Development stage-dependent susceptibility of cocoa fruit to pod rot caused by Phytophthora megakarya

Soh, Patrice Takam; Ndoumbè-Nkeng, M.; Sache, Ivan; Nguema, E. P. Ndong; Gwet, Henri

doi:10.1007/s10658-012-0092-4

Cited by 9 publications

(6 citation statements)

References 21 publications

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“…Yet, this question warrants further research. Delay of the onset of symptoms in the Forastero and Trinitario, or disease progression in Criollo varieties, is related to the physicochemical parameters of the pericarp of the fruit (Nyadanu et al 2013, Takam et al 2013.…”

Section: Discussionmentioning

confidence: 99%

Degree of domestication influences susceptibility of Theobroma cacao to frosty pod rot: a severe disease devastating Mexican cacao

et al. 2018

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Background: The three-main cacao (Theobroma cacao) varieties cultivated in México are: Criollo, Forastero, and Trinitario. Each variety has a different fruit setting time and has been subjected to several selection stages. The aim of this study was to determine the susceptibility of the three cacao varieties to Frosty pod rot caused by Moniliophthora roreri. We also analyzed the physicochemical properties of the pericarp of the three varieties and its domestication age.Question: Is there a relationship between the degree of domestication of the cacao variety and its susceptibility to Frosty pod rot?Studied species: Theobroma cacao fruits.Study site: A cacao plantation in Chiapas, Mexico.Methods: The content of moisture, lignin, phenols, peroxidase activity and hardness of the pericarp were analyzed in the middle zone of healthy fruits at 4, 8 and 12 weeks of development. Number of healthy and infected fruits were recorded every week.Results: The highest susceptibility to Frosty pod rot was found in the immature stage of fruits from the Criollo variety. The disease was mostly found in the mid-zone of the fruit. The Criollo variety was the most susceptible. This variety showed the highest moisture values and the lowest values of the other measured parameters.Conclusions: The finest cacao is obtained from the Criollo variety, the one with the highest degree of domestication, and also the most susceptible to frosty pod rot. We suggest using material from wild Criollo populations and from the Forastero and Trinitario varieties in future breeding and selection programs.

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Section: Discussionmentioning

confidence: 99%

Degree of domestication influences susceptibility of Theobroma cacao to frosty pod rot: a severe disease devastating Mexican cacao

et al. 2018

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“…Although P. megakarya can infect cocoa pods at all developmental stages, studies from Cameroon showed that susceptibility and the risk of attack depend among others on the developmental stage of cocoa pods. 13,14 The growth cycle of a cocoa pod can be divided into three phases, ie, an early accelerating/cell division phase, a linear/cell enlargement phase, and a saturation phase for ripening/maturation (see the work of Goudriaan and van Laar 15 ; see Figure 2, page 3). This growth pattern of cocoa pods generally follows a sigmoid curve (see the work of Ten Hoopen et al 16 ; Figure 2).…”

Section: Phytophthora Megakarya: Life Cycle and Epidemiologymentioning

confidence: 99%

“…This growth pattern of cocoa pods generally follows a sigmoid curve (see the work of Ten Hoopen et al 16 ; Figure 2). Based on the works of Efombagn et al 13 and Takam Soh et al, 14 it is assumed that the first growth stage called cherelles is when pods are most susceptible. Ripe pods, even though at the end of the production cycle they can still become infected, likely contribute little to Phytophthora pod rot epidemics, even though ripe pods can still become infected.…”

Section: Phytophthora Megakarya: Life Cycle and Epidemiologymentioning

confidence: 99%

Modeling the temporal evolution of cocoa black pod rot disease caused by Phytophthora megakarya

