STUDIES ON THE PARASITISM OF CLADOSPORIUM FULVUM

1967 ◽  
Vol 45 (11) ◽  
pp. 2125-2135
Author(s):  
Thomas Curren
Keyword(s):  
Nitrogen Nutrition ◽  
Chromatographic Study ◽  
Cladosporium Fulvum ◽  
Tomato Plants ◽  
Carbon And Nitrogen ◽  
Amino Compounds ◽  
Race 1 ◽  
Partial Deficiency ◽  
Susceptible Tomato ◽  
Reduced Light

A study was made of the carbon and nitrogen nutrition of races 7, 8, and 10 of Cladosporium fulvum, and an attempt was made to relate the findings to the differential pathogenicity of the races.Cysteine was found to exert a differential effect on the growth of two races of the pathogen. Race 1 was stimulated by concentrations inhibitory to race 6. C. fulvum was found to have a partial deficiency for thiamine. The sporulation of race 10 on susceptible tomato plants was heavier with alanine-grown cultures than with any other nutritional treatment. Altering the nitrogen nutrition of varieties Potentate (S) and V-121 (R) did not affect their differential reactions to race 1. A reduction in nitrogen feeding to Stirling Castle (R) increased its resistance to race 1.A chromatographic study was made of the changes in amino compounds and sugars in Potentate and V-121 after infection by races 1 and 6. The relation of the findings to the resistance of V-121 to race 1 is discussed.The resistance of Stirling Castle was investigated by comparing the amino compounds and sugars in leaves of healthy plants and plants infected by race 1 under optimal conditions and under reduced light, where the resistance breaks down. Chromatographic analyses showed a noticeable depletion of certain metabolites in plants infected under reduced light as compared with the amount of depletion, if any, in the controls.

Histological comparison of Cladosporium fulvum race 1 on immune, resistant, and susceptible tomato varieties

1976 ◽  
Vol 54 (3-4) ◽  
pp. 224-234 ◽  
Author(s):  
George Lazarovits ◽  
Verna J. Higgins
Keyword(s):  
Cell Damage ◽  
Starch Content ◽  
Leaf Tissue ◽  
Aerial Mycelium ◽  
Host Cells ◽  
Cladosporium Fulvum ◽  
Lesion Area ◽  
Race 1 ◽  
Histochemical Tests ◽  
Susceptible Tomato

Histological comparisons were carried out on three varieties of tomato, Potentate (Cf0), V-121 (Cf3), and Vinequeen (Cf2, Cf4), inoculated with race 1 of Cladosporium fulvum. Examination of leaves harvested at regular intervals indicated that under optimal conditions for disease development, spore germination and penetration were similar on the leaves of the three varieties. The susceptible Potentate became extensively colonized by intercellular mycelium, but relatively little visible damage occurred in the affected cells until sporulation was abundant. In V-121, resistance was expressed by slightly slower growth of the mycelium in the leaf tissue, but colonization was still extensive. Host cell damage became prominent just before the formation of aerial mycelium. Cells in the lesion area on V-121 became necrotic or showed various changes, including reduced starch content in the chloroplasts and the association of extracellular material with the cell walls. Histochemical tests indicated that polyphenols were present in the lesions. The mycelia in V-121 became highly vacuolated and sporulation was absent or greatly reduced. In the highly resistant (immune) Vinequeen variety, fungal development was restricted to a few cells in the mesophyll region. Host cells adjacent to and some distance from the fungus showed extensive deposition of material that was at least partly composed of callose.

scholarly journals Pseudomonas syringae pv. tomato Strains from New York Exhibit Virulence Attributes Intermediate Between Typical Race 0 and Race 1 Strains

Plant Disease ◽  
2017 ◽  
Vol 101 (8) ◽  
pp. 1442-1448 ◽  
Author(s):  
Christine M. Kraus ◽  
Carolina Mazo-Molina ◽  
Christine D. Smart ◽  
Gregory B. Martin
Keyword(s):  
New York ◽  
Pseudomonas Syringae ◽  
Host Immune System ◽  
Fresh Market ◽  
Tomato Plants ◽  
Persistent Problem ◽  
Population Sizes ◽  
Bacterial Speck Disease ◽  
Race 1 ◽  
Susceptible Tomato

