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Plant breeding aims to develop cultivars with good agronomic traits through gene recombination and elite genotype selection. To support Coffea arabica breeding programs and assist parent selection, molecular characterization, genetic diversity (GD) analyses, and circulating diallel studies were strategically integrated to develop new cultivars. Molecular markers were used to assess the GD of 76 candidate parents and verify the crossing of potential F1 hybrids. Based on the complementary agronomic traits and genetic distance, eight elite parents were selected for circulating diallel analysis. The parents and 12 hybrids were evaluated based on 10 morpho-agronomic traits. For each trait, the effects of general and specific combining abilities, as well as the averages of the parents, hybrids, and predicted hybrids, were estimated. Crosses that maximize the genetic gains for the main agronomic traits of C. arabica were identified. Joint analysis of phenotypic and molecular data was used to estimate the correlation between molecular GD, phenotypic diversity (PD), phenotypic mean, and combining ability. The selection of parents that optimize the allele combination for the important traits of C. arabica is discussed in detail. Made available in DSpace on 2022-01-27T01:58:47Z (GMT). No. of bitstreams: 1 Combining-Ability-and-Molecular.pdf: 2421339 bytes, checksum: b1fd8d047ff3e47af308c96d0c676428 (MD5) Previous issue date: 2021

The use of resistant cultivars is the most effective strategy for controlling coffee leaf rust caused by the fungus Hemileia vastatrix. To assist the development of such cultivars, amplified fragment-length polymorphism (AFLP) markers linked to two loci of coffee resistance to races I and II as well as pathotype 001 of H. vastatrix were converted to sequence-characterized amplified region (SCAR) and cleaved amplified polymorphic site (CAPS) markers. In total, 2 SCAR markers and 1 CAPS marker were validated in resistant and susceptible parents as well as in 247 individuals from the F2 population. The efficiency of these markers for marker-assisted selection (MAS) was evaluated in F2:3 and backcross (BCrs2) populations genotyped with the developed markers and phenotyped with race II of H. vastatrix. The markers showed 90% efficiency in MAS. Therefore, the developed markers, together with molecular markers associated with other rust resistance genes, were used for F3:4 and BCrs3 coffee selection. The selected plants were analyzed using two markers associated with coffee berry disease (CBD) resistance, aiming for preventive breeding. MAS of F3:4 and BCrs3 individuals with all resistance loci was feasible. Our phenotypic and genotypic approaches are useful for the development of coffee genotypes with multiple genes conferring resistance to coffee leaf rust and CBD. Made available in DSpace on 2022-01-27T01:59:16Z (GMT). No. of bitstreams: 1 marker-assisted-pyramiding.pdf: 22779626 bytes, checksum: 7a76b7c036947b04bf1229d56a0e8c4e (MD5) Previous issue date: 2021

Breeding programs of the species Coffea canephora rely heavily on the significant genetic variability between and within its two varietal groups (conilon and robusta). The use of hybrid families and individuals has been less common. The objectives of this study were to evaluate parents and families from the populations of conilon, robusta, and its hybrids and to define the best breeding and selection strategies for productivity and disease resistance traits. As such, 71 conilon clones, 56 robusta clones, and 20 hybrid families were evaluated over several years for the following traits: vegetative vigor, incidence of rust and cercosporiosis, fruit ripening time, fruit size, plant height, canopy diameter, and yield per plant. Components of variance and genetic parameters were estimated via residual maximum likelihood (REML) and genotypic values were predicted via best linear unbiased prediction (BLUP). Genetic variability among parents (clones) and hybrid families was detected for most of the evaluated traits. The Mulamba-Rank index suggests potential gains up to 17% for the genotypic aggregate of traits in the hybrid population. An intrapopulation recurrent selection within the hybrid population would be the best breeding strategy because the genetic variability, narrow and broad senses heritabilities and selective accuracies for important traits were maximized in the crossed population. Besides, such strategy is simple, low cost and quicker than the concurrent reciprocal recurrent selection in the two parental populations, and this maximizes the genetic gain for unit of time. Made available in DSpace on 2022-01-21T18:12:54Z (GMT). No. of bitstreams: 1 Designing-the-best-breeding-strategy.pdf: 655699 bytes, checksum: 48ca9369815f12532dc85e9deeeb3ec2 (MD5) Previous issue date: 2021