Nembot

Soh

Hoopen

et al. 2018

Math Methods in App Sciences

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Black pod rot, caused by Phytophthora megakarya, is the main cause of cocoa losses in Cameroon. A few studies have focused on describing black pod epidemics in cocoa yet numerous questions remain. Here, an epidemiological model describing the temporal evolution of cocoa black pod, taking into account the development stages of pods, is developed and studied. In particular, the relative importance of primary and secondary infection in disease dynamics is investigated. Our theoretical study shows the existence of a disease free equilibrium and at least one endemic equilibrium. We highlight two threshold parameters, related to direct and indirect infections that summarize all possible dynamics of the system. Then, based on the literature, we define a periodic pod recruitment function and provide several numerical simulations to study the impact of phytosanitary pod removal on disease dynamics. We show that intense and regular sanitary harvest could lead to complete disease eradication.Our results also highlight the importance of the environmental spores reservoir in disease dynamics, such that future field experiments and observations should focus on it. KEYWORDS analysis, black pod rot, cocoa, disease, epidemiological model, simulations 8816

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“…This age-related resistance, commonly called ontogenic resistance (when young tissues are susceptible) or receptivity (when old tissues are susceptible), could be defined as the dynamic modification of tissue receptivity during organ development, triggering resistance/tolerance to pathogenic micro-organisms. Ontogenic resistance has been described for many plant-pathogen systems [e.g., strawberry-powdery mildew (Carisse and Bouchard, 2010), cucurbit fruit— Phytophthora capsici (Ando et al, 2009), tobacco— Phytophthora parasitica (Hugot et al, 1999), apple-apple scab (Li and Xu, 2002), cocoa— Phytophthora megakarya (Takam Soh et al, 2012), pea-powdery mildew (Fondevilla et al, 2006), pea-aschochyta blight (Richard et al, 2012)]. They are therefore common traits but remain underexploited in disease management, principally because of a lack of understanding of the underlying mechanisms and of the potential variability linked to the physiological responses of the host to environmental factors.…”

Section: Introductionmentioning

confidence: 99%

Pathogenicity Traits Correlate With the Susceptible Vitis vinifera Leaf Physiology Transition in the Biotroph Fungus Erysiphe necator: An Adaptation to Plant Ontogenic Resistance

et al. 2018

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How and when the pathogen cycle is disrupted during plant development is crucial for harnessing ontogenic resistance in sustainable agriculture. Ontogenic resistance against powdery mildew (Erysiphe necator) was quantified on Vitis vinifera. Shoots were sampled in the vineyard at several dates during seasonal growth and processed in the laboratory under controlled conditions. Experiments were conducted on two susceptible Vitis vinifera Cabernet Sauvignon and Merlot. The process of leaf ontogenic resistance was investigated by measuring three quantitative traits of pathogenicity: the infection efficiency, sporulation and mycelium growth. Morphological and physiological plant indicators were used to identify leaf changes that resulted in ontogenic resistance and to predict pathogen variations that were linked to pathogenicity traits. The process of ontogenic resistance was established early in correspondence with the physiological transition of the leaf from sink to source status and was characterized by its increase in sugar content. The three traits of pathogenicity that we measured were affected, and their variation was strongly correlated with leaf age. Using leaf age, we were able to accurately predict the susceptibility of the leaf: a leaf aged, on average, 13.3 days had a very high probability (0.8) of being susceptible, while this probability decreased to 0.5 one week later. Sporulation was more closely correlated with variations in sugar and the infection efficiency in leaf water. The results for both cultivars were consistent. Ontogenic resistance on grapevine leaves is thus interpreted to be a strong, immutable physiological process that E. necator is able to circumvent by restricting its development to sink tissue. Future research should explore how this native plant resistance can be incorporated into grape management strategies to better control powdery mildew (PM) epidemics with reduced amounts of fungicides.

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Development stage-dependent susceptibility of cocoa fruit to pod rot caused by Phytophthora megakarya

Cited by 9 publications

References 21 publications

Degree of domestication influences susceptibility of Theobroma cacao to frosty pod rot: a severe disease devastating Mexican cacao

Degree of domestication influences susceptibility of Theobroma cacao to frosty pod rot: a severe disease devastating Mexican cacao

Modeling the temporal evolution of cocoa black pod rot disease caused by Phytophthora megakarya

Pathogenicity Traits Correlate With the Susceptible Vitis vinifera Leaf Physiology Transition in the Biotroph Fungus Erysiphe necator: An Adaptation to Plant Ontogenic Resistance

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