Hibrido De Timor Research Articles

Chemical ingredients characterization basing on 1H NMR and SHS-GC/MS in twelve cultivars of Coffea arabica roasted beans

This work aimed to study the composition differences of roasted beans between 12 coffee cultivars (Catimor 7963, HIBRIDO DE TIMOR, Ruiru 11, Castillo, DTARI 296, DTARI 366, DTARI 392, DTARI 585, SL28, SL34, Catuai-Amarelo and Catuai-Vermelho) from Bourbon-Typica group and Introgressed group under subtropical humid monsoon climate. The water-soluble compounds of roasted coffee beans were characterized by proton nuclear magnetic resonance spectroscopy (1H NMR), and the aroma components were analyzed by static headspace gas chromatography mass spectrometry (SHS-GC/MS). In total, 20 water soluble compounds and 43 volatile compounds were identified. Both water-soluble and volatile compounds are rich in acidic substances, and the content varied depending on the cultivars. Furthermore, principal component analysis (PCA) clustered 12 coffee cultivars into four groups. The four different chemically defined clusters of Arabica cultivars produced by chemical differences cannot reflect the traditional grouping based on introgressed, and it is one-sided to judge coffee quality based on lineage. These results give further insight into the quality characteristics of different coffee cultivars, which is of great significance for guiding the adjustment of cultivars' structure and the breeding of new cultivars.

English

The Coffee Berry Disease (CBD) epidemics destroy up to 100% of the crop on a susceptible variety. Resistance to CBD is conferred by the T-gene in Hibrido De Timor  (HDT), R-gene in Rume Sudan (RS), and k-gene in K7, which were assembled in resistance varieties Ruiru 11(R11) and Batian. This study aimed to evaluate the genetic relationship between R11 and Batian with their parents' HDT, RS,  SL8 and confirm the occurrence of T and R genes using DNA markers. Genome-wide single nucleotide polymorphism (SNP) markers were obtained through Diversity Arrays Technology sequencing (DArTseq). The genetic relationship was analyzed by Principal Component Analysis and hierarchical clustering. The Tgene was confirmed using Microsatellite primer, Sat 235 while the R gene was by marker sequence search within the DArTseq result files. The PC1 accounted for 42% of the total variation. Hierarchical clustering revealed less than 10% dissimilarity index apart from HDT that recorded above 20%. All the R11 and Batian genotypes carry the T gene. Eleven genotypes carry both T and R genes, therefore, with broad-based resistance to CBD. The study confirmed the narrow genetic relations within the Coffea arabica coffee varieties and further confirmed the occurrence of multiple gene resistance in R11 and Batian that will not break easily to new pathogen races.   Key words: Coffee berry disease, diversity arrays technology sequencing, T gene, R gene, Ruiru 11, Batian, SL 28, codominant.

English

Coffee Berry Disease (CBD) is a major constraint that limits Coffea arabica production, whose resistance is governed by three genes, T, R that are dominant and recessive k in varieties Hibrido de Timor (HDT), Rume Sudan (RS) and K7 respectively. This study identified the genomic region occupied by R-gene using F2 genotypes from varieties RS and SL28; and Single Nucleotide Polymorphic (SNP) markers obtained through Genotyping by Sequencing. Redundant markers were removed and 699 markers obtained for linkage mapping and quantitative trait loci (QTL) analysis. The Linkage map spread over 5525.39 cM across eleven coffee chromosomes (Chr). The QTL was analyzed by both Interval Mapping (IM) and Inclusive Composite Interval Mapping (ICIM) using SNP markers and CBD resistance mean scores of the F2 genotypes and their parents. Three QTLs, qCBD 1-1 in Chr 1, qCBD 2-1 and qCBD 2-2 in Chr 2 were significantly associated with CBD resistance, detected by both IM and ICIM at LOD ≥ 2.5 (P≤0.05). Two flanking markers that were closer to the three QTLs; 100025973|F|0-59:T>C-59:T>C at a distance of 3 centi Morgans (cM) from qCBD 1-1 and 100034991|F|0-44:C>T-44:C>T, that was flanking in both qCBD 2-1 and qCBD 2-2 at 12.5 cM, whose SNPs were significant (P≤0.05), are recommended for validation and use in marker-assisted breeding. Key words: Coffee berry disease, linkage map, quantitative trait loci, genotyping by sequencing, single nucleotide polymorphism, SL 28, R-gene.

