Sandro Barbosa

Duplicação cromossômica de híbridos triplóides de capim-elefante e milheto

ABSTRACTCHROMOSE DUPLICATION OF TRIPLOID HYBRIDS BETWEEN ELEPHANTGRASSAND PEARL MILLET The aim of this study was to duble the chromose number of elephantgrass and pearl millet triploidhybrids in order to obtain hexaploid fertile plants. This strategy would allow the use of the hexaploidsin the elephantgrass breeding program as a bridge for transfering alleles of desired characteristics andmaking possible propagation by seed. Seedlings, plantlets and stem segments were cultivated in vitroand treated with 0.05% or 0.1% colchicine for 12 or 24 h. Seedlings of different hybrid genotypes andmeristems of two interspecific hybrids were cultivated in vivo and treated for 24 h with 0.05% colchicine.Chromose duplication was confirmed by countings in the root tip cells. Pollen viability, in vitro ( 1 ) Recebido para publicacao em 13 de junho de 2006 e aceito em 22 de marco de 2007.( 2 ) Departamento de Ciencias Biologicas, Universidade Federal de Alfenas, UNIFAL-MG, Rua Gabriel Monteiro da Silva, 714,Centro, 37130-000 Alfenas (MG), Brasil. E-mail: sandro@unifal-mg.edu.br (*) Autor correspondente.(

Mixoploidia em híbridos de capim-elefante x milheto tratados com agentes antimitóticos

The objective of this work was to evaluate methods of chromosome duplication, using antimitotic agents and several botanical materials as explant hybrids between napiergrass (Pennisetum purpureum Shum.) and pearl millet (Pennisetum glaucum (L.) R. Br.). Colchicine (50 mg L-1 and 100 mg L-1) and cycloheximide:8-hydroxyquinoline (1:1) (25 mg L-1:300 mg L -1) solutions have been applied in vivo to shoots and in vitro to seedlings and tillers. The antimitotic effect has been evaluated through survival rate, chromosome number and presence of cell cycle anomalies at the root tips of surviving plants. The best results have been obtained when seedlings have been treated with colchicine and tillers with cycloheximide: 8-hydroxyquinoline. Mixoploidy has been observed in cells having 14 to 42 chromosomes, indicating that duplication, followed by chromosome elimination, has occurred, which has been confirmed by chromosome aberrations. In the average, 86.4% of the analyzed cells have presented a chromosome number different from 21.

Meiotic behavior in early and recent duplicated hexaploid hybrids of napier grass (Pennisetum purpureum) and pearl millet (Pennisetum glaucum)

The production of hybrids between napier grass (Pennisetum purpureum, 2n = 4x = 28, genomes A′A′BB) and pearl millet (P. glaucum, 2n = 2x = 14, genome AA) results in sterile triploid plants. Such sterility of the triploid hybrid creates a hurdle for napier grass breeding programs, since it prevents propagation through seeds. Fertility can be restored by means of chromosome duplication. In most cases, these duplicated Pennisetum hybrids are mixoploids. However, we do not know if there are differences between the meiotic behavior of Pennisetum hybrids between napier grass and pearl millet which were duplicated early on and those duplicated more recently. This work evaluated the meiotic behavior and the pollen viability of American and Brazilian hexaploid hybrids, which differ by about 25 years in duplication time. In all analyzed hybrids, irregularities were observed from the initial phases of meiosis to pollen grain production, independently from the time elapsed for the duplication induction. The most frequent meiotic abnormalities are related to chromosome segregation due to irregular pairing. These irregularities will directly affect the viability and the size of the pollen grains.

