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Showing papers on "Plant disease resistance published in 1990"


Journal ArticleDOI
TL;DR: The cloning of avirulence genes has greatly aided the understanding of plant-pathogen specificity and established firm genetic and biochemical evidence supporting the elicitor-receptor model for recognition of incompatible pathogen races by plants.
Abstract: The cloning of avirulence genes has greatly aided our understanding of plant-pathogen specificity. It has proven that the gene-for-gene relationship first noted by Flor is correct--single avirulence gene encoding single protein products indeed are the genetic elements that interact with plant disease resistance genes. Furthermore, firm genetic evidence has provided insight into how two cloned avirulence genes (the TMV coat gene and avrD) cause the HR. The differences in structure of pathogen elicitors also indicates that plants have evolved diverse recognitional mechanisms to detect pathogens. It is appealing to speculate, therefore, that elicitors represent the plant equivalent of antigens in vertebrates. Another consequence of these results has been the establishment of firm genetic and biochemical evidence supporting the elicitor-receptor model for recognition of incompatible pathogen races by plants. In both TMV and bacterial pathogens, we are also beginning to understand how avirulence genes are altered to confound plant recognition of the pathogen. The next few years should yield additional information on avirulence gene structure as well as the important questions of their function in the pathogen and the molecular mechanisms whereby plant recognition occurs. The marked successes in cloning avirulence genes underscore only more forcefully the pressing need to clone and characterize plant disease resistance genes. Certainly an understanding of these genes is required to further our basic knowledge of active defense in plants and to permit their manipulation for improved control of plant diseases in practical agriculture.

761 citations


Journal ArticleDOI
26 Jul 1990-Nature
TL;DR: The resistance gene avrBs2 is reported, which implies that plants carrying Bs2 can recognize an essential gene of the bacterial pathogen, which may explain why Bs1 confers the only effective field resistance to X. c.
Abstract: Disease-resistance genes introduced into cultivated plants are often rendered ineffective by the ability of pathogen populations to overcome host resistance. The bacterial pathogen Xanthomonas campestris pathovar vesicatoria causes bacterial spot disease of tomato and pepper, and this pathogen has been shown to overcome disease resistance in pepper (Capsicum annuum) by evading the recognition and defence response of the host plant. Numerous resistance genes to bacterial spot have been identified in pepper and its wild relatives, each providing resistance to specific races of X.c. vesicatoria. The resistance gene Bs1, for example, provides resistance to X.c. vesicatoria strains expressing the avirulence gene avrBs1; Bs2 provides resistance to stains expressing avrBs2 and so on. We now report that avr Bs2 is highly conserved among strains of X.c. vesicatoria, and among many other pathovars of X. campestris. Furthermore, we find that avrBs2 is in fact needed for full virulence of the pathogen on susceptible hosts. This implies that plants carrying Bs2 can recognize an essential gene of the bacterial pathogen, which may explain why Bs2 confers the only effective field resistance to X.c. vesicatoria in pepper.

272 citations


Journal ArticleDOI
TL;DR: Treatment with any of the cinnamyl-alcohol dehydrogenase inhibitors decreased the frequency of lignified necrotic host cells and concomitantly led to increased fungal growth, pointing to a causal relationship between the formation of lIGNin precursors and the resistance of wheat to stem rust.
Abstract: When highly resistant wheat (Triticum aestivum L.) varieties are infected by an avirulent race of the stem rust fungus (Puccinia graminis Pers. f. sp. tritici Erics. and E. Henn.), penetrated host cells undergo rapid necrotization. This hypersensitive cell death is correlated with cellular lignification which efficiently restricts further fungal growth. Three competitive inhibitors of phenylalanine ammonia-lyase, the first enzyme of the general phenylpropanoid pathway and, thus, of lignin biosynthesis, namely α-aminooxyacetate, α-aminooxy-β-phenylpropionic acid, and (1-amino-2-phenylethyl)phosphonic acid, and two highly specific irreversible suicide inhibitors of the lignification-specific enzyme cinnamyl-alcohol dehydrogenase, namely N(O-aminophenyl)sulfinamoyl-tertiobutyl acetate and N(O-hydroxyphenyl)sulfinamoyl-tertiobutyl acetate, were applied to genetically resistant wheat plants prior to inoculation with stem rust. Treatment with any of these inhibitors decreased the frequency of lignified necrotic host cells and concomitantly led to increased fungal growth. The cinnamyl-alcohol dehydrogenase inhibitors were generally more effective than the phenylalanine ammonia-lyase inhibitors, occasionally allowing some sporulation to occur on the resistant wheat leaves. These results clearly point to a causal relationship between the formation of lignin precursors and the resistance of wheat to stem rust.