Bacterial speck disease, caused by Pseudomonas syringae pv. tomato, is a persistent problem for fresh-market tomato growers in New York. Race 0 strains of this pathogen express either or both of the type III effectors AvrPto or AvrPtoB, which are recognized by tomato varieties expressing the Pto resistance gene. Pto encodes a protein kinase that activates the host immune system, thereby inhibiting bacterial multiplication and preventing disease development. Race 1 P. syringae pv. tomato strains do not express these effectors and are virulent on tomato whether or not the variety expresses Pto. Very few fresh-market tomato varieties have the Pto gene. We collected six P. syringae pv. tomato strains from naturally infected tomato plants across New York in 2015 and characterized them for their virulence and for the presence of specific effectors. In experiments conducted in the greenhouse, all strains reached population sizes in Pto-expressing tomato leaves that were intermediate between typical race 0 and race 1 strains. This phenotype has not been observed previously and suggests that the strains are recognized by Pto but such recognition is compromised by another P. syringae pv. tomato factor. The strains were found to encode avrPto, which is transcribed and translated. They also express avrPtoB although, as reported for other P. syringae pv. tomato strains, protein expression for this effector was not detectable. Deletion of avrPto from a representative New York strain allowed it to reach high populations in Pto-expressing tomato varieties, without compromising its virulence on susceptible tomato plants. Collectively, our data suggest that introgression of the Pto gene into fresh-market tomato varieties could enhance protection against extant P. syringae pv. tomato strains.

The Influence of Carbon and Nitrogen Nutrition on Growth and Sterolinduced Sexuality of Pythium sp. PRL 2142

Mycologia ◽  
1969 ◽  
Vol 61 (6) ◽  
pp. 1096 ◽  
Author(s):  
J. J. Child ◽  
G. Defago ◽  
R. H. Haskins
Keyword(s):  
Nitrogen Nutrition ◽  
Carbon And Nitrogen

scholarly journals Multiyear Evaluation of the Durability of the Resistance Conferred by Ma and RMia Genes to Meloidogyne incognita in Prunus Under Controlled Conditions

2013 ◽  
Vol 103 (8) ◽  
pp. 833-840 ◽  
Author(s):  
Samira Khallouk ◽  
Roger Voisin ◽  
Ulysse Portier ◽  
Joël Polidori ◽  
Cyril Van Ghelder ◽  
...  
Keyword(s):  
Meloidogyne Incognita ◽  
Economic Losses ◽  
R Gene ◽  
R Genes ◽  
Tomato Plants ◽  
Controlled Conditions ◽  
Meloidogyne Spp ◽  
Resistance Breakdown ◽  
Susceptible Tomato ◽  
Prunus Spp

Root-knot nematodes (RKNs) (Meloidogyne spp.) are highly polyphagous pests that parasitize Prunus crops in Mediterranean climates. Breeding for RKN-resistant Prunus cultivars, as an alternative to the now-banned use of nematicides, is a real challenge, because the perennial nature of these trees increases the risk of resistance breakdown. The Ma plum resistance (R) gene, with a complete spectrum, and the RMia peach R gene, with a more restricted spectrum, both provide total control of Meloidogyne incognita, the model parthenogenetic species of the genus and the most important RKN in terms of economic losses. We investigated the durability of the resistance to this nematode conferred by these genes, comparing the results obtained with those for the tomato Mi-1 reference gene. In multiyear experiments, we applied a high and continuous nematode inoculum pressure by cultivating nematode-infested susceptible tomato plants with either Prunus accessions carrying Ma or RMia R genes, or with resistant tomato plants carrying the Mi-1 gene. Suitable conditions for Prunus development were achieved by carrying out the studies in a glasshouse, in controlled conditions allowing a short winter leaf fall and dormancy. We first assessed the plum accession ‘P.2175’, which is heterozygous for the Ma gene, in two successive 2-year evaluations, for resistance to two M. incognita isolates. Whatever the isolate used, no nematodes reproducing on P.2175 were detected, whereas galls and nematodes reproducing on tomato plants carrying Mi-1 were observed. In a second experiment with the most aggressive isolate, interspecific full-sib material (P.2175 × [‘Garfi’ almond × ‘Nemared’ peach]), carrying either Ma or RMia (from Nemared) or both (in the heterozygous state) or neither of these genes, was evaluated for 4 years. No virulent nematodes developed on Prunus spp. carrying R genes, whereas galling and virulent individuals were observed on Mi-1-resistant tomato plants. Thus, the resistance to M. incognita conferred by Ma in Prunus material in both a pure-plum and an interspecific genetic background, or by RMia in an interspecific background, appears to be durable, highlighting the value of these two genes for the creation of Prunus rootstock material.

Occurrence of Pseudomonas syringae pv. Tomato race 1 in Italy on Pto Gene-Bearing Tomato Plants

1996 ◽  
Vol 144 (9-10) ◽  
pp. 437-440 ◽  
Author(s):  
R. Buonaurio ◽  
V. M. Stravato ◽  
C. Cappelli
Keyword(s):  
Pseudomonas Syringae ◽  
Tomato Plants ◽  
Race 1
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