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1.
Z. Quresh    C. C. Jan  T. J. Gulya 《Plant Breeding》1993,110(4):297-306
Resistance to the prevailing races of sunflower rust, Puccinia hehanthi Schw., is lacking in the commercial hybrids (Helianthus annuus L.). The objective of this study was to identify new sources of resistance to the four North American rust races in wild Helianthus species, and to determine their mode of inheritance. Seventy-eight accessions of H. annuus L., H. argophyllus Torrey and Gray, and H. petiolans Nutt. were evaluated in the greenhouse. Resistance to races 1, 2, 3, and 4 was observed in 25, 28, 15, and 26% of the plants, respectively, and 10% of the plants were resistant to all four races. Seven accessions that had a high percentage of resistant plants to all the four races were selected and one resistant plant from each accession was crossed with susceptible inbred line HA89. Three to four F1 plants resistant to all four races from each cross were backcrossed with HA89. F1 plants from PI-413118 × HA89 and PI 413175 × HA89 were resistant to all four races. The PI 413023 × HA89 F1 plants were 100 % resistant to races 3 and 4 and segregated in a 3: 1 resistant (R) to susceptible (S) ratio to races 1 and 2. The other four F1 combinations segregated 3R: IS ratios to all four races. Bc1F1 progenies revealed that plants from PI 413048, PI 413037, PI 413038, and PI 413171 used in the crosses possessed two dominant genes in heterozygous condition for resistance to each of the four races, whereas plants from PI 413023 possessed two dominant genes in heterozygous condition for resistance to each of races 1 and 2, and one dominant resistance gene in homozygous condition for each of races 3 and 4. Plants from PI 413118 and PI 413175 carried a single dominant gene in homozygous condition for resistance against each of the four races.  相似文献   

2.
Worldwide, soybean cyst nematode (SCN, Heterodera glycines Ichinohe) is the most destructive pathogen of soybean [Glycine max (L.) Merr.]. Crop losses are primarily mitigated by the use of resistant cultivars. Nematode populations are variable and have adapted to reproduce on resistant cultivars over time because resistance primarily traces to two soybean accessions, Plant Introduction (PI) 88788 and Peking. Soybean cultivar Hartwig, derived primarily from PI437654, was released for its comprehensive resistance to most SCN populations. A synthetic nematode population (LY1) was recently selected for its reproduction on Hartwig. The LY1 nematode population currently infects known sources of resistance except soybean PI567516C; however, the resistance to LY1 has not been characterized. The objective of this study was to identify quantitative trait loci (QTLs) underlying resistance to the LY1 SCN population in PI567516C, identify diagnostic DNA markers for the LY1 resistance, and confirm their utility for marker-assisted selection (MAS). Resistant soybean line PI567516C was crossed to susceptible cultivar Hartwig to generate 105 recombinant inbred lines (F2-derived F5 families). QTLs were mapped using simple sequence repeats (SSRs) covering 20 Linkage Groups (LGs) and three diagnostic markers, Satt592, Satt331, and Sat_274, were identified on LG O. These markers have a combined efficacy of 90% in identifying resistant lines in a second cross that has been generated by crossing a susceptible cultivar 5601T with resistant PI567516C. F2-derived F4 segregating population was used in MAS to identify resistant lines.  相似文献   

3.
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   

4.
Initial studies have shown variable resistance in Brassica fruticulosa to the aphid Brevicoryne brassicae The aim of this work was to fix high levels of resistance to B. brassicae in true breeding lines of B. fruticulosa and obtain data on the genetic control of resistance. Plants from initially variable B. fruticulosa accessions were selfed to produce inbred resistant and susceptible lines that were studied in three separate experiments to determine the extent to which resistance to B. brassicae had been fixed. Results from three experiments using successive generations of resistant and susceptible inbred lines showed that continued selection resulted in resistant inbred lines that supported an average of three aphids per plant compared with an average of 96 aphids per plant for susceptible inbred lines. Data collected from an experiment determining the resistant phenotype of lines including the selfed progenies and the F1 and F2 progeny of a cross between resistant and susceptible individual plants indicated that the resistance was not controlled by a single gene.  相似文献   