172 citations


Journal ArticleDOI
TL;DR: Resistance to PVX and PVY is effective in the field and can prevent yield losses due to dual infection by these viruses, and is confirmed in transgenic Russet Burbank plants.
Abstract: Transgenic Russet Burbank potato plants expressing the coat protein genes of potato virus X (PVX) and potato virus Y (PVY) were transplanted into the field after propagation in tissue culture. Virus resistance, plant growth and tuber yield were determined. Our results show that expression of PVX and PVY CP genes confer a very high level of resistance to PVX and PVY infection in clone 303, one of the four different transgenic potato clones tested. After inoculation with PVX and PVY, tuber yield of control Russet Burbank plants decreased, while the yield of clone 303 was unaffected. Four different uninoculated transgenic clones had tuber yields as high as control Russet Burbank. These results confirm that resistance to PVX and PVY is effective in the field and can prevent yield losses due to dual infection by these viruses.

163 citations


Journal ArticleDOI
TL;DR: Heritability estimates indicated that for selection for Fusarium head blight resistance, visually assessed head blight was a better selection criterion than yield reduction, and that genetic variation for resistance is very large.
Abstract: During a four year period, a total of 258 winter and spring wheat genotypes were evaluated for resistance to head blight after inoculation with Fusarium culmorum strain IPO 39-01. It was concluded that genetic variation for resistance is very large. Spring wheat genotypes which had been reported to be resistant to head blight caused by Fusarium graminearum were also resistant to F. culmorum. The resistant germplasm was divided into three gene pools: winter wheats from Eastern Europe, spring wheats from China/Japan and spring wheats from Brazil. In 32 winter wheat genotypes in 1987, and 54 winter wheat genotypes in 1989, the percentage yield reduction depended on the square root of percentage head blight with an average regression coefficient of 6.6. Heritability estimates indicated that for selection for Fusarium head blight resistance, visually assessed head blight was a better selection criterion than yield reduction.

160 citations


Journal ArticleDOI
TL;DR: It should be possible but difficult to separate the rust resistance genes from the secalin gene(s), which are thought to contribute to dough stickiness of wheat-rye translocation lines carrying 1RS.
Abstract: The genes controlling resistance to three wheat rusts, viz., leaf rust (Lr26), stem rust (Sr31) and stripe or yellow rust (Yr9), and ω-secalins (Sec1), located on the short arm of rye chromosome 1R, were mapped with respect to each other and the centromere. Analysis of 214 seeds (or families derived from them) from testcrosses between a 1BL.1RS/1R heterozygote and ‘Chinese Spring’ ditelocentric 1BL showed no recombination between the genes for resistance to the three rusts, suggesting very tight linkage or perhaps a single complex locus conferring resistance to the three rusts. The rust resistance genes were located 5.4 ± 1.7 cM from the Sec1 locus, which in turn was located 26.1 ± 4.3 cM from the centromere; the gene order being centromere — Sec1 — Lr26/Sr31/Yr9 — telomere. In a second test-cross, using a different 1BL.1RS translocation which had only stem rust resistance (SrR), the above gene order was confirmed despite a very large proportion of aneuploids (45.8%) among the progeny. Furthermore, a map distance of 16.0 ± 4.8 cM was estimated for SrR and the telomeric heterochromatin (C-band) on 1RS. These results suggest that a very small segment of 1RS chromatin is required to maintain resistance to all three wheat rusts. It should be possible but difficult to separate the rust resistance genes from the secalin gene(s), which are thought to contribute to dough stickiness of wheat-rye translocation lines carrying 1RS.

