Brassica napus plants infected by Leptosphaeria maculans after the third to fifth leaf growth stage in south-eastern Australia do not develop blackleg stem canker

Marcroft, S. J.; Sosnowski, Mark; Scott, Eileen S.; Ramsey, M. D.; Salisbury, P. A.; Howlett, Barbara J.

doi:10.1007/s10658-005-1050-1

Cited by 19 publications

(8 citation statements)

References 11 publications

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“…However, it did influence the severity of leaf spot and cankers in the resulting epidemics (Figures 2 and 3). These results are consistent with observations that early season infections lead to canker development (Marcroft et al., 2005) and that ascospore loads impact blackleg severity (Wherrett et al., 2004). Reducing ascospore loads is desirable, because in field experiments over three cropping seasons, canola pod number and seed yield declined linearly as blackleg severity increased (Hwang et al., 2016).…”

Section: Discussionmentioning

confidence: 99%

Spatio‐temporal connectivity and host resistance influence evolutionary and epidemiological dynamics of the canola pathogen Leptosphaeria maculans

Bousset

Sprague

Thrall

et al. 2018

Evolutionary Applications

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Genetic, physiological and physical homogenization of agricultural landscapes creates ideal environments for plant pathogens to proliferate and rapidly evolve. Thus, a critical challenge in plant pathology and epidemiology is to design durable and effective strategies to protect cropping systems from damage caused by pathogens. Theoretical studies suggest that spatio‐temporal variation in the diversity and distribution of resistant hosts across agricultural landscapes may have strong effects on the epidemiology and evolutionary potential of crop pathogens. However, we lack empirical tests of spatio‐temporal deployment of host resistance to pathogens can be best used to manage disease epidemics and disrupt pathogen evolutionary dynamics in real‐world systems. In a field experiment, we simulated how differences in Brassica napus resistance deployment strategies and landscape connectivity influence epidemic severity and Leptosphaeria maculans pathogen population composition. Host plant resistance, spatio‐temporal connectivity [stubble loads], and genetic connectivity of the inoculum source [composition of canola stubble mixtures] jointly impacted epidemiology (disease severity) and pathogen evolution (population composition). Changes in population composition were consistent with directional selection for the ability to infect the host (infectivity), leading to changes in pathotype (multilocus phenotypes) and infectivity frequencies. We repeatedly observed decreases in the frequency of unnecessary infectivity, suggesting that carrying multiple infectivity genes is costly for the pathogen. From an applied perspective, our results indicate that varying resistance genes in space and time can be used to help control disease, even when resistance has already been overcome. Furthermore, our approach extends our ability to test not only for the efficacy of host varieties in a given year, but also for durability over multiple cropping seasons, given variation in the combination of resistance genes deployed.

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Section: Discussionmentioning

confidence: 99%

Spatio‐temporal connectivity and host resistance influence evolutionary and epidemiological dynamics of the canola pathogen Leptosphaeria maculans

Bousset

Sprague

Thrall

et al. 2018

Evolutionary Applications

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“…Infections on the earliest leaves may not contribute much to stem base canker epidemics if these leaves senesce before the pathogen has grown into the stem (Hammond and Lewis 1986), while infections on the latest leaves do not result in stem base cankers Marcroft et al 2005). Severe basal stem cankers are associated only with phoma leaf spotting on basal leaves whilst leaf spots on later leaves taken up the plant during stem extension result in less damaging upper stem lesions (Sun et al 2000).…”

Section: Discussionmentioning

confidence: 99%

“…The differential effect of temperature on the rates of pathogen progress and leaf senescence determines whether leaf abscission occurs before the pathogen reaches the stem. Occurrence of phoma leaf spot early in the autumn often results in the most severe stem base cankers (Sun et al 2000) and in glasshouse experiments leaf spots on leaves after leaf 5 did not produce severe stem cankers (Marcroft et al 2005), although this pattern may be different in farm crops under natural weather conditions. The thermal time (8C-days) between first leaf spots (autumn) and first cankers (spring), was constant over seasons for a given cultivar but differed between cultivars (Sun et al 2001).…”

Section: Introductionmentioning

confidence: 95%

Relating plant and pathogen development to optimise fungicide control of phoma stem canker (Leptosphaeria maculans) on winter oilseed rape (Brassica napus)