5.
Summary Potato virus Y (PVY) infects most Solanaceous crops grown in Mediterranean countries in open fields and in greenhouses. Necrogenic strains, which have been isolated from diseased tomatoes in France since the 1980's, seriously cause yield and quality loss of tomato fruits. Lycopersicon hirsutum PI 247087 was found to be resistant to PVY. Virus could not be detected in inoculated leaves by ELISA and/or by back-inoculation on susceptible plants. This resistance was efficient against the 16 tested isolates or strains. Temperature and inoculum concentration did not affect its expression. All the F1 plants of (Momor × PI 247087), (PI 134417 × PI 247087) and (PI 247087 × PI 134417) had symptom scores and ELISA values similar to those of the susceptible parents. The mechanism of resistance could be immunity-like or inhibition of virus migration from cell to cell. The resistance of L. hirsutum PI 247087 appeared to be governed by two independent recessive genes. In a few F2 plants of (PI 134417 × PI 247087) and F2 (Momor × PI 247087), virus was able to multiply in the inoculated leaves but could not establish a systemic infection. This finding may suggest a mechanism which interfers with the long distance migration of the virus in the plant.  相似文献   

6.
The fungal disease cercospora leaf spot CLS (Cercospora zonata) has affected major faba bean (Vicia faba) production regions in southern Australian in the last several years. This study offers the first report of sources of resistance to CLS in faba bean and describes techniques to evaluate resistance to C. zonata in faba bean genotypes within a controlled environment. The method was rapid (43 days), repeatable (R 2 > 0.74) and demonstrated positive correlations (R 2 > 0.45–0.80) to data collected from field disease nurseries under naturally established CLS epiphytotics. All faba bean cultivars currently adopted by the Australian industry were found to be susceptible to CLS and defoliation was found to be an important component of disease expression. Genetic analysis of segregation patterns in F 2 derived F 3 families of 1322/2*Farah (resistant*susceptible) showed the mode of inheritance of resistance to C. zonata was monogenic dominant. F 3 families were shown to segregate in the ratio of 1:2:1 for homozygous resistant: heterozygous: homozygous susceptible (χ22 = 2.78; P > 0.05) and individual plants within heterozygous F 3 families segregated in the ratio of 3:1 for resistant: susceptible responses (χ12 = 2.93; P > 0.05). Monogenic dominant inheritance also explained the change in frequency of resistant and susceptible plants within a population of cv. Cairo following one generation of self-pollination (χ2 = 0.88, 0.3 < P < 0.5). The sources of resistance identified in this study are being used to transfer CLS resistance to adapted faba bean genotypes for future cultivar releases to the southern Australian industry.  相似文献   

7.
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   

8.
The inheritance of resistance to dry root rot of chickpea caused by Rhizoctonia bataticola was studied. Parental F1 and F2 populations of two resistant and two susceptible parents, along with 49 F1 progenies of one of the resistant × susceptible crosses were rested for their reaction to dry root rot using the blotting-paper technique. All F, plants of the resistant × susceptible crosses were resistant; the F2 generation fitted a 3 resistant: 1 susceptible ratio indicating monogenic inheritance, with resistance dominant over susceptibility. F3 family segregation data confirmed the results. No segregation occurred among the progeny of resistant × resistant and susceptible × susceptible crosses.  相似文献   

9.
Rotylenchulus reniformis is an important root pathogen of cotton in the south‐eastern United States, and management is hindered by the lack of host‐plant resistance in upland cotton (Gossypium hirsutum). The G. arboreum accession PI 417895 is highly resistant to R. reniformis, and a segregating population of 300 F2 plants was developed for phenotypic characterization of resistance. The population showed quantitative variation for nematode infection. Twenty plants showed no infection and were classified as escapes. Fifty‐four plants were classified as resistant or moderately resistant, whereas, 226 were classified as moderately susceptible or susceptible based on the nematode response of the susceptible parent, indicating resistance is a recessive trait, but these data did not support the single recessive gene model. Alternatively, this model would be supported if the 77 plants with a similar nematode response as observed for PI 417895 were classified as resistant. Twelve plants showed high levels of resistance and these data would support a two recessive gene model. Accession PI 417895 represents a new source of R. reniformis resistance with two major genes conferring resistance. Introgression of multiple resistance genes into G. hirsutum will require the development of larger populations to recover the resistant phenotype.  相似文献   

