ABSTRACT. One of the main objectives of sugarcane plantations is to increase their longevity without decreasing agricultural productivity. In the present study, we analyzed the proteome of the axillary buds of ‘RB966928’ to investigate possible changes in the number of proteins at different cutting stages. Using tryptic digestion followed by ultra-performance liquid chromatography coupled with high-resolution time-of-flight mass spectrometry, 122 proteins were identified from the proteome of the axillary buds of ‘RB966928’. Of the 122, respectively 97 and 95 proteins were detected at the first and fifth cutting stages, of which 27 and 25 proteins were unique to the respective stage. Proteins that prevent the misfolding of polypeptides generated under stress were exclusively detected at the first cutting stage. Meanwhile, proteins associated with stress responses and disease resistance were exclusively detected at the fifth cutting stage. The present proteomic analysis in the regrowth cycles and axillary bud development of ‘RB966928’ significantly advanced our understanding of the biological processes linked to the reduction of agricultural productivity of sugarcane with the advancement of cutting age. Absence of proteins to tolerate adverse growth conditions at the fifth cutting stage may be related to reduced agricultural productivity, in addition to environmental stress, soil compaction, nutrient availability, cultural practices, and pests or pathogen attacks at different phenological stages of crops.

ABSTRACT. The genetic differentiation of grapevine rootstock varieties was inferred by the Artificial Neural Network approach based on the Self-Organizing Map algorithm. A combination of RAPD and SSR molecular markers, yielding polymorphic informative loci, was used to determine the genetic characterization among the rootstock varieties 420-A, Schwarzmann, IAC-766 Campinas, Traviú, Kober 5BB, and IAC-572 Jales. A neural network algorithm, based on allelic frequency, showed that the individual grapevine rootstocks (n = 64) were grouped into three genetically differentiated clusters. Cluster 1 included only the Kober 5BB rootstock, Cluster 2 included rootstocks of the varieties Traviú and IAC-572, and Cluster 3 included 420-A, Schwarzmann and IAC-766 plants. Evidence from the current study indicates that, despite the morphological similarities of the 420-A and Kober 5BB varieties, which share the same genetic origin, two new varieties were generated that are genetically divergent and show differences in performance.

RESUMO Somaclones de cactos mandacaru (Cereus peruvianus Mill.) com caules típicos e atípicos foram regenerados a partir do cultivo de calos. Uma vez que a relação genética entre estes somaclones ainda não foi investigada, o presente estudo empregou primers de microssatélites heterólogos para avaliar a diversidade genética dentro e entre os somaclones com fenótipos típicos e atípicos com alta divergência morfológica. O valor de identidade genética entre os somaclones foi alto (I = 0,929) e AMOVA mostrou maior variação genética dentro (96%) do que entre (4%) as amostras de somaclones. O polimorfismo nos locos microssatélites indicou altos níveis de heterozigosidades observada e esperada nos somaclones atípicos, presumivelmente com potencial alto de adaptação e como fonte de genótipos para a geração de novas variedades de cactos ornamentais. Por outro lado, a divergência genética baixa entre os somaclones típicos e atípicos é uma indicação promissora para o uso dos somaclones atípicos como fonte de compostos químicos de interesse comercial e industrial. As variações somaclonais que ocorreram no cultivo in vitro dos calos geraram subpopulações fenotipicamente diferenciadas com baixa divergência genética, porém com alta variabilidade genética, suficiente para recomendar os somaclones atípicos como fonte de genótipos para gerar novas variedades de cactos ornamentais e de plantas com novas características, necessários para a implementação de programas de melhoramento.