The biotrophic fungus Hemileia vastatrix causes coffee leaf rust (CLR), one of the most devastating diseases in Coffea arabica . Coffee, like other plants, has developed effective mechanisms to recognize and respond to infections caused by pathogens. Plant resistance gene analogs (RGAs) have been identified in certain plants as candidates for resistance ( R ) genes or membrane receptors that activate the R genes. The RGAs identified in different plants possess conserved domains that play specific roles in the fight against pathogens. Despite the importance of RGAs, in coffee plants these genes and other molecular mechanisms of disease resistance are still unknown. This study aimed to sequence and characterize candidate genes from coffee plants with the potential for involvement in resistance to H. vastatrix . Sequencing was performed based on a library of bacterial artificial chromosomes (BAC) of the coffee clone ?Híbrido de Timor? (HdT) CIFC 832/2 and screened using a functional marker. Two RGAs, HdT_LRR_RLK1 and HdT_LRR_RLK2, containing the motif of leucine-rich repeat-like kinase (LRR-RLK) were identified. Based on the presence or absence of the HdT_LRR_RLK2 RGA in a number of differential coffee clones containing different combinations of the rust resistance gene, these RGAs did not correspond to any resistance gene already characterized (SH1-9). These genes were also analyzed using qPCR and demonstrated a major expression peak at 24 h after inoculation in both the compatible and incompatible interactions between coffee and H. vastatrix . These results are valuable information for breeding programs aimed at developing CLR-resistant cultivars, in addition to enabling a better understanding of the interactions between coffee and H. vastatrix. Made available in DSpace on 2022-01-26T14:00:41Z (GMT). No. of bitstreams: 1 receptor-like-kinase.pdf: 797260 bytes, checksum: 18841c8c3f9b08408ff2d898ecc48880 (MD5) Previous issue date: 2021

Coffee leaf rust is the most important disease thorought the world. The disease caused by a biotrofic fungi growing areas of the world coffee leaf rust causes losses from Central American coffee park. identified in 1860. Madagascar and Java). I the disease was identified in Brazil. America, Caribean and Mexico. Currently, more than 50 identified by using coffee differentials clones of CIFC in the world. The most comum and widespread resistance genes ( identified by the differential interaction of genes of the host and of the pathogen. M technique, found two different genes in HdT 832/1 and HdT 832/2 not yet identified in differential clones ( to refer the isolates of system. Several pathotypes was found in several countri based on a set of differentials of CIFC was not enough to characterize complex isolates from derivatives into races. HdT832 their resistance was not supplanted in any other part of the world. On the other hand all the progenies derived from HdT 832/1 and resistance to complete resistance was not suplanted yet is S finding is very important due to the fact that cultivars containing the gene by the race that has the gene v reasons coffee breders must consider in their br 6,7,8,9) growers has to rely on the designation of CIFC system the pathogen is recessive and virulent (v resistant ( avirulent (Avr1 characterizing the hypersensitive reaction. Hemileia vastatrix Berk. & Br. has been a serious threat for the sustainability of all coffee . It caused the destruction of the coffee crop in Sri Lanka (Ceylon). Today, 35 ? 50 % on average in Brazil and more tham 50% of the entire Coffee rust probably originates in southwestern Ethiopia and was Then the disease spreaded across the Indian and Pacific Oceans (Philippines, n the 1950s and 1960s, rust advanced across West Africa. In the 1970s-90s, leaf rust advanced to South America, Central H. vastatrix H. vastatrix race II is presente in all over the world. The CIFC diferential clones has nine SH1, SH2, SH3, SH4, SH6, SH7, SH8 and SH9) alone or in combination. Races are SH1-9), named as SH10 and SH11. In the present review, we are proposing the name pathotype H. vastatrix that could not be differentiated into races, according to the CIFC es. It became evident that race nomenclature The resistance of the differential clones HdT 832/1 (S /2 (SH 6,7,8,9,? - v6,7,8,9,?) was only supplanted in India by isolates colleted in the field; but HdT 832/2 cossed with ara H. vastatrix in the field in all the coffee growing areas of the world. The only gene that H3, in the dominant form, from 3, which is absent in most of the coffee growing countries. For these eeding programs cross HdT 832/1 and 832/2 (S with S 288-23 (SH3). Since there is no complete resistance to the disease all over the world chemical control of the disease. races and pathotypes according CIFIC system and Flor gene for gene theory. 1-9) and the host plants are dominant and SH1-9) and the interaction is susceptible (S). In our proposed syst -9) and the host plant is also dominant (SH1-9) and the interaction is resistant (R) In January 1970, physiological races have been olecular biology HdT H 6,7,8,9,? - v6,7,8,9,?) and bica coffee lost the complete C. liberica. Made available in DSpace on 2022-01-26T16:01:13Z (GMT). No. of bitstreams: 1 An-Overview-Of-Physiological-Specialization.pdf: 283604 bytes, checksum: 7fce1d37fda7c9a86e36fa4d3d6f4393 (MD5) Previous issue date: 2021

