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Showing papers on "Plant disease resistance published in 1986"


Journal ArticleDOI
TL;DR: The level ofFusarium dry-rot resistance found in important potato varieties has been improved with agronomically acceptableSolanum tuberosum genotypes and resistance was determined separately for each of these species.
Abstract: The level ofFusarium dry-rot resistance found in important potato varieties has been improved with agronomically acceptableSolanum tuberosum genotypes. Three breeding selections, A74114-4, A76260-16, and BR6316-7 were highly resistant to the two commonFusarium dry-rot species (F. roseum Lk ex Fr. f. sp.sambucinum [Fs], andF. solani var.coeruleum (Sacc), Booth [Fc]). Resistance was determined separately for each of these species. Resistance to Fs was genetically distinct from resistance to Fc since there was no correlation between Fs and Fc reaction for 180 progeny clones from six crosses representing all combinations of resistance. Resistance to each of theseFusarium species was readily transmitted to progeny. Seventy-five percent of the progeny from resistant X resistant parents were also resistant to Fs, while 95% of the progeny from susceptible X susceptible parents were susceptible. Mixed infections withErwinia atroseptica and eitherFusarium species resulted in a qualitative change from a resistant reaction to a susceptible reaction. Bacterial interaction withFusarium spp. is, therefore, an important consideration in determining storage-rot resistance.

55 citations


Journal ArticleDOI
TL;DR: It is concluded that natural populations of wild emmer wheat in Israel contain large amounts of disease resistance genes that could be effectively screened and then utilized by the phytopathologist for identifying resistant genotypes and producing new resistant cultivars.
Abstract: From 114 accessions of wild emmer wheat from 11 sites in Israel, known for their allozymic variation (Nevo & al. 1982), individual genotypes were tested for resistance to one isolate of stripe rust both in the seedling stage in a growth chamber and in the adult plant stage in the field. The results indicate that resistance to stripe rust in seedlings and adults are significantly correlated (rs = 0.40, p < 0.001). Genetic polymorphisms of resistance to stripe rust vary geographically and are predictable by climatic, as well as allozymic markers. Three variable combinations of rainfall, evaporation, and temperature explain significantly 0.40–0.53 of the spatial variance in disease resistance to stripe rust, suggesting the operation of natural selection. Several allozyme genotypes are significantly associated with disease resistance. We conclude that natural populations of wild emmer wheat in Israel contain large amounts of disease resistance genes. These populations could be effectively screened and then utilized by the phytopathologist for identifying resistant genotypes and producing new resistant cultivars.

47 citations



Journal ArticleDOI
TL;DR: It is proposed that high yielding cultivars may be the most sensitive to yield constraint by disease, and there was a closer relationship, by regression analysis, of yield to green leaf area than to disease severity in three cultivars.
Abstract: Powdery mildew and leaf rust caused large yield losses in spring barley grown near Christchurch, New-Zealand, in two seasons. Disease present during early growth stages was as damaging to yield as disease late in the season. Moderate leaf rust severities after anthesis were most damaging when combined with earlier mildew epidemics. Later growth did not compensate for reduced yield potential induced by early infection. This was attributed, at least in part, to an effect on leaf size, and therefore on green leaf area, at later growth stages. There was a closer relationship, by regression analysis, of yield to green leaf area than to disease severity in three cultivars. The three cultivars. which differed in yield potential and disease resistance, were not equally sensitive to disease. It is proposed that high yielding cultivars may be the most sensitive to yield constraint by disease.

45 citations



Journal ArticleDOI
TL;DR: The heritability of resistance to early blight caused byAlternaria solani (Ell. & Martin) Son was estimated for field grown, diploid potatoes at Fletcher, North Carolina in 1981 and narrow-sense heritability, as determined by offspring-midparent regression, was calculated to be 0.825.
Abstract: The heritability of resistance to early blight caused byAlternaria solani (Ell. & Martin) Son was estimated for field grown, diploid potatoes at Fletcher, North Carolina in 1981. Fourteen breeding lines, selected from a random mated hybrid population ofSolanum tuberosum, subsp.phureja andstenotomum, were used. Resistance was measured as the slope obtained by regressing the logit of the disease proportion Y, measured as % defoliation, on time. A wide range of resistance was found. Narrow-sense heritability, as determined by offspring-midparent regression, on an individual plant basis, was calculated to be 0.825.

