Timor Hybrid Research Articles

Potential of the Colombian Coffee Collection as a Source of Genetic Resistance to Colletotrichum kahawae JM Waller PD Bridge

Coffee berry disease (CBD) is not present in the Americas and presents a potential risk for growing coffee. Therefore, Colombia, which has been in scientific cooperation with the Centro de Investigação de Ferrugens do Cafeeiro (CIFC) of Portugal for more than 30 years, has been evaluating the genetic resistance of nine populations of C. arabica to 13 isolates of Colletotrichum kahawae JM Waller and PD Bridge, which are diverse in terms of aggressiveness and geographical origin. The phenotypes observed in the interaction between C. arabica and C. kahawae were used to develop a statistically reliable scale (p-value ≥ 0.001) to categorize resistance in C. arabica into five classes, and this scale was used to classify the nine populations of C. arabica evaluated. The results allowed us to corroborate the potential of Timor Hybrid CIFC 1343 (TH CIFC 1343) as a source of genetic resistance to CBD and to identify new genetic sources not yet explored for the development of varieties in Colombia that may eventually mitigate the effects of CBD in the face of increasing rainfall events and minimum temperatures due to climate change, which can favor disease development. Additionally, the results suggest that the existence of races in the C. arabica–C. kahawae complex is probable, and a selection of genotypes was identified as a possible differential series of races in C. kahawae.

A chromosome-scale assembly reveals chromosomal aberrations and exchanges generating genetic diversity in Coffea arabica germplasm

In order to better understand the mechanisms generating genetic diversity in the recent allotetraploid species Coffea arabica, here we present a chromosome-level assembly obtained with long read technology. Two genomic compartments with different structural and functional properties are identified in the two homoeologous genomes. The resequencing data from a large set of accessions reveals low intraspecific diversity in the center of origin of the species. Across a limited number of genomic regions, diversity increases in some cultivated genotypes to levels similar to those observed within one of the progenitor species, Coffea canephora, presumably as a consequence of introgressions deriving from the so-called Timor hybrid. It also reveals that, in addition to few, early-occurring exchanges between homoeologous chromosomes, there are numerous recent chromosomal aberrations including aneuploidies, deletions, duplications and exchanges. These events are still polymorphic in the germplasm and could represent a fundamental source of genetic variation in such a lowly variable species.

Identification of HIR, EDS1 and PAD4 Genes Reveals Differences between Coffea Species That May Impact Disease Resistance

Coffee, a widely consumed important agricultural product, is mainly produced from two species, Coffea arabica (Arabica coffee) and C. canephora (Robusta coffee). Timor Hybrid (HDT) is a population resulting from a natural cross between C. arabica and C. canephora. HDT derivatives have a high spectrum of resistance to different races of Hemileia vastatrix (Hv), the causal agent of coffee leaf rust. A RNAseq database, obtained from HDT832/2 leaves inoculated with Hv (Host Resistance) and Uromyces vignae (Uv, Nonhost Resistance), showed the presence of genes implicated in the hypersensitive response and salicylic acid pathway. Hypersensitive Induced Reaction (HIR) gene family, Enhanced Disease Susceptibility1 gene (EDS1), and Phytoalexin Deficient 4 (PAD4) gene are involved in host and nonhost resistance. Relative expression calculated by RT-qPCR was used to confirm and expand the transcriptome analysis. HDTHIR4, HDTEDS1, and HDTPAD4 showed the highest upregulation in response to Hv and Uv inoculation, confirming a similar trend in host and nonhost resistance in HDT. HIR and EDS1/PAD4 gene families were characterized for the first time in the three available Coffea genomes. HIR genes were quite conserved between Coffea species. Surprisingly, EDS1 and PAD4 genes revealed major differences in gene structure. The PAD4 predicted protein from C. arabica does not include both conserved domains of the EDS1/PAD4 family, and the EDS1 putative protein from C. canephora includes a formin domain unusual in the same protein family. The variability shown by EDS1/PAD4 gene family may impact the disease resistance response of Coffea species, which can be surveyed for the gene sequences that will produce a more resistant phenotype.

Influence of postharvest processing on the quality and sensory profile of groups of arabica coffee genotypesc.