Genome-Wide Association Study identify the genetic loci conferring resistance to Coffee Berry Disease (Colletotrichum kahawae) in Coffea arabica var. Rume Sudan

Coffee Berry Disease (CBD) caused by the fungal pathogen Colletotrichum kahawae destroys about 80% of the crop on susceptible Coffea arabica cultivars if no control is applied. Resistance to CBD is governed by three genes: T, R that are dominant, and the recessive k in varieties Hibrido de Timor, Rume Sudan (RS), and K7 respectively. The marker for the T-gene had earlier been identified. The study aimed to identify the DNA marker for the R-gene from RS. The mapping population comprised of 106 F2 genotypes from varieties RS (resistant) and SL28 (susceptible). The genotypes were assessed for their reaction to CBD using hypocotyl inoculation test on a scale of 1–12. The Single Nucleotide Polymorphism (SNP) markers were obtained through Genotyping by Sequencing. The population structure was assessed by both principal component analysis and marker-based kinship while pairwise linkage disequilibrium was estimated using squared allele frequency correlations (r2). Genome-Wide Association Study was carried out using a compressed mixed linear model in Genomic Association and Prediction Integrated Tool. Two SNP markers were significantly associated with CBD resistance in coffee Chromosomes (Chr) 1 and 2 accounting for 12.5% and 11% respectively of the total phenotypic variation explained by the model. The sequence search for the markers was associated with proteins for disease resistance within the NCBI database. The two SNP markers 100025973|F|0-59:T > C-59:T > C and 100034991|F|0-44:C > T-44:C > T are identified as DNA markers for the genetic loci conferring resistance to CBD in RS, christened as Ck-2 and Ck-3 and are recommended for marker assisted selection.

English

Coffee supports livelihoods of approximately 125 million families worldwide and over 700,000 households in Kenya. The epidemics of Coffee berry disease (CBD), caused by Colletotrichum kahawae, destroy up to 80% of the developing berries on susceptible varieties. The control of the disease using chemicals accounts for 30 to 40% of the production cost and contributes to environment pollution, hence the use of resistant varieties. Resistance to CBD is conferred by three genes; R, T that are dominant and k which is recessive, from coffee varieties Rume Sudan (RS), Hibrido de Timor (HDT) and K7 respectively. Although the T gene has been mapped, there is need for genetic mapping of the other genes to improve selection efficiency. The objective of this study was to evaluate F2 populations of RS x SL28 for their suitability to genetic mapping of the R gene in RS. Resistance to CBD was evaluated by hypocotyl inoculation on their F3 progenies. The data was subjected to Analysis of Variance (ANOVA) and Chi Square (χ²) test. The ANOVA result showed significant differences (P≤0.05) between the genotypes to CBD resistance. The phenotypic ratio of resistance to susceptible plants fitted the 3:1 monohybrid inheritance ratio for a dominant gene using the χ² test (χ² = 1.0565 and P=0.30207, P≤0.05), hence confirming the suitability of the F2 populations for the identification of the DNA marker for R gene in RS. Key words: Rume Sudan, SL 28, Coffee Berry Disease, mapping population, hypocotyl, inoculation. &nbsp

Indirect somatic embryogenesis in Coffea with different ploidy levels: a revisiting and updating study