132 citations


Journal ArticleDOI
TL;DR: In an attempt to obtain coat protein-mediated protection, the coat protein gene of PLRV was inserted into the genomes of both tobacco and potato.
Abstract: In an attempt to obtain coat protein-mediated protection, the coat protein gene of PLRV, which was previously identified and sequenced, was inserted into the genomes of both tobacco and potato. These plants were characterized, the potato plants challenged with PLRV using viruliferous aphids, and virus titers monitored using ELISA. The results were compared to those of the transgenic plants expressing the coat protein of other viruses

120 citations


Journal ArticleDOI
01 Aug 1990-Genome
TL;DR: A partially dominant gene for adult-plant leaf rust resistance together with a linked, partially dominant genes for stem rust resistance were transferred to the hexaploid wheat cultivar 'Marquis' from an amphiploid of Aegilops speltoides × Triticum monococcum by direct crossing and backcrossing.
Abstract: A partially dominant gene for adult-plant leaf rust resistance together with a linked, partially dominant gene for stem rust resistance were transferred to the hexaploid wheat cultivar 'Marquis' from an amphiploid of Aegilops speltoides × Triticum monococcum by direct crossing and backcrossing. Pathological evidence indicated that the alien resistance genes were derived from Ae. speltoides. Differential transmission of the resistance genes through the male gametes occurred in hexaploid hybrids involving the resistant 'Marquis' stock and resulted in distorted segregation ratios. In heterozygotes, pairing between the chromosome arm with the alien segment and the corresponding arm of the normal wheat chromosome was greatly reduced. The apparent close linkage between the two resistance genes, 3 ± 1.07 crossover units, was misleading because of this decrease in pairing in the presence of the 5B diploidizing mechanism. The newly identified gene for adult-plant leaf rust resistance, located on chromosome 2B, is ...

116 citations


Journal ArticleDOI
TL;DR: The joint-scaling test indicated that the inheritance of Fusarium head blight resistance was adequately described by the additive-dominance model, with additive gene action being the most important factor of resistance.
Abstract: Crosses were made among ten winter wheat genotypes representing different levels of resistance to Fusarium head blight to obtain F1 and F2 generations. Parents, F1 and F2 were inoculated with one strain of Fusarium culmorum. Data on incidence of head blight 21 days after first inoculation were analyzed. Broad-sense heritabilities averaged 0.39 and ranged from 0.05 to 0.89 in the individual F2 families. The joint-scaling test indicated that the inheritance of Fusarium head blight resistance was adequately described by the additive-dominance model, with additive gene action being the most important factor of resistance. With respect to the non-additive effects, dominance of resistance predominated over recessiveness. The number of segregating genes governing resistance in the studied populations was estimated to vary between one and six. It was demonstrated that resistance genes differed between parents and affected resistance differently.

100 citations


Journal ArticleDOI
TL;DR: It is concluded that the associations between the three ml-O alleles and agronomic traits are caused by pleiotropy, that ml-o resistant, high-yielding lines may be selected, and that the association between gene s and thousand grain weight may be due to genetic linkage.
Abstract: A population of 198 chromosome-doubled haploid lines of spring barley was scored for segregation in locus ml-o (powdery mildew reaction) on chromosome 4 and in the linked loci s (rachilla hair length) and ddt (reaction to the insecticide DDT) on chromosome 7. They were also tested in a disease-free field trial for the agronomic traits: grain yield, thousand grain weight, lodging, and necrotic leaf spotting. The three mutagen-induced resistance genes ml-o5, ml-o6 (from ‘Carlsberg II’) and ml-10 (from ‘Foma’) showed no detectable differences with respect to effects on agronomic traits. They all conferred a four per cent reduction in grain yield caused mainly by lower thousand grain weight, and an increase in necrotic leaf spotting. The two original mutants of ‘Carlsberg II’ had additional mutant genes affecting agronomic traits. Lines with gene S (long hair) had on average a three per cent higher thousand grain weight than those with s. The alleles in locus ddt showed no association with the agronomic traits. It is concluded i) that the associations between the three ml-o alleles and agronomic traits are caused by pleiotropy, ii) that ml-o resistant, high-yielding lines may be selected, and iii) that the association between gene s and thousand grain weight may be due to genetic linkage.

86 citations


Journal ArticleDOI
TL;DR: Soft red winter wheat cultivars were inoculated with isolates of Erysiphe graminis f.
Abstract: Twenty-two soft red winter wheat (Triticum aestivum) cultivars were inoculated with isolates of Erysiphe graminis f. sp. tritici to determine genes for resistance. Cultivars were tested with a total of 27 isolates that had been characterized from reactions on differential host lines. Genes determinations were completed separately in two laboratories with different isolates and the results were combined. Intact 10-day-old seedlings or detached primary leaves on benzimidazole-amended agar were inoculated, and evaluations based on pustule number and type were made 10-14 days later (...)

