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[Effects of fertilization on the growth, photosynthetic characteristics and yield of Coffea arabica].

Coffea arabica is a major economic plant in agriculture plantation in tropical and subtropical areas in the world. This paper reports the experimental results on the fertilization strategy in Yunnan, China. Effects of varied levels of nitrogen (N), phosphorus (P), potassium (K) nutrients on the growth, photosynthetic characteristics and yield in three-year old saplings of C. arabica with the density of 4500 individuals per hectare were measured. In general, N is the most important factor influencing the growth, photosynthetic capacity and yield of C. arabica, followed by K and P, respectively. The yield can be improved through spraying appropriate amount of trace elements in the leaves. The optimum matching experiments in fertilization level of N:P2O5: K2O is at the ratio of 1:0.5:1. The high yield of C. arabica need high nutrient demands, but the optimum amount of fertilizer of N, P2O5, K2O is 100, 50, 100 g per individual according to the cost-benefits analysis. The yield of C. arabica was closely related with the numbers of branch, total leaf areas and maximum rate of net photosynthesis (Amax) among different treatments. Different fertilization strategy had no significantly effects on the photochemical efficiency in dawn, but all indicators showed that the higher-fertilized plants could significantly alleviate diurnal photoinhibition.

Biomass↗

Genetic diversity of forest arabica coffee (Coffea arabica L.) in Ethiopia as revealed by random amplified polymorphic DNA (RAPD) analysis.

Genetic diversity within the forest Coffea arabica L. gene pool in Ethiopia has not been extensively examined with molecular markers. In the present study, a total of 75 polymorphic RAPD bands generated by twelve random primers were used to assess genetic diversity among 144 genotypes representing 16 C. arabica populations. The number of polymorphic bands detected with each primer ranged from 2 to 9 with a mean of 6.25 bands per primer. Banding patterns ranged in percentage polymorphism from 37% to 73% with an overall mean of 56% for the populations analyzed. The amount of genetic variation among populations estimated by Shannon-Weaver diversity index was (H = 0.30). The within population and between populations differentiation values were 0.65 and 0.35, respectively. Genetic differentiations within and between zones of sample collection sites were 0.80 and 0.20, respectively. Within population average similarities estimated by simple matching coefficients ranged from 0.72 to 0.85, with an overall average of 0.78. In the cluster analysis that used individual samples as operational taxonomic units, most of the representatives of the same population failed to cluster before they joined members of other populations. Nevertheless, most of the populations were clustered on the basis of their geographic closeness and an east west differentiation was observed at approximately 75% similarity. The results obtained provide information on how to select sites for in situ conservation of C. arabica germplasm.

Coffea↗

Determination of the 2H/1H and 15N/14N ratios of Alkylpyrazines from coffee beans (Coffea arabica L. and Coffea canephoravar. robusta) by isotope ratio mass spectrometry.

The delta15N(AIR) and delta2H(VSMOW) data for several alkylpyrazines formed during the roasting process of coffee are reported. Samples of commercially available roasted (n = 9) as well as self-roasted (n = 8) coffee beans (Coffea arabica L. and Coffea canephora var. robusta) of different origins were investigated. By use of extracts prepared by simultaneous distillation extraction (SDE) and subsequently fractionated by liquid chromatography on silica gel, on-line capillary gas chromatography-isotope ratio mass spectrometry was employed in the combustion (C) and pyrolysis (P) modes (HRGC-C/P-IRMS) to determine the delta15N(AIR) and delta2H(VSMOW) values, respectively. In addition to the constituents of coffee beans, data for commercial synthetic alkylpyrazines and substances declared to be "natural" were determined. The delta15N(AIR) data for coffee alkylpyrazines under study-2-ethyl-5-methylpyrazine (1) and 2-ethyl-6-methylpyrazine (2) (measured as sum 1/2), 2-ethyl-3-methylpyrazine (3), 2-methylpyrazine (4), 2,5-dimethylpyrazine (5) and 2,6-dimethylpyrazine (6) (measured as sum 5/6), and 2,3-dimethylpyrazine (7), as well as 2,3,5-trimethylpyrazine (8)-varied in the range from +8.3 to -10.2 per thousand, thus revealing their biogeneration from amino acids (delta15N(AIR) ranging from +8 per thousand to -10 per thousand). The delta2H(VSMOW) values were determined in the range from -5 per thousand to -127 per thousand. Owing to the analytical differentiation observed between coffee alkylpyrazines and synthetic/"natural" samples of 3, 4, and 7, authenticity assessment of coffee-flavored products seems to be promising, provided that extended data will be available in the future. In the literature, there were no IRMS data available for the alkylpyrazines (1-8) under study.