This study combined qualitative and quantitative approaches to obtain a better understanding of the sensory quality of beverages made from Arabic coffee genotypes subjected to different processing methods. Over 3 consecutive years, 270 accessions of Arabic coffee from the germplasm collection of Minas Gerais State, Brazil, were sensorially characterized after dry postharvest processing. At the end of this period, the 26 genotypes with the greatest potential for the production of specialty coffees were subjected to dry and wet processing. Granulometry and sensory quality were evaluated by scoring and describing the sensory profiles of the samples. Adequate management during all postharvest stages maintained the potential coffee quality, regardless of processing. All of the coffees studied were classified as special. There was variation in the perceived nuances of the sensory attributes among the groups of genotypes and as a function of postharvest processing, with emphasis on the increased frequency of high levels of sweetness in wet processing. Among the aroma/flavor sensory attributes, the caramel subcategory, as a long and pleasant aftertaste, were predominant in all of the genotypes studied, regardless of the type of processing. The differences in the perceptions of aroma/flavor and aftertaste in different processes were easier to identify in the commercial cultivars studied, as well as in the Bourbon accessions of Timor Hybrid and their derivatives. The access MG 0159 Maragogipe Hybrid F1 stood out in terms of all of the evaluated characteristics, regardless of the processing method used. © 2022 Society of Chemical Industry.

Parasitism of Meloidogyne exigua races 1 and 2 in coffee plants derived from Timor Hybrid

ABSTRACT: To investigate the degree of parasitism of two populations of Meloidogyne exigua, the gall index (GI) and the reproduction factor (RF) of M. exigua races 1 (Est E2) and 2 (Est E1) were analyzed in 47 progenies on F3:4 or F4:5 generation derived from the crossing between Coffea arabica cv. Catuaí Amarelo and Timor Hybrid. C. canephora cv. Apoatã IAC 2258 and C. arabica cv. Catuaí Vermelho IAC 144 were used as resistance and susceptibility checks, respectively. The genotypes that were classified as resistant or susceptible by RF were similarly classified by GI, showing a close relationship between both methodologies. The data also indicated no differences in virulence between the nematode populations, since the progenies showed similar resistance reactions to the M. exigua races 1 and 2. According to GI from the 47 mother plants evaluated, 27 progenies (57.4%) were classified as resistant to M. exigua races 1 and 2, with GI ranging from 0.0 to 1.4 and 20 progenies (42.6%) were susceptible with GI from 2.6 to 4.4. These results showed that most of the evaluated germplasm was very promising in relation to the development of new Arabica coffee cultivars with resistance to M. exigua.

Genetic and chemical control of coffee rust (Hemileia vastatrix Berk et Br.): impacts on coffee (Coffea arabica L.) quality.

The occurrence of diseases can alter coffee (Coffea arabica L.) metabolism, causing changes in the composition of coffee beans and beverage quality. However, little is known about which aspects of coffee quality are actually altered by rust (Hemileia vastatrix Berk et Br.) and by its main control methods. The effect of chemical and genetic methods for the control of coffee rust on the quality of coffee beans and beverage was investigated. Both genetic and chemical control reduce the damage caused by the disease in the composition of coffee beans. Genotypes with resistant ancestry, even with resistance breakdown, respond better to chemical control. The combination of genetic and chemical control favors an increase in the sugar content in the beans. Despite the fact that both genetic and chemical control are effective in reducing disease damage regarding the chemical composition of beans, the quality potential of Timor Hybrid genotypes associated with the cancellation of rust expression through the joint action of genetic and chemical control favors the composition of beans and, consequently, the quantitative assessment of sensory attributes, adding value to the final product. © 2020 Society of Chemical Industry.

Resistencia genética a la Enfermedad de la Cereza del Café en variedades cultivadas en Colombia.