ABSTRACT Somaclones of mandacaru cactus (Cereus peruvianus Mill.) with typical and atypical shoots were regenerated from a callus. Since the genetic relationship among regenerated somaclones has not been investigated, current study employed heterologous microsatellite primers to examine the molecular diversity within and among somaclones, showing typical and atypical phenotypes with high morphological divergence. Nei identity value calculated between the somaclones was high (I = 0.929) and AMOVA showed higher genetic variation within (96%) than among (4%) the samples of somaclones. The polymorphism in the microsatellite loci indicated high levels of mean observed and expected heterozygosity in atypical somaclones, presumably with high adaptive potential and as source of genotypes for generation of new varieties of ornamental cacti. On the other hand, low molecular divergence between typical and atypical morphologies of somaclones is a promising perspective for use of the atypical somaclones as source of chemical compounds of commercial and industrial interest. The somaclonal variations occurring in vitro callus culture has generated phenotypically differentiated subpopulations with low molecular divergence, however with high genetic variability, enough to be recommended as a source of genotypes to generate new varieties of ornamental cacti and of plants with new traits, necessary for breeding programs.

The development of micropropagation techniques in orchid has many advantages such as the reproduction of elite, rare, sterile and/or disease-free genotypes. The aim of this study was to evaluate the use of organic supplements (coconut water and banana pulp) in the in vitro development of seedlings of Laeliocattleya (Hadrolaelia purpurata x Cattleya intermedia), comparing their response to plant growth regulators: auxins and cytokinins. For this, the following four experiments were carried out: 1. Organic supplements compared to different concentrations ofkinetin (N6-furfuryl aminopurine; KIN) and naphthaleneacetic acid (NAA), 2. Organic supplements compared to different concentrations of 3-indolebutyric acid (IBA) and N6-benzyladenine (6BA), 3. Organic supplements compared to different concentrations of IBA and KIN, and 4. Organic supplements compared with different concentrations ofANA and 6BA. Coconut water was statistically superior to the others (P <0.01) for the variable number of leaves, in all experiments performed with 7.3 leaves per seedling cultivated in vitro. While banana pulp showed the best results in the number of roots (P <0.01) for all experiments, with an average value of 7.4 roots. The addition of banana pulp and/or coconut water is suitable for the production of orchid hybrids, which present a positive effect on the development of seedlings. Its low cost is also a plus in relation to the use ofplant growth regulators.

El desarrollo de técnicas de micropropagación en orquídeas ofrece múltiples ventajas como la reproducción de genotipos superiores, raros, estériles o libres de enfermedades. El objetivo del presente trabajo fue evaluar el uso de suplementos orgánicos (agua de coco y pulpa de banana) en el crecimiento y desarrollo in vitro de plántulas del híbrido intergenérico Laeliocattleya (Hadrolaelia purpurata x Cattleya intermedia), comparando su respuesta con fitorreguladores de auxinas y citoquininas. Para ello se realizaron los siguientes cuatro experimentos: 1. Suplementos orgánicos comparados con diferentes concentraciones de kinetina (N6-furfuril amino purina; KIN) y ácido naftalenacético (ANA), 2. Suplementos orgánicos comparados con diferentes concentraciones de ácido 3-indolbutírico (IBA) y N6-benzyladenine (6BA), 3. Suplementos orgánicos comparados con diferentes concentraciones de IBA y KIN, y 4. Suplementos orgánicos comparados con diferentes concentraciones de ANA y 6BA. El suplemento orgánico de agua de coco fue estadísticamente superior al resto (P<0,01), para la variable número de hojas, en todos los experimentos realizados, con 7,3 hojas por plántula cultivada in vitro. En tanto que la adición de pulpa de banana mostró los mejores resultados en el número de raíces (P<0,01), para todos los experimentos en estudio, con un valor medio de 7,4 raíces. Se concluye que la adición de pulpa de banana o de agua de coco es conveniente para la producción de orquídeas híbridas por presentar un efecto positivo en el desarrollo de las plántulas, y por su costo reducido en relación con el uso de reguladores de crecimiento.