Karyotipic asymmetry of both wild and cultivated species of Pennisetum

This study aimed the establishment of the relation between karyotipic asymmetry values obtained for different accessions of both wild and cultivated species of Pennisetum from Germplasm Bank of Embrapa Gado de Leite/Juiz de Fora-Minas Gerais State, Brazil. Conventional cell cycle synchronization protocols and Feulgen staining method were used to obtain metaphases plates. The wild-type accessions corresponded to the species P. setosum (2n=6x=54), P. nervosum (2n=4x=36), and P. orientale (2n=4x=36), and the cultivated to P. purpureum (2n=4x=28) and P. glaucum (2n=2x=14). No significant difference was found for the total length of chromosomes (p≥0.05) among the species. The analysis of intra-chromosomal asymmetry (A1) and inter-chromosomal asymmetry (A2) has shown that P. setosum has a tendency to chromosome asymmetry. P. nervosum, P. orientale, and P. purpureum have presented an intermediary level of asymmetry and P. glaucum , low asymmetry. Considering Stebbins criteria, the karyotype of P. glaucum and those from the three wild species fitted into the category 1A-symmetrical. With regard to P. purpureum, karyotypes of the accessions BAGs 54, 65 and 91 fitted into the category 2B and the other two genotypes (BAGs 63 and 75) fitted into the 1A. Comparison between the karyotype classification according to the inter- and intra-chromosomal asymmetry and Stebbins methodologies revealed that this last one alone was not able to detect small variations between karyotypes of the taxa closely related.

Anatomy and physiology of Cattail as related to different population densities

The objective of this work was to evaluate the effects of the population density of Typha angustifolia plants in the anatomical and physiological characteristics. Plants were collected from populations of high density (over 50% of colonization capacity) and low density (less than 50% of colonization capacity) and cultivated under controlled greenhouse conditions. Plants from both populations were grown in plastic trays containing 4 L of nutritive solution for 60 days. At the end of this period, the relative growth rate, leaf area ratio, net assimilatory rate, root/shoot ratio, leaf anatomy, root anatomy, and catalase and ascorbate peroxidase activities were evaluated. Plants from high density populations showed increased growth rate and root/shoot ratio. Low density populations showed higher values of stomatal index and density in leaves, as well as increased palisade parenchyma thickness. Root epidermis and exodermis thickness as well as the aerenchyma proportion of high density populations were reduced, these plants also showed increased vascular cylinder proportion. Only catalase activity was modified between the high and low density populations, showing increased values in low density populations. Therefore, different Typha angustifolia plants show differences in its anatomy and physiology related to its origins on high and low density conditions. High density population plants shows increased growth capacity related to lower apoplastic barriers in root and this may be related to increased nutrient uptake capacity.

Growth curve, biochemical profile and phytochemical analyses in calli obtained from the procambium segments of Bacupari

ABSTRACT Garcinia brasiliensis , popularly known as Bacupari, is native to the Amazon and commonly used in folk medicine for its therapeutic properties. This plant is rich in bioactive compounds like benzophenones. However, there are no works about the in vitro establishment and achievement of secondary metabolites in this plant. Thus, the aim of this work was to determine the growth curve and to perform the biochemical and phytochemical analyses in calli obtained from the procambium segments of Bacupari. The growth curve of calli followed a sigmoidal pattern, with four distinct phases (lag, exponential, linear, deceleration). Total soluble sugars were higher on the inoculation day and the reducing sugars on the 20 th day. Amino acids increased from the 60 th day up to the stabilization on the 120 th day. The protein content varied, but it seemed to be related to the amino acids metabolism. The phytochemical screening showed the presence of phenolic and flavonoid compounds in the calli and the HPLC analysis allowed the identification of Fukugetin, Guttiferone A and 7-epiclusianone. Key words: Bacupari, benzophenones, calli

Fitotoxicidade e citogenotoxicidade da água e sedimento de córrego urbano em bioensaio com Lactuca sativa

The aim of this study was to evaluate the spatial and temporal influence of the phytotoxicity and cytogenotoxicity of water and sediment of urban stream on the germination and initial growth of Lactuca sativa. Samples were collected from water and sediment at five sites of the Pântano Stream (Alfenas, Minas Gerais) during the period from October 2010 to July 2011. The concentrations of the metals Cd, Pb and Zn were quantified. Moreover, phytotoxicity and cytogenotoxicity were tested with samples of water and aqueous extracts of sediments. The evaluated end points were the germination rate, root length, fresh and dry weight, mitotic index and frequency of chromosomal abnormalities. Higher levels of Cd and Pb were verified in water samples collected during the rainy months. Water and sediment showed phytotoxic effect on germination, fresh weight and dry weight of Lactuca sativa. Root length was stimulated and only samples of water reduced the mitotic index. Significant temporal variation related to rainfall was observed only for phytotoxicity tests.

Métodos para a superação da dormência fisiológica de Caryocar brasiliense Camb.