2007

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In winter oilseed rape experiments at Rothamsted in 2000/01 to 2002/03 growing seasons, the severity of phoma stem canker epidemics in summer depended on the timing of phoma leaf spot epidemics in the previous autumn, and hence on the timing of Leptosphaeria maculans ascospore release. The first major release of L. maculans ascospores was earlier in 2000 (26 September) and 2001 (18 September) than in 2002 (21 October). Consequently, the autumn phoma leaf spot epidemic was also earlier in 2000 and 2001 than in 2002. The resulting stem canker epidemics were severe by harvest (July) in 2001 and 2002 but not in 2003. No correlation was found between the severity or duration of phoma leaf spotting (lesion days or lesion ??C-days) and the subsequent severity of phoma stem canker epidemics. Rates of leaf production and loss were similar in the three growing seasons. Out of ca. 25 leaves produced on plants during each season, leaf numbers 10???14 generally remained on plants for the longest. Treatment with flusilazole + carbendazim in autumn decreased the severity of phoma leaf spotting for several weeks after treatment, decreased the severity of stem canker the following summer and increased yield significantly in 2001 and 2002 but not in 2003. The most effective timings for flusilazole + carbendazim application were when leaves 7???11 were present on most plants and at least 10% of plants were affected by phoma leaf spot. Two half-dose applications of fungicide reduced phoma stem canker and increased yield more than a single full dose application when phoma leaf spot epidemics were early (<800 ??C-days after sowing)

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“…Microorganisms can aid crops against the attack of phytopathogens, by direct antagonism (growth inhibition, p.e.) or by the early activation of the plant defense mechanisms -priming- [2].In this study, 49 Brassica napus bacterial endophytes were tested in vitro as antagonists of the fungus Leptosphaeria maculans, the causal agent of the most damaging disease of this crop [3]. The screening allowed us to find 13 endophytes with high in vitro antifungal potential.…”

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confidence: 99%

<em>Brassica napus</em> Endophytes Have the Potential to Protect the Crop against the Blackleg Disease Causal Agent, the Fungus <em>Leptosphaeria maculans</em>

Peral-Aranega

Saati‐Santamaría

Rivas

et al. 2020

Proceedings of the 1st International Electronic Conference on Plant Science

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According to the UN, the World population is going to achieve 8.000 million people imminently [1]. Finding a sustainable and efficient way to feed the growing population is one of the major challenges of this generation.Crop yields can be promoted by plant growth promoting (PGP) bacteria in substitution of chemical fertilization, which has shown to cause a wide list of environmental harms. On the other side, pest control with chemical biocides is not only harmful for the environment but could also be a direct cause of human disease. For this reason, BCA (biological control agents) are being studied. Microorganisms can aid crops against the attack of phytopathogens, by direct antagonism (growth inhibition, p.e.) or by the early activation of the plant defense mechanisms -priming- [2].In this study, 49 Brassica napus bacterial endophytes were tested in vitro as antagonists of the fungus Leptosphaeria maculans, the causal agent of the most damaging disease of this crop [3]. The screening allowed us to find 13 endophytes with high in vitro antifungal potential. Two Pseudomonas strains, belonging to the species P. brassicacearum and P. orientalis, respectively, greatly inhibited the fungus. Genomes sequences of these strains were sequenced, and their genetic potential to produce secondary metabolites was analyzed on the antiSMASH platform (v5.1.2). Both strains genome analyses showed diverse biosynthetic gene clusters (BGCs) that may be implicated in the production of novel secondary metabolites that might be implicated in the antifungal activity, according to its relative similarity to other BGCs in the platform database.

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Brassica napus plants infected by Leptosphaeria maculans after the third to fifth leaf growth stage in south-eastern Australia do not develop blackleg stem canker

Cited by 19 publications

References 11 publications

Spatio‐temporal connectivity and host resistance influence evolutionary and epidemiological dynamics of the canola pathogen Leptosphaeria maculans

Spatio‐temporal connectivity and host resistance influence evolutionary and epidemiological dynamics of the canola pathogen Leptosphaeria maculans

Relating plant and pathogen development to optimise fungicide control of phoma stem canker (Leptosphaeria maculans) on winter oilseed rape (Brassica napus)

<em>Brassica napus</em> Endophytes Have the Potential to Protect the Crop against the Blackleg Disease Causal Agent, the Fungus <em>Leptosphaeria maculans</em>

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