Showing papers on "Plant disease resistance published in 1991"
TL;DR: It is found that Arabidopsis ecotype Col-0 was susceptible to Pst strain DC3000 but resistant to the same strain carrying avrRpt2, suggesting that a single locus in Col-1 determines resistance, and genetically mapping the postulated resistance locus is begun.
Abstract: To develop a model system for molecular genetic analysis of plant-pathogen interactions, we studied the interaction between Arabidopsis thaliana and the bacterial pathogen Pseudomonas syringae pv tomato (Pst). Pst strains were found to be virulent or avirulent on specific Arabidopsis ecotypes, and single ecotypes were resistant to some Pst strains and susceptible to others. In many plant-pathogen interactions, disease resistance is controlled by the simultaneous presence of single plant resistance genes and single pathogen avirulence genes. Therefore, we tested whether avirulence genes in Pst controlled induction of resistance in Arabidopsis. Cosmids that determine avirulence were isolated from Pst genomic libraries, and the Pst avirulence locus avrRpt2 was defined. This allowed us to construct pathogens that differed only by the presence or absence of a single putative avirulence gene. We found that Arabidopsis ecotype Col-0 was susceptible to Pst strain DC3000 but resistant to the same strain carrying avrRpt2, suggesting that a single locus in Col-0 determines resistance. As a first step toward genetically mapping the postulated resistance locus, an ecotype susceptible to infection by DC3000 carrying avrRpt2 was identified. The avrRpt2 locus from Pst was also moved into virulent strains of the soybean pathogen P. syringae pv glycinea to test whether this locus could determine avirulence on soybean. The resulting strains induced a resistant response in a cultivar-specific manner, suggesting that similar resistance mechanisms may function in Arabidopsis and soybean.
694 citations
TL;DR: High levels of chitInase in transformants did not substantially increase resistance to the chitin-containing fungus Cercospora nicotiana, which causes Frog Eye disease, and class I chit inase does not appear to be the limiting factor in the defense reaction to this pathogen.
Abstract: Endochitinases (E.C. 3.2.14, chitinase) are believed to be important in the biochemical defense of plants against chitin-containing fungal pathogens. We introduced a gene for class I (basic) tobacco chitinase regulated by Cauliflower Mosaic Virus 35S-RNA expression signals into Nicotiana sylvestris. The gene was expressed to give mature, enzymatically active chitinase targeted to the intracellular compartment of leaves. Most transformants accumulated extremely high levels of chitinase-up to 120-fold that of non-transformed plants in comparable tissues. Unexpectedly, some transformants exhibited chitinase levels lower than in non-transformed plants suggesting that the transgene inhibited expression of the homologous host gene. Progeny tests indicate this effect is not permanent. High levels of chitinase in transformants did not substantially increase resistance to the chitin-containing fungus Cercospora nicotiana, which causes Frog Eye disease. Therefore class I chitinase does not appear to be the limiting factor in the defense reaction to this pathogen.
214 citations
TL;DR: A model pathosystem to dissect genetically the disease resistance response of plants against phytopathogenic bacteria is presented and it is shown that at least parts of this system fit the paradigms of Flor's 'gene-for-gene' hypothesis.
Abstract: We present a model pathosystem to dissect genetically the disease resistance response of plants against phytopathogenic bacteria. The interaction between Pseudomonas syringae pathovar maculicola (Psm) and Arabidopsis thaliana displays phenotypic varia-ion which depends on the genotype of both partners. Compatible interactions are defined by sustained in-planta bacterial growth and are normally accompanied of their appearance. For compatible interactions, resistance is defined by limited in-planta bacterial growth accompanied by a typical 'hypersensitive response' (HR). We show that at least parts of this system fit the paradigms of Flor's 'gene-for-gene' hypothesis. We identify functionally a putative bacterial avirulence gene (avrRpm 1) from a Psm isolate which conditions the HR on A. thaliana ecotypes Oy-0 abd Col- 0, but not Nd-0. We also demonstrate that resistance to the Psm strain from which avrRpm1 was isolated segregates as a single trait in the crosses Col-o x Nd-0 and Nd-0 x Oy-0. Furthermore, we map this locus (RPM1) molecularly in the Col-0 x Nd-0 cross to a relatively small interval defined by two RFLP markers on A. thliana chromosome 3. Resistance in the second cross also maps to this locus and co-segregates with resistance to avrRpm1.
