Coffee leaf rust caused by the fungus Hemileia vastatrix is the most damaging disease to coffee worldwide. The pathogen has recently appeared in multiple outbreaks in coffee producing countries resulting in significant yield losses and increases in costs related to its control. New races/isolates are constantly emerging as evidenced by the presence of the fungus in plants that were previously resistant. Genomic studies are opening new avenues for the study of the evolution of pathogens, the detailed description of plant-pathogen interactions and the development of molecular techniques for the identification of individual isolates. For this purpose we sequenced 8 different H. vastatrix isolates using NGS technologies and gathered partial genome assemblies due to the large repetitive content in the coffee rust hybrid genome; 74.4% of the assembled contigs harbor repetitive sequences. A hybrid assembly of 333Mb was built based on the 8 isolates; this assembly was used for subsequent analyses. Analysis of the conserved gene space showed that the hybrid H. vastatrix genome, though highly fragmented, had a satisfactory level of completion with 91.94% of core protein-coding orthologous genes present. RNA-Seq from urediniospores was used to guide the de novo annotation of the H. vastatrix gene complement. In total, 14,445 genes organized in 3,921 families were uncovered; a considerable proportion of the predicted proteins (73.8%) were homologous to other Pucciniales species genomes. Several gene families related to the fungal lifestyle were identified, particularly 483 predicted secreted proteins that represent candidate effector genes and will provide interesting hints to decipher virulence in the coffee rust fungus. The genome sequence of Hva will serve as a template to understand the molecular mechanisms used by this fungus to attack the coffee plant, to study the diversity of this species and for the development of molecular markers to distinguish races/isolates.

The coffee berry borer (CBB; Hypothenemus hampei) is a major pest of coffee responsible for significant crop losses worldwide. The entomopathogenic fungus Beauveria bassiana represents a natural means of controlling this insect pest; however, little is known concerning the molecular determinants that contribute to the virulence of the fungus towards the CBB. In order to examine genes involved in insect virulence, two expressed sequence tag (EST) libraries, representing germinating conidia and growing hyphae/mycelia of B. bassiana cells grown on cuticular extracts of the CBB were constructed and analysed. In total, 4186 cDNA transcripts were obtained, which included 2141 from the cuticle-germinated conidia and 2045 from the cuticle-grown mycelium libraries, respectively. The average sequence length obtained was 470 bp and transcript assembly resulted in a set of 1271 and 1305 unique gene sequences for the conidial and mycelia libraries, respectively. Around 50 % of the sequences in each library could be annotated by gene ontology terms. An analysis of the two generated libraries as well as a previously reported EST library of B. bassiana grown on chitin was performed. Between the cuticle-germinated conidia and the cuticle-grown mycelia libraries, 322 unique gene sequences were shared, of which 90 % could be annotated, leaving 949 unique cuticle-germinated conidial genes and 983 unique growing hyphae/mycelia genes of which around 65 % were annotated. ESTs shared between the libraries indicated a basic response pattern for B. bassiana against H. hampei, which included genes implicated in pathogenicity. The expression profiles of four genes were evaluated with a cyclophilin, an alkaline-like serine protease and a mitogen-activated protein kinase (MAPK), showing elevated expression during initial phases of infection, i.e. conidia germinating on insect extracts. These data provide clues and gene candidates for further exploration concerning the biology and molecular mechanisms of entomopathogenicity by this fungus.

Coffee stands as a vital pillar of Colombia’s economic prosperity, constituting approximately 7% of the nation’s agricultural GDP. Moreover, it serves as a significant contributor to national agricultural employment, with direct jobs stemming from coffee cultivation comprising 26% of the total agricultural workforce. This underscores the pivotal role coffee plays in shaping Colombia’s social and economic landscape, solidifying its position as the primary origin of mildly washed coffees for global consumers. However, Colombia’s coffee production grapples with the challenge of operating amidst persistently rainy conditions, fostering an environment conducive to fungal diseases. This, compounded by environmental, economic, commercial, and safety constraints for disease control, creates a multifaceted scenario that continuously tests disease management strategies. Addressing this complex dynamic demands a crop protection framework that seamlessly integrates efficient and sustainable methodologies. Such methodologies should prioritize outbreak prevention, cost-effectiveness, adherence to national and international regulations, and the preservation of environmental and human health. Integrated disease management emerges as a solution capable of optimizing productivity tailored to the unique conditions of each plot. By mitigating the impact of pathogens while responsibly utilizing and conserving natural resources, this approach safeguards the well-being of both producers and consumers alike.

Coffee crispiness (“crespera”), a disease of uncertain etiology, has been endemic in coffee (Coffea arabica L.) plantations in Colombia for at least 60 years. Symptoms typically consist of bud proliferation, abundant short and narrow leaves, phyllody, floral abortion, monospermic fruit, and dwarfing of plants. In severe cases, coffee crispiness disease (CCD) can affect production significantly. In this study, association of a phytoplasma with CCD was indicated by the accumulation of Diene's stain, or 4′, 6-diamidino-2-phenylindole fluorescence, only in phloem of affected plant tissues. The presence of polymorphic phytoplasma cells in phloem sieve tube elements was confirmed by transmission electron microscopy. The disease was transmitted successfully by grafting symptomatic shoots from CCD-affected C. arabica plants onto young, healthy rootstocks; however, symptoms failed to develop after mechanical inoculation of young plants with extracts derived from diseased plant tissues. A nested polymerase chain reaction (PCR) assay employing primer pairs P1/P7 followed by FU5/rU3 amplified a 16S ribosomal DNA product (941 bp) exclusively from DNA of diseased plants. Sequence and phylogenetic analysis of the nested PCR product identified the CCD phytoplasma as a new strain member of group 16SrIII (X-disease group). This is the first report of a phytoplasma infecting coffee plants.