Resumo: O objetivo deste trabalho foi avaliar a eficiência da aplicação foliar de fungicidas na redução da incidência de patógenos fúngicos, de grãos ardidos e de fumonisinas totais em grãos de milho (Zea mays). Foram conduzidos três ensaios: um no município de Luís Eduardo Magalhães, na Bahia, e dois em Sete Lagoas, em Minas Gerais, nas safras 2010/2011 e 2011/2012, com cultivo de diferentes híbridos comerciais. Os seguintes fungicidas foram aplicados zero, uma e duas vezes: picoxistrobina + ciproconazol, piraclostrobina + epoxiconazole, trifloxistrobina + tebuconazole, azoxistrobina + ciproconazol e tiofanato metílico. Em todos os ensaios, foram realizados a quantificação da incidência de grãos ardidos, o teste de patologia de sementes e a quantificação dos teores de fumonisinas totais. Não foi observada diferença significativa para os fatores fungicida e número de aplicações, exceto para rendimento de grãos, em todos os ensaios. Esses resultados são indicativos da ineficiência da aplicação de fungicidas na redução da incidência de patógenos fúngicos, de grãos ardidos e dos teores de fumonisinas totais em grãos de milho. Abstract: The objective of this work was to evaluate fungicide leaf application on the reduction of fungal pathogen incidence, kernel rot, and total fumonisins in corn (Zea mays) kernels. Three experiments were performed: one in the municipality of Luís Eduardo Magalhães, in the state of Bahia, and two in the municipality of Sete Lagoas, in the state of Minas Gerais, Brazil, during the 2010/2011 and 2011/2012 crop seasons, with planting of different commercial hybrids. The following fungicides were applied zero, one, and two times: picoxystrobin + cyproconazole, pyraclostrobin + epoxiconazole, trifloxystrobin + tebuconazole, azoxystrobin + cyproconazole, and thiophanate-methyl. For all trials, the quantification of kernel rot incidence, the grain pathology test, and the quantification of total fumonisins were performed. No significant difference was observed for the factors fungicide and number of applications, except for grain yield, in all trials. These results show the ineffectiveness of fungicide applications in reducing fungi incidence, kernel rot, and levels of total fumonisins in corn kernels.