Information on genetic diversity is essential to the characterization and utilization of germplasm. The genetic diversity of twenty-two sweet corn cultivars (seventeen open-pollinated varieties, OPV, and five hybrids, H) was investigated by applying simple sequence repeat markers. A total of 257 primers were tested, of which 160 were found to be usable in terms of high reproducibility for all the samples tested; 45 were polymorphic loci, of which 30 were used to assess the genetic diversity of sweet corn cultivars. We detected a total of 86 alleles using 30 microsatellite primers. The mean polymorphism was 82 %. The highest heterozygosity values (Ho = 0.20) were found in the PR030-Doce Flor da Serra and BR427 III OPVs, whereas the lowest values (0.14) were recorded in the MG161-Branco Doce and Doce Cubano OPVs. The polymorphism information content ranged from 0.19 (Umc2319) to 0.71 (Umc2205). The analysis of molecular variance revealed that most of the genetic variability was concentrated within the cultivars of sweet corn (75 %), with less variability between them (25 %). The consensus tree derived from the neighbor-joining (NJ) algorithm using 1,000 bootstrapping replicates revealed seven genetically different groups. Nei’s diversity values varied between 0.103 (Doce do Hawai × CNPH-1 cultivars) and 0.645 (Amarelo Doce × Lili cultivars), indicating a narrow genetic basis. The Lili hybrid was the most distant cultivar, as revealed by Principal Coordinates Analysis and the NJ tree. This study on genetic diversity will be useful for planning future studies on sweet corn genetic resources and can complement the breeding programs for this crop.

Background The genetic diversity and structure of 31 popcorn accessions of the germplasm bank of the State University of Maringá were assessed using 30 microsatellite primers. Results 127 alleles were identified from 30 evaluated loci. The number of alleles per locus ranged from two to eight. The overall mean of the polymorphic loci averaged 79.89%. The primers UMC1549 and UMC1072 detected polymorphism in all accessions analyzed. The mean observed heterozygosity ranged from 0.07 to 0.30 and the highest proportion of heterozygous plants was observed in accession BOZM 260 (Ho = 0.30). The analysis of molecular variance revealed that 60% of the total genetic variation was found within accessions and 40% was found between accessions. The Bayesian clustering approach grouped the 31 accessions into two genetically differentiated clusters. The dendrogram revealed that accessions TATU 2 and ARZM 05 083 are genetically less similar than the others. Conclusions The analysis allowed to identify microsatellite loci with high levels of heterozygosity (UMC1549 and UMC1072). These loci can be indicated as promising for detecting polymorphisms in popcorn accessions and in the monitoring of genetic improvement programs. Moreover, allowed to identify heterozygous accessions (BOZM 260), this accession showed allelic variation at all analyzed microsatellite loci and can be recommended for crosses with plants that have desirable agronomic characteristics, with a view to the broadening of the genetic base of popcorn accessions and developing new cultivars.

Diatraea saccharalis são consideradas as principais pragas da cana-de-açúcar, estando distribuídas em todas as regiões canavieiras do Brasil. As informações sobre a genética de populações em D. saccharalis são raras e sua análise é muito importante para o sucesso de programas de controle da praga. O controle de praga necessita de uma constante avaliação da variabilidade genética para que estratégias adequadas sejam empregadas. A estrutura de populações de D. saccharalis presentes em culturas de cana-de-açúcar foi analisada por meio do marcador PCRRAPD. As amostras foram coletadas em canaviais de quatro regiões do noroeste do estado do Paraná e uma do estado de São Paulo. Foram empregados 12 primers RAPD, os quais produziram 216 fragmentos, com 99,54% de polimorfismo. O índice de Shannon foi em média 0,3797 (± 0,1729) e o valor médio encontrado do GST nas cinco populações foi de 0,0909, mostrando que as populações estão diferenciadas. Análise molecular de variância mostrou que 92% do polimorfismo ocorre dentro das populações. O amplo polimorfismo intrapopulacional mostra que esses insetos têm potencial para desenvolver resistência a inseticidas. O controle e o manejo da D. saccharalis deve ser realizado com cautela e integrado, ou seja, controle químico e biológico.