La enfermedad de las cerezas del café (CBD), antracnosis causada por el hongo Colletotrichum kahawae subsp. kahawae, ha sido registrada solo en África y puede ocasionar pérdidas de producción hasta del 80%. Cenicafé desarrolla variedades resistentes a las enfermedades más limitantes para el cultivo, aún en ausencia de los patógenos en Colombia, usando al Híbrido de Timor (HT) como la principal fuente de resistencia a la roya del cafeto y a CBD. El propósito de este estudio fue conocer la presencia del gen Ck-1 de resistencia a CBD en las principales variedades de café cultivadas en Colombia, establecer la correlación entre la presencia de Ck-1 y la respuesta a inoculación de hipocótilos y explorar las bases genómicas de la resistencia. Los marcadores moleculares ligados a Ck-1 se ubicaron en el cromosoma 1 de Coffea canephora, región genómica con quince genes de resistencia a enfermedades. Se encontraron marcadores para Ck-1 en todas las líneas mejoradas derivadas del HT-1343 y ausentes en las variedades Típica, Borbón y Caturra, y en líneas derivadas del HT-832/1. No hubo correlación entre las formas alélicas de resistencia a CBD y la resistencia medida por inoculación de hipocótilos. La alta frecuencia de formas alélicas asociadas con resistencia a CBD en materiales seleccionados por resistencia a roya sugiere cosegregación de genes de resistencia para ambas enfermedades. La estrategia de variedades multilínea desarrolladas por Cenicafé, que actualmente corresponde a cerca del 80% del café sembrado en el país, hace que la población en general esté protegida ante la eventual llegada del patógeno a Colombia.

Discrimination of genotypes coffee by chemical composition of the beans: Potential markers in natural coffees

The chemical composition of coffee beans varies according to the cultivar used, but there is little information about the differences among them resulting in different sensory profiles. The purpose was to find potential chemical markers to discriminate genealogical groups of coffee using regression analysis by partial least squares. Twenty-two accessions of C. arabica were used with two repetitions each. There were chromatographic and physical–chemical analyses to determine the composition of raw beans and chemometric analysis as the PCA and the PLS-DA. The analysis of PCA did not showed detailed information about the differences between the groups. The model PLS-DA identified the most important variables in the discrimination of the genealogical groups. Arachidic acid and stearic acid the markers for the Bourbon group; the myristic and linoleic acids and sucrose for the Exotic group; and lauric, palmitoleic and oleic acids, and the protein content to the Timor Hybrid group.

Agronomic performance of coffee in response to framework pruning in cycles of the “safra zero”

In this paper, we aimed at selecting genotypes of Coffea arabica L. that are responsive to framework prunin, with high productive potential and desirable agricultural features. We evaluated 18 progenies in the F5 generation, 8 of them being from the group Catucai (breeding of seedlings of Red Catuai with coffee seeds of the Icatu germplasm) and ten descendants from the Timor Hybrid (breeding of the Red and Yellow Catuai with the Timor Hybrid), as well as two commercial cultivars as witnesses (Tupi IAC 1669-33 and Obata IAC 1669-20). The experiment was carried out at the experimental field of the Federal University of Lavras. The coffee was pruned in August 2014 after the sixth crop and once again in August 2016, being two cycles in the “safra zero” system. The design used was in randomized blocks (RBD) with three repetitions and 20 treatments (18 progenies and two commercial cultivars) totaling 60 experimental plots. We evaluated the area under the progress curve of incidence and severity of leaf rust and cercosporiosis, the productivity (sacs ha-1), sieve #16 and over (%), mocha-type grains (%) and apparent specific mass of grains (ton.m3). The genotype 12 (H516-2-1-1-18-1-4) was responsive to the framework pruning and kept its productivity stable in both pruning cycles, being efficient in such system of crop conduction, besides presenting low incidence and severity of coffee leaf rust and cercosporiosis and high sieve. Key words: Timor hybrid; Cercosporiosis; Leaf rust.