42 citations


Journal Article
TL;DR: It is demonstrated that the dual culture technique can be used as a reproducible screening procedure, independent of season, to select for host resistance to an obligate parasite.
Abstract: The responses of grapevine varieties and hybrids, with a range of field disease resistance, to infection by downy mildew ( Plasmopara viticola ) were studied in vitro . Dual cultures of host and pathogen were established for Chambourcin, JS 23-416, Verdelet, Muscat St. Vallier, Cabernet Sauvignon, and Sultana by inoculating sterile rooted shoot cultures with a contaminant-free fungal spore isolate. It was demonstrated that resistance to downy mildew was expressed in vitro , and a scale of infection, based on foliar symptom development 10 days after inoculation, was described to rank the varieties. It can be summarized as I - discrete necrotic spots; II - extensive necrotic lesions; or III - extensive sporulation. The order of ranking of the varieties correlated with field and glasshouse assessments, although due to the high efficiency of in vitro inoculation and infection, symptom expression was more severe than in the field. These results were verified using full siblings of JS 23-416 x Sultana and Chambourcin x (Merlot x Sultana) differing in resistance to downy mildew. This report demonstrates that the dual culture technique can be used as a reproducible screening procedure, independent of season, to select for host resistance to an obligate parasite.

41 citations


01 Jan 1986
TL;DR: Recherche des sources de resistance dans les materiels des groupes III and IV de maturite de la collection mondiale.
Abstract: Recherche des sources de resistance dans les materiels des groupes III et IV de maturite de la collection mondiale

27 citations


Journal ArticleDOI
TL;DR: GP-NC 343 and FESR 5-P2-B1 were the best parents for incorporating genes for resistance to both early and late leafspots and general combining ability, attributed largely to additive genetic variance, accounted for the largest portion of the variability among the F1 and F2 generations for most parameters of resistance to the 2 pathogens.
Abstract: Parental lines (4) with resistance to early leafspot caused by Cercospora arachidicola [Mycosphaerella arachidis] and 4 parental lines with resistance to late leafspot caused by Cercosporidium personatum [M. berkeleyi] and the F1 hybrid progeny from crosses between the 2 groups of parents were evaluated for resistance to both leafspot diseases in the greenhouse using a detached leaf technique. The subsequent F2 plants of all crosses were evaluated in the field for resistance to early leafspot in order to estimate combining ability effects for components of partial resistance and to identify parents useful in developing groundnut lines resistant to both diseases. General combining ability, attributed largely to additive genetic variance, accounted for the largest portion of the variability among the F1 and F2 generations for most parameters of resistance to both early and late leafspots. Reciprocal effects and heterosis toward the susceptible parents were also significant for parameters of resistance to the 2 pathogens. GP-NC 343 and FESR 5-P2-B1 were the best parents for incorporating genes for resistance to both early and late leafspots. Progeny of NC 17090 had a high level of resistance to late leafspot in detached leaf tests and progeny of PI 350680 had reduced defoliation from early leafspot in the field. Broad-sense heritabilities ranged from 0.2 to 0.4 for parameters of resistance to early leafspot estimated from the pooled variances of F2 plants of all crosses planted in the field. Parameters of resistance evaluated in the greenhouse for F1 hybrids were compared with parameters evaluated in the field for the F2 population by rank correlation of entry means. Latent period and sporulation of the fungus on detached leaves of F1 generation plants correlated (r = 0.46 and 0.54, respectively) with defoliation of F2 plants in the field.

