Death Of Infected Plants Research Articles

First report of Fusarium meridionale causing canker in hop plants

Fusarium canker in hop is caused by Fusarium spp. Its symptoms are wilting, cankers in the crown, foliar necrosis and death of infected plants. Morphological and molecular observations were consistent with those previously reported for F. meridionale. Koch’s postulates were fulfilled. To the best of our knowledge, this is the first report of F. meridionale causing Fusarium canker in hop.

Identification of moth bean plant susceptibility and variability factors to Macrophomina phaseolina and pathogencity assay for the root rot in India

Root rot of moth bean (Vigna aconitifolia (Jacq.) Marechal, caused by Macrophomina phaseolina is quite prevalent in the moth bean growing areas of Rajasthan and Uttar Pradesh state. The pathogen infects the moth bean plant at all ages and it results in a huge loss. The present study was undertaken to study the development of necrosis and occurrence of sclerotia and pycnidiospores in order to study the pathogenic variability of M. phaseolina and to determine the morphological and pathogenic variability and their correlation with the age of Vigna plant. The isolates showed variation in mycelia growth and sporulation. Variability is the very basis of survival of the pathogen and it was observed that the sclerotia were produced in collar regions of 15, 30, 45 and 60 day old plants but symptoms were found to be more prevalent at maturity stage as compared to initial, seedling and flowering stages. Data reported here indicates that the sclerotia contribute to death of infected plants. It was observed that maximum disease incidence in plants occurs at maturity stage and susceptibility of plants to Macrophomina increased with age.

“Flavescence dorée” impacts growth, productivity and ultrastructure of Vitis vinifera plants in Portuguese “Vinhos Verdes” region

“Flavescence dorée” (FD) is a quarantine disease associated with the presence of a phytoplasma transmitted by the insect vector Scaphoideus titanus. This disease affects grapevines and is of a great concern to the stability and sustainability of the wine industry, due to the harvest losses and death of infected plants. In Portugal, FD has seriously affected the “Vinhos Verdes” region, but so far the research on this topic is very limited. The current study confirmed that the FD phytoplasma strain involved in the outbreak in Vitis vinifera cv. Loureiro belongs to the 16SrV-D subgroup and shows very low RFLP variability in the tuf and secY genes. Transmission electron microscopy analysis of leaf midribs from infected grapevine plants revealed that the shape and structure of phloem cells were altered, presenting collapsed cells, callose accumulation in sieve plates and lipid accumulation in chloroplasts of phloem parenchyma cells. Moreover, data from two subsequent years showed that FD presence was associated with an average delay of 10 to 15 days on the time to visible inflorescences and to veraison, compared to healthy plants. At veraison, FD also lead to a significant decrease in the budburst percentage (7% to 12%), fertility index (35% in 2015), leaf area (56% to 63%), and chlorophyll content (18% to 35% lower SPAD values). Hence, infected plants showed a drastic reduction in the yield, corresponding to a decrease between 51% and 92% compared to healthy plants, which mostly resulted from a lower number of bunches (63% to 92% less), but also a decreased bunch weight (35% lower in 2015). Concerning berry quality, there were no significant differences in terms of total soluble solids and titrable acidity in both years. Here, this study concluded that the FD infection delays the grapevine development and leads to drastic production losses, which may be partly linked to the ultrastructural modifications observed in the phloem cells of infected plants.

Recording the first white mold disease Sclerotinia sclerotiorum on ornamental plants Alrannkil Ranunculus asiaticus in Iraq and effectiveness of the fungus Trichoderma viride and Pseudomonas aeruginosa bacteria in inhibition in vitro.

