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Bacteria halo blight (BHB), a coffee plant disease caused by Pseudomonas syringae pv. garcae, has been gaining importance in producing mountain regions and mild temperatures areas as well as in coffee nurseries. Most Coffea arabica cultivars are susceptible to this disease. In contrast, a great source of genetic diversity and resistance to BHB are found in C. arabica Ethiopian accessions. Aiming to identify quantitative trait nucleotides (QTNs) associated with resistance to BHB and the influence of these genomic regions during the domestication of C. arabica, we conducted an analysis of population structure and a Genome-Wide Association Study (GWAS). For this, we used genotyping by sequencing (GBS) and phenotyping for resistance to BHB of a panel with 120 C. arabica Ethiopian accessions from a historical FAO collection, 11 C. arabica cultivars, and the BA-10 genotype. Population structure analysis based on single-nucleotide polymorphisms (SNPs) markers showed that the 132 accessions are divided into 3 clusters: most wild Ethiopian accessions, domesticated Ethiopian accessions, and cultivars. GWAS, using the single-locus model MLM and the multi-locus models mrMLM, FASTmrMLM, FASTmrEMMA, and ISIS EM-BLASSO, identified 11 QTNs associated with resistance to BHB. Among these QTNs, the four with the highest values of association for resistance to BHB are linked to g000 (Chr_0_434_435) and g010741 genes, which are predicted to encode a serine/threonine-kinase protein and a nucleotide binding site leucine-rich repeat (NBS-LRR), respectively. These genes displayed a similar transcriptional downregulation profile in a C. arabica susceptible cultivar and in a C. arabica cultivar with quantitative resistance, when infected with P. syringae pv. garcae. However, peaks of upregulation were observed in a C. arabica cultivar with qualitative resistance, for both genes. Our results provide SNPs that have potential for application in Marker Assisted Selection (MAS) and expand our understanding about the complex genetic control of the resistance to BHB in C. arabica. In addition, the findings contribute to increasing understanding of the C. arabica domestication history. [ABSTRACT FROM AUTHOR]

Sensory attributes were evaluated from Arabica coffee genotypes growing in two places in Brazil, Mandaguari and Londrina. Post-harvest and roasted process was standardized. Free choice profiling sensory analysis was apply to investigate the influence of genetic variability and local cultivation (Londrina and Mandaguari, Brazil) on the sensory characteristics of coffee genotypes. A sensory panel evaluated coffees from Mandaguari in two groups: one (Sarchimor derived, IPR100, IPR102, IPR105, IPR106) characterized by transparency, coffee colour, green aroma, taste (green, bitter, fermented, astringent) and a watery texture, another group (Catuaí, Sarchimor derived, IPR101, IPR103) was characterized by coffee colour, brightness, aroma (coffee, acid, sweet, chocolate), acidity, bitterness, burnt aroma, sweetness and full-bodied. Coffees from Londrina presented brightness, coffee colour, sweet, green, burnt aroma, astringent, bitter, fermented, green taste; and watery texture (Catuaí, IPR97, IPR98, IPR100). Another group (Sarchimor derived, IPR101, IPR102, IPR103, IPR105, IPR106) were associated with turbidity, aroma (green, coffee, sweet), acidity, astringency, bitterness, sweetness and full-bodied. Catuaí, Iapar59, IPR99, IPR101, IPR103 and IPR108 exhibited positive attributes when grown in either locale. Edaphoclimatic conditions play a major role in the sensory profiles of coffee. [ABSTRACT FROM AUTHOR]

Lipids are compounds that play an important role in coffee bean development, contributing to beverage quality. Genome-wide association studies (GWAS) were conducted to pinpoint quantitative trait nucleotides (QTNs) linked to lipid metabolism in Coffea arabica. Genotyping by sequencing (GBS) and phenotyping data from 104 wild C. arabica accessions, Mundo Novo cultivar, and C. arabica var. Typica were utilized. GBS data were aligned to C. arabica Et039 reference genome, and both single-locus and multi-locus GWAS methods were employed. Methods were adjusted for kinship matrix, population structure, and principal component analysis. Of the 19 QTNs identified, 5 showed consistency across different population structure adjustments. The multi-locus methods mrMLM and FarmCPU proved more effective in identifying QTNs associated with lipid content. Four QTNs were situated near seven genes potentially involved in lipid metabolism. Higher frequencies of identified QTNs in accessions with elevated lipid content suggest their utility as markers for coffee plant breeding. [ABSTRACT FROM AUTHOR]

The aim of this work was to validate markers linked to the SH3 gene of coffee leaf rust (CLR) resistance and use them in assisted selection. Initially, we validated the markers in genotypes already known to carry SH3. Next, we performed phenotype and genotype evaluation for resistance to CLR in coffee plants growing under field conditions. We used Arabica coffee progenies derived from BA-10, which carries the SH3 gene due to introgression of C. liberica. Three SCAR markers (SP-M16-SH3, BA-48-21O-f, and BA-124-12K-f) and one SSR marker (Sat244) linked to SH3 gene were used to amplify the coffee plants' DNA. Our assessments of markers validation in resistant genotypes, SP-M16-SH3 and BA-124-12K-f, were efficient to identify the SH3 gene. These two markers were used to evaluate the progenies derived from BA-10 and were significantly linked to the phenotype evaluations. The SP-M16-SH3 marker was more efficient, with the advantage of being codominant. [ABSTRACT FROM AUTHOR]