Project description:Caffeine is a metabolite of great economic importance, especially in coffee, where it influences the sensorial and physiological impacts of the beverage. Caffeine metabolism in the Coffea species begins with the degradation of purine nucleotides through three specific N-methyltransferases: XMT, MXMT and DXMT. A comparative analysis was performed to clarify the molecular reasons behind differences in caffeine accumulation in two Coffea species, namely Coffea arabica and Coffea canephora var. robusta. Three different genes encoding N-methyltransferase were amplified in the doubled haploid Coffea canephora: CcXMT1, CcMXMT1 and CcDXMT. Six genes were amplified in the haploid Coffea arabica: CaXMT1, CaXMT2, CaMXMT1, CaMXMT2, CaDXMT1, and CaDXMT2. A complete phylogenic analysis was performed to identify specific key amino acids defining enzymatic function for each protein identified. Furthermore, a quantitative gene-expression analysis was conducted on leaves and on maturing coffee beans, simultaneously analyzing caffeine content. In the different varieties analyzed, caffeine accumulation is higher in leaves than in the coffee bean maturation period, higher in Robusta than in Arabica. In Robusta, CcXMT1 and CcDXMT gene expressions are predominant and transcriptional activity is higher in leaves than in maturing beans, and is highly correlated to caffeine accumulation. In Arabica, the CaXMT1 expression level is high in leaves and CaDXMT2 as well to a lesser extent, while global transcriptional activity is weak during bean maturation, suggesting that the transcriptional control of caffeine-related genes differs within different organs and between Arabica and Robusta. These findings indicate that caffeine accumulation in Coffea species has been modulated by a combination of differential transcriptional regulation and genome evolution.
Project description:Epidemics of coffee leaf rust (CLR) lead to great yield losses and huge depreciation of coffee marketing values, if no control measures are applied. Societal expectations of a more sustainable coffee production are increasingly imposing the replacement of pesticide treatments by alternative solutions. A good protection strategy is to take advantage of the plant immune system by eliciting its constitutive defenses. Based on such concept, plant resistance inducers (PRIs) have been developed. The Greenforce CuCa formulation made by UFLA (Brazil) is, in addition to acibenzolar-S-methyl (ASM), showing promising results in the control of CLR (Hemileia vastatrix) in Coffea arabica. In order to improve our understanding of the molecular mechanisms of the PRIs, proteomic (2DE-MALDI/TOF/TOF-MS/MS), physiological (leaf gas-exchange) and biochemical (enzymatic) analyses of coffee leaves treated with Greenforce CuCa and ASM and inoculation with H. vastatrix were performed. Proteomic data showed metabolic adjustments mainly related with photosynthesis, protein metabolism and stress responses but, the proteins modulated by the two PRIs were different. Greenforce CuCa, on its own, increased photosynthesis and stomatal conductance, while ASM caused a decrease in these parameters. Upon H. vastratix infection, the Greenforce CuCa showed a higher protective effect on the leaf physiology than ASM. The enzymatic analyses indicated that Greenforce CuCa reinforces the redox homeostasis of the leaf, while ASM seems to increase the involvement of secondary metabolism. So, the PRIs prepare the plant to resist CLR but, inducing different defense mechanisms upon pathogen infection. The data also evidenced the existence of a link between the primary metabolism and defense responses. Furthermore, Greenforce CuCa emerged as a significant agent for CLR management. The identification of components of the plant primary metabolism, essential for plant growth and development that, simultaneously, participate in the plant defense responses can open new perspectives for plant breeding programs.
Project description:Background: Understanding the genetic elements that contribute to key aspects of coffee biology will impact future agronomical improvements for this economically important tree. The past years, EST collections were generated in Coffee, opening the possibility to create new tools for functional genomics. Results: The project PUCE CAFE, set up by the scientific consortium NESTLE/IRD/CIRAD has developed of long oligonucleotide coffee array using public coffee EST sequences mainly obtained from different stages during fruit development and leaves in Coffea canephora (Robusta). We have performed a validation experiment in order to check the array usability and the reproducibility of hybridizations. Conclusion: We have generated the first 15K Coffee array during this three years project PUCE CAFE, granted by The French National Research Agency (ANR, Programme Génoplante) . This new tool was dedicated to large scale transcriptomic analysis during grain development of Coffea canephora grown in different countries . Furthermore, other analysis have been also initiated by the different partners like analysis of polyploidy or drought resistance. In any case, at the end of the project, the generated arrays will be available to the international scientific community.
Project description:As microRNAs (miRNAs) are important regulators of many biological processes, a series of small RNAomes from plants have been produced in the last decade. However, miRNA data from several groups of plants are still lacking, including some economically important crops. Here microRNAs from Coffea canephora leaves were profiled and 58 unique sequences belonging to 33 families were found, including two novel microRNAs that have never been described before in plants. Some of the microRNA sequences were also identified in Coffea arabica that, together with C. canephora, correspond to the two major sources of coffee production in the world. The targets of almost all miRNAs were also predicted on coffee expressed sequences. This is the first report of novel miRNAs in the genus Coffea, and also the first in the plant order Gentianales. The data obtained establishes the basis for the understanding of the complex miRNA-target network on those two important crops.