10.
A. K. Joshi    S. Kumar    R. Chand  G. Ortiz-Ferrara   《Plant Breeding》2004,123(3):213-219
Three F1 progenies and their families in the segregating generations (F3, F4, F5 and F6), obtained after crossing resistant × susceptible wheat genotypes were studied in the field to determine the genetics of resistance to spot blotch caused by Bipolaris sorokiniana. Spot blotch scores in the F1 generation showed absence of dominance. Individually threshed F2 plants were used to advance the generations. Progenies (200‐250) of resistant genotypes Acc. No. 8226, Mon/Ald, Suzhoe#8 crossed with susceptible ‘Sonalika’ were evaluated in the F3, F4, F5 and F6 generations under induced epiphytotic conditions. Based on disease score distribution in individual progeny rows, F3 progenies were grouped into four classes: homozygous resistant, homozygous susceptible, segregating resistant and segregating susceptible. Resistance appeared to be under the control of three additive genes. The presence of three genes was also noted in the distribution of F4 and F5 lines. In the case of F6 progeny rows, both quantitative and qualitative models were used to estimate the number of segregating genes based on a 2‐year trial. It appeared that resistance to spot blotch was controlled by the additive interaction of more than two genes, possibly only three.  相似文献   

11.
Soybean bacterial leaf pustule (BLP) is a serious disease caused by Xanthomonas axonopodis pv. glycines. Typical symptoms of BLP are pustules surrounded by small yellow haloes. Interestingly, PI 96188 only exhibits pustules without chlorotic haloes which suggests a resistant response. The objectives of this study are to understand the inheritance mode of the novel symptom to BLP in PI 96188 and to investigate whether or not a gene controlling BLP resistance in PI 96188 is identical to the rxp gene. First, a new BLP resistant genotype, PI 96188 was crossed with the resistant cultivar SS2-2. All F1 plants showed the same phenotype as SS2-2 and the F2 population segregated into 75 typical symptoms (haloes presence: 28 novel symptoms (haloes absence) indicating the presence of a single recessive gene. To map the novel symptom to BLP in PI 96188, a population of 88 F7 recombinant inbred lines was developed from a cross between PI 96188 and the susceptible cultivar Jinjoo1. The BLP resistance gene from PI 96188 was mapped on chromosome (Chr.) 10 (LG O) rather than Chr. 17 (LG D2). This gene was linked with the simple sequence repeat marker, Sat_108 at the distal end of Chr. 10. Thus, the BLP resistance gene from PI 96188 was determined to be a new gene.  相似文献   

12.
Reciprocal crosses were made between resistant hexaploid spring wheat cultivars/lines Sumai 3, Ning8331, and 93FHB21, and susceptible tetraploids Stewart 63 and DT486 to generate 35 chromosome pentaploids. Four heads from each of five F1 pentaploid plants from each cross were screened with Fusarium graminearum for fusarium head blight (FHB) reaction. No pentaploid was as resistant to FHB as the resistant parents. Pentaploids derived from several crosses were more resistant than the susceptible parents, a few were more susceptible, and all plants from crosses with 93FHB21 failed to survive. Most viable seeds were obtained from the cross Sumai 3 × DT486. From this cross four of the five F1 pentaploid parents were fertile and 354F2 seeds derived from these four pentaploids were sown and evaluated for their FHB reaction. The majority of F2 plants from pentaploids 1 and 3had the visual appearance and level of resistance of Sumai 3, whereas progeny from pentaploids 4 and 5 were more varied morphologically and generally more susceptible. Forty-three of the screened F2 plants were tested for the presence of specific D chromosomes by wheat microsatellite analysis. There was no relationship between presence/absence of D chromosomes and FHB reaction. Twenty-four lines had all D chromosomes present of which 10 were intermediate-susceptible and 14 were resistant to FHB. Three lines, one resistant and two intermediate, had no D chromosomes. The remainder had between 1 and 6 of the D chromosomes present and ranged from resistant to susceptible in FHB reaction. It appears that FHB resistance is not conferred by the D genome of Sumai 3. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