Indirect somatic embryogenesis (ISE) is required for plant propagation and a prerequisite for applications that may provide new germplasms. Genetic, epigenetic and physiological features of the explant donor are barriers for ISE establishment, hindering its wide use. Despite the identification and/or expression analysis of genes during ISE, no approach to establish the karyotype aspects has been performed so far. So, this study aims to establish the ISE and compare the in vitro responses between diploid (Coffea canephora and Coffea eugenioides), allotriploid (“Hibrido de Timor”—HT) and true allotetraploid (Coffea arabica) Coffea in a taxonomic and evolutive scenario. Under the same in vitro conditions, the four Coffea differed from each other during ISE. Leaf explants of the true allopolyploids yielded the highest mean number of friable calli (FC) in relative short time and visually exhibiting more pronounced length. FC of the allotetraploid C. arabica presented the highest mean number of mature cotyledonary somatic embryos (MCSE), which were also recovered faster in this species. However, MCSE mean number in HT was the same or lower than diploid Coffea. Besides, intraspecific variation related to the ISE responses was observed in each Coffea, mainly the mean number of FC obtained from ex vitro and in vitro C. arabica and C. eugenioides explants. So, epigenetic and physiologic features may also have influenced the ISE responses. The findings provide the basis for performing other approaches considering the ploidy level, epigenetic and physiological backgrounds. Besides, the data also contributed for understanding about the consequences of polyploidy.

The Híbrido de Timor germplasm: identification of molecular diversity and resistance sources to coffee berry disease and leaf rust

The main phytosanitary problems affecting global coffee production are the fungal diseases known as rust, caused by Hemileia vastatrix Berkeley and Broome, and coffee berry disease (CBD), induced by Colletotrichum kahawae Waller and Bridge. The main disease control strategy is the use of resistant coffee cultivars. Hibrido de Timor is the most important source of resistant varieties used in breeding programs worldwide. The objective of this work was to characterize the diversity and disease resistance of 152 HdT genotypes from the germplasm collection at the Universidade Federal de Vicosa (UFV). Accessions were phenotyped with H. vastatrix races II and XXXIII. Molecular analysis was carried out with 29 random microsatellite markers or single sequence repeats (SSRs), and two SSRs associated with the CBD resistance gene Ck-1. All accessions in the germplasm collection were resistant to H. vastatrix race II, and 141 were resistant to H. vastatrix race XXXIII. Based on the presence of markers, there were 106 accessions containing the CBD resistance gene Ck-1. In the diversity study, the 152 accessions clustered into 21 different groups. A unique molecular profile (fingerprint) was determined for each individual, using 52 alleles from 22 SSR markers. The HdT germplasm of UFV was highly diverse, and included 99 accessions with multiple disease resistance genes, including the CBD resistance gene Ck-1, and others conferring resistance to H. vastatrix races II and XXXIII.

Productivity and Sensory Quality of Arabica Coffee in Response to Pruning Type ‘Esqueletamento’

Through the pruning type ‘esqueletamento’ it was developed a technology for the management of trees called “Zero Yield” in order to keep the size of the crop and eliminate the harvesting in a low yield season, which usually compromises the earnings of the coffee grower. With this technology, the harvest takes place every two years, always in years of high yield season. This technology is highly dependent on climate, and genotype. Given this, the objective of the study was to select genotypes of Coffea arabica L. responsive to pruning type ‘esqueletamento’, with high productivity and high potential for quality of drink for specialty coffee production. The experiment was deployed in the Coffee Sector at the Universidade Federal de Lavras (UFLA) in December 2005 and after six crops, it has undergone the pruning type ‘esqueletamento’ in August 2014. 20 genotypes were evaluated, being 18 progenies in F5 generation, derived from the cross between cultivars of the Catuaí Group with coffees of germplasm Icatu and germplasm “Hibrido de Timor” and two commercial cultivars as witnesses. (Tupi IAC 1669-33 and Obatã IAC 1669-20). The following characteristics were evaluated: productivity (before and after pruning), vegetative vigor, the incidence of leaf rust, dull fruits, sieve No.16 and above, grain type mocha, aspect, and quality of drink. The genotypes 9 (H516-2-1-1-18-1-1), 12 (H516-2-1-1-18-1-4), 16 (H419-3-4-5-2-1-3), 18 (H419-3-4-5-2-1-5) and the cultivar Tupi IAC 1669-33 were responsive to the ‘esqueletamento’, with productivity after pruning higher than the maximum reached before the adoption of the pruning. All genotypes with the exception of Catucaí Amarelo 24/137 showed potential for the production of specialty coffees.

