Echeverria-Beirute, Fabian (2018-05). Plant Performance and Bean Quality of Coffee (Coffea arabica L.) under Rust (Hemileia vastatrix Berk. et Br.) Control and Fruit Thinning Treatments. Doctoral Dissertation. Thesis uri icon

abstract

  • The coffee (Coffea arabica L.) plant is known for its special beverage. However, genotype (G), environment (E), management (M), coupled with biotic and abiotic stresses, the post-harvest processing, and roasting can change sensory, chemistry, and gene expression profiles. We investigated how yield (abiotic stress) and coffee leaf rust disease (CLR) (Hemileia vastatrix Berk. et Br.) management affected the cup quality and gene expression in two susceptible varieties. At the field level, CLR chemical control treatment had the highest effect in reduction of incidence (-12%) and severity (-27%). The hybrid's vigor improved tolerance to CLR (4 to 5% less disease) and increase in yield (~20%). Cup quality was qualitatively and quantitatively measured in optimal ripened fruits by two sensory analyses (SCAA and WCR sensory lexicon), revealing that 10 of 70 attributes were significantly affected by the treatments without substantial changes in perception. Parallel analysis of the volatile fraction using SPME-GC/MS, revealed that 18 of 154 chemical volatile compounds changed their abundance according to the treatments. Remarkably, acetaminophen was found for the first time in roasted coffee and in higher concentrations under stress. Further study of the coffee green bean's volatiles revealed that the compounds related to fatty acids were increased under biotic stress. Using immature and mature fruits, we were able to explore the transcriptome of both cultivars under stress and found an active oxidation process occurring in the cell walls. A total of 471 gene ontology (GO) functional terms organized in 19 categories were associated with differentially expressed genes (DEGs) according to the treatments, cultivars, and maturity stages. Sixteen candidate genes for later validation were reported. We also explored the leaf transcriptome under stress. We found a differential response of the cultivars under biotic stress revealed by 88 DEGs mediating qualitative or hypersensitive response (HR) and quantitative or systemic acquired resistance (SAR). Both differential-defense responses are hypothesized as the cause of changes in cup quality and tolerance to CLR stress. This study is a first step in understanding the complexity of the physiological, metabolic, and molecular changes in genotype by management interactions for coffee production, useful for future cultivar improvement.
  • The coffee (Coffea arabica L.) plant is known for its special beverage. However, genotype (G), environment (E), management (M), coupled with biotic and abiotic stresses, the post-harvest processing, and roasting can change sensory, chemistry, and gene expression profiles. We investigated how yield (abiotic stress) and coffee leaf rust disease (CLR) (Hemileia vastatrix Berk. et Br.) management affected the cup quality and gene expression in two susceptible varieties.

    At the field level, CLR chemical control treatment had the highest effect in reduction of incidence (-12%) and severity (-27%). The hybrid's vigor improved tolerance to CLR (4 to 5% less disease) and increase in yield (~20%).

    Cup quality was qualitatively and quantitatively measured in optimal ripened fruits by two sensory analyses (SCAA and WCR sensory lexicon), revealing that 10 of 70 attributes were significantly affected by the treatments without substantial changes in perception. Parallel analysis of the volatile fraction using SPME-GC/MS, revealed that 18 of 154 chemical volatile compounds changed their abundance according to the treatments. Remarkably, acetaminophen was found for the first time in roasted coffee and in higher concentrations under stress. Further study of the coffee green bean's volatiles revealed that the compounds related to fatty acids were increased under biotic stress.

    Using immature and mature fruits, we were able to explore the transcriptome of both cultivars under stress and found an active oxidation process occurring in the cell walls. A total of 471 gene ontology (GO) functional terms organized in 19 categories were associated with differentially expressed genes (DEGs) according to the treatments, cultivars, and maturity stages. Sixteen candidate genes for later validation were reported.

    We also explored the leaf transcriptome under stress. We found a differential response of the cultivars under biotic stress revealed by 88 DEGs mediating qualitative or hypersensitive response (HR) and quantitative or systemic acquired resistance (SAR). Both differential-defense responses are hypothesized as the cause of changes in cup quality and tolerance to CLR stress.

    This study is a first step in understanding the complexity of the physiological, metabolic, and molecular changes in genotype by management interactions for coffee production, useful for future cultivar improvement.

publication date

  • May 2018