13.
Inheritance of black leaf mold resistance in tomato   总被引：1，自引：0，他引：1  
Summary Inheritance of black leaf mold (BLM) (caused by Pseudocercospora fuligena) resistance was studied in four crosses involving two resistant Lycopersicon accessions (PI134417, L. hirsutum and PI254655, L. esculentum) and four susceptible Asian Vegetable Research and Development Center tomato lines (CLN657BC1F2-267-0-3-12-7, CL143-0-10-3-0-1-10, CLN698BC1F2-358-4-13 and CL5915-93D4-1-0-3). For each cross, six generations, i.e. P1, P2, F1, F2, BC1F1 and BC1F2 were evaluated following inoculations with isolate Pf-2 of P. fuligena. Chi-square analyses of the data based on the ratio of resistant to susceptible plants in the F2 in three of four crosses gave a good fit to a segregation ratio of 1 R : 15 S, and BC1F2 data in three of four crosses gave an acceptable fit to the segregation ratio of 1 R : 63 S. The results indicate that resistance to BLM may be conditioned by two recessive genes acting epistatically in both PI134417 and PI254655.  相似文献   

14.
Wheat streak mosaic (WSM) caused by wheat streak mosaic virus (WSMV) is a serious disease of wheat and many plants in the grass family. In previous studies genotypes collected from different parts of Iran, were screened for WSM resistance. Two resistant genotypes, “Adl Cross” and “4004” were crossed to one susceptible genotype “Marvdasht.” Reciprocal crosses were also made. Seedlings of parents, F1, F2, backcrosses to susceptible (BCS) and resistant (BCR) were evaluated for WSMV reaction based on scales 0–7, by artificial infection under greenhouse conditions. Allelism was studied by evaluating the F1 and F2 seedlings of the resistant × resistant cross. Inheritance of resistance to WSMV in Adl Cross and 4004 was controlled by one dominant gene. No allelism was observed between resistance genes. Among the F2 seedlings of the resistant × resistant cross relatively more resistant genotypes with a zero score were observed. These two genes, therefore, can be incorporated into an adapted wheat cultivar to produce a more durable resistance.  相似文献   

15.
H. J. Toxopeus 《Euphytica》1961,10(3):307-314
Data on the attack of the tubers of 2,036 F1 seedlings of 32 different cross combinations of potato varieties were collected. A survey is given of the field resistance of a large number of established varieties and of their parents.From both sets of data it appears that crossing two highly resistant parents results in a high percentage of resistant offspring. When crossing a susceptible with a resistant parent one gets a majority of resistant F1 seedlings and even among the offspring of two susceptible varieties a few resistant seedlings are encountered.The genes R 1 and R 3 for hypersensivity of the leaves exert a strong influence. Preliminary data suggest that the cambial layer just below the skin in this case is a strong barrier to the penetration of the parasite as is stated also with some varieties devoid of R-genes (Bravo, Libertas and others).  相似文献   

16.
J. W. Scott  J. P. Jones 《Euphytica》1989,40(1-2):49-53
Summary Resistance to fusarium wilt, incited by Fusarium oxysporum (Schlecht.) f. sp. lycopersici (Sacc.) Snyder & Hansen race 3 in tomato (Lycopersicon esculentum Mill.) was discovered in LA 716, a L. pennellii accession. A resistant BC1F3 breeding line, E427, was developed from LA 716. E427 was crossed with the susceptible cv. Suncoast and F1, BCP1, BCP2 (to Fla 7155, a susceptible parent) F2, F3, and BCP2S1 seeds were obtained. Segregation for resistance following root dip inoculation over three experiments indicated a single dominant gene controlled resistance. Five of the 12 BCP1S1's segregated more susceptible plants, whereas one of the 12 segregated more resistant plants than expected (P<0.05). Three of 23 F3 lines segregated more susceptible plants than expected while 1 of the 23 had more resistant plants than expected (P<0.05). Segregation in all other lines fit expected ratios. Five of the 23 F3's were homozygous resistant which was an acceptable fit to expectations (P=0.1–0.5). The gene symbol I 3 is proposed for resistance to race 3 of the wilt pathogen. Deviations from expected ratios in data reported here and for other breeding lines indicate an effect of modifier genes and/or incomplete penetrance. Plant age at inoculation and seed dormancy did not affect results.Florida Agricultural Experiment Station Journal Series No. 8101.  相似文献   

