Agronomical and molecular factors influencing bananas (Musa acuminata, AAA, cv ‘Grande-Naine’) susceptibility to crown rot disease

Doctoral thesis (2009)

Crown rot affects export bananas in all producing countries and is considered to be one of the main export banana post-harvest disease. Variations are observed in the expression of crown rot symptoms. An ... [more ▼]

Crown rot affects export bananas in all producing countries and is considered to be one of the main export banana post-harvest disease. Variations are observed in the expression of crown rot symptoms. An original approach of the disease is proposed and consists on presenting the fruit quality potential at harvest as a key factor in crown rot development. This potential develops during growth of bananas in the field and depends on a physiological and a parasitical component. The physiological component refers here to the level of fruit susceptibility to crown rot and reflects the physiological state of the fruit. The aim of this study was to clarify the role of the fruit physiological component at harvest in the post-harvest crown rot development. It appears that the fruit physiological component at harvest greatly influence the postharvest disease development and thus the fruit susceptibility. Seasonal variations in disease severity were shown in two production area and are related to a variation of the fruit physiological component. In Guadeloupian conditions, the internal necrotic surface of the crown was nearly multiplied by 4 during 11 successive weeks. Two pre-harvest factors that could influence the fruit physiological component by modifying their susceptibility to crown rot, were identified: (i) hand position on the bunch and (ii) source-sink ratio of the banana plant (hand considered as sink and leaves as source). It was shown that within a bunch, there is a gradient of susceptibility to crown rot (r= -0.95), the hands initiated first (the upper ones) being more susceptible than those initiated last (the lower ones). These results also confirmed that source-sink ratio changes have a significant effect on fruit morphology and demonstrated that there is also an effect on fruit susceptibility to crown rot disease. When the sink is decreased by artificial removal of many hands, the level of fruit susceptibility to crown rot decreases. However, the molecular mechanisms underlying these quantitative host-pathogen relationships were still unknown. A study was designed to compare gene expression, by cDNA-AFLP, between crowns of bananas showing a high susceptibility (S+) and crowns of bananas showing a low susceptibility (S-) to Colletotrichum musae responsible for crown rot disease. This comparison was performed at two situation time: (i) between crowns (S+ and S-) collected one hour before infection and (ii) between crowns (S+ and S-) collected 13 days after infection. Genes implied in signaling pathway and proteolytic machinery were identified. It also appears that a cellulose synthase, a CAF1 gene, 2 glycolipid transfer protein and a dopamine-β-monooxygenase were differently expressed between bananas showing different levels of susceptibility. This is the first study of the characterization of the banana physiological component at harvest which influences the crown rot post-harvest disease development. In addition, to our knowledge, this work is the first to address both pre- and post-infection gene expression with the same host-pathogen combination and different susceptibility levels. [less ▲]

Identification of pre- and post-infection genes potentially implied in quantitative banana response to crown rot disease

Poster (2009)

Integrated biological control of crown rot of bananas with Candida oleophila strain O, calcium chloride and modified atmosphere

in Borja; Nogales; Orrantia (Eds.) et al Memories of 18th Reuniao international ACORBAT meeting (2008)

Evidence for variations in banana fruit susceptibility to Colletotrichum musae, responsible for crown rot, in relation to fruit position in the bunch

Poster (2007)

Les maladies de conservation des bananes causées par Collectotrichum musae

Report (2005)

Contribution to the development of a biological control method against crown rot banana disease

Poster (2004)

Antagonistic activity of yeast against post-harvest diseases of tropical fruits.

in Bulletin des Séances de l’Académie Royale des Sciences d’Outre-Mer = Mededelingen der Zittingen van de Koninklijke Academie voor Overzeese Wetenschappen (2004), 50(2), 153-163

Contribution à la mise au point d'une méthode de lutte biologique contre la maladie des pourritures de la couronne de la banane

Master's dissertation (2003)

The antagonist activity of two yeast strains (Pichia anomala K strain and Candida oleophila O strain) against the parasitic complex responsible for crowns rot of banana has been evaluated. Their ... [more ▼]

The antagonist activity of two yeast strains (Pichia anomala K strain and Candida oleophila O strain) against the parasitic complex responsible for crowns rot of banana has been evaluated. Their efficiency has been tested on three separated fungi : Colletotrichum musae, Fusarium moiliforme, Cephalosporium sp. and on a parasitic complex formed by the association of these three fungi. Antagonist effects have been observed both on the two first fungi and on the complex. Strain O added at 108 ufc/ml on crowns which were previously inoculated with the complex showed the highest protection (56,0 %). This protection was superior to those observed against the fungi inoculated separately. The influence of the time between the addition of the O strain (108 ufc/ml) and the inoculation of the pathogens on the level of protection has also been measured. It appeared that protection by the O strain was remarkably reinforced when the strain was added 24 hours before the complex (57,0 %). This, in comparison with the additions performed 15 minutes or 3 hours after the pathogens inoculation. The utilisation of the O strain at 108 ufc/ml has been combined with the utilisation of 50μm polybags. These latter allow the formation of a modified atmosphere during the length of the bunches transfer. The protection level was at 61,0% when both methods were combined whereas protection by the yeast alone was of 41,0%. A strict correlation between the severity of the symptoms and the protection by the yeast has been highlighted. When the severity of the disease increases, protection by the yeast decreases. [less ▲]