Papers by Frédéric Breton
The objective of this research was to investigate the relationship between the aggressiveness, as... more The objective of this research was to investigate the relationship between the aggressiveness, assessed by nursery screening tests, of Ganoderma with a pathogenic factor which is quantifiable in the laboratory. This should lead to a rapid test to screen for isolate aggressiveness. A Czapek modified liquid medium was first improved for the culturing of Ganoderma boninense. The culture filtrate was used to study metabolites secreted by the fungus which could be involved in pathogenicity, as the production of toxin(s). As a first step a wilting leaf bioassay, using the fungus filtrate, was set up to develop this approach. This tool was used in another pathosystem (Breton et al., 2000) and allowed a quantitative estimate of the production of toxin(s) which was estimated by water loss from leaves (wilting). In parallel, the ability of isolates to degrade rubber wood blocks (RWB) was studied in vitro. Preliminary results led to the hypothesis that (i) there is no correlation between RWB degradation by isolates with their natural aggressiveness and (ii) Ganoderma isolates seem to produce toxic compound(s) which lead to leaf wilting in vitro. The chemical nature of these compounds is unknown and it is too early to assert whether (i) there is a role of these compounds in Ganoderma pathogenicity and (ii) there is a positive correlation between the production of toxic compound(s) with isolate aggressiveness observed in the nursery. However, preliminary results indicate that such relationships may exist.
Journal of Oil Palm Research, 2006
Basal stem rot (BSR) of oil palm (Elaeis guineensis Jacq.) is caused by Ganoderma boninense, and ... more Basal stem rot (BSR) of oil palm (Elaeis guineensis Jacq.) is caused by Ganoderma boninense, and is one of the most commercially devastating diseases in Southeast Asia. So far, cultural practices, combined to some extent with biological control, have been considered as the best approach for controlling the disease. However, in recent years, sources of genetic resistance and susceptibility have been identified in field trials, leading to the consideration of a genetic approach as an integrated component in controlling the disease. To develop this approach, an early screening test at the nursery or pre-nursery stage is needed, based on artificial inoculation and correlated with field observations. The success of nursery seedling artificial inoculation relies on a set of parameters such as defining the inoculum potential like the aggressiveness of G. boninense isolates, the incubation period of pre-infected rubberwood blocks (RWB), the ratio between the size of pre-infected RWBs and the volume of soil for infection, and the quality of nursery or pre-nursery shade as pre-disposing factors. When this set of parameters was optimized, disease symptoms were observed three months after the inoculation of germinated seeds. This avoided the transfer of seedlings from the pre-nursery to the main nursery, minimized
Plantations, Recherche, Développement, 1997
This article corresponds to a paper presented at the Workshop on Corynespora leaf fall disease of... more This article corresponds to a paper presented at the Workshop on Corynespora leaf fall disease of Hevea rubber, organized in Medan by the Indonesian Rubber Research Institute, on 16th and 17th December 1996.
Une activite beta-1,3-glucanase a ete observee dans des extraits de lutoides de latex de 3 clones... more Une activite beta-1,3-glucanase a ete observee dans des extraits de lutoides de latex de 3 clones d'Hevea brasiliensis (GT 1, PB 86, PB 235). Ces activites, detectees par focalisation isoelectrique en conditions non denaturantes, aboutissent a la visualisation de 5 bandes correspondant a 3 izozymes basiques et 2 acides. L'immunodetection par des anticorps polyclonaux de tabac des beta-1,3-glucanases acide et basique revele le meme profil proteique caracterise par 3 bandes principales de poids moleculaire 38,9; 36,4 et 30,1 kD. La presence de beta-1,3-glucanases et de chitinases apparemment constitutives dans les lutoides, et leurs roles dans la resistance, de l'hevea aux agents pathogenes, sont discutes
Journal of Rubber Research, 2000
Histological study confirmed rapid and direct penetration of Corynespora cassiicola (12 h after i... more Histological study confirmed rapid and direct penetration of Corynespora cassiicola (12 h after inoculation) throughout the lower epidermis, observed also in previous work. The fungal colonisation of leaf tissues was intracellular, irrespective of clonal resistance. For the susceptible clone, fungus penetration led to an important collapse ofabaxial epidermis and to cell disorganisation in front of the hyphal progression, characterised by nuclear degeneration and absence of starchy grains. This observation demonstrated that C. cassiicola behaved as a necrotrophic fungus. For the resistant clone, C. cassiicola invasion was restricted to a few cells leading to a hypersensitive-like reaction. The production of toxin in culture filtrate of the fungus, was confirmed. This toxin, named cassiicolin, reproduced similar leaf disease symptoms as observed after fungal inoculation. The