17.
Summary The genetics of resistance to angular leaf spot caused by Pseudomonas syringae pv. tabaci in Nicotiana tabacum cultivars Burley 21 and Kentucky 14 was investigated by studying disease reactions to three isolates of parental, F1, F2 and backcross generations derived from crosses between the resistant cultivars and the susceptible cultivar Judy's Pride. Studies were conducted in the greenhouse and in field plant beds. Chi-square values were computed to determine whether the observed ratios for disease reactions deviated from expected Mendelian ratios for a single, dominant gene controlling resistance to angular leaf spot in tobacco. Based on the resistance of the F1 and the backcross generation to the resistant parent (BC-R), a 3 resistant: 1 susceptible segregation ratio in the F2, and a 1 resistant: 1 susceptible segregation ratio in the backcross generation to the susceptible parent (BC-S), it was concluded that resistance to three isolates of Pseudomonas syringae pv. tabaci is governed by a single, dominant gene.  相似文献   

18.
Inheritance of adult-plant resistance to Phytophthora capsici in pepper   总被引：4，自引：0，他引：4  
Summary Inheritance studies were conducted to determine the genetic basis of adult-plant resistance in pepper (Capsicum annuum L.) to Phytophthora capsici. F1, backcrosses and F2 populations were developed using the resistant parent Criollo de Morellos 334 and susceptible parents Agronômico 10-G and Yolo Wonder. Pepper plants, at 36 days post-emergence, were inoculated near the base of the stem with an inoculum suspension of 5×104 zoospores/ml. Segregation ratios in the F2 generation of 13 resistant to 3 susceptible plants fit a 2-gene model for resistance with dominant and recessive epistasis.  相似文献   

19.
Inheritance of resistance to a wheat midge, Sitodiplosis mosellana (Géhin), was investigated in spring wheats derived from nine resistant winter wheat cultivars. F1 hybrids were obtained from crosses between resistant winter wheats and susceptible spring wheats, and used to generate doubled haploid populations. These populations segregated in a ratio of 1:1 resistant to susceptible, indicating that a single gene confers the resistance. The F2 progeny from an intercross among spring wheats derived from the nine resistance sources did not segregate for resistance. Therefore, the same gene confers resistance in all nine sources of resistance, although other genes probably affect expression because the level of resistance varied among lines. Heterozygous plants from five crosses between diverse susceptible and resistant spring wheat parents all showed intermediate levels of response, indicating that resistance is partly dominant. Susceptible plants were reliably discriminated from heterozygous or homozygous resistant ones in laboratory tests, based on the survival and development of wheat midge larvae on one or two spikes. This powerful resistance gene, designated Sm1, is simply inherited and can be incorporated readily into breeding programmes for spring or winter wheat. However, the use of this gene by itself may lead to the evolution of a virulent population, once a resistant cultivar is widely grown.  相似文献   

20.
Abstract: A partial linkage map of melon was constructed from a cross between PI414723 and Dulce. Twenty-two SSR, 46RAPD, 2 ISSR markers and four horticultural markers [female flower form (a), Fusarium resistance, striped epicarp (st), and fruit flesh pH (pH)] were analyzed in an F2/F3 population to produce a map spanning 14 linkage groups. We report for the first time map positions for the st, a, and pH genes. One SSR marker was tightly linked to pH. Mapping the a gene for the female flower form to molecular linkage group 4 enabled the merging of the map of horticultural traits with the of molecular markers in this region. Using the 22 SSR markers of this map, two of the three postulated ZYMV resistance genes were located using a BC1 population (PI414723 recurrent parent). One SSR marker was tightly linked to a ZYMV resistance gene, designated Zym-1. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   

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