Divergência genética entre cafeeiros do germoplasma Maragogipe

Abstract

ResumoEste trabalho objetivou identificar a divergência genética entre acessos de cafeeiro do grupo Maragogipe, situados no Banco Ativo de Germoplasma de Café do Estado de Minas Gerais, no município de Patrocínio (MG), por meio de análises multivariadas. Foram avaliados 27 descritores morfo-agronômicos, e a distância generalizada de Mahalanobis foi usada para quantificar a divergência genética entre os acessos. Como estratégias de agrupamento, foram empregados o agrupamento de Tocher, o método hierárquico Unweighted Pair-Group Method Using Arithmetic Averages (UPGMA) e a análise de variáveis canônicas. A análise de agrupamento pelos métodos de Tocher e UPGMA separaram os acessos em três e seis grupos, respectivamente. A análise da contribuição relativa de cada característica para a dissimilaridade genética destacou as características intensidade da ondulação da folha, quantidade de inflorescência por axila foliar e produtividade média como as que mais contribuíram para a obtenção da divergência genética. Observou-se que as três primeiras variáveis canônicas explicaram mais de 90% da variância total contida no conjunto das características analisadas. A combinação entre os acessos MG0167 e MG0170 é a mais promissora em um possível cruzamento para uso imediato em programas de melhoramento.Palavras-chave: Coffea arabica, análise multivariada, melhoramento genético. Genetic divergence between coffee trees of the Maragogipe germplasm AbstractThis study aimed to identify the genetic divergence among coffee trees of the Maragogipe group in the active germplasm coffee bank in Patrocínio, Minas Gerais, Brazil, using multivariate analyzes. In the study, 27 morpho-agronomical descriptors were assessed. Mahalanobis generalized distance was applied to quantify the genetic divergence among genotypes. The following methods were used: Tocher clustering, Unweighted Pair-Group Method Using Arithmetic Averages (UPGMA) hierarchical clustering and the canonical variables analysis. The cluster analysis by Tocher method and the UPGMA separated the accessions into three and six groups, respectively. The analysis of the relative contribution of each characteristic to the genetic dissimilarity highlighted the intensity of curling leaf, inflorescence number per leaf axil and average yield as those that contributed most to the achievement of genetic divergence. It was observed that the first three canonical variables explained more than 90% of the total variance contained in the set of the analyzed characteristics. The combination between MG0167 and MG0170 accessions is the most promising for a possible crossing for immediate use in breeding programs.

Development of clonal seedlings of promising Conilon coffee (Coffea canephora) genotypes

“…The results of the UPGMA method ( Figure 1) were similar to those of Tocher's optimisation method, particularly when a lower limit of 50% similarity among genotypes was imposed. Guedes et al (2013) and Ivoglo et al (2008) also observed similarities among results obtained through Tocher's optimisation and UPGMA, especially when the lower limits were set at 45 and 15% similarity, respectively. It is noteworthy that the distribution of individuals in the dendrogram does not follow a criterion for group formation, since the main aspect of this method consists of the branches that are obtained (Cruz et al, 2004).…”

“…Genotypes P2, AP, B01, Verdinho R, and Beira Rio were placed in different groups by Tocher's optimisation and UPGMA, thus indicating divergence between the two methods. Likewise, Guedes et al (2013) and Ivoglo et al (2008) also observed the formation of distinct groups using the UPGMA method. The genotypes CHR, 18, and Z39 remained isolated, corroborating the results obtained by Tocher's method (Table 5).…”

“…Dias et al (2005) evaluated 25 progenies of Arabica coffee, observed the formation of five distinct groups. Guedes et al (2013), studying 12 samples of Arabica coffee of the Maragogipe variety, observed the formation of four distinct groups. Silva et al (2015) evaluated 71 genotypes of Conilon coffee and 56 of Robusta coffee; they observed the formation of 13 and five distinct groups, respectively.…”

“…It is noteworthy that the distribution of individuals in the dendrogram does not follow a criterion for group formation, since the main aspect of this method consists of the branches that are obtained (Cruz et al, 2004). Individuals are grouped in pairs, using the arithmetic means of dissimilarity, wherein the dendrogram prioritizes the genotypes with high similarity (Guedes et al, 2013). The UPGMA method allowed the formation of seven groups among the 34 genotypes tested (Fig.…”

Genetic divergence among cupuaçu accessions by multiscale bootstrap resampling

“…Cluster III, formed by accessions 378 and 402, was the equal to cluster II, which was obtained by the UPGMA method in situation 1. Cluster IV was formed of accessions was also observed by Zuin et al (2009) in cassava, by Nunes et al (2011) in melon and by Guedes et al (2013) in coffee. The number of clusters formed in the three methodologies demonstrates the existence of genetic variability among the evaluated accessions, considering all variables simultaneously.…”