IAC 125 RN - A dwarf coffee cultivar resistant to leaf rust and root-knot nematode

Abstract IAC 125 RN was derived from a cross between the coffee cultivar Villa Sarchi and the Hibrido de Timor CIFC 832/2. The coffee trees are short and resistant to races 1 and 2 of the nematode Meloidogyne exigua and to all races of coffee rust, Hemileia vastatrix, present in Brazil. Brazil.

Population structure and genetic diversity of coffee progenies derived from Catuaí and Híbrido de Timor revealed by genome-wide SNP marker

The use of single nucleotide polymorphism (SNP) molecular markers has provided advances in selection methodologies used in breeding programs of different crops, reducing cost and time of cultivar release. Despite the great economic and social importance of Coffea arabica, studies with SNP markers are scarce and a small number of SNP are available for this species, when compared with other crops of agronomic importance. Thus, the objective of this study was to identify and validate SNP molecular markers for the species Coffea arabica and to introduce these markers to genetic breeding by means of an accurate analysis of the diversity and genetic structure of breeding populations of this species. After quality filtering, 11,187 SNP markers were selected from the coffee population obtained from crosses between the genotypes Catuai and Hibrido de Timor. A great number of markers were distributed in the 11 chromosomes, within transcribed regions, and were used to estimate the genetic dissimilarity among the individuals of the breeding population. Dendrogram analysis and a Bayesian approach demonstrated the formation of two groups and the discrimination of all genotypes evaluated. The expressive number of SNP molecular markers distributed throughout C. arabica genome was efficient to discriminate all the accessions evaluated in the experiment, clustering them according to their genealogies. This work identified mixtures within the progenies. The genotyping data also provided detailed information about the parental genotypes and led to the identification of new candidate parents to be introduced to the breeding program. The study discussed population structure and its consequence in obtaining improved varieties of C. arabica.

From chromosome doubling to DNA sequence changes: outcomes of an improved in vitro procedure developed for allotriploid “Híbrido de Timor” (Coffea arabica L. × Coffea canephora Pierre ex A. Froehner)

Since 1966, chromosome doubling has been performed mainly in vitro, associating anti-tubulin treatment and different plant tissues showing proliferative cells. Despite the achieved improvements, some bottlenecks have been pointed out, such as the low rate of polyploids and high rate of mixoploid plantlets. To overcome these hurdles, some approaches have indicated that indirect somatic embryogenesis (ISE) constitutes an alternative trigger for chromosome doubling, especially for homoploid and anorthoploid germplasms. In this way, a guideline has been developed for hexaploidization of the Coffea line “Hibrido de Timor” (HT) ‘CIFC 4106’ (anorthoploid, 3x = 33 chromosomes, 1C = 2.10 pg, Coffea canephora × Coffea arabica) from friable embryogenic calli (FEC) treated with colchicine. From this, a relatively high percentage (49.3%) of HT hexaploids (6x = 66 chromosomes, 2C = 4.20 pg) was obtained, without recovery of mixoploids. Besides confirmation of endomitosis induction through the obtained hexaploids, SSR markers revealed that the FEC/colchicine strategy also resulted in loss of allelic diversity in 39 regenerated HT plantlets, demonstrating its genotoxic effect. Considering these results, the present procedure resolved the main bottlenecks for chromosome doubling, which have been reported since the discovery and isolation of the anti-tubulin colchicine in 1930. Hexaploid HT plantlets have enriched Coffea germplasm banks as a new genetic resource since the resolution of their karyotype and DNA sequence. Just as the true allotetraploid C. arabica and the allotriploid HT ‘CIFC 4106’, the hexaploid HT is relevant to investigate the genomic and phenotypic changes arising from polyploidization events.

