Seedling and adult plant evaluation of race variability in Leptosphaeria maculans on Brassica species in Australia

Ballinger, D. J.; Salisbury, P. A.

doi:10.1071/ea9960485

Cited by 51 publications

(27 citation statements)

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“…Although Australian isolates of L. maculans are generally more virulent than those in Europe or Canada (Balesdent et al 2005), there was significant variability in the severity of root rot caused by different isolates. This finding is consistent with other studies that have shown variability in the pathogenicity of Australian L. maculans isolates on leaves at the seedling stage (Ballinger and Salisbury 1996) and on stems at the adult plant stage (Pang and Halloran 1995;Ballinger and Salisbury 1996).…”

Section: Discussionsupporting

confidence: 94%

“…Sapphire (RR 7.5) and B. juncea line Zem 1 (Marcroft et al 2002). Brassica juncea was used as this species is more resistant to L. maculans than B. napus (Ballinger and Salisbury 1996;Purwantara et al 1998;Marcroft et al 2002). Plants were grown in a glasshouse (20/15°C±2°C day/night) and were inoculated 5 weeks after sowing when they were at the four-leaf growth stage.…”

Section: Assessment Of Root Rot In Fumigated Field Plotsmentioning

confidence: 99%

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Epidemiology of root rot caused by Leptosphaeria maculans in Brassica napus crops

2009

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The infection of above-ground tissues of Brassica napus by Leptosphaeria maculans is well understood. However, root infection (root rot) under field conditions, the development of root rot over time and its relationship to other disease symptoms caused by L. maculans has not been described. A survey of B. napus crops was conducted in Australia to investigate the incidence and severity of root rot. Additionally, the pathway of root infection was examined in field experiments. Root rot was present in 95% of the 127 crops surveyed. The severity and incidence of root rot was significantly correlated with that of crown canker; however, the strength of this relationship was dependent on the season. Root rot symptoms appeared before flowering and increased in severity during flowering and at maturity, a pattern similar to crown canker suggesting that the infection of the root is an extension of the crown canker phase of the L. maculans lifecycle. All isolates of L. maculans tested in glasshouse experiments caused root rot and crown canker in B. napus and Brassica juncea. In the field, the main pathway of root infection is via invasion of cotyledons or leaves by airborne ascospores, rather than from inoculum in the soil. Root rot was present in crops in fields that had never been sown to B. napus previously, in plants grown in fumigated fields, and in glasshouse-grown plants inoculated in the hypocotyl with L. maculans.

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Section: Discussionsupporting

confidence: 94%

Section: Assessment Of Root Rot In Fumigated Field Plotsmentioning

confidence: 99%

Epidemiology of root rot caused by Leptosphaeria maculans in Brassica napus crops

2009

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“…For many pathosystems, such as Leptosphaeria maculans--B. napus, different components of resistance are thought to operate in seedlings and in older plants (Ballinger and Salisbury 1996). This may also be true for P. brassicae--B. napus, although it is possible that the large effect of environmental factors on the incidence of light leaf spot in crops contributes to the poor correlation.…”

Section: Measurement Of B Napus Resistance To P Brassicaementioning

confidence: 98%

Resistance to infection by stealth: Brassica napus (winter oilseed rape) and Pyrenopeziza brassicae (light leaf spot)

et al. 2007

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Light leaf spot (Pyrenopeziza brassicae)is an important disease on winter oilseed rape crops (Brassica napus) in northern Europe. In regions where economically damaging epidemics occur, resistance to P. brassicae in commercial cultivars is generally insufficient to control the disease without the use of fungicides. Two major genes for resistance have been identified in seedling experiments, which may operate by decreasing colonisation of B. napus leaf tissues and P. brassicae sporulation. Much of the resistance present in current commercial cultivars is thought to be minor gene-mediated and, in crops, disease escape and tolerance also operate. The subtle strategy of the pathogen means that early colonisation of host tissues is asymptomatic, so a range of techniques and molecular tools is required to investigate mechanisms of resistance. Whilst resistance of new cultivars needs to be assessed in field experiments where they are exposed to populations of P. brassicae under natural conditions, such experiments provide little insight into components of resistance. Genetic components are best assessed in controlled environment experiments with single spore (genetically fixed) P. brassicae isolates. Data for cultivars used in the UK Recommended List trials over several seasons demonstrate how the efficacy of cultivar resistance can be reduced when they are deployed on a widespread scale. There is a need to improve understanding of the components of resistance to P. brassicae to guide the development of breeding and deployment strategies for sustainable management of resistance to P. brassicae in Europe.