role of the host-selective toxin in C. cassiicola pathogenesis was demonstrated using toxin antibodies and pure toxin. Results have shown that cassiicolin was essential for pathogenicity and can be considered as the primary determinant to C. cassiicola pathogenesis. A close correlation between sensitivity of Hevea clone to cassiicolin and their susceptibility to the fungus has been proven using an aggressive isolate from Philippines. Higher toxin concentrations could overcome the resistance of GT1 which exhibited resistance to lower concentrations. Thus, clonal resistance to cassiicolin was not absolute and seemed to be strictly linked to the toxin concentration tested. The amount of toxin production by Jl C. cassiicola isolates from different countries was positively correlated to their pathogenicity. On the basis of these results which must be confirmed with a wide range of isolates, the using of cassiicolin for assessing the level of resistance of Hevea clones to C. cassiicola is discussed. Corynespora cassiicola (Berk. & Curt.) Wei is a tropical to subtropical countries 1. During the fungus of worldwide importance with a very past decade, the pathogen has caused extensive wide host range. It has been reported on a great damage to rubber tree plantations and may number of economically important crops from become a potential limiting factor in rubber yield
Acta Botanica Gallica, 1996
Les composes phenoliques et Ia resistance des plantes aux agents pathogenes par Alain Cieri vet, ... more Les composes phenoliques et Ia resistance des plantes aux agents pathogenes par Alain Cieri vet, lbrissam Alami,
This is a hands-on, practical guide covering seedling screening for disease response in oil palm ... more This is a hands-on, practical guide covering seedling screening for disease response in oil palm for pathology, breeding and genetics. Oil palm is the top oil crop in the world and Ganoderma is the most devastating disease of oil palm. The authors are all actively engaged in oil palm seed production and breeding and bring together the many aspects of seedling disease testing in to one integrated manual. Presenting sound practices based on scientific innovation and knowledge, this guide provides techniques integrated with expertise and also looks towards future possibilities. Promoting green, eco-friendly agriculture, this book covers: Health and safety considerations Media preparation for in vitro culture Collecting isolates and culture preparation Preparation of Ganoderma inoculum Nursery inoculation Scoring response Based on experience and protocols, this is an invaluable manual for students and researchers in agriculture, plant breeders, growers, traders and production companies interested in the practicalities of oil palm pathology. It provides a resource for training, a knowledge base for people new to oil palm and a reference guide for managers, to ensure best practices in maximising sustainability and production of this important crop.
This study provides further information on the role of the melanised stromatic-like structure (SL... more This study provides further information on the role of the melanised stromatic-like structure (SLS) for the initiation of Basal Stem Rot (BSR) infection in both the field and nursery. Artificial inoculation of seedlings by using Ganoderma-colonized rubber wood block (RWB) previously cleaned of SLS confirmed the essential role of this structure to induce rapid and homogeneous infections. In mature palms, whatever the sanitary condition, the presence of a highly lignified starshape cavity at the base of the bole (root-bole interface) could play a role as a culture chamber for Ganoderma development and infection. This cavity is considered to provide suitable conditions (dark, lower than ambient temperature, high humidity and a dense substrate) for the development of SLS and probably has less antagonists than in the open soil where Ganoderma is a poor competitor. A lignified scar which will develop as a future cavity has been observed in eight month-old nursery seedlings. Field observations of infected palms confirm the presence of a melanised fungal tissue inside this lignified star-shape cavity. Random observations of the initial stage of infection of young palms revealed that the development of SLS inside the cavity occurred before the penetration and colonisation of the oil palm bole. Transverse and longitudinal sections of the root-bole interface from recently infected palms seem to demonstrate that the initial point of Ganoderma penetration was confined to this lignified cavity. No initial Ganoderma penetration points were observed beyond the periphery of this star-shape cavity. The colonisation of the bole by the fungus shows a centrifugal and radial invasion from the cavity which corroborates the important role of this lignified cavity for Ganoderma penetration. These results do not exclude multiple infections from this cavity by more than one isolate. The common point between field observations of mature palm infection and a nursery inoculation tests is the prior development of SLS on a dense substrate (lignified cavity in field and RWB in nursery). The sequence of events concerning the mature bole invasion by Ganoderma proposed in this paper is discussed.