Identification of acid-tolerant coffee genotypes in a coffee germplasm collection of Colombia

One of the limitations of coffee production in many regions of Colombia is the soil acidity. According to historical soil chemical analysis records, more than 50% of coffee farms have pH values below 5.0. Because acid-tolerant coffee varieties are not available, farmers use calcareous additives to correct the problem, which incurs associated labor and input costs. The objective of this work was to identify acid-tolerant genotypes of Coffea arabica. For two contrasting soils in the coffee-growing area of Colombia (Andisol and Entisol), the effect of soil acidity on the growth of 20 genotypes of Coffea arabica during the seedling stage was evaluated. The genotypes were wild accessions that make up the Colombian Coffee Germplasm Collection and the Castillo® Naranjal Variety, used as commercial material. Six months after the seedlings were transplanted into soils treated with or without acidity correction additives, the weight of the dry matter of the roots, stems and leaves was recorded. Later, the acid-tolerant genotypes were identified by means of the quadrant method and the tolerance index. The Timor Hybrid and Rume Sudan genotypes were identified as tolerant of the acidity of the two soil types. These genotypes could be used as progenitors in a coffee breeding program leading to a commercial coffee variety tolerant to soil acidity. Key words: Andisol; entisol; Coffea arabica L.; timor hybrid; rume sudan.

Characterization of chlorogenic acids (CGA) and nine isomers in an F2 population derived from Coffea arabica L.

Chlorogenic acids (CGA) and their isomers have been associated with sensory attributes of the coffee beverage such as acidity, astringency, and bitterness. They have been linked to coffee rust resistance and acknowledged as bioactive compounds due to their antioxidant power with benefits for human health. The total chlorogenic acids (TCGA) and nine isomers of three groups, caffeoylquinic acid or CQA (5-CQA, 4-CQA, 3-CQA),dicaffeoylquinic acid or diCQA (3,4-diCQA; 3,5-diCQA, 4,5-diCQA) and feruloylquinic acid or FQA (5-FQA, 4-FQA, 3-FQA) were determined in an F2 population of Coffea arabica from the crossbreed (Bourbon x Maragogype) x Timor Hybrid. TCGA contents were quantified by UV-VIS spectrophotometryand High-Resolution Liquid Chromatography - HPLC. The group of caffeoylquinic acids (CQA) represented 82% of the TCGA. From the diCQA, 4,5-diCQA showed lower contents, whereas the highest isomer was 3,5-diCQA. Results per quartile for TCGA-UV and for every isomer showed statistical differences among group averages per isomer. The populationbehaved as a parental Maragogype according to contents of 5-CQA, 3,5-diCQA, and TCGA-UV. TCGA contents were higher in the parental GQ956 derived from the Timor hybrid 832-1, with resistance to coffee rust. From the three groups, the first characteristic of parental Bourbon showed a higher concentration of diCQA and FQA; the second one showeda lower concentration of TCGA and CQA isomers and the third group higher TCGA and 5-CQA concentrations. This research allowed establishing the basis for plant selection in the F2 generation of C. arabica due to the TCGA content and isomers derived from CQA, diCQA, and FQA.

SENSORY PROFILE OF ARABICA COFFEE ACCESSES OF THE GERMPLASM COLLECTION OF MINAS GERAIS – BRAZIL

This study was developed to determine the beverage quality and the sensory profile of <em>Coffea arabica</em> accesses of the Germplasm Collection of Minas Gerais State in two consecutive harvests. Mature coffee fruits from 49 accesses were selectively harvested in the 2015 and 2016 harvests, and after processing and drying they were sensorially evaluated by a team of trained judges in accordance to the protocols of the Specialty Coffee Association. The data were analyzed by Principal Component Analysis, Cluster Hierarchical Analysis, and Content Analysis. The year of harvest influences the scores of the sensory attributes of the beverage of some coffee accesses. The access 27 (Pacamara) stood out with the highest sensory score seen in the first year of harvest. The accesses 36 (Timor Hybrid UFV376-52) and 43 (BE5 WushWush) stood out for the final sensory score in the two years of evaluation. All accesses belonging to the Timor Hybrid Germplasm stood out in the beverage quality in the second year of harvest. A total of 139 sensory attribute descriptors were identified, and the content analysis showed different levels for the frequency of terms in each access group formed as a function of quality. The Germplasm Collection of Minas Gerais has a wide variability for the production of superior quality coffees, and the year of harvest influences to a greater or lesser degree the potential of quality of the accesses.