213 citations
Book•
01 Jan 1991
TL;DR: Part 1 Fungal life-style: fungal morphogenesis and physiology fungal strategies, and effects of pathogenic fungal invasion on host plant physiology: physiological changes in host plant tissues effects of invasion on cell growth.
Abstract: Part 1 Fungal life-style: fungal morphogenesis and physiology fungal strategies. Part 2 Plants as an environment: living tissues as an environment effects of environmental conditions on plant health the plants' response to abiotic and biotic influences effects of fungi on plant health control of plant disease. Part 3 Fungal-plant confrontation: fungal invasion mechanisms of disease resistance. Part 4 Effects of pathogenic fungal invasion on host plant physiology: physiological changes in host plant tissues effects of invasion on cell growth. Part 5 Mutualistic symbioses: mycorrhizal symbioses lichens endophytic sybioses. Part 6 Biotechnology in the study of fungal-plant interaction: plant breeding for resistance to disease the study of disease resistance using tissue culture technique molecular biological techniques.
206 citations
TL;DR: It is suggested that S 97 might evolve substances already during seed germination that are translocated to the foliage; there they might accumulate around the site of bacterial multiplication and contribute to their restricted growth.
Abstract: With the aim of elucidating the immunizing ability of plant-growth-affecting rhizosphere pseudomonads, seeds of a susceptible bean (Phaseolus vulgaris L) cv. Bonita, were subjected to bacterization before challenging with the halo blight bacterial pathogen Pseudomonas syringae pv. phaseolicola. In the greenhouse, induced systemic resistance to halo blight was found in bean plants treated with a plant growth stimulatory strain of P. fluorescens (S 97), whereas deleterious pseudomonads MA 250 and VS 50 were found to induce susceptibility towards the disease. Immunization ability of S 97 was reduced at low inoculum densities (<107 live cells per ml) or eliminated when the suspension was autoclaved. The maximum disease protection, measured in terms of number of halo blight lesions in trifoliate leaves, was obtained at the highest inoculum concentration (108 live cells per ml). Agar diffusion assay in vitro revealed that S 97 exhibits bacteriostatic activity against the bean pathogen. It is suggested that S 97 might evolve substances already during seed germination that are translocated to the foliage; there they might accumulate around the site of bacterial multiplication and contribute to their restricted growth.
196 citations
TL;DR: The inheritance of TSWV resistance was found to be a single dominant gene, which indicates a 98.7% penetrance of the resistance gene in plants infected four months after the inoculations.
Abstract: Inheritance of resistance to tomato spotted wilt virus (TSWV) derived from the cultivar ‘Stevens’ was studied. Five TSWV isolates, which differ in geographic origin and elicit different symptoms on tomato, were used to screen the resistant parent plants. Enzyme-linked immunosorbent assay (ELISA) was used to distinguish healthy and infected plants. Two susceptible advanced breeding lines were crossed with four F4 plants of a ‘Stevens’ × ‘Rodade’ obtained from South Africa (SA). There were no differences in the progeny responses of the four SA parents to TSWV. The inheritance of TSWV resistance was found to be a single dominant gene. The SA, F1, and the backcrosses to the resistant parent were found to have eight out of 612 plants infected four months after the inoculations, which indicates a 98.7% penetrance of the resistance gene.
184 citations
TL;DR: The wheat-rye recombinants were used as a mapping tool to assign two RFLP markers to specific regions on chromosome arms 1DS and 1RS of wheat and rye, respectively.