Diatraea saccharalis is the principal pest of sugarcane in Brazil and is found throughout the sugarcane crop. Information about its population genetics is scarce, but population genetic analysis is of particular importance as a basis for a successful pest control program. Pest control requires a constant evaluation of genetic variability so that appropriate strategies can be employed. In this study, the structure of D. saccharalis populations in sugarcane crops was analyzed with PCR-RAPD (Polymerase Chain Reaction-Random Amplified Polymorphic DNA) markers. Samples were collected from four sugarcane fields in ParanáState and one in São PauloState. Twelve PCR-RAPD primers were used. The analysis produced 216 fragments, with a 99.54% polymorphism rate. The Shannon index averaged 0.3797 (± 0.1729), and the average value of GST for the five populations was 0.0909. These results showed that the populations are differentiated. An analysis of molecular variance showed that 92% of the polymorphism occurs within populations. The high polymorphism rate within these populations shows that these insects have the potential to develop resistance to insecticides. The control and management of D. saccharalis should be conducted cautiously and integrated using chemical and biological control.

O presente trabalho teve como objetivos investigar a capacidade combinatória e o efeito heterótico de linhagens tropicais e temperadas sobre o rendimento de grãos (RG), teor de óleo (TO) e proteína (PB). Os híbridos e as linhagens foram avaliados a partir de um dialelo completo, sem recíprocos, em dois experimentos delineados em blocos casualizados com três repetições. O desdobramento da soma de quadrado de genótipos em soma de quadrados para capacidade geral (CGC) e específica (CEC) de combinação e a subsequente constatação de significância de CGC e de CEC evidenciaram que tanto efeitos aditivos quanto não-aditivos estiveram envolvidos no controle genético das características avaliadas. Pelas estimativas dos componentes quadráticos, houve superioridade dos efeitos genéticos não-aditivos no controle das características. Contudo, percebe-se que para PB e TO o efeito não-aditivo influenciou negativamente as combinações híbridas. O cruzamento L6x L10foi considerado promissor, pois associou positivamente RG com PB e TO.

This study aimed to investigate the combining ability and heterotic effects on grain yield (GY), oil content (OC) and crude protein (CP) in tropical and temperate maize lines. Hybrids and inbred lines were evaluated in a complete diallel scheme without reciprocals, in two experiments in randomized blocks with three replications. The partitioning of the sum of squares for general (GCA) and specific (SCA) combining ability indicated that both additive and non-additive effects were involved in the genetic control of the studied traits. The estimates of the quadratic components showed predominance of non-additive genetic effects in the trait control. However, for OC and CP, the non-additive effect had a clearly negative influence on the hybrid combinations. The cross L6x L10was considered promising, because it associated RG positively with BP and OC.

La variabilidad genética de las hormigas Atta sexdens rubropilosa colectadas en cinco lugares distintos de Brasil fueron evaluados por la técnica PCR-RAPD. Un total de 15 primers produjeron 148 fragmentos, de los cuales 123 fueron polimórficos, lo que corresponden al 83,11 %. La estimación de la diversidad genética por el índice de Shannon fue 0,3836 y el desviación estándar fue de ± 0,2335. Estos valores demuestran una alta diversidad genética. El valor de G ST fue 0,2372 y ΦPT = 0,184 lo que indica que las poblaciones están moderadamente diferenciadas y que el 82 % de la variación obtenida se produce dentro de las poblaciones. Aunque la prueba de Mantel ha demostrado una correlación entre la distancia genética y geográfica se observó que Ivatuba e Itambé (33,8 km) tiene una pequeña distancia geográfica y la mayor distancia genética. La distancia inferior genética fue estimada para Maringá e Ivatuba pero estas localidades cuentan con una distancia geográfica pequeña (42,3 km), lo que indica que no hay barreras para el apareamiento entre los reproductores en estas poblaciones. El alto valor de polimorfismo (83,11 %) y la capacidad de emparejamiento entre las poblaciones presentes en las regiones estudiadas, indican que esta especie de hormiga cortadora está bien adaptada a la región, y deben ser desarrollados programas integrados de control si se convierten en plagas.