Marker-assisted selection provides arabica coffee with genes from other Coffea species targeting on multiple resistance to rust and coffee berry disease

Selecting superior genotypes is facilitated by marker-assisted selection (MAS), which is particularly suitable for transferring disease resistance alleles because it nullifies environmental effects and allows selection of resistant individuals in the absence of the pathogen or race, enabling preventive breeding. Molecular markers linked to two major genes (SH3 and SH?), conferring resistance to coffee rust, and those linked to the Ck-1 gene, conferring resistance to coffee berry disease (CBD), have previously been identified. These markers were validated and used in a progeny of crosses between Indian selections with Coffea arabica cultivars. Eleven resistant individuals homozygous for SH3 were identified by MAS. Of these, seven carry SH? from Hibrido de Timor and the gene introduced from Coffea liberica (SH3). SH? was characterized as derived from Coffea canephora. Thus, it was possible to identify C. arabica genotypes carrying important genes for rust resistance introgressed from other coffee species. MAS also allowed identification of sources of CBD resistance for use in preventive breeding for resistance to this serious disease. Using two validated molecular markers, two coffee plants carrying Ck-1 were identified: the UFV 328-60 genotype (F2) was resistant and homozygous based on both molecular markers but exhibited no markers related to SH3 and SH?, and the UFV 317-12 genotype (F1) was resistant and homozygous but resistant and heterozygous based on CBD-Sat207 and CBD-Sat235, respectively. Along with possessing Ck-1, the latter carries SH?. Overall, plants carrying different genes for resistance to rust and CBD were identified. These plants are important sources for gene pyramiding in breeding programs aimed at multiple and durable resistance.

Divergence among arabica coffee genotypes for sensory quality

The production of specialty coffees is the main criterion to add value to the product. However, there is a lack of information regarding genetic variability of C. arabica for quality improvement. The aim of this study was to analyze the genetic divergence among Coffee arabica genotypes regarding the potential cup quality, possible limitations and their potential use in breeding programs to improve quality. We evaluated 101 coffee genotypes from the Germplasm Active Bank of Empresa de Pesquisa Agropecuaria de Minas Gerais, covering different groups of genealogical origin. A randomized block design was used with two replications. Sensory analysis of the beverage was performed by two tasters per sample (repetition), using the Cup of Excellence methodology enhanced by the Brazilian Specialty Coffee Association. The attributes assessed were clean cup, sweetness, acidity, body, flavor, aftertaste, balance, overall and final score. K-means and Ward clustering methods were used to study the genotypes divergence. Based on sensory scores, the formed clusters differed with regards to all sensory characteristics (P ? 0.01). Three K-means clusters were formed among 40, 45 and 16 genotypes, with final average scores of 80.11, 83.17 and 87.56 points, respectively. Ninety percent of the genotypes evaluated have the genetic potential to produce specialty coffees. The observed divergence indicates the potential of genetic gains for quality and the Hibrido de Timor germplasm can be used for this purpose.

Following the track of “Híbrido de Timor” origin by cytogenetic and flow cytometry approaches

The supposedly first plant of the coffee cultivar “Hibrido de Timor” (HT) was found in 1927, being denoted as HT CIFC 4106. According to different researchers, this plant originated from a natural interspecific hybridation between Coffea arabica (4x = 44) and Coffea canephora (2x = 22). From HT CIFC 4106, other HT accessions were obtained and employed to establish germplasm banks in some countries. As HT has been widely used in Coffea breeding programs, this study aimed to characterize different HT accessions with regard to ploidy, nuclear DNA content and base composition. Based on these data, the ploidy of HT CIFC 4106 was determined, suggesting that this accession is an allotriploid formed from reduced reproductive cell of C. canephora and of C. arabica. All HT CIFC 4106 plants exhibited the same 2C-value, AT% and chromosome number, showing that vegetative propagation has enabled the multiplication and germplasm conservation of this cytotype since 1927. Further five analyzed HT accessions showed distinct nuclear 2C-value and AT%. Since HT CIFC 4106 has been considered the first HT, it is suggested that aneuploid reproductive cells of this HT originated the other plants. Considering that HT accessions are used in the development of C. arabica cultivars, the findings of this study are important for the design of strategies to obtain new cultivars for breeding programs. Moreover, these data represent the first step to understand the origin and genome evolution of the HT.