Abstract: The introgression of genetic material from alien species is assuming increased importance in wheat breeding programs. One example is the translocation of the short arm of rye chromosome 1 (1RS) onto homoeologous wheat chromosomes, which confers disease resistance and increased yield on wheat. However, this translocation is also associated with dough quality defects. To break the linkage between the desirable agronomic traits and poor dough quality, recombination has been induced between 1RS and the homoeologous wheat arm IDS. Seven new recombinants were isolated, with five being similar to those reported earlier and two havina new type of structure. All available recombinantsw ere characterized with DNA probes for the loci Nor-R1, 5SDna-R1, and Tel-R1. Also, the amount of rye chromatin present was quantified with a dispersed rye-specific repetitive DNA sequence in quantitative dot blots. Furthermore, the wheat-rye recombinants were used as a mapping tool to assign two RFLP markers to specific regions on chromosome arms 1DS and 1RS of wheat and rye, respectively.
170 citations
TL;DR: The two main objectives of the study were to postulate the known Lr genes conferring low seeding reactions to 18 pathotypes of Puccinia recondita Roberge ex Desmaz.
Abstract: Bread wheat (Triticum aestivum L.) cultivars derived from CIM-MYT germplasm are currently grown on a large area worldwide. Since limited information is available on genes for resistance to leaf rust in these wheats, the two main objectives of the study were to postulate the known Lr genes conferring low seeding reactions to 18 pathotypes of Puccinia recondita Roberge ex Desmaz. f. sp. tritici in 50 Mexican cultivars released between 1960 and 1988; and to evaluate the presence of additional adult-plant resistance
134 citations
TL;DR: This article obtained transgenic tobacco plants expressing the papaya ringspot virus (PRV) coat protein (CP) gene by transformation via Agrobacterium tumefaciens, which was effectively monitored by enzyme-linked immunosorbent assays (ELISA) of crude tissue extracts.
Abstract: We obtained transgenic tobacco plants expressing the papaya ringspot virus (PRV) coat protein (CP) gene by transformation via Agrobacterium tumefaciens. Expression was effectively monitored by enzyme-linked immunosorbent assays (ELISA) of crude tissue extracts. Subcloned plants derived from eight original Ro transformants were inoculated with potyviruses: tobacco etch (TEV), potato virus Y (PVY), and pepper mottle (PeMV). Plants that accumulated detectable levels of the PRV CP showed significant delay in symptom development and the symptoms were attenuated. Similar results were obtained with inoculated R1 plants. We conclude that the expression of the PRV CP-gene imparts protection against infection by a broad spectrum of potyviruses.
128 citations
TL;DR: Twenty-three Lycopersicon accessions representing five tomato species were screened for resistance to the tomato yellow leaf curl virus (TYLCV).
Abstract: Twenty-three Lycopersicon accessions representing five tomato species were screened for resistance to the tomato yellow leaf curl virus (TYLCV). Plants were grown in a field naturally infested with Bemisia tabaci, the natural vector of this geminiviral disease. The screened genotypes were examined for the presence of viral DNA and symptom development at 2-wk intervals. Tomato cultivars harbored the virus and developed symptoms. Accessions of the wild species L. pimpinellifolium, L. hirsutum, and L. peruvianum showed variance in their response to infection (.)
115 citations
TL;DR: Resistance gene Rpg4 therefore may account in part for the resistance of soybean to Pseudomonas syringae pv tomato and other pathogens harboring avrD.
Abstract: Soybean [Glycine max (L.) Merr.] cultivars Flambeau and Merit differed in their resistance to Pseudomonas syringae pv glycinea (Psg) race 4, carrying each of four different avirulence (avr) genes cloned from Psg or the related bacterium, Pseudomonas syringae pv tomato. Segregation data for F2 and F3 progeny of Flambeau x Merit crosses indicated that single dominant and nonallelic genes account for resistance to Psg race 4, carrying avirulence genes avrA, avrB, avrC, or avrD. Segregants were also recovered that carried all four or none of the disease resistance genes. One of the disease resistance genes (Rpg1, complementing bacterial avirulence gene B) had been described previously, but the other three genes — designated Rpg2, Rpg3, and Rpg4 — had not here to fore been defined. Rpg3 and Rpg4 are linked (40.5 ± 3.2 recombination units). Rpg4 complements avrD, cloned from Pseudomonas syringae pv tomato, but a functional copy of this avirulence gene has not thus far been observed in Pseudomonas syringae pv glycinea. Resistance gene Rpg4 therefore may account in part for the resistance of soybean to Pseudomonas syringae pv tomato and other pathogens harboring avrD.