Genomic Selection (GS) has allowed the maximization of genetic gains per unit time in several annual and perennial plant species. However, no GS studies have addressed Coffea arabica, the most economically important species of the genus Coffea. Therefore, this study aimed (i) to evaluate the applicability and accuracy of GS in the prediction of the genomic estimated breeding value (GEBV); (ii) to estimate the genetic parameters; and (iii) to evaluate the time reduction of the selection cycle by GS in Arabica coffee breeding. A total of 195 Arabica coffee individuals, belonging to 13 families in generation of F2, susceptible backcross and resistant backcross, were phenotyped for 18 agronomic traits, and genotyped with 21,211 SNP molecular markers. Phenotypic data, measured in 2014, 2015, and 2016, were analyzed by mixed models. GS analyses were performed by the G-BLUPmethod, using the RKHS (Reproducing Kernel Hilbert Spaces) procedure, with a Bayesian algorithm. Heritabilities and selective accuracies were estimated, revealing moderate to high magnitude for most of the traits evaluated. Results of GS analyses showed the possibility of reducing the cycle time by 50%, maximizing selection gains per unit time. The effect of marker density on GS analyses was evaluated. Genomic selection proved to be promising for C. arabica breeding. The agronomic traits presented high complexity for they are controlled by several QTL and showed low genomic heritabilities, evidencing the need to incorporate genomic selection methodologies to the breeding programs of this species. Made available in DSpace on 2019-03-09T00:34:09Z (GMT). No. of bitstreams: 1 Earlyselectionenabledbytheimplementation.pdf: 585900 bytes, checksum: fde1543a047334f2e1fa8511738aba4e (MD5) Previous issue date: 2019-03-08

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 Híbrido 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.

New cultivars are released every year to meet market demands. However, in species with a narrow genetic base, such as Coffea arabica, the cultivars are closely related and phenotypically similar. This hinders the accurate discrimination of genotypes sing morphological descriptors in distinctness, uniformity, and stability (DUS) testing, which is required for the registration and protection of new cultivars. In this sense, molecular markers are an auxiliary tool for accurate and precise discrimination of cultivars. This study aimed to verify the informative capacity and effectiveness of a molecular marker set to discriminate among C. arabica varieties, create a database of DNA profiles and allele frequencies, analyze the genetic diversity in this collection, and explore genetic kinships. Thirty-four C. arabica cultivars/progenies, which belong to the Brazilian Cultivar Trial, were analyzed using 31 microsatellite markers. Markers with weak bands were removed, and of the remaining, 74.07% were polymorphic and revealed 47 alleles. The obtained molecular profiles revealed segregation between and within cultivars/progenies, and genetic variability was observed between all the cultivars/progenies. Sixteen markers were selected for dendrogram construction and for fingerprinting analysis of the cultivars. The ability of these markers to detect varietal mixture and analyze diversity between and within cultivars was also discussed in detail. The results demonstrated the effectiveness of markers in distinguishing related genotypes from those with similar phenotypic traits. This biotechnological tool will assist breeders in DUS testing of cultivars.

Coffee tree is a shrub with dimorphic branches. The orthotropic stem grows vertically with two near-horizontal plagiotropic branches, per node, in opposite phyllotaxy. The consecutive nodes of the orthotropic stem are organized in parastichies. We report here mutant plants of Coffea arabica with triple plagiotropic branch, resulted from the whorled phyllotaxy of the orthotropic stem. In mutant plants three plagiotropic branches in the same node are separated by angles of approximately 120o, while in normal plants two plagiotropic branches in the same node are separated by angles of approximately 180o. In mutant plants the angles of the parastichies increase approximately 50o clockwise between consecutive nodes, while in normal plants the angles increase approximately 87o. The plant architecture is changed. The triple plagiotropic branch is a putative mutant with potential to be explored in coffee breeding programs. The hypotheses for the origin of the mutation and the research perspectives are discussed. Made available in DSpace on 2017-12-08T23:20:41Z (GMT). No. of bitstreams: 1 Tripleplagiotropicbranchincoffee.pdf: 1082488 bytes, checksum: d1c695b3f5ec77d98016f1f28434324c (MD5) Previous issue date: 2017-12-08