Coffea↗

Genome-wide analysis of lipoxygenase genes in Coffea arabica and its diploid progenitors.

Lipoxygenase proteins (LOXs) play a crucial role in plant growth, development, and defense notably through their involvement in jasmonic acid (JA) biosynthesis. Here, we aimed to identify and characterize genes encoding LOXs in three coffee species, Coffea arabica, Coffea canephora, and Coffea eugenioides, and to evaluate whether LOX genes are differentially expressed following hexanoic acid application in Coffea arabica. We found 18 LOX genes in Coffea arabica and 9 genes each in Coffea eugenioides and Coffea canephora. Chromosomal localization analyses revealed strong correspondence between the LOX genes of tetraploid Coffea arabica and those of its putative diploid progenitors, Coffea eugenioides and Coffea canephora. Transcriptomic and enzymatic analyses showed that hexanoic acid application modulates the expression of specific LOX genes and alters LOX activity in leaves and roots of Coffea arabica cvs. Catuaí Vermelho and Obatã. Notably, three LOX genes displayed strong correlations between transcript abundance and enzymatic activity. Together, these results indicate that a subset of LOX genes in Coffea arabica represents promising candidates for detailed functional analyses, as they likely contribute substantially to LOX activity and elicitor-induced defense responses in Coffea species.

Coffea↗

Factors influencing gene introgression into the allotetraploid Coffea arabica L. from its diploid relatives.

Factors controlling gene introgression into cultivated arabica coffee (Coffea arabica L.) were investigated. Interspecific triploid hybrid plants between the tetraploid species C. arabica (2n = 44) and a diploid species (2n = 22), either Coffea canephora or Coffea eugenioides, were backcrossed to C. arabica (male parent). Flow cytometric analysis of the nuclear DNA content revealed that most of the BC(1) individuals derived from triploid hybrids involving C. eugenioides were tetraploid or nearly tetraploid. Among the gametes produced by the interspecific triploid hybrids, those possessing approximately 22 chromosomes appeared strongly favored. The amount of introgression in BC(1) individuals (21 and 43 for the BC(1) progenies involving C. canephora and C. eugenioides, respectively) was estimated using species-specific microsatellite markers. A large number of introgressed markers was observed in all BC(1) individuals. Nevertheless, while the frequency of introgressed markers seemed as expected, assuming random chromosome segregation and diploid gamete formation, in the BC(1) derived from triploid hybrids involving C. canephora, this frequency appeared significantly lower in the BC(1) derived from triploid hybrids involving C. eugenioides. Furthermore, the comparison of reciprocal progenies between C. arabica and triploid interspecific hybrids (C. arabica x C. canephora) used as male or female parent revealed a very strong effect of the backcross direction.

Chimera↗

Separate de Novo and Salvage Purine Pools Are Involved in the Biosynthesis of Theobromine but Not Caffeine in Leaves of Coffea arabica L.