Etude de la cinetique d'apparition de certaines proteines dans de jeunes feuilles detachees d... more Etude de la cinetique d'apparition de certaines proteines dans de jeunes feuilles detachees de clones d'hevea presentant differents niveaux de sensibilite a la maladie, apres inoculation artificielle avec des suspensions de spores de C. gloeosporioides. Une etude preliminaire sur un clone sensible a montre une baisse des proteines totales dans les 6 jours suivant l'inoculation, et une augmentation de l'activite de certaines enzymes, laquelle est precisee grâce a la technique du "leaf blotting". La cinetique des teneurs en scopoletine, une phytoalexine responsable d'une fluorescence bleue sous UV des gouttelettes de suspension de conidies sur les feuilles inoculees, est differente selon les clones
Journal of Plant Physiology, 1997
Inoculation of leaves of resistant and susceptible Hevea brasiliensis clones with Corynespora cas... more Inoculation of leaves of resistant and susceptible Hevea brasiliensis clones with Corynespora cassiicola induced foliar necrosis and biosynthesis of scopoletin (Scp) , considered as a Hevea phytoalexin. Foliar symptoms appeared, as soon as 24 h after infection, and precede Scp accumulation in inoculum droplets (peak: 48 h after inoculation). Scp concentration was 5-fold higher in the susceptible than in the resistant clone 48 h after infection. Nevertheless, a fungitoxic effect of Scp on spore germination and on mycelium growth was shown in bioassays, but the efficient concentrations were greater than those found with another foliar pathogenic fungus of rubber tree such as Microcyclus ulei and Colletotrichum gloeosporioides. Bioassay showed that the low Scp fungitoxicity to C cassiicola could also be related to the ability of fungus to detoxify Scpo Isoelectric focusing analysis of peroxidase activity in Hevea infected leaflets has shown an increase in acidic and basic isoperoxidases that are able to use Scp as substrate. The rapid increase of Scpoxidase activity (as soon as 16 h after inoculation) was higher in the resistant than in the susceptible clone. In vitro testing of Scp peroxidation products has shown a toxic effect on C cassiicola (conidia germination and mycelium growth), but not significantly higher than Scpo It appears that the level of Scp accumulation was a balance between its synthesis and its degradation by the pathogen orland by foliar Scp-peroxidases. In conclusion, these results lead to the fact that Scp cannot be considered as a major defense mechanism of Hevea towards C cassiicola disease.
Revista Palmas, 2010
Hipótesis sobre infección natural e implementación de una prueba de inoculación artificial para l... more Hipótesis sobre infección natural e implementación de una prueba de inoculación artificial para la detección temprana del nivel de resistencia de progenies de palma de aceite Ganoderma disease of the oil palm: Hypothesis on natural infection and implementation of an early artificial inoculation test to screen oil palm progenies for their level of resistance Resumen Genetic resistance to basal stem rot (BSR) of oil palm is an important component of an integrated disease control strategy. Early detection of susceptibility or resistance level is essential for a breeding program and for the sustainability of this crop, particularly in Southeast Asia. A screening test for oil palm progenies was developed and validated using planting material from two private companies in Indonesia,
Basal stem rot caused by Ganoderma boninense is the major threat to oil palm cultivation in South... more Basal stem rot caused by Ganoderma boninense is the major threat to oil palm cultivation in South-East Asia, which accounts for 80% of palm oil production worldwide, and this disease is increasing in Africa. The use of resistant planting material as part of an integrated pest management of this disease is one sustainable solution. However, breeding for Ganoderma resistance requires long-term and costly research, which could greatly benefit from marker assisted selection (MAS). In this study, we evaluated the effectiveness of an in silico genetic mapping approach that took advantage of extensive data recorded in an ongoing breeding program. A pedigree-based QTL mapping approach applied to more than 10 years’ worth of data collected during pre-nursery tests revealed the quantitative nature of Ganoderma resistance and identified underlying loci segregating in genetic diversity that is directly relevant for the breeding program supporting the study. To assess the consistency of QTL effe...
Genetic resistance to basal stem rot (BSR) of oil palm is an important component of an integrated... more Genetic resistance to basal stem rot (BSR) of oil palm is an important component of an integrated disease control strategy. Early detection of susceptibility or resistance level is essential for a breeding program and for the sustainability of this crop, particularly in Southeast Asia. A screening test for oil palm progenies was developed and validated using planting material from two private companies in Indonesia, PT PP London Sumatra Indonesia (Lonsum) and PT Socfin Indonesia (Socfindo) -. The first symptoms of the disease appeared between 8 and 10 weeks after inoculation of germinated seeds. The analysis of the crosses tested showed a positive correlation between 16 and 28 weeks, indicating that early detection is realistic and that there is minimal interaction of the susceptibility to the disease over time. The main objective of this paper is to highlight the efficiency and reproducibility of this early pre-nursery inoculation test to detect approximately 100 progeny per month.
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Papers by Frédéric Breton