Journal ArticleDOI
TL;DR: It is concluded that the powdery mildew resistance of Amigo is regulated by one gene with conditioned dominance, which is missing in Amigo and replaced by the rye chromosome arm 1RS.
Abstract: Powdery mildew resistance of Amigo wheat has been analyzed and mapped by combining F 2 segregation data with cytogenetic and storage protein analyses. It is concluded that the powdery mildew resistance of Amigo is regulated by one gene with conditioned dominance. Cytogenetic and electrophoretic analyses revealed that the complete wheat chromosome arm 1AS is missing in Amigo and has been replaced by the rye chromosome arm 1RS. No susceptible recombinant was found among 1,034 F 2 plants of crosses of Amigo with Pm3 resistant lines; Pm3 is known to be located on 1AS (...)

Journal ArticleDOI
TL;DR: Correlation of resistance to the different viruses was observed in aneuploid hybrids lacking parental chromosomes, suggesting that resistance/susceptibility is associated with the loss of individual S. brevidens or S. tuberosum chromosomes.

Journal ArticleDOI
TL;DR: Eighty-three third backcross lines which comprise a set of near isogenic lines (NIL's) of the barley cultivar ‘Clipper’ but each carrying a different chromosomal segment from Hordeum spontaneum, marked with a distinct isozyme, were tested for resistance to three races ofThe barley leaf rust pathogen (Puccmia hordei).
Abstract: Eighty-three third backcross lines which comprise a set of near isogenic lines (NIL's) of the barley cultivar ‘Clipper’ but each carrying a different chromosomal segment from Hordeum spontaneum, marked with a distinct isozyme, were tested for resistance to three races of the barley leaf rust pathogen (Puccmia hordei). Fourteen lines showed resistance to at least one race and three showed resistance to all three races. The resistance in two of these lines was controlled by separate, single partially dominant genes. In one case the resistance gene named Rph1O was on chromosome 3 and linked (r = 0.15 ±0.05) with the isozyme locus Est2. In the second case, the gene (Rph11) was on barley chromosome 6 and linked (r = 0.07±0.02) with the isozyme locus Acp3 and (r = 0.11±0.02) with Dip2.

Journal ArticleDOI
TL;DR: Immune reactions were most prevalent on leaflets of flowering plants (8–10-wk-old), and the incidence of immune reactions was greater with the drop than with the spray method of inoculation and decreased as spore concentration increased.

Journal ArticleDOI
TL;DR: The 1RS chromosome segment being used in Australian wheats will be discussed in detail to present the molecular biological studies carried out on this chromosome segment as well as its agronomic contributions to wheat.
Abstract: Specific alien chromatin segments have been used for many years to introduce novel disease resistance genes into bread wheat. The 1RS chromosome segment being used in Australian wheats will be discussed in detail to present the molecular biological studies carried out on this chromosome segment as well as its agronomic contributions to wheat. Studies are also being carried out on the manipulation of the D genome of wheat. Within Australia we have initiated the screening of a collection of 420 accessions of Triticum tauschii (the donor of the D genome) involving groups in the Departments of Agriculture in New South Wales, Victoria, Western Australia and the University of Sydney as well in the Division of Plant Industry. Disease resistance has been sought and found for cereal cyst nematode, Septoria nodorum, Septoria tritici, Puccinia striiformis, P. recondita and P. graminis. At the DNA level the collection has been screened for variation at the 5Sdna and Nor loci, as well as generating Pst (a restriction endonuclease) genomic clones, in preparation for providing RFLP markers for a genetic linkage map. Lines of T. tauschii showing high levels of disease resistance have been crossed directly to Australian wheat cultivars or are being used to form synthetic hexaploids by crossing to tetraploid wheats.

Journal ArticleDOI
TL;DR: A list with information about named host genes controlling resistance to rust in both cultivated and wild flax has been compiled and will be useful for genetic, physiological and biochemical research as well as breeding for resistance.
Abstract: A list with information about named host genes controlling resistance to rust in both cultivated and wild flax has been compiled. These will be useful for genetic, physiological and biochemical research as well as breeding for resistance. Information regarding mutation, temperature sensitivity and the effect of inhibitor/avirulence gene interaction on expression of certain host genes is included.