– Anthracnose stalk rot (ASR) disease caused by Colletotrichum graminicola can lead to major corn yield losses in Brazil. Studies on plant resistance and genetic variation in pathogen populations are required towards the development of ASR disease management strategies. However, the lack of adequate methods for C. graminicola inoculation in maize stalk has hindered these efforts. The main objective of the study was to develop a confident and feasible method for C. graminicola inoculation into maize stalk. Three inoculation methods were evaluated: TCMP (toothpick colonized by pathogen mycelium), TICS (toothpicks immersed in conidial suspension), and ICS (injection of conidial suspension). The effect of the internode position, the phenological stage, and the period of time required for maize reactions to ASR infection were also evaluated. The infection severity was assessed by a diagrammatic scale with six levels of severity from 0 (no necrotic spots) to 5 (100 % infection). The TICS was the best method, inoculation in the third internode and assessment of disease severity at tasselling stage (VT) 30 days after inoculation presented the more accurate results. The procedure was validated under field conditions. Key words: Zea mays; stalk rot; anthracnose. METODO PARA INOCULACAO DE Colletotrichum graminicola EM COLMOS DE MILHO RESUMO – A podridao do colmo do milho causada por Colletotrichum graminicola causa perdas severas em lavouras de milho. Estudos com resistencia de plantas e variabilidade genetica do patogeno sao necessarios para o desenvol-vimento de estrategias de manejo desta doenca. Por outro lado, ha ausencia de uma metodologia adequada para a inoculacao de C. graminicola em colmos. O objetivo principal do trabalho foi estabelecer uma metodologia confiavel e pratica para a inoculacao de C. graminicola. Foram avaliados tres metodos de inoculacao em colmo: palitos de dente colonizados por micelio; palitos de dente imersos em suspensao de conidios; e injecao de suspensao de conidios. Nos tambem determinamos o efeito da posicao do entreno inoculado, o estadio fenologico para a inoculacao e o periodo de tempo ideal apos a inoculacao para avaliar a severidade da doenca. O metodo de palitos de dente imersos em suspensao de conidios inoculado no terceiro entreno no estadio fenologico de pendoamento (VT) e avaliado aos 30 dias apos a inoculacao obteve o melhor resultado. A metodologia foi validada em plantas cultivadas em condicoes de campo. Palavras-chave: Zea mays; podridao de colmo, antracnose.

Coffee leaf rust (CLR) caused by Hemileia vastatrix Berk. et Br. is one of the major Coffea arabica diseases world-wide. 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.

Microsatellite markers (SSR) have broad utility in genetic studies due to a high rate of polymor-phisms, 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 molecular-assisted selection.

O objetivo deste trabalho foi avaliar a eficiência do uso de multilinhas dinâmicas, por meio de misturas genéticas em populações de híbridos triplos, no manejo da antracnose do sorgo, causada pelo fungo Colletotrichum sublineolum. Foram obtidos 18 híbridos triplos a partir de sete linhagens que continham genes distintos para resistência à doença. Os 25 genótipos de híbridos e linhagens foram avaliados em campo. Verificou-se, em alguns híbridos, grau de resistência superior ao observado para a linhagem mais resistente utilizada nos cruzamentos, o que indica efeito aditivo dos genes de resistência das diferentes linhagens na composição da resistência final dos híbridos. O usodas multilinhas dinâmicas reduziu a intensidade da doença no campo e aumentou a produtividade. Essa estratégia torna possível a utilização de linhagens que apresentam características agronômicas desejáveis, mas são suscetíveis à antracnose. The objective of this work was to evaluate the efficiency of dynamic multilines, using genetic mixing in populations of three-;way hybrids, in the management of sorghum anthracnose, caused by the fungus Colletotrichum sublineolum. Eighteen three-;way hybrids were obtained from seven different lines containing genes for resistance to the disease. The 25 genotypes of hybrids and lines were evaluated in field conditions. In some hybrids, a higher resistance level was observed when compared to that of the more resistant line used in the crosses, indicating an additive effect of the resistance genes of the different lineages in the composition of the final resistance of hybrids. The use of dynamic multilines reduced the disease intensity in field and increased productivity. This strategy makes it possible to use lineages that have desirable agronomic characteristics, but are susceptible to anthracnose.

