-Cacao was introduced in Bahia in

Sexual compatibility limits the production of cacao plantations, being an important selection criterion in breeding programs. However, the current method for characterizing compatibility, based on the frequency of flower setting after controlled pollination, is time consuming, requiring a long time to identify self-compatible individuals. The identification of molecular markers in genomic regions can be an alternative to allow early selection of self-compatible plants. The present study aimed to identify SNP markers associated with sexual compatibility in cacao, by utilizing genome-wide association (GWAS) mapping. A population of 295 individuals mostly from third-generation breeding populations, but also founder clones, was used. This population was phenotypically characterized by hand pollinating 8199 flowers and evaluating the flower retention 15 days after pollination. In addition, leaf samples of each individual were collected and DNA extracted for genotyping by sequencing, generating 5301 SNP markers after cleaning. Genome-wide association mapping analysis was performed using Synbreed, GCTA, and TASSEL softwares. Significant markers associated to incompatibility, likely in strong linkage disequilibrium, were found within a region of 196 kb, in the proximal end of chromosome 4, suggesting the existence of a major gene in that region. However, this result should be validated in a larger population, considering that only 295 trees were used here. When the SNP effects were treated as random in the estimation process, many other regions in the genome appears to be involved with sexual incompatibility in cacao. Candidate genes were found not only in the proximal end of chromosome 4 but also spread in several other regions of the genome.

LOPES, U.V. Caracterização de uma população de cacaueiro para mapeamento de genes de resistência à vassoura-de-bruxa e podridão-parda. Fitopatologia Brasileira 30: 380-386. 2005. RESUMOO cacaueiro (Theobroma cacao) é alvo de diversas enfermidades, sendo que a podridão-parda, causada por Phytophthora spp. é a principal delas mundialmente. Entretanto, no Brasil, a vassoura-de-bruxa causada por Crinipellis perniciosa, é a mais devastadora. A busca de fontes de resistência às doenças é a etapa básica para programas de melhoramento genético e, nesse sentido, este estudo objetivou caracterizar quantitativamente uma progênie oriunda do cruzamento entre os clones SIC-864 e CCN-51, dois genótipos contrastantes para diversas características, inclusive para resistência à vassourade-bruxa e podridão-parda. Foram avaliados em condições de campo o número médio de frutos por planta por ano, porcentagem de frutos sadios, porcentagem de frutos com vassoura-de-bruxa, porcentagem de frutos com podridão-parda, número médio de vassouras vegetativas por planta por ano e número médio de vassouras de almofada floral por planta por ano, durante um período de quatro anos. As estatísticas descritivas da produtividade e da resistência a doenças foram calculadas considerando os valores máximo, médio e mínimo, o desvio padrão, o coeficiente de variação, e a distribuição da freqüência. O coeficiente de repetibilidade foi calculado para estimar a acurácia da variação fenotípica por efeitos ambientais pelos métodos da análise de variância, componentes principais e análise estrutural. Foi demonstrado o caráter segregante dessa progênie para resistência à vassoura-de-bruxa e à podridão-parda e para outras características, mostrando a utilidade da população para estudos de mapeamento genético utilizando marcadores moleculares, visando identificar genes de resistência e "quantitative trait loci" (QTLs) dissimilares dos encontrados no clone Scavina-6, tradicionalmente usado em programas de melhoramento genético do cacaueiro.Palavras-chave adicionais: Crinipellis perniciosa, Phytophthora spp., Theobroma cacao, melhoramento genético. ABSTRACT Characterization of a cocoa population for mapping of genes of resistance to Witches' Broom and Phytophthora pod rotCocoa (Theobroma cacao) is a target for several diseases, the main one being black-pod, caused by Phytophthora spp. However, witches' broom caused by Crinipellis perniciosa is the most devastating cocoa disease in Brazil. The search for sources of disease resistance is the first step in breeding programs. To this end, this study aimed to quantitatively characterize a progeny from the cross between the cocoa clones SIC-864 and CCN-51, two contrastant genotypes for several traits, including resistance to witches' broom and black pod. The progeny was assessed under field conditions for the average number of pods per tree per year, the percentage of healthy pods, the percentage of pods with witches' broom, the percentage of pods with black pod, the average number of vegetative brooms per tree per year a...