Arabica coffee progenies with multiple resistant to root-knot nematodes

The root-knot nematode Meloidogyne paranaensis is considered the major threat in Coffea arabica plantations. Due to the aggressiveness of this nematode, cultivation is virtually impossible without a resistant cultivar. The main goal of this research was to identify resistant progenies derived from crossings of Catuai and Timor hybrid cultivars in a greenhouse experiment. Additionally, genetic parameters for resistance were estimated to trace selection strategies. Coffee plants were inoculated with 9000 M. paranaensis eggs and second-stage juveniles (J2). Eighty-six plants previously selected in a Meloydogine exigua infested field gave rise to 86 progenies that were evaluated based on the dry matter of aerial parts (DMAP), fresh matter of extracted root (FMER), height (H), and diameter (DIA). The responses of the progenies to nematodes were assessed using the gall index and thickness (GIT), number of eggs J2/g root (NEJGR), and reproduction factor (RF).The cultivars Mundo Novo IAC 379-19, Catuai Vermelho IAC 99, Paraiso MG H 419-1, and IPR 100 were used as susceptible and resistant controls. The GIT is genetically correlated with NEJGR and RF, and could be used in plant selection programs. Five progenies were resistant to M. paranaensis, with two of them not segregated to susceptibility. These progenies are considered multiple resistant to root-knot nematodes because they are also resistant to M. exigua.

Introgresion of the SH3 gene resistant to rust (Hemileia vastatrix) in improved lines of CASTILLO variety (Coffea arabica L.)

The genetic improvement at Cenicafe has developed varieties with resistance to Coffee Leaf Rust (CLR) (Hemileia vastatrix) derived from the Timor Hybrid. These varieties have durable rust resistance, especially against race II, the predominant race. In Colombia, these varieties have been cultivated for three decades and still show resistance. Recently, new rust races have appeared attacking these varieties. Consequently incorporation of different resistance genes into new varieties is being sought. The present study aims to determine the presence of the SH3 resistance gene using the SCAR marker BA-124-12K-f and to evaluate its effect in F1 and F2 progenies derived from crosses of 4 lines of the Castillo® variety (C. arabica) with the varieties S288/23 and BA-2 introgressed with the SH3 gene. Eight F1 populations were inoculated using the detached leaf method and evaluated by the incubation and the latency periods (IP and LP). Plants 9 months old from the F2 populations were inoculated in the greenhouse and compared for sporulation presence. All F1 and F2 populations whose progenitor contained the SH3 gene-marker were resistant. However, rust resistant plants that did not present the band in the F2 progenies derived from BA-2 progenitor also had the rust resistance SH2 gene and, some plants derived from S.288 progenitor, in addition to the SH3 gene, also had the SH1 gene. The resistant F2 plants were planted in the field to be evaluated for agronomic traits and to continue the breeding process. The best progenies will be the basis future varieties aimed for durable resistance to CLR. Key words: Coffea arabica, Hemileia vastatrix, Coffea liberica, SH3 gene, marker assisted selection.

Genetic variability of Meloidogyne paranaensis populations and their aggressiveness to susceptible coffee genotypes

Meloidogyne paranaensis is one of the most destructive root‐knot nematode (RKN) species parasitizing coffee in Brazil and in the Americas generally. The objectives of this study were to assess the genetic variability, aggressiveness and virulence of seven different M. paranaensis populations on susceptible and resistant Coffea spp. All seven RKN populations were identified by biochemical and molecular methods. Coffee seedlings were inoculated in the greenhouse, and the nematode reproduction factor was used to infer their reproduction on coffee genotypes. Phylogenetic studies showed a low genetic variability in M. paranaensis populations, regardless of the existence of three esterase phenotypes (Est P1, P2 and P2a), except for the population Est P2a from Guatemala, which is genetically different from other M. paranaensis populations from Brazil. The Est P2a and Est P2 (Herculândia, SP, Brazil) populations were the most aggressive on two susceptible C. arabica cultivars under greenhouse conditions. None of the M. paranaensis populations were virulent on resistant coffee genotypes, confirming their resistance to the seven M. paranaensis populations tested. The resistant coffee cultivars, namely Clone 14 INCAPER, Catuaí Vermelho × Amphillo MR2161 (E1 16‐5 III), Apoatã IAC 2258, Timor Hybrid UFV 408‐01 (E1 6‐6 II) and IPR 100, exhibited segregation for resistance in the ratio of 0%, 2.4%, 12%, 26% and 29%, respectively. These are promising results, because they validate resistance against several M. paranaensis populations in different Coffea spp. genetic resources, which can be used in breeding programmes or as rootstocks, such as Apoatã IAC 2258 and Clone 14 INCAPER.