In Coffea arabica leaves, the purine ring of theobromine (3,7-dimethylxanthine) and caffeine (1,3,7-trimethylxanthine) is provided by de novo purine biosynthesis: (a) [14C]glycine, [14C]bicarbonate, and [14C]formate were incorporated into inosine 5[prime]- monophosphate (IMP), sum of adenine nucleotides ([sigma]Ade), theobromine, and caffeine; and (b) incorporation of [14C]formate into IMP, [sigma]Ade, theobromine, and caffeine was inhibited by azaserine, a known inhibitor of de novo purine biosynthesis. Capacity of coffee leaves to salvage added purines was demonstrated by incorporation of [14C]hypoxanthine into [sigma]Ade and the incorporation of [14C]adenosine, [14C]adenine, [14C]inosine, and [14C]hypoxanthine into both theobromine and caffeine. Consistent with synthesis of theobromine from two separate purine nucleotide pools, one synthesized de novo and one via salvage, added xanthine 5[prime]-monophosphate (XMP), inosine, or hypoxanthine failed to reduce the incorporation of [14C]formate into theobromine but diluted the specific radioactivity of [14C]adenosine and [14C]adenine incorporated into theobromine. Evidence that theobromine is not the immediate precursor of caffeine is provided: (a) [14C]xanthine was incorporated into caffeine but not into theobromine; (b) exogenous xanthine diluted the specific radioactivity of caffeine synthesized from [14C]adenine and [14C]hypoxanthine but caused accumulation of radiolabel in theobromine; (c) allopurinol, a known inhibitor of the conversion of hypoxanthine to xanthine, reduced incorporation of [14C]adenine and [14C]hypoxanthine into caffeine but caused accumulation of radiolabel in theobromine; and (d) incorporation of [14C]formate into caffeine, but not into theobromine, was reduced by added XMP, inosine, or hypoxanthine.

Journal Article↗

Regulation of Purine Metabolism in Intact Leaves of Coffea arabica.

The capacity of Coffea arabica leaves (5- x 5-mm pieces) to synthesize de novo and catabolize purine nucleotides to provide precursors for caffeine (1,3,7-trimethylxanthine) was investigated. Consistent with de novo synthesis, glycine, bicarbonate, and formate were incorporated into the purine ring of inosine 5[prime]-monophosphate (IMP) and adenine nucleotides ([sigma]Ade); azaserine, a known inhibitor of purine de novo synthesis, inhibited incorporation. Activity of the de novo pathway in C. arabica per g fresh weight of leaf tissue during a 3-h incubation period was 8 [plus or minus] 4 nmol of formate incorporated into IMP, 61 [plus or minus] 7 nmol into [sigma]Ade, and 150 nmol into caffeine (the latter during a 7-h incubation). Coffee leaves exhibited classical purine catabolism. Radiolabeled formate, inosine, adenosine, and adenine were incorporated into hypoxanthine and xanthine, which were catabolized to allantoin and urea. Urease activity was demonstrated. Per g fresh weight, coffee leaf squares incorporated 90 [plus or minus] 22 nmol of xanthine into caffeine in 7 h but degraded 102 [plus or minus] 1 nmol of xanthine to allantoin in 3 h. Feedback control of de novo purine biosynthesis was contrasted in C. arabica and Cucurbita pepo, a species that does not synthesize purine alkaloids. End-product inhibition was demonstrated to occur in both species but at different enzyme reactions.

Journal Article↗

AFLP analysis of genetic diversity within and among Coffea arabica cultivars.

Genetic diversity of Coffea arabica cultivars was estimated using amplified fragment length polymorphism (AFLP) markers. Sixty one Coffea accessions composed of six arabica cultivars, including Typica, Bourbon, Catimor, Catuai, Caturra and Mokka Hybrid, plus two diploid Coffea species, were analyzed with six EcoRI- MseI primer combinations. A total of 274 informative AFLP markers were generated and scored as binary data. These data were analyzed using cluster methods in the software package NTSYSpc. The differences among cultivars at the DNA level were small, with an average genetic similarity of 0.933. Most accessions within a cultivar formed a cluster, although deviant samples occurred in five of the six cultivars examined due to residual heterozygosity from ancestral materials. Among the six cultivars fingerprinted, the highest level of genetic diversity was found within the cultivar Catimor, with an average genetic similarity of 0.880. The lowest level was found within Caturra accessions, with an average genetic similarity of 0.993. Diversity between C. arabica and two other Coffea species, Coffea canephora and Coffea liberica, was also estimated with average genetic similarities of 0.540 and 0.413, respectively, suggesting that C. canephora is more closely related to C. arabica than is C. liberica. The genetic variation among arabica cultivars was similar to the variation within cultivars, and no cultivar-specific DNA marker was detected. Although arabica cultivars appear to have a narrow genetic base, our results show that sufficient polymorphism can be found among some arabica cultivars with a genetic similarity as low as 0.767 for genetic/QTL mapping and breeding. The assessment of genetic diversity among arabica cultivars provided the necessary information to estimate the potential for using marker-assisted breeding for coffee improvement.