19 citations


01 Jan 1986

14 citations



Book ChapterDOI
01 Jan 1986
TL;DR: Although the genetics, physiology and cytology of plant:pathogen interactions have been extensively studied, until recently relatively little was known at the biochemical level about how plants respond to infection to activate these defence responses.
Abstract: Plants exhibit natural resistance to disease which has been exploited by breeders to reduce crop losses and hence increase yield. Disease resistance involves not only static protection, but also inducible defence mechanisms including: (i) accumulation of host-synthesized phytoalexins; (ii) deposition of lignin-like material; (iii) accumulation of hydroxyproline-rich glycoproteins and (iv) increases in the activity of certain hydrolytic enzymes such as chitinase and glucanase [1]. Although the genetics, physiology and cytology of plant:pathogen interactions have been extensively studied, until recently relatively little was known at the biochemical level about how plants respond to infection to activate these defence responses.


01 Jan 1986
TL;DR: Experiments were planted at two sites in southeast Queensland to determine whether dominant genes for resistance to the anthracnose disease pathogen, Colletotrichum gloeosporioides, could be transferred by natural outcrossing from resistant genotypes of Stylosanthes guianensis to a set of susceptible selections.
Abstract: Experiments were planted at two sites in southeast Queensland to determine whether dominant genes for resistance to the anthracnose disease pathogen, Colletotrichum gloeosporioides, could be transferred by natural outcrossing from resistant genotypes of Stylosanthes guianensis to a set of susceptible selections. The smooth stem/bristly stem phenotypic contrast, shown to be controlled by a single gene (Bri/bri bri), and disease resistance itself were used to detect outcrosses. Disease resistance was transferred to 244 of the 385 susceptible progenies tested. Estimates of outcrossing rate based on stem bristles varied from 1.6 to 21.907o between selections (P< 0.001) but differences between sites were not significant. The advantages of increasing outcrossing rate through selection and an outline for a recurrent selection scheme based on outcrossing are briefly discussed.



Journal ArticleDOI
TL;DR: Promising wheat lines from FAO's International Program for Horizontal Resistance in Brazil and Zambia were tested in the Netherlands against brown rust and apparently, lines selected according to the IPHR principles can perform well when exposed to brown rust isolates to which they have not been exposed during selection.
Abstract: Promising wheat lines from FAO's International Program for Horizontal Resistance (IPHR) in Brazil and Zambia were tested in the Netherlands against brown rust (Puccinia recondita. f.sp.tritici). Race nursery tests were performed on isolated field plots using five monopustular isolates from the Netherlands representing at least four races. Mature plants of several lines showed high incomplete resistance. For most lines, the reactions to the different races showed a high uniformity. Apparently, lines selected according to the IPHR principles can perform well when exposed to brown rust isolates to which they have not been exposed during selection.


Journal Article
TL;DR: Tissue culture-induced variability in regenerated plant appears to be an effective way of obtaining undirected genetic change that can enhance disease resistance and yield and alter the growth habit of crops that are normally propagated vegetatively or by seed.
Abstract: In vitro procedures are playing a major role in plant breeding. Embryo rescue, either through the culture of excised embryos derived from incompatible crosses or by means of ovule culture, has been a standard procedure for the introgression of genes conferring disease resistance into economically important plants. Somatic hybridization (i.e., protoplast fusion) has also been demonstrated to have some potential in obtaining hybrids that result from very wide interspecific and intergeneric crosses. Wide crosses have also been achieved by means of in vitro pollination of excised ovaries or ovules. Tissue culture-induced variability in regenerated plant (i.e., somaclonal variation) appears to be an effective way of obtaining undirected genetic change that can enhance disease resistance and yield and alter the growth habit of crops that are normally propagated vegetatively (e.g., potato) or by seed (e.g., tomato). In the near future, the isolation and sequencing of genes that confer resistance to specific plant pathogens will be possible, and transfer of this information between species will become a reality.