O pequizeiro e uma frutifera nativa dos cerrados brasileiros com grande potencial economico. Neste trabalho, objetivouse avaliar o efeito de substâncias potencialmente estimuladoras da germinacao. As sementes foram extraidas dos carocos e colocadas para germinar em rolos de papel embebidos com as seguintes solucoes: agua destilada (Controle); 2mmol L-1 KNO3 (Nitrato); 2mmol L-1 Etephon (ET); 1mmol L-1 GA3 (GA); 1mmol L-1 GA3 + 2mmol L-1 Etephon (GA + ET). Os resultados de percentagem de germinacao e o tempo medio para germinacao foram, respectivamente, de 54,0% e 9,3 dias no tratamento GA; 47,3% e 11,0 dias no tratamento GA + ET; 32,0% e 12,2 dias no tratamento Controle; 30,7% e 13,1 dias no tratamento Etephon e 20,1% e 13,1 dias no tratamento Nitrato. No tratamento GA + ET houve queda da taxa de germinacao ate os nove dias da semeadura, com relacao ao tratamento GA, o que indica uma possivel inibicao da germinacao de sementes de pequizeiros pela presenca de etileno.

MICROMORFOMETRIA FOLIAR DE Schinus molle L. (ANARCADIACEAE) EM DIFERENTES ALTURAS NA COPA

A caracterizacao foliar em arvores e essencial para a sua identificacao e utilizacao, bem como para se compreender as suas relacoes com o ambiente. Neste trabalho, objetivou-se o estudo da anatomia dos foliolos e das caracteristicas biometricas das folhas de S. molle em diferentes alturas na copa, em funcao das modificacoes ambientais e fisiologicas promovidas. As folhas foram coletadas em tres diferentes alturas na copa: base, meio e alto da copa em uma populacao cultivada de S. molle. Para as analises anatomicas, as folhas foram fixadas em FAA e armazenadas em etanol sendo, posteriormente, submetidas a seccoes paradermicas e transversais. As lâminas foram fotomicrografadas e as imagens analisadas no software UTHSCSA-Imagetool. Para as analises biometricas foram avaliadas a area, comprimento, largura, massa seca foliares, bem como a area foliar especifica. Os foliolos possuem epiderme unisseriada, estomatos anomociticos e ciclociticos, mesofilo isobilateral e camada subepidermica em ambas as faces da epiderme. Canais secretores e colenquima foram observados na nervura central e bordo dos foliolos. Ocorreram modificacoes nas espessuras da cuticula e do mesofilo, no sistema vascular, espessura do floema e na densidade estomatica de acordo com a altura em que os foliolos se encontram na copa das arvores. As folhas foram menores e demonstram reduzida area foliar para as partes mais altas da copa. A anatomia foliar de S. molle e diferente de outras especies do genero Schinus e demonstra modificacoes sob as diferentes condicoes ambientais e fisiologicas promovidas pelas diferentes alturas na copa.

Variation of karyotype and nuclear DNA content among four species of Plectranthus L’ Héritier, 1788 (Lamiaceae) from Brazil

Abstract Plectranthus is a genus which includes species of ornamental and medicinal potential. It faces taxonomic problems due to aggregating species previously belonging to the genus Coleus, a fact that has contributed to the existence of various synonymies. The species Plectranthus amboinicus, Plectranthus barbatus, Plectranthus grandis and Plectranthus neochilus are included in this context. Some authors consider Plectranthus barbatus and Plectranthus grandis as synonyms. The present work was carried out with the aim of comparing plants of the above-mentioned species, originating from different localities in Brazil, with regards to chromosome number and karyotypic morphology, correlated to the nuclear DNA content. There was no variation in chromosome number among plants of the same species. Plectranthus amboinicus was the only species to exhibit 2n=34, whereas the others had 2n=30. No karyotypic differences were found among the plants of each species, except for Plectranthus barbatus. The plants of the Plectranthus species revealed little coincidence between chromosome pairs. The nuclear DNA content allowed grouping Plectranthus amboinicus and Plectranthus neochilus, with the highest mean values, and Plectranthus grandis and Plectranthus barbatus with the lowest ones. Differences in DNA amount among the plants were identified only for Plectranthus barbatus. These results allow the inference that the populations of Plectranthus amboinicus and Plectranthus neochilus present coincident karyotypes among their plants, and Plectranthus grandis is probably a synonym of Plectranthus barbatus.