Journal Article↗

[Coffea arabica--production, botanical classification, new components and active agents and their pharmacological effects].

The present paper surveys the latest knowledge about coffee grains (Coffea arabica) as an important part of our everyday life. It lists the botanical classification of its principal species, such as Coffea arabica, Coffea robusta, and Coffea liberica, the most important improved cultivars of production species in the world. The review paper also discusses the economic aspect, lists the most important regions of production, the optimal and farming technological conditions. It points out the occurrence of the individual constituents which have been hitherto isolated, characterized, and chemically defined with some of their physiological effects on the human organism, e.g., the substances of the diterpene type such as kafestol and kahweol and their structure.

Coffee↗

A chromosome-level genome assembly of Coffea arabica L. var. 'Kona Typica'.

Coffea arabica L. var. 'Kona Typica' is renowned for its premium cup quality, but its vulnerability to pests and diseases limits production. To accelerate cultivar improvement, we generated a chromosome-level genome assembly of 'Kona Typica' using PacBio HiFi sequencing and Hi-C scaffolding technology. The final assembly spans 1.13 Gb, with a scaffold N50 of 50.50 Mb, organized into 22 chromosomes. BUSCO assessment indicated a high completeness at 99.1%. We annotated 65,458 protein-coding genes and identified 1,073,545 interspersed repeats, accounting for 65.16% of the genome. Analysis of transposon insertion ages revealed that most long terminal repeat retrotransposons proliferated after the polyploidization event. This high-quality genome assembly of 'Kona Typica' provides a valuable resource for exploring coffee genomic evolution and genetic mechanisms of complex traits, facilitating genomics studies and the development of improved coffee cultivars with enhanced disease resistance and quality traits.

Coffea↗

Effects of water deficit on flower opening in coffee (Coffea arabica L.).

The response of coffee (Coffea arabica L.) floral buds to different water deficits followed by re-irrigation was investigated. Flower opening was stimulated by irrigation after one period of water deficit if predawn leaf water potential declined below -0.8 MPa. Similar stimulation of flowering was observed when less severe but more prolonged water deficits (ca. -0.3 to -0.5 MPa for two weeks) were imposed, even if water deficit was relieved by re-irrigation several times during this period. Consistent results were obtained in the field and in two greenhouse locations. Stimulation of flower opening by water deficit followed by re-irrigation was restricted to buds at the "open white cluster" stage of development (Stage 4). Only buds at this stage exhibited development of secondary xylem. Split-root experiments indicated that a root signal stimulated flower opening, independently of predawn or midday leaf water status. Frequent irrigation to prevent flowering, followed by a controlled water deficit and re-irrigation to stimulate flowering, may represent a practical method to synchronize flowering and shorten the harvest period in leeward coffee production areas in Hawaii.

Journal Article↗

Toxigenic fungi associated with processed (green) coffee beans (Coffea arabica L.).

Processed (green) coffee beans from Coffea arabica in Brazil were assessed for the presence of Aspergillus and Penicillium species both before and after surface sterilisation, the aflatoxigenic and ochratoxigenic potential of the isolates and ochratoxin A levels. Contamination by Aspergillus and Penicillium species was found on 96% and 42%, respectively, of 45 samples from 11 localities. After disinfection with 1% sodium hypochlorite, the levels fell to 47% and 24%, respectively. One hundred and eighty isolates were identified to species level and comprised Aspergillus sections Circumdati (10 species), Flavi (3), Nigri (3), Versicolores (4), while two were teleomorphic species. Eight species of Penicillium were isolated. Within section Circumdati, 75% of the isolates produced ochratoxin A and all except Aspergillus elegans and Aspergillus insulicola have previously been reported to produce ochratoxin A. One-third of the 18 isolates of Aspergillus flavus produced aflatoxin B1 and B2. None of the isolates belonging to Aspergillus section Nigri or Penicillium produced ochratoxin A. Of the 40 bean samples analysed, 58% were infected with potentially ochratoxigenic fungi but only 22% of these were contaminated with ochratoxin A at levels that varied from 0.47 to 4.82 ng/g, with an average contamination level of 2.45 ng/g.

Aflatoxins↗

Nickel elicits a fast antioxidant response in Coffea arabica cells.

