Chemical and structural barriers to <i>Microcyclus ulei</i>, the agent of South American leaf blight, in <i>Hevea</i> spp.

García, Dominique; Cazaux, E.; Rivano, Franck; D'Auzac, Jean

doi:10.1111/j.1439-0329.1995.tb01013.x

Cited by 22 publications

(8 citation statements)

References 14 publications

(12 reference statements)

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“…The delay observed for the appearance of stromata is only a part of the possible influence of host resistance on the sexual reproduction of the fungus. Clonal resistance was shown to be primarily due to histological reactions that occurred shortly after the fungus penetrated the host cells (Blasquez and Owen 1963;Hashim et al 1978;Garcia et al 1995). Sambugaro et al (2004) extended the investigations to different clonal behaviour up to the appearance of sexual structures.…”

Section: Discussionmentioning

confidence: 96%

Influence of host resistance and phenology on South American leaf blight of the rubber tree with special consideration of temporal dynamics

Guyot¹,

Cilas²,

Sache

2007

Eur J Plant Pathol

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South American leaf blight (SALB), the most dangerous disease of the rubber tree, is responsible for the lack of significant natural rubber production in South America and is a major threat to rubber tree plantations in Asia and Africa. Although the selection of resistant clones is the preferred disease control method, greater knowledge is required of the relationship between host and pathogen, in order to construct more durable resistance. Based on small-scale trials, this study set out to compare the dynamics of SALB on two highly susceptible and one moderately susceptible clone and to analyse the effect of host phenology on disease severity, at leaflet and flush scales. Clonal resistance was found to have a noticeable effect on disease severity, asexual sporulation and stromatal density at both leaflet and flush levels, and on disease dynamics at a leaflet level; time for symptom and sporulation appearance were longer on the moderately susceptible clone than on the susceptible clones. On the moderately susceptible clone, the stromatal density was largely dependent on disease severity. The phenology did not differ among the three clones and could not be considered as a factor in genetic resistance to SALB. However, for the three clones, the position of the leaflet in the flush affected the duration of the immature stages and the disease: the shorter the duration of leaflet development, the lower the disease severity, the sporulation intensity and the stromatal density.

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Section: Discussionmentioning

confidence: 96%

Influence of host resistance and phenology on South American leaf blight of the rubber tree with special consideration of temporal dynamics

Guyot¹,

Cilas²,

Sache

2007

Eur J Plant Pathol

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“…SALB research programmes have largely focused on identifying resistance mechanisms in Hevea spp. (Garcia et al 1995(Garcia et al , 1999, and selecting resistant rubber tree clones, with a view to combining them with latex productivity (Chee 1976;Rivano 1997b). Two types of resistance have been found.…”

Section: Introductionmentioning

confidence: 99%

Assessing resistance of rubber tree clones to Microcyclus ulei in large-scale clone trials in Ecuador: a less time-consuming field method

et al. 2009

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Resistance of rubber tree clones to South American Leaf Blight (SALB) caused by the fungus Microcyclus ulei is normally assessed in specific large-scale clone trials, which in general entail a considerable amount of work. Four variables are observed monthly on each tree over many years: disease severity and conidial sporulation intensity on young leaves, and severity and stroma density on mature leaves. In order to simplify this field assessment method, we tested the resistance of eight rubber tree clones to M. ulei in Ecuador in a Fisher block design with four replicates per treatment. Three months after planting, monthly observations were made for a period of 12 months on the foliage focusing on the four variables, in order to quantify disease development. Given the correlations between the four variables, assessment of conidial sporulation intensity on young leaves and stroma density on mature leaves should be sufficient. The most suitable period to start the assessment was 6 months after planting, for a duration of six to nine months. As repeated observations on the same trees were autocorrelated, it was possible to reduce the assessment frequency to once every 2 months. To conclude, assessing the resistance of rubber tree clones to SALB in large-scale clone trials can be optimized to reduce the number of observation times by 50%.

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“…Complete resistance in the M. ulei–Hevea interaction was characterized by necrotic or chlorotic lesions without production of any kind of spores (Junqueira et al ., 1988). This type of interaction is frequently referred to as a hypersensitive reaction (HR) of foliar tissues which contributes to stop the infection process at an early stage (Hashim & Pereira, 1989; Garcia et al ., 1995). A conservative amount of 10 significant resistance QTLs have been identified by Lespinasse et al .…”

Section: Discussionmentioning

confidence: 99%

Bypassing of a polygenic Microcyclus ulei resistance in rubber tree, analyzed by QTL detection

Guen

García

Mattos³

et al. 2006

New Phytologist

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Research Summary• Genetic resistance components of the Hevea brasiliensis × H. benthamiana RO 38 cultivar to Microcyclus ulei disease were investigated by inoculating isolates which succeeded in partially or completely infecting genotypes of a mapping population.• Progeny of a cross between RO 38 and a susceptible cultivar was inoculated under controlled conditions with three isolates and scored for two resistance traits. Interval mapping and a nonparametric test were used to detect resistance quantitative trait loci (QTLs).• Eight significant QTLs were detected, all of them inherited from the interspecific parent. Among these QTLs, only one contributed to the partial resistance against a highly pathogenic isolate, and no QTL was detected for resistance against the most pathogenic isolate. As an unexpected result, a single isolate can thus completely bypass this polygenic resistance.• This complex situation, where no clear relationship can be established between number of resistance factors and qualitative vs quantitative or partial vs complete resistance, is discussed and suggestions as to the detection of new and sustainable resistance sources are proposed.

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Chemical and structural barriers to Microcyclus ulei, the agent of South American leaf blight, in Hevea spp.

Cited by 22 publications

References 14 publications

Influence of host resistance and phenology on South American leaf blight of the rubber tree with special consideration of temporal dynamics

Influence of host resistance and phenology on South American leaf blight of the rubber tree with special consideration of temporal dynamics

Assessing resistance of rubber tree clones to Microcyclus ulei in large-scale clone trials in Ecuador: a less time-consuming field method

Bypassing of a polygenic Microcyclus ulei resistance in rubber tree, analyzed by QTL detection

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