Showed isolation results from plants Alrannkil planted in one of the greenhouses belonging to the Department of Horticulture - Faculty of Agriculture, University of Baghdad, which showed symptoms of yellowing and wilting leaves and rot loose down the stems of flowering and death of infected plants was accompanied by those symptoms, there are objects of stone small black color diameter 1 - 6 mm that the pathogen is a fungus Sclerotinia sclerotiorum. Pathogenicity tests have proven the ability to isolate the fungus S. sclerotiorum plants Alrannkil age of 30 days under the conditions of the plastic house plants Alrannkil by injury and severity of the injury was 100% and 87.5% on the relay. It was obtained isolation of the fungus Trichoderma viride as a result of insulation from stone-fungal objects and personalize this isolation based on Cultural and Morphological traits and molecular diagnosis of technology using PCR. Achieved isolation T. viride hottest against fungus S. sclerotiorum on culture media PDA under laboratory conditions has been the degree of antagonism 2 and the isolation of the bacteria Pseudomonas aeruginosa achieved over the center Zorai PDA ratio under laboratory conditions inhibition of 83.62%. The test showed the effect of each of the fungus Results T. viride and P. aeruginosa bacteria in the emergence of fruiting bodies of the stone objects of the fungus S. sclerotiorum in the laboratory when continuous lighting and a temperature of 15 ° C reduction was significant for the number of fruiting bodies formed conditions, amounting to 0.20 and 0.83 fruit body / stone body in relation to the treatment of comparative 1:58 body My fruit body / stone body.

Recent occurrence of Fusarium wilt caused byFusarium oxysporumon marjoram in Argentina

In spring 2006, marjoram (Origanum vulgare) plants were found decayed and collapsed in Cordoba Province, in Argentina. Disease symptoms consisted of wilting, foliar necrosis, vascular discoloration, and death of infected plants. Several fungal isolates were obtained and identified as Fusarium oxysporum. Koch’s postulates were completed. This appears to be the first record of a recent occurrence of Fusarium wilt of marjoram caused by this pathogen in Argentina.

Transformation of the ryegrass endophyte Neotyphodium lolii can alter its in planta mycelial morphology

The fungus Neotyphodium lolii grows in the intercellular spaces of perennial ryegrass as a mutualistic endosymbiont. One of the benefits it conveys to the plant is the production of alkaloids toxic to herbivores. We wanted to determine in planta expression patterns of the N. lolii 3-hydroxy-3-methylglutaryl-CoA reductase (HMG CoA reductase) gene, believed to be involved in the synthesis of two of these alkaloid toxins, lolitrem B and ergovaline. We transformed the N. lolii strain Lp19 with plasmids, in which DNA fragments upstream of the open reading frame of the N. lolii HMG CoA reductase gene controlled expression of the GUS ( gusA; Escherichia coli β-glucuronidase) reporter gene. In exponentially growing cultures, the GUS gene was not expressed if the length of upstream sequence was less than 400 bp, and >1100 bp were required for maximum expression. When reintroduced into ryegrass plants, transformants often showed highly increased hyphal branching compared to the wild-type parent strain, although in culture their growth kinetics and morphology were indistinguishable from that of the wild-type. Deterioration of hyphae and the hypha–plant interface occurred and in one transformant reduced tillering (formation of new plants, referred to in agronomy as tillers) and death of infected plants. We found no evidence that these abnormalities were caused by interference of the construct with the function of the native gene, as judged by analysis of the site of integration of the promoter-GUS cassette, expression of the native gene and lolitrem B and ergovaline levels in infected plants. However, there was some correlation between GUS expression and the degree of hyphal branching, suggesting that high levels of β-glucuronidase may disturb the symbiotic interaction. Levels of another alkaloid, peramine, were also not significantly affected by transformation. In previous studies increased in planta branching of the endophyte has been shown to be associated with a severe reduction of alkaloid production. Our results show that a plant–endophyte association in which increased branching occurs is still able to produce alkaloids.

Genetic parameters and correlations of collar rot resistance with important biochemical and yield traits in opium poppy (Papaver somniferum L.)