The genetic variability of Atta sexdens rubropilosa leaf-cutting ants collected from five brazilian localities was evaluated with PCR-RAPD technique. We used 15 primers producing 148 fragments of which 123 (83.11 %) contained polymorphisms. The estimated Shannon index was 0.3836 ± 0.2335 showing that these ants possess high genetic diversity. The G ST value was 0.2372 and ΦPT = 0.184, indicating that the analyzed populations are moderately differentiated and 82 % of the variation obtained occur within populations. Although Mantel's test had shown correlation between genetic distances and geographic was observed that Ivatuba and Itambé (33.8 km) have the small geographical distance and the largest genetic distance. The lower genetic distance was estimated for Maringá and Ivatuba but this localities have a small geographic distance (42.3 km), indicating that there are no barriers for mating among reproducers in these populations. The high degree of polymorphism (83.11 %) and the ability to cross among the populations in the studied regions indicate that this species of leaf-cutting ant is well adapted to the region; therefore, integrated control programs can be developed.

No presente estudo foram adicionados ao meio de cultura Knudson-C (KC), suplementos específicos (micronutriente, peptona, carvão ativado) e complexos (água de coco e polpa de banana) para estimular a propagação in vitro das espécies de orquídeas Hadrolaelia purpurata (=Laelia purpurata) e Encyclia randii. O número maior de plântulas de H. purpurata foi observado no meio KC contendo 90 g L-1 de polpa de banana com iluminação contínua (24h). O efeito positivo da adição de polpa de banana foi descrito para a formação de plântulas e folhas de E. randii. O número de plântulas de E. randii mantidas com iluminação contínua também foi alto em meio contendo água de coco. Um efeito positivo da adição de peptona foi descrito somente na formação de plântulas de E. randii mantidas sob iluminação contínua. O maior número de plântulas de H. purpurata e folhas de E. randii ocorreu com iluminação contínua. O sucesso na germinação assimbiótica de sementes com três anos de idade, das duas espécies de orquídeas nativas do Brasil, de regiões diferentes, com custo reduzido, é uma técnica oportuna para ser usada em viveiros comerciais, e para a conservação ex-situ destas espécies nativas e exploradas de orquídeas.

In the current study, complex (coconut water and ripe-banana pulp) and specific (micronutrients, peptone and activated charcoal) supplements were added to Knudson-C medium (KC) medium to stimulate the in vitro propagation of Hadrolaelia purpurata (=Laelia purpurata) and Encyclia randii orchid species. The highest number of H. purpurata seedlings occurred in KC medium containing 90 g L-1 banana pulp maintained with 24-hour illumination. Positive effects of the banana pulp addition in KC medium were reported for the formation of seedlings and leaves from E. randii seeds. The seedling number from seeds of E. randii maintained with continuous illumination was also high in KC medium containing coconut water. Positive effects due to the addition of peptone were reported only in the case of seedling formation from E. randii seeds maintained under continuous illumination. The highest number of H. purpurata seedlings and leaves of E. randii occurred in cultures maintained in continuous illumination. The successful asymbiotic germination of the three-year-old seeds of two Brazilian native species from different regions at reduced costs offers an opportunity for the use of the techniques in commercial nurseries and for ex situ conservation of the native and explored orchid species.

Nenhum estudo prévio tem investigado o uso de grafite como substituto do carvão ativado em orquídeas. No presente trabalho, concentrações diferentes de carvão ativado ou de grafite foram adicionadas ao meio KC para escurecer o meio de cultura e estimular a propagação in vitro de Cattleya bicolor e de um duplo híbrido de orquídea ('BLC Pastoral Innocence'). As plântulas foram inoculadas em meio KC sem reguladores de crescimento; os efeitos de concentrações de carvão ativado (0,0; 1,5; 3,0; 4,5; 6,0 and 7,5 g L-1) e de grafite (0,0; 1,5; 3,0; 4,5; 6,0 and 7,5 g L-1) foram testados separadamente. Foram inoculadas quinze plântulas em cada frasco e os experimentos foram conduzidos sob esquema de planejamento fatorial com dois fatores: meios de cultura e luminosidade; o meio de cultura com onze níveis (diferentes concentrações de grafite ou de carvão ativado) e luminosidade com dois níveis (fotoperíodo de 14h e iluminação contínua). Para cada combinação do nível fatorial foram feitas três repetições. Após seis meses de cultivo, foram registrados os números médios de brotos e raízes induzidos em cada concentração de carvão ativado e de grafite. O maior número de brotos nas plântulas de C. bicolor foi observado no meio contendo 6,0 e 7,5 g L-1 de grafite, e o maior número de raízes foi verificado no meio contendo 6,0 g L-1 de carvão ativado. No duplo híbrido o maior número de brotos e raízes foi observado no meio contendo 4,5 g L-1 de carvão ativado. O grafite não pode ser recomendado para substituir o carvão ativado.

