Scald Disease Research Articles

Responses of Two‐, Three‐, and Four‐Component Barley Mixtures to a Variable Pathogen Population

Cultivar mixtures have been suggested as a means to control foliar diseases in small grains, but little information is available on how to choose component lines for use in cultivar mixtures. This 3‐yr study tested the ability of two‐, three‐, and four‐component barley (Hordeum vulgare L.) mixtures to control scald disease caused by the fungus Rhynchosporium secalis (Oud) Davis. The mixtures were composed of lines from the parents of Composite Cross II (CCII), a naturally evolving barley population, and from the 45th generation of CCII. The lines differed in resistance or susceptibility to four diagnostic pathotypes of the scald fungus. The results indicate that some barley lines, when grown in mixture, interact to reduce or increase incidence of scald. Lines from the 45th generation of CCII interacted to reduce incidence of scald more often than parental lines of CCII. The largest reductions in sca.ld were observed in mixtures containing lines that were susceptible when grown in pure stand. Genes for resistance to R. secalis were deployed singly in mixtures and also pyramided into single lines. Differences between these methods of gene deployment were nonsignificant statistically. Some two‐component mixtures made up of one resistant and one susceptible line and some three‐component mixtures made up of two susceptible components and one resistant component had no more disease than the resistant component of the mixture grown alone. The results were interpreted as indicating that cultivar mixtures offer an effective strategy for controlling damage due to R. secalis.

Evidence that an albicidin-like phytotoxin induces chlorosis in sugarcane leaf scald disease by blocking plastid DNA replication

Albicidin is the best characterized member of a family of antibiotics produced by Xanthomonas albilineans which inhibit prokaryote DNA replication. Results with mutants of X. albilineans have suggested that a toxin biosynthetically closely related to albicidin causes the blocked chloroplast differentiation which leads to chlorosis in sugarcane leaf scald. This paper describes effects of albicidin on sugarcane plants and plastids. Albicidin was detected in white leaf stripes surrounding invaded vascular bundles in diseased plants. Time-course and dose-response data showed that in isolated sugarcane proplastids inhibition of DNA replication is a primary action of albicidin, followed by partial inhibition of protein synthesis. Albicidin caused permanent white chlorosis of shoots re-differentiating from treated callus, but did not cause chlorosis when injected into the spindles of intact sugarcane plants. These results coupled with earlier ultrastructural and mutant studies strongly support the hypothesis that a member of the albicidin family of compounds produced by X. albilineans in invaded xylem causes chlorosis in sugarcane leaf scald disease by preferentially inhibiting plastid DNA replication, resulting in blocked chloroplast differentiation.

Correlation between albicidin production and chlorosis induction by Xanthomonas albilineans, the sugarcane leaf scald pathogen

Chlorosis of emerging leaves of sugarcane plants invaded by Xanthomonas albilineans results from blocked chloroplast differentiation, apparently caused by a phytotoxin. Chlorosis inducing isolates of X. albilineans produce a family of antimicrobial compounds, including albicidin which inhibits prokaryote DNA replication. The objective of this study was to determine whether albicidin, or a related compound produced in diseased plants, causes chlorosis of uninvaded tissues characteristic of sugarcane leaf scald disease. Spontaneous loss of albicidin production occurs at a high rate but does not involve extrachromosomal genetic elements. Results with mutants and revertants in albicidin production show a close correlation between albicidin production and ability to cause chlorosis, strongly suggesting that the chlorosis inducing toxin is biosynthetically closely related to albicidin. Plasmid pJB4JI is transmitted at high frequency from Escherichia coli to X. albilineans, where it is stably maintained as a conjugative plasmid, providing a basis for further genetic analysis of X. albilineans using well-characterized P1 group plasmids.

In vitro reactions of sugarcane (Saccharum SP.) plantlets inoculated with 2 strains of Xanthomonas albilineans (Ashby) Dowson

The symptoms of the leaf scald disease can be reproduced in vitro through the inoculation of sugarcane tissue culture plantlets. The pathogen is detected in the inoculated plantlet and is maintained at the surface of the base of the plantlets grown in vitro. Two strains of X. albilineans belonging to different serovars and lysovars reacted like pathotypes. The importance of the plant incubation temperature is clearly demonstrated. Further, in vitro the disease goes through the same phase of latency as in the field.

