Leptosphaeria maculans the ascogenous state of Phoma lingam

Smith, H. C.; Sutton, B. C.

doi:10.1016/s0007-1536(64)80049-8

Cited by 30 publications

(18 citation statements)

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“…Two isolates of L. maculans , A290v genotype (Mat1‐2, AvrLm1 , avrLm2 , avrLm3 , avrLm4 , AvrLm5 , AvrLm6 , AvrLm7 , AvrLm8 , avrLm9 , AvrLm10 ) (Somda et al ., 1999) and P27d genotype (Mat1‐2, AvrLm1 , avrLm2 , avrLm3 , avrLm4 , AvrLm5 , AvrLm6 , AvrLm7 , avrLm9 , AvrLm10 ), were obtained from single ascospores isolated from diseased B. napus stubble collected in Le Rheu (France) according to the method described by Smith & Sutton (1964). Inoculum, consisting of suspensions of 10 7 conidia mL −1 , was obtained as described by De March et al .…”

Section: Methodsmentioning

confidence: 99%

Systemic growth of Leptosphaeria maculans from cotyledons to hypocotyls in oilseed rape: influence of number of infection sites, competitive growth and host polygenic resistance

et al. 2009

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The influence of competitive effects between two isolates, of the number of infection sites on cotyledons and of host polygenic resistance on the systemic growth of Leptosphaeria maculans , the cause of phoma stem canker in oilseed rape ( Brassica napus ), were investigated. Controlled-condition experiments were conducted with two oilseed rape doubled haploid lines, one susceptible and the other with a high level of polygenic resistance, inoculated via wounded cotyledons with conidial suspensions obtained from two isolates. Expression of cankers in plants was enhanced by exposing inoculated plants to low temperature (6 ° C) followed by warm temperature (20 ° C). The fungus was detected by PCR amplifications of three minisatellite markers in all stems with visible canker symptoms and also in the stems of 14 of the 59 plants without visible cankers on the hypocotyls. Disease severity increased with the number of infection sites on cotyledons: in one of the three replicate experiments, the mean external necrosis length on the hypocotyl ranged from 6·47 to 35·3 mm for one and eight infections sites on cotyledons, respectively. The probability of an isolate reaching the hypocotyl from inoculated cotyledons decreased with increasing competing inoculum load on cotyledons: for instance, for isolate A290v it decreased from 1 when inoculated alone to 0·28 when coinoculated with six drops of competing isolate P27d. Polygenic resistance significantly reduced disease incidence and severity. For instance, in one of the three replicate experiments, disease incidence ranged from more than 74% in susceptible plants to 16% in resistant ones, while mean external necrosis length was up to 35·3 and 6·5 mm on susceptible and on resistant plants, respectively. This study offers new possibilities for assessing levels of polygenic resistance to stem canker in B. napus and studying the aggressiveness of L. maculans isolates.

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Section: Methodsmentioning

confidence: 99%

Systemic growth of Leptosphaeria maculans from cotyledons to hypocotyls in oilseed rape: influence of number of infection sites, competitive growth and host polygenic resistance

et al. 2009

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“…They are produced in abundance within the pycnidium, and on culture medium they emerge to form pinkish masses. The size of the fungus is the same as in the literatur (Henderson 1918, Smith and Sutton 1964, Giessmann and Daebeler 1973. P. lingam was found in the seeds of white cabbage, cauliflower, red cabbage, swede and radish.…”

Section: Botrytis Cinerea Persmentioning

confidence: 94%

Seed-borne fungi on cruciferous cultivated plants in Finland and their importance in seedling raising