Journal ArticleDOI
TL;DR: Ten homozygous winter wheat genotypes representing different levels of resistance to Fusarium head blight were crossed in all possible combinations excluding reciprocals and it is suggested that in the progenies with one of the awned lines as parent, one resistance gene was linked with the gene coding for presence of awns, located on chromosome 4B.
Abstract: Ten homozygous winter wheat genotypes representing different levels of resistance to Fusarium head blight were crossed in all possible combinations excluding reciprocals. Parents, F1 and F2 were inoculated with one pathogenic strain of Fusarium culmorum. Data for head blight, observed 21 days after first inoculation (OBS-2), and for the area under the disease progress curve, based on observations 14, 21 and 28 days after first inoculation (AUDPC), were analyzed. The contrast between parents and F1 crosses indicated dommance effects of the resistance genes. Diallel analysis according to Griffing's Method 4, Model 1 showed significant general combining ability (GCA) effects for both F1 and F2; specific combining ability effects were not significant. With the exception of one genotype for which general performance for Fusarium resistance was not in agreement with its GCA, the resistance to F. culmorum was uniformly transmitted to all offspring, and the parents can be described in terms of GCA. It is suggested that in the progenies with one of the awned lines as parent, one resistance gene was linked with the gene coding for presence of awns, located on chromosome 4B. A single observation date, taken at the right time, was as effective in assessing resistance as the AUDPC.

Journal ArticleDOI
TL;DR: For barley, wheat, and potato somaclones have been found that were less susceptible to a toxin of Helminthosporium, fusaric acid, Fusarium coeruleum, F. sulphureum, or Phytophthora infestans when screened in the first in-vitro-derived generation.
Abstract: Because plant cells cultured in vitro express genetic variability and since they can be regenerated into functional plants, procedures have been designed to use this system for the production of plants with new important agronomic characteristics, particularly for disease resistance. For barley, wheat, and potato somaclones have been found that were less susceptible to a toxin of Helminthosporium, fusaric acid, Fusarium coeruleum, F. sulphureum, or Phytophthora infestans, when screened in the first in-vitro-derived generation. Here the progeny of such somaclones is evaluated after natural and artificial infection, using greenhouse-grown or field material. The progenies of the same somaclones did not express detectable differences, which indicated that no heterozygous mutations occurred. Most lines and clones differed in their level of susceptibility to the pathogen compared to the level of the starting material, but these data were in no instance significant. It is discussed here whether this lack of significance is due to a lack of genetic differences or whether the test procedures are in adequate for detecting and securing the slight, probably quantitative, alterations.

Journal ArticleDOI
F. Gadani, L. M. Mansky1, R. Medici, W. A. Miller1, John H. Hill1 
TL;DR: The most promising method for genetic engineering of plants for virus resistance has been the expression of coat-protein coding sequences in plants transformed with a coat protein gene.
Abstract: Historically, control of plant virus disease has involved numerous strategies which have often been combined to provide effective durable resistance in the field. In recent years, the dramatic advances obtained in plant molecular virology have enhanced our understanding of viral genome organizations and gene functions. Moreover, genetic engineering of plants for virus resistance has recently provided promising additional strategies for control of virus disease. At present, the most promising of these has been the expression of coat-protein coding sequences in plants transformed with a coat protein gene. Other potential methods include the expression of anti-sense viral transcripts in transgenic plants, the application of artificial anti-sense mediated gene regulation to viral systems, and the expression of viral satellite RNAs, RNAs with endoribonuclease activity, antiviral antibody genes, or human interferon genes in plants.

Book ChapterDOI
01 Jan 1990
TL;DR: Wide crosses between different plant species and even between different genera have interested plant breeders and botanists since before the turn of the century and hybrids between Wheat and barley are the starting materials for determining the evolutionary and genetical relationship between wheat and barley chromosomes.
Abstract: Wide crosses between different plant species and even between different genera have interested plant breeders and botanists since before the turn of the century. Wheat (Triticum),being the most important food crop of the world, has attracted most attention and it has been hybridized extensively with “alien” species belonging to several neighboring genera (Islam 1980a; Sharma and Gill 1983). The objectives in hybridizing wheat with barley are manifold. The prospect of transferring desirable agronomic characters like tolerance to drought or soil salinity from barley to wheat prompted some early workers to attempt wheat-barley hybridizations. More recent considerations are to transfer nematode and disease resistance genes from barley to wheat. Furthermore, hybrids between wheat and barley are the starting materials for determining the evolutionary and genetical relationship between wheat and barley chromosomes.