Serological and Lysotypical Variability of Xanthomonas albilineans (Ashby) Dowson, Causal Agent of Sugarcane Leaf Scald Disease

AbstractThe serological and lysotypical properties of 28 strains of X. albilineans originating from different geographic zones were analysed. Using the indirect immunofluorescence technique with 3 anti X. albilineans immunsera, the existence of three serovars was shown. The isolation of lytic bacteriophages from the soil enabled us to classify the bacterial strains into 6 lysovars. A correspondance between serovars and lysovars was revealed. These results show a variability of the X. albilineans species, and enable an analysis of the structure of its populations to be proposed, especially that of Tropical Africa.

Stereospecific synthesis of rhynchosporosides, a family of fungal metabolites causing scald disease in barley and other grasses

Stereospecific synthesis of rhynchosporosides, a family of fungal metabolites causing scald disease in barley and other grasses

Dry-Season Survival of Rhynchosporium oryzae in Rice Leaves and Stored Seeds

Rhynchosporium oryzae Hashioka & Yokogi causes leaf scald disease in many rice varieties in West Africa (1, 7, 8). Preliminary data suggest that R. oryzae does not survive in soil (6). A secondary host of R. oryzae has not been identified at the University Farm (UF), University of Liberia (unpublished data). Rhyncho? sporium oryzae is seedborne and rice seeds might be important in spreading leaf scald disease (4, 6). Very little is known about dry-season survival of R. oryzae in lowland tropical ecosystems. The objective of this study was to determine if R. oryzae can survive in rice leaves and seeds during the dry season (November to April) in Liberia. After harvest on October 18, 1982, all rice plants ofthe variety Lac 23 in three of several 4.5 m x 2.4 m plots at UF were either left standing, placed on soil surface, or buried 10 cm deep in soil, respectively. In October, 1983, after harvest, plants in one plot were left standing. Sets of 25 leaves with leaf scald symptoms from another plot were placed on the surface of the soil and held in place at the proximal end with wooden stakes. Other sets of 25 leaves with leaf scald symptoms from a third plot were placed between nylon mesh and buried 10 cm deep in soil. Ten leaves were retrieved periodically from each ofthe three treatments for each year and kept separate. Five 4 mm diam disks per leaf from scald lesions for each ofthe 10 leaves from each treatment were surface-sterilized

Leaf Scald Disease of Rice in Karnataka, India

Leaf Scald Disease of Rice in Karnataka, India

Effects of common stubble treatments and sowing sequences on scald disease (Rhynchosporium secalis) in barley crops

Scald disease was absent in barley (Hordeurn vulgare L. cv. Clipper) grown in field plots where nonhosts of Rhynchosporiurn secalis had been grown successively, and from which living hosts of R. secalis had been absent for at least 18 months. In another field experiment, the burning or grazing of barley stubble containing R. secalis reduced the amount of scald disease of barley sown subsequently in the same plots, but only at early and not at later plant growth stages. Application of the fungicide maneb to burnt stubble gave no control additional to that given by burning. However, inoculation of field plots of barley at seedling emergence with differing amounts of R. secalis inoculum produced a corresponding range of levels of scald disease at both early and late growth stages.

Survival over summer of Rhynchosporium secalis in host debris in the field

The ability of Rhynchosporiurn secalis to survive over summer in plant debris and to produce inoculum for scald disease development in barley crops was investigated. Viable inoculum was recovered from dead host leaves (Hordeurn vulgare and H. leporinurn) kept on soil surfaces in the field for up to 30 weeks after crop maturity in a range of South Australian barley-growing environments. When infected leaves were suspended 30 cm above soil surfaces, the fungus survived for up to 37 weeks. When buried 6 cm below soil surfaces, the fungus survived for 20 weeks. Following an initial decline in infectivity of inoculum over summer, infectivity increased during autumn to levels similar to those obtained at the start of the trials.

The Relation of Blocked Chloroplast Differentiation to Sugarcane Leaf Scald Disease

Etude ultrastructurale de la localisation du pathogene dans les tissus de l'hote et de son role sur le blocage de differenciation des chloroplastes

Efficacy of some fungicides against leaf scald disease of rice

Abstract In field evaluation trials nine test fungicides significantly reduced the incidence and severity of leaf scald disease of rice caused by Monographella albescens (Thum)(Rhynchosporium oryzae Hashioka & Yokogi) and increased the yield. Of these fungicides Difolatan (captafol) and Dithane M‐45 (mancozeb) were more effective than the other fungicides. Relatively longer persistence of fungicidal residues was detected in three test chemicals, i.e., Blitox‐50 (copper oxychloride), Difolatan and Dithane M‐45. Amount of rainfall appeared to be a main weather factor in influencing persistence of a fungicide.

