N. R. Sousa

Discriminação de raças primitivas de Pupunha (Bactris Gasipaes) na Amazônia brasileira por meio de marcadores moleculares (RAPDs)

The pejibaye (Bactris gasipaes Kunth, Palmae) was domesticated for it fruits by the first peoples of western Amazonia. Consequently it exhibits a landrace complex that has been partially characterized morphologically and mapped. Along the Amazonas and Solimoes Rivers, in Brazil, three landraces have been proposed [Para (Amazonas River), Solimoes (lower and middle Solimoes River), Putumayo (upper Solimoes River)], with indications that the Solimoes landrace could be an artifact of the morphometric analysis. RAPD markers were used to evaluate the three landrace hypothesis. DNA was extracted from 30 plants of each landrace maintained in the Pejibaye germplasm bank, Manaus, AM, Brazil. During PCR amplification, 8 primers generated 80 markers, Jaccard similarities were estimated, the plants were grouped with UPGMA. The dendrogram contained 2 large groups that joined at a similarity of 0.535: the group of the Para landrace contained 26 plants of this race, 5 of the Putumayo and 1 of the Solimoes; the group of the Solimoes River contained 29 plants of the Solimoes race, 19 of the Putumayo and 1 of the Para. The structure of the second group suggested that there is only one landrace along the Solimoes River, since the plants were mixed in sub-groups without apparent order. This marker-based genetic analysis did not support the three landrace hypothesis and suggests that the Putumayo landrace extends along the Solimoes River to central Amazonia. Genetic and morphological data must now be used to evaluate this new hypothesis.

Divergência genética entre clones de guaranazeiro

As tecnicas multivariadas, para estimar a diversidade genetica de um grupo de progenitores, tem sido utilizadas com frequencia pelos melhoristas de plantas. Os progenitores sao utilizados em cruzamentos biparentais ou multiplos, para formacao de populacoes segregantes que tenham maior probabilidade de recuperacao de genotipos superiores. Este trabalho foi realizado com o objetivo de identificar clones de guaranazeiro produtivos e divergentes que possam ser utilizados em um programa de cruzamentos para obter hibridos com alto valor heterotico e materiais para propagacao vegetativa. Foram avaliados 148 clones de guaranazeiro atualmente em uso no programa de melhoramento genetico da Embrapa-Centro de Pesquisa Agroflorestal da Amazonia Ocidental. Utilizou-se, para estimativa da divergencia genetica, a analise de agrupamento, em que a medida de dissimilaridade utilizada foi a distância euclidiana media padronizada e os metodos de agrupamento de otimizacao de Tocher e do vizinho mais proximo para construcao do dendrograma entre grupos de clones. Houve a formacao de sete grupos divergentes de clones. Concluiu-se que a divergencia genetica entre os clones nao e grande, pois dois grupos foram formados com dois clones e tres grupos foram formados somente com um unico clone. Os clones CMU384 e CMU801 foram os mais proximos geneticamente e podem ser utilizados na formacao de uma populacao com desenvolvimento vegetativo uniforme para uso em plantios comerciais.

Contribution of the institutions in the Northern region of Brazil to the development of plant cultivars and their impact on agriculture

This paper describes the development of breeding programs in northern Brazil and their main impacts on agriculture. Their contribution to the breeding of the species palm oil, acai fruit, cacao, cupuacu, guarana, tomato, camu-camu, cocona, peach palm, and rubber was laid out in detail. Advances in breeding programs of institutions such as Embrapa, Ceplac, Inpa, and Universities require investments in infrastructure and in human and financial resources to ensure continuity and efficiency in economic, social and environmental gains. The improvement of native species, the main focus of the breeding programs of the institutions in the Northern region of Brazil, is a form of exploiting the Amazonian biodiversity for the benefit of society. Therefore, policies to foster research institutions should be a subject of deliberation and action of the scientific and technological community in Brazil.

Indução de brotação apical em mudas provenientes de sementes e do enraizamento de estacas de mangostãozeiro

With the objective to induce apical bud sprouting in young mangosteen seedlings an experiment was carried out with the application of the plant growth regulators kinetin (0, 100 and 400 mg L-1) and gibberellin GA4+7 (50 mg L-1). To obtain rooted cuttings two other experiments were performed: a) application of indolbutyric acid at the concentrations of 0, 100, 500 and 1000 mg L-1 and b) application of α naphtaleneacetic acid, at 6000 mg L-1. In these trials cutting from orthotropic branches were utilized. The results indicated the possibility of using plant growth regulators to obtain more uniform root stocks in a shorter nursery stage and, despite the low percentage of rooting the planting material obtained from cuttings has a great practical potential, since the size of the rooting cuttings is equivalent to that of one year old seedlings.

Impacts of stocking on the genetic diversity of Colossoma macropomum in central Amazon, Brazil.

Tambaqui (Colossoma macropomum) is the main fish species farmed on a commercial scale in northern Brazil. In view of the current scenario of Brazilian aquaculture, studies on the genetic improvement and reproductive management of captive tambaqui are crucial in identifying the genetic variability of broodstocks and devising management practices. Genetic diversity of three tambaqui broodstocks in western Amazon was evaluated using molecular markers. Fin samples were collected from 89 fish; 38 from Balbina, 30 from a hatchery in Rio Preto da Eva, and 21 from the experimental farm of the Federal University of Amazonas (UFAM). Ten primers were used for the analysis of diversity and genetic structure. Of the 152 bands produced, 146 were polymorphic. The proportion of polymorphic loci showed little variation among the three stocks. The lowest and highest rates were found in the Rio Preto da Eva (80.92%) and Balbina (85.53%) stocks, respectively. Heterozygosity (H) and Shannon (I) indices were similar among the stocks; the lowest values were found in Balbina (H = 0.279 and I = 0.419), and the highest in UFAM (H = 0.294 and I = 0.439). Following analysis of the genetic structure and relationship, the sample was divided into two groups, with the Balbina stock clearly deviating from the others. The results suggest that, to increase genetic variability, molecular information may be used instead of replacement of wild breeders. The groups characterized here can be used in genetic improvement programs with other tambaqui broodstocks from different areas of South America.

Reação de dez clones de Seringueira (Hevea benthamiana) a três isolados de Microcyclus ulei

The reaction of ten rubber clones (Hevea benthamiana) to three isolates of Microcyclus ulei (P. Henn.) v. Arx from two pathogenicity groups I and II was evaluated. The monocyclic parameters incubation period, latent period, lesion size and reaction type were studied. A conidial suspension of 2 χ 105 conidia/ml was inoculated on the abaxial leaflet surface in the B1/B2 stage; the seedlings were placed a humid chamber during 24 hours at 24 ± loC, then transfered to a growth chamber at the same temperature until the last evaluation at 15 days. The majority of the clones showed resistance to the three isolates. There was no significant interaction between clones and isolates in relation to incubation period, but there was significant interaction between clones and isolates in relation to lesion diameter. The clones CNSAM 8218 and CNSAM 8219 were highly resistant and showed the smallest mean lesion diameter when inoculated with isolate EB1, while CNSAM 8219 showed a small mean lesion diameter when inoculated with isolate EB2 also. At the other extreme, the clone CNSAM 8205 showed the largest mean lesion diameter when inoculated with isolate EB1 and the same reaction as clone CNSAM 8204 when inoculated with isolates EB2 and MB1 and clone CNSAM 8201 when inoculated with isolate EB2. These clones show vertical resistance making their unsuitable for the rubber breeding program that plans to obtain clones with horizontal resistance to M. ulei.