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“…Leptosphaeria maculans is the more aggressive of the two species and is capable of causing significant yield loss due to stem canker (Howlett, 2004;Fitt et al, 2006). Some isolates of L. maculans have been shown to cause stem cankers on B. juncea (Ballinger & Salisbury, 1996). Leptosphaeria biglobosa, although previously found on the stubble of both B. napus and B. juncea (Van de Wouw et al, 2008;Vincenot et al, 2008) has not been reported to cause stem canker in either species.…”

Section: Introductionmentioning

confidence: 95%

Reaction ofBrassica junceato Australian isolates ofLeptosphaeria maculansandLeptosphaeria biglobosa‘canadensis’

Elliott

Marcroft

Norton

et al. 2011

Canadian Journal of Plant Pathology

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Blackleg (causal agents Leptosphaeria maculans and L. biglobosa) is the most significant disease of canola (Brassica napus) worldwide. This was the first survey of Leptosphaeria isolates recovered from Brassica juncea stubble in Australia. Sixty-four L. maculans isolates and 88 L. biglobosa 'canadensis' isolates were collected from B. juncea stubble over two years (2005)(2006). These isolates were screened over three canola quality B. juncea and three B. napus differentials. As expected, L. biglobosa 'canadensis' isolates caused lower disease severity than the L. maculans isolates. However, 13 L. biglobosa 'canadensis' isolates were capable of causing ≥50% mean internal infection on at least one of the six differentials. Although these isolates were recovered from B. juncea stubble, disease severity was low when canola quality B. juncea differentials were inoculated. The same differential lines were also screened over two field sites by placing pots containing each of the differential lines onto B. napus and B. juncea stubble from commercial fields. At one site, inoculum in B. napus stubble caused higher internal infection severity than the B. juncea stubble in all differentials except B. napus differential 'ATR-Beacon'. At the other site, however, inoculum from B. juncea stubble produced more internal infection in one B. juncea differential in 2007 and in four differentials in 2008. This investigation suggests that when B. juncea is widely grown, increased blackleg symptoms could occur and that L. biglobosa 'canadensis' isolates can contribute to disease severity.Résumé: La jambe noire, causée par Leptosphaeria maculans et L. biglobosa, est la plus importante maladie du canola (Brassica napus) à l'échelle de la planète. Cette étude est la première concernant des isolats de Leptosphaeria provenant de chaume de Brassica juncea australien. Au cours de deux années (2005)(2006), 64 isolats de L. maculans et 88 de L. biglobosa 'canadensis' ont été collectés sur du chaume de B. juncea. Ces isolats ont été criblés sur trois variétés de B. juncea de qualité comparable à celle du canola et sur trois variétés différentielles de B. napus. Comme il était prévu, la gravité de la maladie causée par les isolats de L. biglobosa 'canadensis' était moindre que celle causée par les isolats de L. maculans. Toutefois, 13 isolats de L. biglobosa 'canadensis' ont causé de l'infection interne dans au moins une des six lignées différentielles, et ce, dans une proportion moyenne de ≥50 %. Bien que ces isolats aient été collectés sur du chaume de B. juncea, la gravité de la maladie était faible lorsque des lignées différentielles de B. juncea de qualité comparable à celle du canola étaient inoculées. Les mêmes lignées différentielles ont été criblées sur deux sites en champ en plaçant des pots contenant chacune des lignées différentielles sur le chaume de cultures commerciales de B. napus et de B. juncea. À un site, l'inoculum du chaume de B. napus a causé une plus haute gravité d'infection interne que le chaume de B. juncea dans toutes ...

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Seedling and adult plant evaluation of race variability in Leptosphaeria maculans on Brassica species in Australia

Cited by 51 publications

References 0 publications

Epidemiology of root rot caused by Leptosphaeria maculans in Brassica napus crops

Epidemiology of root rot caused by Leptosphaeria maculans in Brassica napus crops

Resistance to infection by stealth: Brassica napus (winter oilseed rape) and Pyrenopeziza brassicae (light leaf spot)

Reaction ofBrassica junceato Australian isolates ofLeptosphaeria maculansandLeptosphaeria biglobosa‘canadensis’

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