O objetivo deste trabalho foi identificar marcadores moleculares relacionados à resistência do cafeeiro (Coffea arabica) à ferrugem (Hemileia vastatrix). Foram identificadas sequências de DNA potencialmente envolvidas na resistência do cafeeiro a doenças, por meio de análise "in silico", a partir das informações geradas pelo Projeto Brasileiro do Genoma Café. A partir das sequências mineradas, foram desenhados 59 pares de iniciadores para amplificá-las. Os 59 iniciadores foram testados em 12 cafeeiros resistentes e 12 susceptíveis a H. vastatrix. Vinte e sete iniciadores resultaram em bandas únicas e bem definidas, enquanto um deles amplificou fragmento de DNA em todos os cafeeiros resistentes, mas não nos suscetíveis. Esse marcador molecular polimórfico amplificou uma região do DNA que corresponde a uma janela aberta de leitura parcial do genoma de C. arabica que codifica uma proteína de resistência a doenças. O marcador CARF 005 é capaz de diferenciar os cafeeiros analisados em resistentes e susceptíveis a H. vastatrix. The objective of this work was to identify molecular markers related to the resistance of coffee (Coffea arabica) to rust (Hemileia vastatrix). DNA sequences potentially involved in coffee disease resistance were identified, using "in silico" analysis, from data obtained by the Brazilian coffee genome project. After data mining, 59 primer pairs were designed to amplify the sequences identified. The 59 primers were tested on 12 resistant and 12 susceptible coffee plants to H. vastatrix. Twenty-seven primers resulted in unique and well-defined bands, while one of these amplified a DNA fragment in all resistant plants, but not in the susceptible ones. This polymorphic molecular marker amplified a region of DNA that corresponds to a partial open reading frame of C. arabica genome that encodes a disease resistance protein. The marker CARF 005 can be used to differentiate between resistant and susceptible coffee plants to H. vastatrix.

O objetivo deste trabalho foi estudar o crescimento e a esporulação da forma imperfeita de M. ulei em vários meios de cultura e o efeito da idade da cultura sobre a esporulação. Made available in DSpace on 2017-09-02T06:11:54Z (GMT). No. of bitstreams: 1 RevCeres322331.pdf: 4234096 bytes, checksum: b59a7f38ad580cbe6a3cdfa0325b86da (MD5) Previous issue date: 2017-08-25

Estudou-se a reacao de 33 clones de seringueira a infeccao por varios isolados de Microcyclus ulei provenientes de varias regioes heveicolas do Brasil. As inoculacoes foram feitas em condicoes climaticas controladas, utilizando-se conidios/ml, com 70% a 80% de germinacao, provenientes de culturas com doze dias de idade. As reacoes apresentadas pelos clones variaram com os isolados. Os clones, em sua maioria, apresentaram resistencia completa a determinados isolados e foram suscetiveis ou altamente suscetiveis a outros. Verificou-se que o periodo latente e o diametro medio das lesoes podem estar relacionados com a resistencia dos clones ao fungo, mas somente estes parametros nao explicam essa resistencia, sendo necessaria a associacao de varios componentes, dentre os quais destaca-se a esporulacao do tecido infectado. O periodo de incubacao e o numero de lesoes nao sao bons parametros para analise de resistencia da seringueira ao M. ulei. Made available in DSpace on 2018-11-29T23:48:20Z (GMT). No. of bitstreams: 1 PABv23n81989.pdf: 12698653 bytes, checksum: 3289b91ebf9d4bfc815c0f069721a07e (MD5) Previous issue date: 1996-11-19