevidens CPC 2451) using S. phureja IvP35 (2n = 24) for rescue pollination. The parental plants were susceptible to PVX, whereas two hybrids (TET38.2 and TET38.9) and S. phureja IvP35 reacted with hypersensitivity to PVX. Two hybrids (TET 38.9 and TET 38.12) were extremely resistant to PVY°, which was similar to S. brevidens and S. phureja IvP35, whereas the remaining two hybrids were moderately resistant to PVY°. No resistance to PVA and PLRV was observed in the progenies, in contrast to S. brevidens which was extremely resistant to PVA and PLRV. Hypersensitivity to PVX in two progenies suggested (1) integration by somatic translocation or heterofertilization and expression of genes from the rescue pollinator S. phureja IvP35, or (2) transgressive or complementary gene action.  相似文献   

18.
Summary The potato tuber moth, Phthorimaea operculella (Zeller) is an important pest of potatoes in the field and in stores in warm environments throughout the world. In this study genetic resistance to potato tuber moth was identified in clones of Solanum sparsipilum (coded MBN) originally developed for resistance to bacterial wilt and root-knot nematode. Resistance to this pest in S. sucrense and S. tarijense as well as S. sparsipilum was exploited in wide crosses with diploid and tetraploid cultivated potatoes, and haploids derived from S. tuberosum; hybrid progenies were produced. Crosses between resistant S. pinnatisectum or S. commersonii and cultivated potatoes failed completely, although S. commersonii did hybridise with two bridging species S. lignicaule and S. capsicibaccatum which are slightly compatible with cultivated potatoes. Resistance to potato tuber moth was transferred to all progenies except those in which S. tarijense was the resistant parent. The development of potatoes resistant to potato tuber moth is discussed in the context of population breeding for the lowland tropics.  相似文献   

19.
Cucurbita pepo (pumpkin, squash,gourd) is an economically important species that is susceptible to the cucurbit powdery mildew fungus, Podosphaera xanthii(syn. Sphaerotheca fuliginea). ‘True French’, an open-pollinated cultivar of the Zucchini Group of C. pepo, was crossed with an unnamed powdery-mildew resistant straight neck-type accession, the resistance of which was apparently derived from an interspecific cross with a resistant wild species of Cucurbita,and resistant plants were selected in the F2 generation. This was followed by six cycles of backcross-pedigree selection for resistance, and resulted in the development of an accession true-breeding for resistance to powdery mildew and nearly isogenic to ‘True French’. The resistant and susceptible near-isogenics were crossed and seeds of the filial and backcross generations were produced. Plants of the parental accessions and their progenies were grown together in a controlled-environment chamber, exposed to the pathogenic fungus, and scored as resistant, partially resistant, or susceptible 27–33 days after sowing. The results indicated that resistance is conferred by a single incompletely dominant gene, designated Pm-0. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   

20.
Summary Within the two potato cyst nematode (PCN) species, Globodera rostochiensis and G. pallida, eight pathotypes are presently discerned by seven differential Solanum clones, whereby resistance is defined as a Pf/Pi ratio <1.0, and susceptibility as a ratio above 1.0. This pathotyping is felt to be unsatisfactory. Reconsidering the original data and data published by others resulted in the conclusion that there are only three reliably recognizable Ro-pathotypes Ro1/Ro4, Ro2/Ro3 and Ro5. The differential clones 60.21.19 and 65.346.19 differentiate only between the two species. Within G. pallida it does not seem possible to identify pathotypes reliably. The resistance-virulence pattern is of a quantitative nature fitting a polygenic system. There appear to be pathotype-specific effects, which are not large enough to identify and classify pathotypes reliably. It is therefore suggested to rename the Ro-pathotypes into Ro1 (old Ro1 and Ro4), Ro3 (old Ro2 and Ro3) and Ro5 (old Ro5) and to speak of more and less virulent Pa-populations.The rigorous requirements for resistance in various countries present great problems to the breeders and result in the removal of much valuable partial resistance. Especially with G. pallida these rigorous requirements are probably an obstacle rather than an encouragement to solve the pallida problem.  相似文献   

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