Journal ArticleDOI
TL;DR: It is concluded that breeding for high-yielding cultivars combined with Ppr resistance is the most effective way of controlling Ppr of cocoa on the crops of growers with small holdings in Papua New Guinea.
Abstract: Quantitative inheritance of resistance to Phytophthora pod rot (Ppr) was studied in cocoa hybrid progeny from 12 Trinitario x Amazonian crosses and their reciprocal crosses. The crossing scheme was similar to a factorial design. Disease was assessed by the number and percentage of infected pods on each tree. Highly significant differences due to general combining abilities (GCA) were obtained for all characters, except for the GCA of Trinitario on total pod production. Differences for specific combining ability (SCA) were not significant for all characters. There were no significant differences between reciprocal crosses. The Trinitario clone K82 provided the only source for the hybrid progenies of strong Ppr resistance to the hybrid progenies, while K20 provided moderate resistance. Other parental clones — KA2-101, KA5-201, KEE 2, KEE 5, and KEE 52 — produced progenies which were susceptible to Ppr. It is evident that resistance to Ppr in cocoa is inherited additively. Maternal and cytoplasmic effects were assumed to have no influence on inheritance of resistance. It is also concluded that resistance to Ppr of the kind shown by K82 is likely to be horizontal resistance. Breeding for high-yielding cultivars combined with Ppr resistance is the most effective way of controlling Ppr of cocoa on the crops of growers with small holdings in Papua New Guinea.

Journal ArticleDOI
TL;DR: In a controlled environment, the reaction was observed of 42 bread wheat varieties and lines inoculated with 19 isolates of yellow rust differing in their virulence to 20 differential varieties, which showed resistance to all isolates.
Abstract: In a controlled environment, the reaction was observed of 42 bread wheat varieties and lines inoculated with 19 isolates of yellow rust differing in their virulence to 20 differential varieties. Five varieties and lines showed resistance to all isolates. The remaining ones appeared to have the genes Yr2, Yr3, Yr4, Yr6, Yr7, Yr9 and YrA, either singly or in combination. Yr9 derived from rye was present in 67% of the varieties and lines. Yr4 is the only effective gene in that material as, in Eastern and Central Africa, yellow rust has virulence to the other Yr genes. Recognition of virulence to Yr genes is enhanced by the use of a supplemental set of differential varieties supposedly carrying a single gene. Additional keywords: yellow (stripe) rust races, Triticum aestivum, Yr genes.

Journal ArticleDOI
01 Apr 1990-Genome
TL;DR: The avirulence of Erysiphe graminis f.sp.
Abstract: The avirulence of Erysiphe graminis f.sp. agropyri, Ak-1, on Triticum aestivum 'Norin 4' and 'Norin 10' and T. compactum 'No.44' is conditioned by four genes; three operate singly against each cult...

Journal ArticleDOI
TL;DR: Infection types in Triticum aestivum L. Westend seedlings induced by nine French races of Puccinia striiformis Westend were used to assess the hypothetical content of specific genes for resistance to yellow rust in 21 wheat varieties widely grown in France.
Abstract: Infection types in Triticum aestivum L. seedlings induced by nine French races of Puccinia striiformis Westend were used to assess the hypothetical content of specific genes for resistance to yellow rust in 21 wheat varieties widely grown in France. Resistance to the race 0E0 showed that none of the varieties lacked resistance factors. Most of the varieties possessed only 1 to 3 known Yr genes. The postulated genes were Yr1, Yr2, (Yr3a + Yr4a), Yr6 and Yr7 (...)

Journal ArticleDOI
01 Dec 1990-Genome
TL;DR: C-banding analysis showed that the homoeologous crossing-over occurred distally to an interstitial C-band in the satellite and linkage analysis showed Lr36 to be tightly linked to the telomeric C- band.
Abstract: A leaf rust resistant line, 2-9-2, was selected in the fourth backcross generation to Triticum aestivum of an interspecific hybrid, T. aestivum × Triticum speltoides. The resistance segregated independently of T. speltoides leaf rust resistance gene Lr28, previously shown to be incorporated into wheat chromosome 1B in two other transfer lines. Monosomic and telosomic analyses showed that the gene in line 2-9-2, Lr36, was incorporated into the short arm of chromosome 6B. C-banding analysis showed that the homoeologous crossing-over occurred distally to an interstitial C-band in the satellite and linkage analysis showed Lr36 to be tightly linked to the telomeric C-band.Key words: C-banding, physical mapping, linkage, wheat, chromosome 6B, introgression.