The antioxidant responses of coffee (Coffea arabica L.) cell suspension cultures to nickel (Ni) were investigated. Ni was very rapidly accumulated in the cells and the accumulation could be directly correlated with the increase of NiCl(2) concentration in the medium. At 0.05 mM NiCl(2) growth was stimulated, but at 0.5 mM NiCl(2), the growth rate was reduced. An indication of alterations in the presence of reactive oxygen species was detected by an increase in lipid peroxidation at 0.5 mM NiCl(2). Catalase (CAT; EC 1.11.1.6), glutathione reductase (GR; EC 1.6.4.2), ascorbate peroxidase (APX; EC 1.11.1.11), guaiacol peroxidase (GOPX; EC 1.11.1.7) and superoxide dismutase (SOD; EC 1.15.1.1) activities were increased, particularly at earlier NiCl(2) exposure times and the activities were higher at 0.5 mM NiCl(2) for most of exposure times tested. Non-denaturing PAGE revealed one CAT isoenzyme, nine SOD isoenzymes and four GR isoenzymes. The SOD isoenzymes were differentially affected by NiCl(2) treatment and one GR isoenzyme was increased by NiCl(2). NiCl(2) at 0.05 mM did not induce lipid peroxidation and the main response appeared to be via the induction of SOD, CAT, GOPX and APX activities for the removal of the reactive oxygen species and through the induction of GR to ensure the availability of reduced glutathione.

Antioxidants↗

Water utilization, plant hydraulic properties and xylem vulnerability in three contrasting coffee (Coffea arabica) cultivars.

Water use, hydraulic properties and xylem vulnerability to cavitation were studied in the coffee (Coffea arabica L.) cultivars San Ramon, Yellow Caturra and Typica growing in the field under similar environmental conditions. The cultivars differed in growth habit, crown morphology and total leaf surface area. Sap flow, stomatal conductance (g(s)), crown conductance (g(c)), apparent hydraulic conductance of the soil-leaf pathway (G(t)), leaf water potential (Psi(L)) and xylem vulnerability to loss of hydraulic conductivity were assessed under well-watered conditions and during a 21-day period when irrigation was withheld. Sap flow, g(c), and G(t) were greatest in Typica both with and without irrigation, lowest in San Ramon, which was relatively unresponsive to the withholding of irrigation, and intermediate in Yellow Caturra. The cultivars had similar g(s) when well watered, but withholding water decreased g(s) more in Typica and Yellow Caturra than in San Ramon. Typica had substantially lower Psi(L) near the end of the unirrigated period than the other cultivars (-2.5 versus -1.8 MPa), consistent with the relatively high sap flow in this cultivar. Xylem vulnerability curves indicated that Typica was less susceptible to loss of hydraulic conductivity than the other cultivars, consistent with the more negative Psi(L) values of Typica in the field during the period of low soil water availability. During soil drying, water use declined linearly with relative conductivity loss predicted from vulnerability curves. However, cultivar-specific relationships between water use and predicted conductivity loss were not observed because of pronounced hysteresis during recovery of water use following soil water recharge. All cultivars shared the same functional relationship between integrated daily sap flow and G(t), but they had different operating ranges. The three cultivars also shared common functional relationships between hydraulic architecture and water use despite consistent differences in water use under irrigated and dry soil conditions. We conclude that hydraulic architectural traits, rate of water use per plant and crown architecture are important determinants of short- and long-term variations in the water balance of Coffea arabica.

Journal Article↗

Genome-wide subgenome-resolved analysis validates chromosome 4 differentiation and prioritizes introgressed Coffea arabica accessions.