Cercosporiosis resistance in coffee germplasm collection

Cercosporiosis, or brown eye spot, is currently one of the main diseases of the coffee tree. It is caused by Cercospora coffeicola Berk. & Cooke. Nevertheless, genetic resistance to this disease has not yet been explored in any depth. Our objectives (a) were evaluate the response of 124 accessions from the germplasm collection of the Minas Gerais State (GC), Brazil, and eight commercial cultivars of C. arabica to cercosporiosis and (b) determine the best way to perform early progenies selections via controlled greenhouse experiments. Three controlled greenhouse experiments (1–3) were run in different seasons to determine the best way to proceed the selection. The seedlings were inoculated with a four isolates mixture obtained from different regions. The experimental data were analyzed individually (1–3), in a joint analysis, and as repetitions of a randomized complete block design. In each analysis we estimated genetic parameters and E-BLUP (empirical best linear unbiased predictor) genotypic values of the access. There was genetic variability to C. coffeicola resistance among the coffee tree accessions germplasm collection. Therefore, genetic improvements could be obtained by selection. Experimental repetitions in different seasons increase the selection efficiency and reliability of resistant genotypes with low cercosporiosis severity. The genotype Sarchimor MG 8840 showed the highest resistance level followed by Guatenano and the Timor Hybrid UFV 377-34, Timor Hybrid UFV 376-14 BE 5, and Wush–Wush × Timor Hybrid UFV 366-08.

Agronomic characterization and responses to coffeeleaf rust in coffee progenies resistant to the gall nematode Meloidogyne exigua

The aim of this study was to determine agronomic characteristics and responses to the coffee leaf rust fungus (Hemileia vastatrix Berk. et Br.) in coffee progenies resistant to the gall nematode Meloidogyne exigua. The experiment was conducted in December 2000 at Ouro Verde Farm (FazendaOuro Verde), located in the municipality of Campos Altos – Minas Gerais (MG). Ten F3:4 progenies were evaluated. They were derived from crosses between CIFC 2570 Timor Hybrid selections and Catuaí cultivars known to be resistant to M. exigua. The Catuaí Vermelho IAC 99 cultivar served as a control. A randomized block design with three replicates was used. In total, there were thirty-three plots consisting of eight plants each. The following characteristics were assessed between the harvests of 2011/2012 and 2014/2015: (a) yield expressed as processed coffee bags ha-1; (b) rust incidence and severity; (c) vegetative vigor; (d) percentage of coffee fruits at the “cherry” stage; (e) percentage of floaters; (f) crown diameter; (g) percentage of coffee beans of size sieve 17 and higher; and (h) sensory analysis of the coffee beverage. The results indicated the following: (a) the H514-7-14-2, H514-7-4-5, H493-1-2-2, H514-7-16-3, H514-7-8-11, H518-2-10-1, and H514-5-2-4 progenies were the most productive; (b) all progenies showed promising resistance to coffee leaf rust; (c) all genotypes had the potential for specialty coffee production; (d) the H493-1-2-2 progeny showed resistance both to rust and the nematode, and has good potential for specialty coffee production; and (e) the yields of the H514-7-8-11, H518-2-10-1, H514-5-2-4, H514-7-16-3, H514-7-14-2, H514-7-4-5, and H493-1-2-2 progenies were significantly higher than that of the Catuaí IAC 99 control.