No previous studies have investigated the use of graphite instead of activated charcoal in orchids. In this work, different concentrations of activated charcoal or graphite were added to KC medium to darken the culture medium and stimulate the in vitro propagation of Cattleya bicolor and of a double hybrid orchid ('BLC Pastoral Innocence'). The seedlings were inoculated on growth regulator-free KC medium; the effects of activated charcoal (0.0, 1.5, 3.0, 4.5, 6.0, and 7.5 g L-1) and graphite (0.0, 1.5, 3.0, 4.5, 6.0, and 7.5 g L-1) concentrations were tested separately. Each flask contained fifteen seedlings, and the experiments had a randomised, two-way factorial design. The two tested variables were culture medium and illumination levels; eleven culture levels (different concentrations of graphite or activate charcoal) and two illumination levels (14-hr photoperiod or continuous illumination) were evaluated. Three replicates of each combination were utilised. After six months of culture, the average numbers of induced buds and roots per seedling were recorded for each concentration of activated charcoal or graphite. Whereas the largest number of buds in C. bicolor seedlings occurred on media containing 6.0 or 7.5 g L-1 graphite, the largest number of roots occurred on media containing 6.0 g L-1 activated charcoal. In the hybrid 'BLC Pastoral Innocence', the largest number of buds and roots was reported in medium with 4.5 g L-1 activated charcoal. When using graphite in place of activated charcoal, we obtained disparate the results in root formation that suggest that graphite is not a recommended substitute for activated charcoal.

O objetivo deste trabalho foi avaliar a diversidade genética de um estoque de Salminus brasiliensis utilizado em programas de repovoamento do rio Paranapanema, por meio do marcador RAPD. Dez reprodutores (cinco machos e cinco fêmeas) e sua progênie (40 larvas e 40 alevinos) foram analisados. Os oito iniciadores analisados produziram 96 fragmentos, dos quais 81,2% foram polimórficos. Houve diferença significativa na frequência de 32 dos 96 fragmentos, com a presença de um fragmento exclusivo nos alevinos. O índice de Shannon, a percentagem de fragmentos polimórficos e a distância e a identidade genética mostraram menor divergência genética entre os reprodutores e as larvas, além de diminuição da variabilidade nos alevinos. A divergência genética foi menor nos alevinos em comparação às larvas e aos reprodutores. A análise de variância molecular mostrou que a maior parte da variação está dentro de cada grupo (90,05%) e não entre os grupos (9,95%). O estoque de reprodutores apresenta alta variabilidade genética e houve diferenciação genética entre a fase de larva e alevino.

The objective of this work was to estimate by RAPD markers the genetic diversity of a Salminus brasiliensis lot used in stock enhancement programs in the Paranapanema River, Paraná, Brazil. Ten broodstocks (five males and five females) and their progeny (40 larvae and 40 fingerlings) were analyzed. Eight analyzed primers produced 96 fragments, of which 81.2% were polymorphic. There was significant difference in the frequency of 32 out of the 96 fragments, with the presence of an exclusive fragment in the fingerlings. The Shannon index, the percentage of polymorphic fragments, and the genetic distance and identity showed less genetic divergence between broodstocks and larvae, besides a decrease of genetic variability in the fingerlings. Genetic divergence was lower in the fingerlings in comparison to the larvae and broodstocks. The molecular variance results showed that most of the genetic variation is within (90.05%) and not between groups (9.95%). The broodstock lot has high genetic variability, and genetic differences were observed between the larval and fingerling stages.