Book ChapterDOI
01 Jan 1986
TL;DR: It is proposed that the “gene for gene” interaction associated with a given disease reaction involves the interaction of a product (inducer) coded by an avirulence gene in the pathogen with a resistance geneassociated with a host response.
Abstract: Many of the disease resistance traits in plants can be transferred within the species using conventional cross-breeding techniques. These specific traits are often inherited as single mendelian genes and often occur as alleles at a given locus, suggesting that a single enzyme or protein product is associated with each gene. We have proposed that the “gene for gene” interaction associated with a given disease reaction involves the interaction of a product (inducer) coded by an avirulence gene in the pathogen with a resistance gene associated with a host response [1,2].


Book ChapterDOI
01 Jan 1986
TL;DR: To evaluate the significance of phytoalexins in plant disease resistance, quantitative knowledge of their exact spatial and temporal distribution within plant tissue near infection structures of invading microorganisms is of great importance.
Abstract: Phytoalexins are low molecular weight compounds with antimicrobial properties which accumulate postinfectionally in plants from various families (Bailey and Mansfield 1982). To evaluate the significance of phytoalexins in plant disease resistance, quantitative knowledge of their exact spatial and temporal distribution within plant tissue near infection structures of invading microorganisms is of great importance.

Book ChapterDOI
I. Wahl1, A. Segal1
TL;DR: It is suggested that A. sterilis populations can be regarded as natural multilines sheltered against the crown rust organism mainly by slow rusting resistance, and Iowa Oat Multilines are protected from P. coronata avenae primarily by low reaction resistance.
Abstract: There is a general consensus that in natural ecosystems indigenous plant communities only seldom suffer from serious disease outbreaks caused by indigenous parasites. The host-parasite system has undergone long-lasting coevolution accompanied by reciprocal selection pressure resulting in balanced polymorphism. In Israel the following endemic host-parasite associations were studied: (1) Avena sterilis – Puccinia coronata avenae- Rhamnus spp.; (2) A. sterilis – P. graminis avenae ; (3) Hordeum spontaneum – Erysiphe graminis hordei ; (4) H.'spontaneum – P. hordei – Ornithogalum spp. Slow rusting or slow mildewing resistance prevail in all associations, while low reaction resistance is obvious in A. sterilis stricken by the crown rust agent and H. spontaneum attacked either by the powdery mildew or leaf rust causal agents. Low reaction resistance is very rare in the A. sterilis – P. graminis avenae couplet, and on Ornithogalum plants harboring the gametophytic stage of P. hordei . The composition of the defense structure in each host-parasite system is influenced by its components and ecologic factors. Comparative studies involving Iowa Oat Multilines suggest that A. sterilis populations can be regarded as natural multilines sheltered against the crown rust organism mainly by slow rusting resistance. In contrast, Iowa Oat Multilines are protected from P. coronata avenae primarily by low reaction resistance. In agroecosystems obligate parasites show distinct host specificity and can grow only on certain host varieties. Specificity is the basis of conventional breeding for disease resistance. In natural ecosystems the parasite shows compatibility with a broad spectrum of hosts. Elucidation and exploitation of factors conditioning protection from disease in compatible host-parasite systems is most important, and is expected to stabilize resistance since this type of association does not seem to be influenced by specialization. The relevance of knowledge about plant diseases in natural ecosystems to genetic disease control in agroecosystems is emphasized.

01 Jan 1986
TL;DR: Population blend, a form of population engineering which places compatible genotype together, uses conventional breeding methods and techniques that allow for the increase of genetic variability by intermating selected groups and assembling compatible genotypes.
Abstract: The semi-arid Bugesera, Gisaka-Migongo region of Rwanda is plagued by insects, crop diseases, drought and poor soil. To increase food production and protein intake in this region, drought-tolerant cowpea varieties were introduced. Because most cowpea lines (Vigna unguiculate) were highly susceptible to cowpea scab disease (Elsinoe phaseoli Jenkins) and ascochyta blight (Ascochyta phaseolorum Sacc.), the major objective of cowpea breeding was to develop populations resistant to these and other major diseases. This was achieved in 1983 by using a modified version of Jensen's (1970) dialled selective cyclic mating method in combination with other methods. Blend populations with greater yield stability, disease resistance, and adaptability were produced. Population blend, a form of population engineering which places compatible genotypes together, uses conventional breeding methods and techniques that allow for the increase of genetic variability by intermating selected groups and assembling compatible genotypes. At any cycle or generation, superior genotypes can be added to the population and the mating system, or inferior genotypes can be eliminated. Most significantly, heavy natural and artificial selection pressures are applied, thus eliminating high numbers of inferior genotypes.