Journal Article•
TL;DR: The inheritance and linkage relationships of a gene for resistance to Fusarium oxysporum f.
Abstract: The inheritance and linkage relationships of a gene for resistance to Fusarium oxysporum f. sp. lycopersici race 1 were analyzed. An interspecific hybrid between a resistant Lycopersicon pennellii and a susceptible L. esculentum was backcrossed to L. esculentum. The genotype of each backcross-1 (BC1) plant with respect to its Fusarium response was determined by means of backcross-2 progeny tests. Resistance was controlled by a single dominant gene, I1, which was not allelic to I, the traditional gene for resistance against the same fungal pathogen that was derived from L. pimpinellifolium. Linkage analysis of 154 molecular markers that segregated in the BC1 population placed I1 between the RFLP markers TG20 and TG128 on chromosome 7. The flanking markers were used to verify the assignment of the I1 genotype in the segregating population. The results are discussed with reference to the possibility of cloning Fusarium resistance genes in tomato.
TL;DR: Fusarium wilt of watermelon [Citrullus lanatus (Thunb.) Matsum] is caused by Fusarium oxysporum Schlecht, which was first described by Smith (1894) from South Carolina and Georgia in the United States.
Abstract: Fusarium wilt of watermelon [Citrullus lanatus (Thunb.) Matsum. & Nakai] is caused by Fusarium oxysporum Schlecht. (emend. Snyd. & Hans.) f. sp. niveum (E.F. Sm.). The disease was first described by Smith (1894) from South Carolina and Georgia in the United States. It is now well-established throughout the watermelon-growing regions of the world. Once a field is infested, the Fusarium wilt pathogen may survive for many years and can seriously limit watermelon production in those fields. Long-term crop rotation (5 to 10 years) and leaving the soil fallow for several years helps reduce the pathogen population in the soil, but generally does not eradicate the pathogen. Even in cases where the pathogen is reduced to noneconomic levels, reintroduction via contaminated soil or seed is possible. Over the years, attempts to control Fusarium wilt have focused on several approaches, including soil polarization (Martyn and Hartz, 1986), induced resistance (Biles and Martyn, 1989; Davis, 1967; Shimotsuma et al., 1972), cultural practices (Hopkins and Elmstrom, 1976; Jones et al., 1975; Sun and Huang, 1985), fumigation (Hopkins and Elmstrom, 1979), and grafting (Kuniyasu, 1981). However, genetic resistance has
TL;DR: Local populations of the plant Amphicarpaea bracteata often contain genetically divergent lineages that differ strongly in disease resistance toward the specialist pathogen Synchytrium decipiens, resulting in strong correlations between disease resistance and other ecologically important characters.
Abstract: Local populations of the plant Amphicarpaea bracteata often contain genetically di- vergent lineages that differ strongly in disease resistance toward the specialist pathogen Synchytrium decipiens. In one population, lineages with disease resistance were observed to significantly decrease in frequency over a two-year period, despite the continued presence of pathogens. Extensive self- pollination in A. bracteata restricts the opportunity for recombination of alleles affecting separate traits, resulting in strong correlations between disease resistance and other ecologically important characters, including plant morphology, phenology, and patterns of reproductive allocation. Natural selection on these correlated characters may thus cause nonadaptive changes in disease resistance. These results imply that A. bracteata's mating system is a basic constraint interfering with its adaptation to pathogen attack.
TL;DR: Recombination analysis indicates that genes within each of the M and N groups are probably closely linked and that of the L group are genetically complex, while a molecular approach of cloning host genes in flax is described.