Collar rot, caused by Rhizoctonia solani Kühn, is one of the most severe fungal diseases of opium poppy. In this study, heritability, genetic advance and correlation for 10 agronomic, 1 physiological, 3 biochemical and 1 chemical traits with disease severity index (DSI) for collar rot were assessed in 35 accessions of opium poppy. Most of the economically important characters, like seed and capsule straw yield per plant, oil and protein content of seeds, peroxidase activity in leaves, morphine content of capsule straw and DSI for collar rot showed high heritability as well as genetic advance. Highly significant negative correlation between DSI and seed yield clearly shows that as the disease progresses in plants, seed yield declines, chiefly due to premature death of infected plants as well as low seed and capsule setting in the survived population of susceptible plants. Similarly, a highly significant negative correlation between peroxidase activity and DSI indicated that marker-assisted selection of disease-resistant plants based on high peroxidase activity would be effective and survived susceptible plants could be removed from the population to stop further spread.

In vitro testing of strawberry resistance to Verticillium dahliae and Phytophthora cactorum

The effects of culture filtrates and homogenates of Verticillium dahliae and Phytophthora cactorum on in vitro growth and development of strawberry shoots of cvs. Elsanta, Real and Senga Sengana were investigated. The filtrates of fungal cultures as well as filtrates of homogenated mycelia did not affect strawberry shoot growth and development, whereas inoculation with mycelia of V. dahliae and P. cactorum resulted in leaf yellowing, growth inhibition, inhibition of root formation, and after several days, the death of infected plants. However, fungal growth on the media that were used was irregular and the infection rate of individual plants was very variable. Mycelial homogenates affected growth and development of strawberry shoots in a similar way to that of an intact mycelium. Because the homogenate was distributed evenly in the culturing medium, the effect was uniform and thus possible to quantitate. It was also possible to differentiate a pathogen’s inoculum potential by adequate dilution of the homogenate. The best effect was obtained with V. dahliae. Fungal homogenate inhibited root formation and shoot growth, caused leaf necrosis and death of the plants after 7–8 weeks. The reaction of the cultivars tested was similar to their sensitivity to verticillium wilt in the field. P. cactorum affected in vitro strawberry shoot growth and development in a similar way to V. dahliae, but the effect was not cultivar-dependent. Preliminary tests showed that the method developed is useful for selection of somaclonal variants resistant/tolerant to infection with these pathogens.

Productivity and persistence of prairie grass (Bromus willdenowii Kunth)

AbstractA field trial measured effects of the head smut fungus Ustilago bullata Berk, on forage productivity of prairie grass (Bromus willdenowii Kunth). Simulated swards containing different proportions of U. bullata infected and non infected plants were established in the autumn, and sward and plant parameters were measured over the following 15 months. Total herbage produced from swards containing only non‐infected plants was 27.3 t ha−1, while that from totally infected swards was 14.6 t ha−1. Infected plants produced fewer and lighter tillers than non‐infected plants when both were growing together in swards. Almost all the U. bullata infected plants died during an epidemic of bacterial wilt disease (caused by Xanthomonas campestris pv. graminis (Egli, Goto and Schmidt) Dye), while most of the‘non‐infected plants survived. The deleterious effects of U. bullata on individual plant productivity affected sward productivity only when the proportion of infected plants in swards was greater than 50%. Plants not infected with U. bullata compensated for low productivity and death of infected plants by producing large numbers of tillers.

Populations of Pseudomonas solanacearum biovar 3 in naturally infested soil

Populations of Pseudomonas solanacearum biovar 3 were monitored in a clay loam soil sampled from the root zone of infected tomato plants during 1978, 1979 and 1980. Soil numbers increased during symptom development and declined with the death of infected plants. The decline in population size in the soil was continuous where no cover crop was planted between the autumn and spring crops. This decline in population size was interrupted, however, following the planting of an oats cover crop numbers decreased with the ploughing under of the oats. Rainfall was associated with high soil numbers but soil temperature did not appear to directly affect population size. Soil populations in the root zone of susceptible tomato plants cultivar Floradel reached a maximum 1000-fold greater than in soil from the root zone of a resistant line. P. solanacearum survived in bare fallow soil for 21 months. Tomatoes planted 2 months later wilted rapidly.