Journal ArticleDOI
TL;DR: Results show that the cultivars ‘Banteng’ and ‘Arrivate’, the Ethiopian line CI 5791, and the Syrian line 79 SIO-10, had a high partial resistance in all experiments and could be successfully used for breeding purposes.
Abstract: Reciprocal crosses were made between 9 different barley genotypes with high genetic variability for net blotch resistance. Parents and 72 F1 plants were used to determine the inheritance of partial resistance to net blotch. Four experiments, one in a growth chamber on seedlings and 3 others in the field on adult plants, were undertaken using a randomised complete block design. An isolate of net blotch from local cultivars was used for inoculation. Non-inoculated plants of one of the field experiments were used for the detached leaf test in petri dishes. Results show that the cultivars ‘Banteng’, and ‘Arrivate’, the Ethiopian line CI 5791, and the Syrian line 79 SIO-10, had a high partial resistance in all experiments. Diallel analysis showed high significant general and specific combining ability when maternal and reciprocal effects were not significant. As the resistance genotypes have a high additive genetic effect, they could be successfully used for breeding purposes.


Journal ArticleDOI
TL;DR: Segregation ratios for F 1, F 2, and BC 1 populations of crosses between resistant MR-1 and susceptible Topmark indicated that resistance to races 1 and 2 of Fusarium wilt is conferred by single dominant genes and that Resistance to race 0 is also conferred by a single dominant gene.
Abstract: In artificial inoculation studies, muskmelon (Cucumis melo) breeding line MR-1 was resistant to races 0, 1, and 2; but not 1,2y or 1,2w of Fusarium oxysporum f. sp. melonis. Segregation ratios for F 1 , F 2 , and BC 1 populations of crosses between resistant MR-1 and susceptible Topmark indicated that resistance to races 1 and 2 of Fusarium wilt is conferred by single dominant genes and that resistance to race 0 is also conferred by a single dominant gene. Linkage tests indicated that the genes for resistance to race 1 and race 2 assort independently (...)

Journal ArticleDOI
TL;DR: Coevolution of sender and receiver: Effect on local mate preference in cricket frogs 1988-1989 and 1988-89.
Abstract: NEVO, E. 1973. Adaptive variation of size in cricket frogs. Ecology 54:1271-1281. NEVO, E., AND R. R. CAPRANICA. 1985. Evolutionary origin ofethological reproductive isolation in cricket frogs, Acris. Evol. BioI. 19:147-214. PATERSON, H. E. H. 1982. Perspectives on speciation by reinforcement. So. Afr. J. Sci. 78:53-57. RICHARDS, D. G., AND R. H. WILEY. 1980. Reverberations and amplitude fluctuations in the propagation of sound in the forest: Implications for animal communication. Am. Nat. 115:381-399. RYAN, M. J., AND B. K. SULLIVAN. 1989. Transmission effects on the temporal structure of the advertisement call of two species of toads, Bufo woodhousii and Bufo valliceps. Ethology 80:182-185. RYAN, M. J.,ANDW. WILCZYNSKI. 1988. Coevolution of sender and receiver: Effect on local mate preference in cricket frogs. Science 240: 1786-1788. ---. Evolution of intraspecific variation in the advertisement call ofthe cricket frog (Aerts crepitans, Hylidae). BioI. J. Linn. Soc. In press. SALTHE, S. N., AND E. NEVO. 1969. Geographic variation of lactate dehydrogenase in the cricket frog, Acris crepitans. Biochem. Gen. 3:335-341. WAGNER, W. E., JR. 1989b. Social correlates ofvariation in male calling behavior in Blanchard's cricket frog,Acris crepitans blanchardi. Ethology 82:27-45. ---. 1990. Fighting, assessment, and frequency alteration in Blanchard's cricket frog. Behav. Ecol. Sociobiol. 25:429-436. ---. 1989a. Graded aggressive signals in Blan-