-To increase the genetic diversity sources of resistance to witches

A propagação vegetativa da seringueira em escala comercial, através do enraizamento de estacas, é uma alternativa viável para a multiplicação de clones melhorados e recomendados para o cultivo comercial. A presente investigação teve como objetivo avaliar a possibilidade de produção de mudas clonais através do enraizamento de brotações (estacas) obtidas diretamente de seringueiras adultas, assim como o efeito de reguladores de crescimento no enraizamento das estacas. Trata-se de uma técnica alternativa para a produção de mudas clonais de forma mais rápida, econômica e que permite contornar os efeitos negativos das mudas enxertadas devido às interações entre o enxerto (clone) e o portaenxerto (cavalo). A coleta de hastes foi realizada em vários estádios de desenvolvimento e após o período de reenfolhamento das seringueiras no cultivo comercial. As estacas foram devidamente preparadas e a sua base tratada com indutores de enraizamento, ou seja, com soluções de ácido indolbutírico (AIB) e de ácido naftaleno acético (ANA), nas concentrações de 5.000 e 1.000 mg dm -3 , respectivamente. Os resultados obtidos, ainda que preliminares, foram bastante promissores, pois as estacas tratadas apresentaram primórdios de raízes logo aos 15 dias e o enraizamento se definiu aos 45 dias, em toda a seção da base das estacas. A muda de estaquia mostrou-se superior em relação a muda enxertada por borbulhia, considerando o crescimento da parte aérea (respectivamente 1,46 m contra 0,90 m de altura), obtido em mudas com um ano de idade, e ao volume e características do sistema radicular. Palavras-chave:Hevea, método de propagação, estaquia, indução de raízes.Production of rubber tree seedlings through the rooting of cuttings collected from adult plants. Vegetative propagation of rubber tree on a commercial scale by rooting cuttings is a viable alternative to the multiplication of improved and recommended clones for planting. This research aimed to evaluate the possibility of production of clonal seedlings through the rooting of shoots obtained directly from adult rubber trees, as well as growth regulators effect on rooting. This is an alternative technique for production of clonal seedlings more quickly, economically, avoiding the negative effects due to interactions between the graft (clone) and the rootstock. The rubber tree shoots were collected in the commercial planting, regarding various stages of development and after the defoliation period. The cuttings were properly prepared and their base treated with root inducers, such as the solutions of 3-Indolebutyric acid (IBA) and 1-naphthalene acetic acid (NAA), at concentrations of 5000 and 1000 ppm, respectively. The results, although preliminary, are very encouraging because the treated shoots begun to present the root primordios as early as 15 days and it was completely defined at 45 days across the whole section of the base of the stems. The rooted cutting seedlings was superior the seedlings derived by budding with respect to the plant size (1.46 m to 0.90 m) measured at one year ...

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Searching for new approaches to confer resistance to diseases in plants is one of the main objectives of the Cacao breeding program (CBP). Witches' broom (WB) and black pod rot (BPR) are important cacao diseases in Bahia,Brazil. This study aimed to evaluate the resistance in plants from 40 progenies of genetic crosses between elite clones to natural infection by high levels of Moniliophthora perniciosa and Phytophthora spp. WB and BPR infection assessments were conducted in the field, including evaluation of vegetative brooms (VB), cushion brooms (CB), and total brooms (TB), as well as the percentage of WB-diseased (FRUWB) and BPR-diseased (FRUBPR) fruits. Ten progenies showed resistance to infection in both the canopy and fruits. No significant differences between the progenies were detected for FRUBPR.