IPR 99 - Dwarf arabica coffee cultivar resistant to coffee ringspot virus

'IPR 99' was derived from a cross between "Villa Sarchi 971/10" and "Hibrido de Timor 832/2". It is a dwarf cultivar, resistant to coffee ringspot virus, partially resistant to leaf rust with semi-late ripening. 'IPR 99' presents partial resistance to necrosis and mummification of young fruits on field conditions. It presents special cup quality and high yield in lower and higher temperature coffee regions in Paraná State.

Rust resistance in Arabic Coffee cultivars in northern Paraná

The objective of the study was to evaluate the resistance to rust in coffee cultivars developed by research institutes of Brazil in Parana state. Resistance to the local leaf rust races was assessed in high disease intensity field conditions at Londrina and Congonhinhas in 2009 and 2010.The cultivars were developed by the EPAMIG/UFV, IAPAR, IAC and MAPA/Procafe. The resistant standard 'IAPAR 59' and the susceptible standards Catuai Vermelho IAC 144' and 'Bourbon Amarelo' were used. A randomized block design with three replications and plots with 10 plants was used. A scale from 1 to 5 based on the rust intensity was used to evaluate the resistance. The Catigua MG 1, Catigua MG 2, IAPAR 59, IPR 98, IPR 104, Palma II, Paraiso H-419-10-6-2-5-1, Paraiso H-419-10-6-2-10-1, Paraiso H-419-10-6-2-12-1, Pau Brasil MG 1 and Sacramento MG 1 cultivars presented complete resistance to rust at Londrina and Congonhinhas. The cultivars derived from the Catucai germplasm were susceptible or showed different levels of partial resistance. Partial resistance to the rust was observed in several coffees derived from Hibrido de Timor. 'Acaua' and 'Obata IAC 1669-20' presented complete resistance at Londrina, but at Congonhinhas, they were partially resistant, indicating that different rust races have occurred at these two locations.

Genetic diversity among commercial coffee varieties, advanced selections and museum collections in Kenya using molecular markers

Molecular markers have effectively been applied to study genetic diversity and as markers of particular traits. This study assessed the diversity of twenty four (24) coffee genotypes using 10 Random Amplified Polymorphic DNA (RAPD) primers and 2 microsatellites (M24 and Sat 235). A total of 35 polymorphic bands were generated by the RAPD primers. The bands were scored for presence (1) and absence (0) of amplified products. The data was subjected to cluster analysis using R statistical software and a dendrogram constructed using Unweighted Pair Group Method with Arithmetic Average (UPGMA). The genotypes separated into three main clusters. C. eugenioides clustered alone in the first cluster while un-introgressed Arabica genotypes dominated the second cluster. The third cluster comprised of Coffea canephora (Robusta) and introgressed genotypes, Ruiru 11, Hibrido de Timor and Catimor. Robusta and C. eugenioides were the most distantly related and generated most of the diversity observed. The similarities observed among un-introgressed Arabica genotypes attest to the narrow genetic diversity within Coffea arabica. The divergence observed among introgressed genotypes could be utilized in future breeding programmes. Key words: Coffee accessions, RAPD, microsatellites, diversity, Kenya.

Cellular and molecular analyses of coffee resistance to Hemileia vastatrix and nonhost resistance to Uromyces vignae in the resistance-donor genotype HDT832/2