Tahvonen

1979

AFSci

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The seed-borne fungi of cabbage, swede, turnip, rape, turnip rape, radish and black radish and their importance in seedling raising have been examined in this study. The seed lots used in the study were on sale at seed merchants in Finland during the period 1968 —1976. Alternaria brassicicola (Schw.) Wiltshire was the most common pathogen, being more common on cabbage than on any of the other plant species. 91 % of the white cabbage and red cabbage seed lots were infected. The mean A. brassicicola contents of the infected seed lots were 29.5 % and 30.6 %. Plenodomus lingam (Tode ex Fr.) Höhnel occurred in 10 % of the white cabbage and 27 % of the red cabbage seed lots, the fungus content varying from 0.5 % to 14 %. The fungus was also found on cauliflower, swede and radish. Alternaria brassicae (Berk.) Sacc. was found in 4 % of the cabbage and in 31 % of the rape seed lots at fungus contents of 0.5—6.5 %. Alternaria raphani Groves & Skolko was found in 30 % of the radish and black radish seed lots at fungus contents of 0.5—8 %. The following fungi were also found on the seeds of Cruciferous plants: Pleospora herbarum (Pers.) Rabenh., Whetzelinia sclerotiorum (Lib) Korf & Dumont, Botrytis cinerea Pers., Ulocladium concortiale (Thum.) Simmons, Fusarium spp. and Rhizoctonia solani Kühn as well as 18 fungus genera and species either saprophytic or pathogenic to other plants. When the Alternaria brassicicola content of the seeds was 20 % it caused 10 % damping-off damage on the sand substrate. A similar level of damage occurred on the peat substrate when the fungus content reached 70 %. In addition to causing damping off and damaging the seedlings, the fungus also slowed-down seedling growth without apparently damaging them. When the seedlings were grown at a lower temperature the amount of damage caused by A. brassicicola was much less than that which occurred when a higher temperature was used. Plenodomus lingam caused as much damping-off as there were seeds infected with the fungi. Other seed-borne fungi had no importance in seedling raising. Sphagnum fuscum peat, which is used in Finland as a growth substrate, reduced the amount of damping-off caused by seed-borne fungi in comparison to disinfected substrates and prevented the spread of A. brassicicola and P. lingam from diseased to healthy seeds. Dressing the seeds with thiram proved to be very effective against A. brassicicola.

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“…Leptosphaeria maculans, teleomorph of Phoma lingam, is the causal agent of blackleg (Smith & Sutton, 1964), one of the most yield-limiting diseases of cruciferous crops. This disease has been of particular concern in France over the last 10 years because Brassica napus cultivars are susceptible or moderately resistant to L. maculans at both the seedling and adult plant stages.…”

Section: Introductionmentioning

confidence: 99%

**Morphology, pathogenicity and isozyme variation amongst French isolatesof Leptosphaeria maculans recovered from Brassica juncea cv. Picra**

Somda¹,

Renard

Brun³

1996

Plant Pathology

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The characteristics of 36 isolates of Leptosphaeria maculans originating from cv. Picra were investigated using cultural, pathogenicity and isozyme analyses in comparison with six known isolates of A‐ and B‐groups. Picra‐related isolates were similar to the three known B‐group isolates from Brassica napus using a cultural test. Two known B‐group isolates and 29 of the 36 Picra‐related isolates tested were aggressive on cv. Picra, whereas all the three known A‐group isolates were not. All the 42 isolates tested were aggressive onthe B. napus–B. juncea recombinant line MX and on B. napus cv. Westar. Phosphoglucose isomerase analysis showed two different patterns, separating A‐group known (fast band) from B‐group known isolates (slow band). All cv. Picra isolates displayed the slow band. Considerable differences in isoesterase patterns were found between known A‐ and B‐group isolates. Isolates recovered from cv. Picra displayed six different electrophoretic patterns, including that of the known B‐group isolates. Clusters of the 42 isolates, generated by UPGMA analysis based on similarity coefficients of electrophoretic types, matched the previous classification into A‐ and B‐groups, although two atypical Picra‐related isolates with a singular pattern clustered with the A‐group. The importance of these isolates for blackleg epidemiology and resistance breeding is discussed.

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Leptosphaeria maculans the ascogenous state of Phoma lingam

Cited by 30 publications

References 1 publication

Systemic growth of Leptosphaeria maculans from cotyledons to hypocotyls in oilseed rape: influence of number of infection sites, competitive growth and host polygenic resistance

Systemic growth of Leptosphaeria maculans from cotyledons to hypocotyls in oilseed rape: influence of number of infection sites, competitive growth and host polygenic resistance

Seed-borne fungi on cruciferous cultivated plants in Finland and their importance in seedling raising

**Morphology, pathogenicity and isozyme variation amongst French isolatesof Leptosphaeria maculans recovered from Brassica juncea cv. Picra**

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