Abstract: Present knowledge of host genes conferring resistance to rust in flax and their genetics are reviewed. There are at least 34 genes conferring resistance to rust occurring in seven groups, namely, K, L, M, N, P, D and Q. Expression of these host genes is affected by temperature, genetic background and by the inhibitor gene present in certain rust strains. Recombination analysis indicates that genes within each of the M and N groups are probably closely linked and that of the L group are genetically complex. When testcross progeny between two genes of the L group were screened, susceptible and modified recombinants were recovered. Some of these susceptible recombinants yielded rare resistant revertants in their progeny. Mechanism of such reversion is not defined but appears to follow a definite pattern. It is also indicated that some of the recombinants represent new specificity. A molecular approach of cloning host genes in flax is described.
TL;DR: Attempts to improve disease resistance by gene transfer of different gene constructs into farm animals include the use of monoclonal antibody gene constructs, transgenes consisting of antisense RNA genes directed against viruses and Mx1 cDNA containing transGenes.
Abstract: Genetic variations in disease resistance of farm animals can be observed at all levels of defence against infectious agents. In most cases susceptibility to infections has polygenic origins. In domestic animals only a few instances of a single genetic locus responsible for disease resistance are known. A well-examined example is the Mx1 gene product of certain mice strains conferring selective resistance to influenza virus infections. Attempts to improve disease resistance by gene transfer of different gene constructs into farm animals include the use of monoclonal antibody gene constructs, transgenes consisting of antisense RNA genes directed against viruses and Mx1 cDNA containing transgenes.
TL;DR: The present study demonstrated the existence of somaclonal variation for disease resistance against a soil-borne fngal pathogen in strawberry to the fungal wilt disease caused by Fusarium oxysporum f.
Abstract: Resistant lines of strawberry to the fungal wilt disease caused by Fusarium oxysporum f. sp. fragariae were selected strawberry plants regenerated from leaf-derived callus tissues. Regenerants were transplanted to a field heavily infested with this pathogen, and normally growing plants were selected as the putative resistant lines. Daughter plants produced vegetatively through runner formation of the lines were similarly tested in the pathogen-infested field over an additional three generations. Finally, two resistant lines were obtained from a total of 1,225 regenerants. The stable propagation of disease resistance in these lines was confirmed by directly inoculating the daughter plants with the pathogen and planting in a pathogen-infested soil. All of the control plants were efficiently infected and died within one month. The isolated plant lines grew and developed runners even after direct inoculation and produced daughter plants in this soil. Thus, the present study demonstrated the existence of somaclonal variation for disease resistance against a soil-borne fngal pathogen.
TL;DR: 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.
Abstract: 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.
TL;DR: Field studies were conducted in 1983 and 1984 to assess the effect of rust (Uromyces viciae-fabae) on the yield components, pods per plant, seed per plant), seed per pod, total dry matter and harvest index of two faba bean (Vicia faba) cultivars and one susceptible line.
Abstract: Field studies were conducted in 1983 and 1984 to assess the effect of rust (Uromyces viciae-fabae) on the yield components, pods per plant, seed per plant, seed per pod, total dry matter and harves...
TL;DR: Results demonstrate that activation of beta-1,3-glucanase genes may be a general response of cereals to infection by fungal pathogens.
Abstract: The sequence of a partial cDNA clone corresponding to an mRNA induced in leaves of barley (Hordeum vulgare) by infection with fungal pathogens matched almost perfectly with that of a cDNA clone coding for β-1,3-glucanase isolated from the scutellum of barley. Western blot analysis of intercellular proteins from near-isogenic barley lines inoculated with the powdery mildew fungus (Erysiphe graminis f. sp. hordei) showed a strong induction of glucanase in all inoculated lines but was most pronounced in two resistant lines. These data were confirmed by β -1,3-glucanase assays. The barley cDNA was used as a hybridization probe to detect mRNAs in barley, wheat (Triticum aestivum), rice (Oryza sativus), and sorghum (Sorghum bicolor), which are induced by infection with the necrotrophic pathogen Bipolaris sorokiniana. These results demonstrate that activation of β -1,3-glucanase genes may be a general response of cereals to infection by fungal pathogens.
TL;DR: Management of single-gene effects remains the central objective of resis tance breeding and the hope is often expressed that even if individual tree resistance can be broken, other genes for Resistance can be found and that this resistance will endure and increase in subsequent generations.