Chromosome 4 introgression in Timor hybrid-derived Coffea arabica is established, but the robustness of accession prioritization and the relative strength of cultivated-introgressed differentiation across the canephora-derived (sgC) and eugenioides-derived (sgE) subgenomes remained unclear under explicit subgenome filtering. We reanalyzed public genomic resources from 44 coffee accessions using strict contig-level subgenome filtering, Arabica-only population-structure analysis, SNP-panel sensitivity testing, genome-wide differentiation scans, permutation testing, and direct sequence alignment. Population structure and accession rankings were stable across marker densities and random seeds, and the same six introgressed references were retained throughout. Chromosome 4 ranked first in both subgenomes, with a strong sgC signal and a markedly weaker sgE signal; independent baseline-panel permutation tests supported both chromosome 4-associated signals. Direct alignment supported correspondence to the expected chromosome 4 pseudomolecules while showing incomplete source coverage and unresolved exact boundaries. Alignment-supported blocks contained 88 sgC and 62 sgE provisional defense-, signaling-, and regulatory-associated annotations. These results provide a genome-wide, quantitatively validated framework for prioritizing introgressed germplasm and candidate chromosome 4 regions for phenotype-linked coffee research without implying equivalent introgression, exact liftover, or causal resistance genes.

Coffea arabica↗

Characterizing plasma membrane H+-ATPase in two varieties of coffee leaf (Coffea arabica L.) and its interaction with an elicitor fraction from the orange rust fungus (H. vastatrix Berk and Br.) race II.

Early intercellular signaling in Coffea arabica L.-Hemileia vastatrix host-pathogen interaction was studied, using inside-out plasma membrane from two varieties of coffee leaf and a fungal fraction to determine the plant's biochemical responses. Microsomal pellets (100,000 x g) from the susceptible (Caturra) and resistant (Colombia) coffee leaf varieties were purified by partitioning in two-polymer DEX (6.3% w/w) and PEG (6.3% w/w) system aqueous phase. Fungal material was obtained from orange rust Hemileia vastatrix Berk and Br. race II urediospore germ tubes. Plasma membrane vesicles were preferentially localized to PEG phase, as indicated by its enzyme marker distribution. Both H(+)-ATPase activities displayed similar kinetic and biochemical characteristics, comparable to those described for P-type ATPases. Several enzymes may play pivotal roles in plants regarding early interaction with fungal elicitors. Studies of fungal fractions' effects on H(+)-ATPase and both varieties' proton pumping activities were thus carried out. Concentration as low as 0.1 Gluc eq. ml(-1) fungal fraction induced specific inhibition of H(+)-ATPase and the resistant variety's proton pumping activities. The present work describes characterizing the H(+)-ATPase plasma membrane from two Coffea arabica L. varieties (Caturra and Colombia) for the first time and the race specific inhibitory effect of a crude fungal fraction on both H(+)-ATPase and the resistant variety's proton pumping activities.

Cell Membrane↗

Culture-induced variation in plants of Coffea arabica cv. caturra rojo, regenerated by direct and indirect somatic embryogenesis.

Amplified fragment-length polymorphism (AFLP) was used to evaluate the stability of DNA in regenerated plantlets of Coffea arabica obtained by direct (DSE) and indirect somatic embryogenesis (ISE). Cluster analysis using the unweighted pair-group method (UPGMA), showed no specific grouping pattern related to the type of embryogenesis. These results suggest that the somatic embryogenesis (SE) process has a mechanism for the selection of normal and competent cells. Bulked DNA from regenerated plants obtained by DSE and ISE, and from the mother plants, was used to characterize specific AFLP fragments associated with each SE process. Twenty-three primer combinations were tested. A total of 1446 bands were analyzed, with 11.4% being polymorphic and 84% being specific for regenerated plants. Furthermore, specific bands were detected for DSE, ISE, and the mother plants. These results indicate that the SE process induces rearrangements at the DNA level and demonstrates discrepancies between the mechanisms involved in each SE process. Coffea arabica breeding programs that involve DSE and ISE can use AFLP as an additional tool for assessing DNA stability.

Breeding↗

Intermittent light irradiation with a second-scale interval enhances caffeine production by coffea arabica cells

We developed novel equipment that intermittently illuminates Coffea arabica cell suspensions at a second-scale interval and investigated how intermittent irradiation enhances caffeine biosynthesis by C. arabica cells. The light/dark cycles consisting of 2 s of illumination and 18 s of darkness enhanced caffeine production, reaching the same level as for continuous light. The intermittent illumination increased the production efficiency regarding light consumption by a factor of 10. Caffeine production was determined by light intensity regardless of intermittent or continuous light irradiation. We propose a new concept for designing a photobioreactor that is applicable to secondary metabolite production by plant cell culture.

Journal Article↗