The most important disease of Coffea arabica is coffee leaf rust caused by the fungus Hemileia vastatrix. The purpose of this study was to characterize the inheritance of coffee resistance gene(s) to race II of this pathogen and to identify and map molecular markers linked to this trait. Different populations were used: F 2 (160 plants), BCr (20), and BCs (135), derived from a cross between the resistant genotype Híbrido de Timor UFV 427-15 and the susceptible cultivar Catuaí Amarelo UFV 2143-236 (IAC 30). The segregation analysis showed that the resistance of Híbrido de Timor to race II of the H. vastatrix is conferred by a single dominant gene. The amplification of 176 AFLP (Amplified fragment length polymorphism) primer combinations using bulked segregant analysis (BSA) allowed the identification of three molecular markers linked to the resistance gene. Genetic mapping of these three markers in the F 2 population indicated that they are distributed on both sides, flanking the resistance gene. The markers E.CTC/M.TTT405 and E.CGT/M.TGT 300 were found linked to the resistance gene at 8.69 cM (LOD 18.91) and 25.10 cM (LOD 5.37), respectively, while E.CCT/M.TTC230 was localized on the other side of the gene, at 20.50 cM (LOD 6.15). These markers are the first rust resistance markers identified in Híbrido de Timor and can be useful for marker assisted selection in coffee breeding programs.

Coffee leaf rust (CLR) caused by Hemileia vastatrix Berk. et Br. is one of the major Coffea arabica diseases worldwide. CLR resistance has been attributed to at least nine dominant genes, as single or in combination. We present an inheritance study and mapping loci involved in the Híbrido de Timor (HDT) UFV 443-03 resistance to race I, race II, and pathotype 001 of H. vastatrix. Molecular markers were used to ascertain the phenotypic results and to map the putative resistance loci. For all tree isolates, the inheritance study indicated that the resistance of HDT UFV 443-03 is conditioned by two independent dominant loci or by three independent loci (two dominant and one recessive). Molecular marker analyses ascertained that the resistance of HDT UFV 443-03 to race II is conditioned by at least two independent dominant loci, while the resistance to race I and pathotype 001 is conditioned by at least four independent dominant loci. Gene pyramiding might result in a cultivar with durable resistance; however, it is difficult to distinguish between plants with one or more resistance genes due to epistatic effects. Molecular markers linked to these genes were indicated for marker-assisted selection, as it is an efficient breeding alternative for CLR resistance with no such epistatic effects.

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The coefficient of parentage among 121 cultivars of Coffea arabica L. in Brazil released from 1939 to 2009 was estimated and used to study the genetic diversity and the breeding pattern of the breeding programs. A low genetic diversity was observed within the C. arabica cultivars of Brazil. The genetic base of 121 cultivars released in Brazil between 1939 and 2009 was defined by 13 ancestors. Seven ancestors contribute with 97.55% of the genetic base of C. arabica cultivars. Bourbon Vermelho contributed with 52.76% for the genetic pool of the C. arabica cultivars of Brazil followed by Sumatra (19.05%) and Híbrido de Timor (11.59%). Mundo Novo and Icatu Vermelho contributed with 87.65% for the genetic base of the C. arabica cultivars. It was calculated that 97.55% of the genetic base of the Brazilian C. arabica cultivars is derived from seven ancestors, indicating a narrow genetic base. Among the first progenies, Mundo Novo contributed with 69.39% of the genetic base of C. arabica cultivars in Brazil. The increase in the genetic diversity among C. arabica cultivars observed in recent decades is due to the introduction of parental lines with diverse genetic base. High genetic diversity was observed among cultivars released by Empresa de Pesquisa Agropecuária de Minas Gerais/Universidade Federal de Viçosa, Fundação Procafé, and Instituto Agronômico do Paraná. The 121 Brazilian cultivars were clustered into four groups based on coefficient of parentage. The distributions of genotypes over the cluster groups showed the effect of parental line contribution.

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Microsatellite markers (SSR) have broad utility in genetic studies due to a high rate of polymorphisms, a codominant nature and multiallelism. EST-SSRs are markers derived from the expressed sequences of a genome and represent transcribed genes. Despite the importance of the genus Coffea, only a small number of EST-SSR markers are currently available. Thus, this study was designed to mine and develop a new set of EST-SSR markers from the Brazilian Coffee Genome Project. We investigated 130,792 expressed sequence tags (ESTs), from which 24,031 DNA sequences with microsatellites were identified. After stability and amplification testing, 101 new EST-SSR markers were developed and analyzed in different coffee species. The average rate of transferability was 88 %, showing that these markers are useful in genetic studies across the genus Coffea. Polymorphism levels and the degree of diversity were consistent with the evolutionary history of the species. All coffee genotypes were discriminated, even the C. arabica genotypes that have known narrow genetic basis. It was also possible to locate 14 EST-SSRs into different linkage groups of the C. arabica genetic map, which demonstrate that these markers can be useful in QTL mapping studies and in molecularassisted selection. Keywords Coffea sp. Á Coffee Á Microsatellites Á Brazilian Coffee Genome Project Á Molecular markers The coffee tree is a member of the Rubiaceae family and belongs to the genus Coffea, of which 103 species have been currently described. Among them, two are commercially grown: Coffea arabica (2n = 4x = 44), grown in the highlands and in mild climates, and Coffea Electronic supplementary material The online version of this article (

-AFLP, RAPD and SSR molecular markers

Coffee leaf rust caused by the fungus Hemileia vastatrix is one of the most important leaf diseases of coffee plantations worldwide. Current knowledge of the H . vastatrix genome is limited and only a small fraction of the total fungal secretome has been identified. In order to obtain a more comprehensive understanding of its secretome, we aimed to sequence and assemble the entire H . vastatrix genome using two next-generation sequencing platforms and a hybrid assembly strategy. This resulted in a 547 Mb genome of H . vastatrix race XXXIII (Hv33), with 13,364 predicted genes that encode 13,034 putative proteins with transcriptomic support. Based on this proteome, 615 proteins contain putative secretion peptides, and lack transmembrane domains. From this putative secretome, 111 proteins were identified as candidate effectors (EHv33) unique to H . vastatrix , and a subset consisting of 17 EHv33 genes was selected for a temporal gene expression analysis during infection. Five genes were significantly induced early during an incompatible interaction, indicating their potential role as pre-haustorial effectors possibly recognized by the resistant coffee genotype. Another nine genes were significantly induced after haustorium formation in the compatible interaction. Overall, we suggest that this fungus is able to selectively mount its survival strategy with effectors that depend on the host genotype involved in the infection process.