Genetic Gain in the Resistance of Arabica Coffee Progenies to Root‐Knot Nematode

The nematode Meloidogyne exigua infests Arabica coffee (Coffea arabica L.) plants, leading to severe growth reduction in young trees and decreased bean yield. We investigated the responses of coffee plants to this nematode and estimated the genetic gain in progenies derived from the cross between the cultivar Catuaí and the Timor hybrid. We evaluated 85 F4:5 progenies; the cultivars Mundo Novo IAC 379‐19 and Catuaí Vermelho IAC 99 were used as susceptible controls, and Paraíso MG H 419‐1 and IPR 100 were used as resistant controls. Progeny responses were evaluated using the gall index (GI), reproduction factor (RF), reproduction factor reduction (RFR), and number of eggs and juveniles (J2) per gram of roots (NEJGR). The cultivars IPR 100 and Paraíso MG H 419‐1 and 75 progenies were resistant to M. exigua. Little or no segregation for resistance was observed within the progenies, indicating potential homozygosity at this locus. The GI, RF, RFR, and NEJGR showed high genotypic correlation. The correlated response of decreased NEJGR when selected indirectly by GI was higher than that by direct selection. The GI scale allowed genetic gain to decrease the nematode population and increase resistance; therefore, it can be used as a selection criterion. Linear regression showed that the NEJGR mean was reduced by a value of 450 per selection cycle, which led to a change in the phenotypic mean and explained 95% of the variation. Thus, successive selection cycles could prevent nematode development in coffee tree roots.

Caracterização de genótipos de Coffea arabica l. em área infestada pelo nematoide Meloidogyne paranaensis

nto vegetativo e reprodutivo culminando com a morte de plantas. Objetivou-se avaliar, em área naturalmente infestada por M. paranaensis, o crescimento vegetativo, a produção no primeiro biênio (2011/2012) e a população de M. paranaensis nos genótipos (GEN) Híbrido de Timor UFV 408-01 pl.1 R1 GEN 5); Sarchimor pl.1 R1 (GEN 34); dos cruzamentos de Catuai Vermelho x Amphillo 2161 pl.1 R1 (GEN 15); Catuai Vermelho x Amphillo 2161 pl.3 R1 (GEN 21); Catuai Vermelho x Amphillo 2474 pl.1 R2(GEN 22) e das testemunhas (cultivares IPR 100, Catuaí Amarelo IAC 62 e Mundo Novo 379-19). No trabalho avaliaram-se a população (ovos+Juvenis de segundo estádio.g-1de raiz) de M. paranaensis, produção no primeiro biênio, vigor vegetativo, diâmetro de copa, altura da planta e tamanho do grão. Os resultados permitem concluir que: em área infestada por M. paranaensis, o GEN 15 (Catuai Vermelho x Amphillo 2161 pl.1 R1) foi o mais semelhante ao IPR 100 nas características agronômicas avaliadas; o GEN 21 apresenta elevada produção, além de alta população de M. paranaensis, indicando um comportamento de tolerância ao nematoide e o GEN 34 apresenta suscetibilidade ao nematoide M. paranaensis.

Resistance of Coffea arabica genotypes against Meloidogyne paranaensis and M. incognita under controlled and field conditions

Root-knot nematodes negatively impact on coffee yield worldwide. The use of resistant cultivars is the most effective way to manage these pests. The goal of this study was to identify Coffea arabica genotypes with resistance to Meloidogyne paranaensis and M. incognita race 1. Eighteen C. arabica genotypes (EPAMIG’s Germplasm Bank), previously selected for poor host suitability in a M. paranaensis-infested field, plus a resistant and a susceptible standard, were inoculated with these two Meloidogyne species to determine their resistance using nematode reproduction factor (). Accessions for which were considered resistant, while those for which were considered moderately resistant or susceptible, also according to statistical analysis. Five accessions from crossing ‘Catuaí Vermelho’ × ‘Amphillo MR 2-161’, one from ‘Catuaí Vermelho’ × ‘Amphillo MR 2-474’, two from ‘Timor Hybrid (UFV 408-01)’ and the standard ‘IPR-100’ were resistant to M. incognita race 1 with . Four accessions from ‘Catuaí Vermelho’ × ‘Amphillo MR 2-161’, one from ‘Timor Hybrid (UFV 408-01)’, one from ‘Catuaí Vermelho’ × ‘Amphillo MR 2-474’ and the resistant standard ‘IPR100’ were resistant to M. paranaensis (). Field evaluations with parental genotypes showed that plants that originated from progenies ‘Catuaí Vermelho’ × ‘Amphillo MR 2-161’ were resistant to M. paranaensis and also gave a good yield compared to commercial cultivars, showing promising agronomic traits that can be used in breeding programmes to develop new cultivars of C. arabica.