Abstract: As with other crop species (24), resistance to diseases and insects is a prime target in breeding operations with trees (7, 38, 48, 97, 133). Reliable and repeatable resistance-testing techniques have been developed (see e.g. 2, 6, 65, 89-91, 141). High correlations between nursery tests and field trials have been achieved (118), and disease resistance has been increased markedly in the first generation of selection (151, 160). Most tree breeders try to capture an easily identifiable kind of resistance in breeding populations and hope that this resistance will endure and increase in subsequent generations. This approach tends to identify single-gene effects. Such genes must either be present in the evolving breeding populations, or they must be incorporated by backcrossing or otherwise transgenic ally transferred into these populations. The approach was widely adopted despite the fact that no specific genes for resistance had been identified (58), and no genes for resistance had been transgenically transferred in any plant species (24). Management of single-gene effects remains the central objective of resis tance breeding. The hope is often expressed that even if individual tree resistance can be broken, other genes for resistance can be found and that
TL;DR: Seedling resistance to wheat stem rust was determined in populations of wild emmer wheat, Triticum dicoccoides, and characterized by means of ecological factors and allozyme genotypes, and appeared to be associated with resistance or susceptibility to rust.
Abstract: Seedling resistance to wheat stem rust was determined in populations of wild emmer wheat, Triticum dicoccoides, and characterized by means of ecological factors and allozyme genotypes. Reactions to wheat stem rust were studied in 102 single plant accessions of T. dicoccoides from ten populations by inoculation with Puccinia graminis tritici race 14, isolate GSR-739. Six populations displayed different degrees of response polymorphism with reactions ranging from high resistance to complete susceptibility, whereas four populations contained only susceptible plants. In some of the accession, unexplained intrasib variation in resistance and intraplant variation of infection-types were found. Resistance to stem rust was negatively correlated with two ecological factors, altitude and number of ‘Sharav’ (hot-dry) days which are unfavorable to disease development. Variation in stem rust response was shown to exist in ecogeographic regions where climatic variables enhanced the development of the fungus, conceivably maintained by natural selection. Likewise, allozyme genotypes, single or in multiple loci combinations, appeared to be associated with resistance or susceptibility to rust. Such association need to be verified by genetic studies in order to become established as useful markers.
TL;DR: Overall, S12 and S13 were more resistant to D. noxia in terms of antibiosis and tolerance than S16 and S17, while S13 is a widely tested, high-yielding barley genotype with multiple disease resistance and represents for breeders a useful source of resistance to the aphid in a superior genetic background.
Abstract: Experiments were carried out to determine the relative levels of antibiosis, tolerance, and antixenosisin four barley ( Hordeum vulgare L.) genotypes, S12. (ASE/2CM//B.7.6.B.B.), S13 (Gloria/Come), S16 (‘Esperanza’) and S17 (‘Shyri’) to the Russian wheat aphid, Diuraphis noxia (Mordvilko). Oats (Avena sativa L. var. ‘Paramo’) were used as a resistant check. From field screenings, S12 and S13 were selected as resistant to D. noxia and S16 and S17 susceptible. S12 and S13, in comparison with S16 and S17, showed high levels of antibiosis, demonstrated by low rates of nymph production on whole plants and on excised leaves. S13 showed higher tolerance than the other genotypes; mature plant height was reduced slightly by D. noxia feeding, and dry mass foliage loss per unit of aphid mass produced was relatively low. No antixenosis was demonstrated for the barley genotypes. Overall, S12 and S13 were more resistant to D. noxia in terms of antibiosis and tolerance than S16 and S17. S13 is a widely tested, high-yielding barley genotype with multiple disease resistance and represents for breeders a useful source of resistance to D. noxia in a superior genetic background.
Book•
01 Jan 1991
TL;DR: Biochemical aspects of plant disease resistance are studied in detail in order to establish a clear picture of the response of the immune system to various types of plant diseases.