In Arabica coffee breeding, some of the most used sources of resistance to leaf rust (Hemileia vastatrix) are natural Coffea arabica x canephora hybrids (“Hibrido de Timor”). To decipher the cellular and molecular nature of that resistance, leaves of genotype HDT832/2, were challenged with H. vastatrix race II, and monitored using light microscopy and RT-qPCR expression analysis of genes involved in plant immunity mechanisms (receptor-like kinase, WRKY transcription factor 1, phenylalanine ammonia-lyase, chalcone synthase, 13-lipoxygenase, glycosyltransferase, pathogenesis related PR1b and PR10). These were compared to the nonhost resistance responses of HDT832/2 to the infection by the cowpea rust fungus (Uromyces vignae). H. vastatrix ceased growth more frequently after stomata penetration, forming few haustoria, inducing a hypersensitive-like response, phenol accumulation and haustorium encasement with callose. U. vignae could enter stomata but failed to form haustoria, while inducing hypersensitive-like responses and phenol accumulation. In host and nonhost interactions, activation of genes involved in signalling coincided with the differentiation of appressoria, and cellular responses (hypersensitive-like responses and accumulation of phenolic compounds) were recorded from the full appressorium or penetration hypha stages onwards. Similarly, a gene related to the JA pathway was first activated at the penetration hypha stage for both interactions, while genes related to the SA pathway were only activated in the host interaction, the latter being the single clear difference between host and nonhost interactions. The cellular and molecular resistance responses of HDT832/2 to these rust fungi suggest that common immunity components are shared between host and nonhost resistance, which may explain the longer durability of this resistance.

Natural infection of several Coffea species and hybrids and Psilanthus ebracteolatus by the coffee ringspot virus (CoRSV)

Coffee ringspot is a minor coffee disease caused by the nuclear type of Brevipalpus mite-transmitted virus, Coffee ringspot virus (CoRSV). Recently outbreaks of the disease in some growing regions of the state of Minas Gerais, Brazil, were registered with qualitative and quantitative yield losses. Coffea arabica was the only species registered as natural host. A survey was made on a germplasm collection of Coffea and related species kept at the Centro de Cafe Alcides Carvalho, Instituto Agronomico, Campinas, state of Sao Paulo (SP), Brazil, to assess natural susceptibility of Coffee species, other than C. arabica and some interspecific hybrids of Coffea as well as other non-Coffea plant species to the Coffee ringspot virus (CoRSV). The following plants were found with ringspot symptoms on their leaves and/or fruits besides C. arabica L.: C. kapakata (IAC 4511), C. dewevrei cv. Excelsa, C. canephora cv. Robusta, hybrid derivative of the C. arabica × C. racemosa (IAC1195-5-6-2), C. arabica × C. dewerei (Piata IAC 387), Hibrido de Timor CIFC 832/1 (derivative from a natural crossing between C. arabica × C. canephora) and C. racemosa. Also Psilanthus ebracteolatus, a species close to the genus Coffee was also found with ringspot lesions on their leaves. All these plants were also found infested by Brevipalpus mites identified as B. phoenicis. Infection of these plants by CoRSV was confirmed by the observation of characteristic cytopathic effects in the tissues of the lesion and by RT-PCR using a pair of primer specific for CoRSV. Only with C. racemosa RT-PCR failed to amplify the CoRSV genome. The susceptibility of P. ebracteolatus to CoRSV adds new dimension regarding its controversial taxonomic position.

High-density genetic mapping for coffee leaf rust resistance

Coffee leaf rust caused by the fungus Hemileia vastatrix causes considerable economic losses for coffee producers. Although agrochemical products can provide sufficient disease control, the use of resistant cultivars is a safer alternative. This resistance may be constrained by one or a few genetic factors, mainly those found in material originating from interspecific hybrids. In this study, the genetic analysis of an F2 population consisting of 224 plants derived from a crossing of Hibrido de Timor UFV 427-15 (resistant) with Catuai Amarelo IAC 30 (susceptible) showed that a dominant gene confers the resistance of coffee to race II of H. vastatrix. From a genetic map saturated with 25 amplified fragment length polymorphism (AFLP) markers linked to the resistance gene, we developed a high-density genetic map with six sequence-characterized amplified region (SCAR) markers delimiting a chromosomal region of 9.45 cM and flanking the dominant gene at 0.7 and 0.9 cM. This is the first saturated and high-density genetic map obtained from this region containing the resistance gene. The results of this study are of great importance for the introduction of molecular markers for marker-assisted selection; they will also facilitate studies related to the cloning, structure, and function of race-specific genes involved in the resistance of coffee trees to H. vastatrix.