Sources of Resistance to Leaf Scald Disease

Sources of Resistance to Leaf Scald Disease

Distribution and Severity of Plum Leaf Scald Disease in Brazil

Distribution and Severity of Plum Leaf Scald Disease in Brazil

Field Loss Due to Leaf Scald Disease

Field Loss Due to Leaf Scald Disease

Leaf Scald Disease of Rice in Andhra Pradesh

Leaf Scald Disease of Rice in Andhra Pradesh

Etiology of Phony Peach and Plum Leaf Scald Diseases

Etiology of Phony Peach and Plum Leaf Scald Diseases

Leaf Scald Disease of Rice in Sierra Leone

Leaf Scald Disease of Rice in Sierra Leone

Rhynchosporoside binding proteins of barley

FEBS LettersVolume 96, Issue 1 p. 34-36 Full-length articleFree Access Rhynchosporoside binding proteins of barley J.Pio Beltran, J.Pio Beltran Department of Plant Pathology, Johnson Hall of Life Science, Montana State University, Bozeman, MT 59717, USASearch for more papers by this authorGary A. Strobel, Corresponding Author Gary A. Strobel Department of Plant Pathology, Johnson Hall of Life Science, Montana State University, Bozeman, MT 59717, USAAddress correspondence to: G.A. StrobelSearch for more papers by this author J.Pio Beltran, J.Pio Beltran Department of Plant Pathology, Johnson Hall of Life Science, Montana State University, Bozeman, MT 59717, USASearch for more papers by this authorGary A. Strobel, Corresponding Author Gary A. Strobel Department of Plant Pathology, Johnson Hall of Life Science, Montana State University, Bozeman, MT 59717, USAAddress correspondence to: G.A. StrobelSearch for more papers by this author First published: December 01, 1978 https://doi.org/10.1016/0014-5793(78)81056-4Citations: 7AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article. References 1 C.C. Ryan, C.J. Grivell, Aust. J. Plant Physiol., 1, (1974), 313– 317. 2 P. Jones, P.G. Ayres, Physiol. Plant Pathol., 4, (1974), 229– 233. 3 P. Jones, P.G. Ayres, Physiol. Plant Pathol., 2, (1972), 383– 392. 4 E.N. Ayesu-Offei, B.G. Clare, Aust. J. Biol. Sci., 23, (1970), 299– 307. 5 P. Auriol, G. Strobel, J.P. Beltran, G. Gray, Proc. Natl. Acad. Sci. USA, (1978), in press 6 J.P. Beltran, G.A. Strobel, Plant Physiol., (1978), in press 7 G.A. Strobel, J. Biol. Chem., 248, (1973), 1321– 1328. 8 N. Fornstedt, J. Porath, FEBS Lett., 57, (1975), 187– 191. 9 O.H. Lowry, N.J. Rosebrough, A.L. Farr, R.J. Randall, J. Biol. Chem., 193, (1951), 265– 275. 10 J. Waddell, J. Lab. Clin. Med., 48, (1956), 311– 314. 11 B.J. Davis, Ann. NY Acad. Sci., 121, (1965), 404– 427. 12 K. Weber, M. Osborn, J. Biol. Chem., 244, (1969), 4406– 4412. Citing Literature Volume96, Issue1December 01, 1978Pages 34-36 ReferencesRelatedInformation

Rhynchosporoside, a host-selective toxin produced by Rhynchosporium secalis , the causal agent of scald disease of barley

Rhynchosporoside, a phytotoxic compound, has been isolated from cultures of Rhynchosporium secalis, the causal agent of scald disease of barley. The toxin is a cello-bioside of 1,2-propanediol. The compound may play some role in symptom expression because it was isolated from diseased plants in concentrations similar to those that could cause symptoms in toxin-treated plants. The toxin causes leaf tip and marginal necrosis and subsequent chlorosis of the entire leaf. The toxin affects only certain cultivars and lines of barley and rye; however, it also affects certain nonhosts of R. secalis. The genetic factor controlling host resistance to the fungus is not identical to that controlling insensitivity to the toxin.