Abstract: Biochemical aspects of plant disease resistance , Biochemical aspects of plant disease resistance , مرکز فناوری اطلاعات و اطلاع رسانی کشاورزی
Journal Article•
TL;DR: A certain level of BYDV resistance was found in thirteen Triticeae species, including Thinopyrum intermedium, and one disomic addition line, L1 derived from TAF46, showed good resistance to ByDV by enzyme linked immunosorbent assay (ELISA).
Abstract: Barley yellow dwarf virus (BYDV) is one of the most serious wheat diseases in China So far no resistance has been described in common wheat A certain level of BYDV resistance was found in thirteen Triticeae species Thinopyrum intermedium, two octoploids derived from TH intermedium/wheat, Zhong 4 awnless and TAF46, and one disomic addition line, L1 derived from TAF46, showed good resistance to BYDV by enzyme linked immunosorbent assay (ELISA) Two wheat/TA intermedium translocation lines, CPI 119880 and CPI 119899, showing good BYDV resistance were developed from L1 by using both CSph mutant and tissue culture It is found that their BYDV resistance was controlled by a single dominant gene Two cDNA probes pEleAcc3 and pPJN8 (E1-T1) were screened for detecting Th intermedium DNA in wheat background A specific band for the DNA of Th intermedium and its derivatives was found in Southern hybridization It is also possible to determine the size of the alien segment by comparing the relative density of the specific band Therefore, this can be used as a marker to identify the BYDV resistance in wheat breeding program
Journal Article•
TL;DR: These results confirmed the successful transfer and expression of heat-stable resistance to M. incognita from L. peruvianum to hybrids with L. esculentum as a preliminary step to introgressing additional root-knot nematode resistance into tomato.
Abstract: Genotypes of Lycopersicon peruvianum (L.) Mill. and L. peruvianum var. glandulosum (Rick), selected from accessions that possess resistance to Meloidogyne incognita ((Kofoid and White) Chitwood) at high soil temper- ature (30C), were used as male parents in crosses with L. esculentum (Mill.) susceptible cultivars UC82, Lukullus, Tropic, and male-sterile line ms-31, respectively. The incongruity barrier between the two plant species was overcome by embryo callus and embryo cloning techniques. Hybridity of the F, progeny obtained from each cross was confirmed by differences in leaf and flower morphology, plant growth habits, and by acid phosphatase isozyme phenotypes using polyacrylamide gel electrophoresis. In greenhouse inoculation experiments, F 1 plants were highly resistant to M. incognita in soil at 25 and 30C. These results confirmed the successful transfer and expression of heat-stable resistance to M. incognita from L. peruvianum to hybrids with L. esculentum as a preliminary step to introgressing additional root-knot nematode resistance into tomato. The resistance to root-knot nematodes (Meloidogyne spp.), present in all resistant commercial cultivars of tomato (Lyco- persicon esculentum Mill.), is generally considered to be con- ferred by a single dominant gene, designated Mi (Ammati, 1985; Medina Filho and Stevens, 1980; Roberts and Thomason, 1989; Sidhu and Webster, 1981). This resistance was identified in L. peruvianum PI 128657. Using embryo rescue, Smith (1944) obtained one resistant F 1 plant from the cross L. esculentum Michigan State Forcing x PI 128657. Watts (1947) cloned this unique F1 plant and obtained the first two backcrosses to L. esculentum. Additional backcrosses to the cultivated tomato were obtained by Frazier and Dennett (1949). This material was dis- tributed to tomato breeders and led to the release of the first tomato cultivars resistant to Meloidogyne incognita. All culti- vars with gene Mi have been derived from this one F1 resistant plant obtained by Smith (1944). Plants possessing gene Mi are resistant to three of the four economically important species of root-knot nematode (RKN): M. incognita, M. arenaria (Neal) Chitwood, and M. javanica (Treub) Chitwood (Ammati, 1985; Fatunla and Salu, 1977; Medina Filho and Stevens, 1980; Roberts and Thomason, 1989; Sidhu and Webster, 1981). Gene Mi does not confer resistance to M. hapla Chitwood. In addition, the resistance conferred by Mi is not effective in soils above 28C (Ammati, 1985; Ammati et al., 1986; Dropkin, 1969). Nonselected virulent populations