No presente estudo o polimorfi smo de seqüencias de DNA amplificadas aleatoriamente foram usadas como marcadores moleculares para detectar variação genética em somaclones de Cereus peruvianus e para examinar a relação entre os somaclones e as plantas que crescem a partir de sementes, em populações cultivadas. A possível associação entre fragmentos de DNA com características morfológicas de somaclones também foi investigado. O polimorfi smo nos somaclones (62,24%) foi maior do que o detectado em plantas cultivadas (42,57%). O agrupamento casual dos somaclones apresentando caules com morfologias atípicas e típicas mostrou que o polimorfismo dos fragmentos de DNA amplifi cados no presente estudo não está associado com morfologias de caules. A similaridade nos somaclones e nas plantas cultivadas variou de 70,2 a 93,7% e de 76,7 a 86,8, respectivamente. Portanto, a cultura de tecido in vitro de C. peruvianus pode ser recomendada para ampliar a base genética desta espécie. A variabilidade genética encontrada nos somaclones é importante com uma fonte de novas características que podem ser necessárias para procedimentos em programas de melhoramento ou de conservação da espécie.

In current study Random Amplified DNA-Polymorphism markers were used to detect genetic variations in C. peruvianus somaclones and to examine relationships among somaclones and plants grown from seeds in cultivated populations. The possible association of DNA fragments with morphological traits of somaclones was also investigated. Polymorphism in somaclones (62.24%) was higher than that detected in cultivated plants (42.57%). The casual grouping of somaclones presented atypical and typical shoot phenotypes showed that the random amplifi ed DNA-fragment polymorphisms detected in present study were not associated with shoot morphologies. Similarity in somaclones and cultivated plants ranged from 70.2 to 93.7% and 76.7 to 86.8%, respectively. Thus, in vitro tissue culture of C. peruvianus may be recommended to broaden the species's genetic base. The genetic variability found in somaclones is important as a source of new traits that may be necessary as breeding or conservation programs proceed.

O objetivo deste trabalho foi avaliar a diversidade genética e a contribuição parental de Piaractus mesopotamicus na produção de descendência no sistema seminatural de reprodução. Vinte peixes parentais (onze machos e nove fêmeas) e o total de 100 larvas foram avaliados por meio do marcador microssátelite. Os parentais e a progênie tiveram trinta e um alelos e heterozigosidade de 0,550 e 0,563, respectivamente. As fêmeas foram fertilizadas por dois até seis machos enquanto machos fertilizaram três até cinco fêmeas. A contribuição de fêmeas e machos para a descendência seja 66,6 e 58,0%, respectivamente. Tais resultados não indicam diminuição da variabilidade genética na progênie e os parentais apresentaram paternidade múltipla e razoável contribuição à produção de descendência.

The objective of this study was to evaluate the genetic diversity and the parental contribution of Piaractus mesopotamicus in the production of offspring in the semi-natural system of reproduction. Twenty parental fishes (eleven males and nine females) and the total of 100 larvae were evaluated by microsatellite marker. The parents and offspring had thirty-one alleles and heterozygosity of 0.550 and 0.563, respectively. The females were fertilised by two up to six males while the males fertilised three up to five females. The contribution of the females and males to the offspring were 66.6 and 58%, respectively. Such results indicated no loss in the genetic variability in the offspring, and the parents had multiple paternity and reasonable contribution to the offspring production.

Information about genetic dissimilarity is very important to corroborate genealogical relationships and to predict the most heterozygotic hybrid combinations. Eight popcorn S6 lines of diverse germplasm types were evaluated using simple sequence repeats (SSR) markers. Of a total of 51 evaluated polymorphic primers, 15 were used for polymerase chain reaction (PCR) amplification. The genetic distance was estimated by Rogers’ modified distance. The different popcorn breeding programs in Brazil are possibly using highly similar base-populations. The genetic similarity of lines P1-3 and P8-1 was lowest, while P3-3 and P8-2 were genetically more similar. The cophenetic correlation showed that the Unweighted Pair-Group Method Using Arithmetic Averages (UPGMA) was reliable to discriminate the genotypes in five groups. The clusters were consistent with the estimates of genetic identity. There was a moderate coincidence degree between the groups and genealogy of lines. Higher levels of heterozygosity are expected from crosses between the group containing lines P3-3 and P7-3 with that of P1-3 and P7-4. Crosses between lines P1-3 and P8-1 are also promising.