Patent
28 Jan 1986
TL;DR: A female asparagus plant denoted No. 56 and "Donna" developed in a program of extensive growth and selection, in turn selected from a field of the variety Mary Washington, because of its vigorous plant growth and ability to transmit disease resistance including resistance to rust (Puccinia asparagi) good field tolerance to root rot (Fusarium oxysporum) and crown rot (fusarium moniliforme) increasing production, the plant having the characteristics of a largest stalk of 31 mm diameter, number of stalks 24, and stalk vigor index
Abstract: A female asparagus plant denoted No. 56 and "Donna" developed in a program of extensive growth and selection, in turn selected from a field of the variety Mary Washington, because of its vigorous plant growth and ability to transmit disease resistance including resistance to rust (Puccinia asparagi) good field tolerance to root rot (Fusarium oxysporum) and crown rot (F. moniliforme) increasing production, the plant having the characteristics of a largest stalk of 31 mm diameter, number of stalks 24, and stalk vigor index (Number X (Mean diameter)2) of 21,313.




01 Jan 1986
TL;DR: It is inferred that L-CTKs might be indirectly related to the resistant genes, while H- CTKs to the genes controlling the symptom-expression, however, the mechanism of which remains to further investigation.
Abstract: The present paper deals with the different effects of the endogenous cytokinins, namely, those of lower R_1 values (L-CTKs) (R_f=0.0—0.5) and those of higher R_1 values (H-CTKs) (R_f=0.5—1.0) on the disease resistance and symptom expression of tomato plants after infection by TMV-T. After the infection of TMV-T, H-CTKs in susceptible tomato cultivars were increased markedly, but not in the resistant cultivars. However, the level of L-CTKs was much higher in resistant cvs than in susceptible ones. Such difference was considered to be used as one of the criteria for the preliminary determination of disease resistance of tomato plants to TMV-T. The application of prepared H-CTKs onto the healthy tomato leaves induced a series of symptoms, including "green islands", while the application of TMV tolerance inducer NS-83 caused a raise of the level of L-CTKs to that of resistant cnltivars. It is, therefore, inferred that L-CTKs might be indirectly related to the resistant genes, while H-CTKs to the genes controlling the symptom-expression, however, the mechanism of which remains to further investigation.

Book ChapterDOI
01 Jan 1986
TL;DR: Improved disease and pest resistance in plants is one of the more lucrative possibilities for utilization of recombinant DNA technology because of recent increases in knowledge of how naturally occurring disease resistance functions and to the fact that modulation of resistance expression is often controlled by single dominant alleles in plants.
Abstract: Improved disease and pest resistance in plants is one of the more lucrative possibilities for utilization of recombinant DNA technology. This optimism results from recent increases in our knowledge of how naturally occurring disease resistance functions and to the fact that modulation of resistance expression is often controlled by single dominant alleles in plants. Historically these disease resistance genes could only be transferred between plants that can be intercrossed. Recently, however, technologies have been developed which permit gene transfer between taxonomically diverse plants by (i) protoplast fusion and selection of somatic recombinants or (ii) introduction of specific DNA sequence into plants via Ti plasmid vectors. Disease resistance genes have not yet been isolated to permit full utilization of these technologies, but several rationales are being pursued in attempts to molecularly clone them. These include the use of transposable elements to tag resistance gene sequences, the screening of c-DNA libraries from inoculated plants and the use of specific pathogen metabolites called elicitors as probes to detect the protein products of plant disease resistance genes.