In vitro assessment of the role of carbohydrates on the coffee’s resistance against coffee berry disease caused by Colletotrichum kahawae

The coffee berry disease (CBD) of Coffea arabica caused by Colletotrichum kahawae is responsible for 80 % loss of coffee production in Cameroun. In order to assess the possible implication of carbohydrates in the defence of Coffea arabica against Colletotrichum kahawae, comparative analyses (qualitative and quantitative) of soluble sugars contents was done after inoculation on berries. The berries of two cultivars java and caturra were recorded at 22nd and 25th weeks after flowering (WAF) from the field. The influence of culture conditions of coffee trees in situ (full sunlight and under shade), the age of the berries at the time of inoculation were discussed. Additionally, the composition and the content of soluble sugars were analysed. The result showed that the infection rate was significantly high on the berries collected at the 22nd (WAF) compared to those collected at the 25th WAF. Qualitative analyse showed only the presence of glucose. The highest glucose content was obtained from the berries of java variety exposed on full sunlight while the lowest content being observed from the berries of caturra variety under shade (2.96 ± 0.42 mg/g against 0.75 ± 0.03 mg/g respectively). No significant different in sugar content was observed between infected and no infected berries inside the two varieties of coffee. However, the java variety showed a high accumulation of glucose compared to caturra variety. These results support a positive implication of sugar in the interaction between coffee berries and Colletotrichum hahawae since a high accumulation of sugar was observed in java variety the resistant cultivar.