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Aluminum (Al) effects on fatty acid composition and on the lipid peroxidation of a puri®ed plasma membrane fraction of root apices of two sorghum cultivars were studied. Palmitic and linoleic acids were the major fatty acids in the root apices of sorghum, independent of the Al presence in nutrient solution. After Al treatment, the C18:0aC18:3 and C18:2aC18:3 ratios increased, while the C18:2aC16:0 ratio remained unchanged in the Al-sensitive cultivar but all three ratios decreased in the Al-tolerant cultivar. The double bond index and unsaturated JOURNAL

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The antioxidant defense system response was evaluated in two rice cultivars (Oryza sativa L.), Fernandes (CNA-1158) and Maravilha (CNA-6843-1), treated with toxic levels of aluminum. After exposure to aluminum we determined plant growth, H 2 O 2 and O 2•-contents, lipid peroxidation, antioxidant enzymes activities and ascorbate and dehydroascorbate contents. Al predominantly accumulated in roots of both cultivars but it reduced root and shoot growth only in the Maravilha cultivar. Treatment with aluminum resulted in a reduction of 84 and 60% in the levels of H 2 O 2 in the roots of the cultivars Maravilha and Fernandes, respectively, and of 26% in the levels of O 2•-only in the roots of Fernandes cultivar. Increased lipid peroxidation was observed only in the roots of the Maravilha cultivar. In general, the antioxidant enzyme activities were higher in roots and increased in the presence of aluminum, especially in the Fernandes cultivar. The levels of ascorbate were higher in leaves and increased with aluminum treatment, while dehydroascorbate decreased in roots of both cultivars after aluminum treatment. However, the ascorbate/dehydroascorbate ratio increased in the roots of both cultivars after treatment with aluminum. Ascorbate, dehydroascorbate and ascorbate/dehydroascorbate levels found here point to an efficient regeneration of ascorbate, essential for the homeostasis of cellular metabolites involved in reactive oxygen species removal by rice plants treated with aluminum. Therefore, the higher tolerance of Fernandes to aluminum relative to Maravilha cultivar may be the result of better growth of the root system and shoots, higher antioxidant enzyme activities and a best use/ regeneration of ascorbate.

. As análises da morfologia externa e interna dos ápices radiculares de plantas tratadas com Al +3 também foram muito similares entre as duas cultivares, não permitindo a utilização dessas características para seleção entre a cultivar sensível e a tolerante. O maior acúmulo de lignina e, principalmente, a menor produção de compostos fenólicos, observados na presença do Al +3 nas raízes das plantas da cultivar tolerante (BR006R), são parâmetros que possibilitam a discriminação das cultivares quanto à tolerância ao Al +3 .Palavras-Chave: alumínio, morfologia, fenólicos, sorgo, Sorghum bicolor. ABSTRACT CHANGES IN MORFOLOGY AND PHENOLICS ACCUMULATION IN SORGHUM (Sorghum bicolor (L.) Moench) PLANTS UNDER ALUMINUM STRESSThe Al +3 effects on the morphology and on the phenolics accumulation were evaluated in two sorghum cultivars exhibiting differential tolerance to Al +3 . The plants were kept in nutrient solution, for ten days, in the presence (185 mM) or Al +3 absence. The root apexes were colored with ferric hematoxylin, and because the intensity of color development is very similar among evaluated cultivars, the use of this method as a selection parameter for Al +3 -tolerance is not indicated. Analyses of superficial and internal morphology from tissues treated with Al +3 also expressed very similar alterations among the two cultivars, not allowing its use for selection between sensitive and Al +3 -tolerant genotype. The higher lignin accumulation and, mainly, the lower phenolics production in roots of the BR006R cultivar in Al +3 's presence, demonstrated the existence of differential tolerance among cultivars.

Lippia lacunosa e L. rotundifolia são duas espécies brasileiras que formam um complexo de difícil delimitação taxonômica. A composição química do óleo essencial das folhas e flores dessas plantas foi investigada por cromatografia com fase gasosa (CG) e por cromatografia com fase gasosa acoplada à espectrometria de massas (CG-EM). Principais constituintes dos óleos essenciais de L. lacunosa (flores e folhas): mirceno (14,7% e 11,9%), mircenona (45,2% e 64,2%), Z-ocimenona (5,7% e 5,2%), e E-ocimenona (14,7% e 4,1%), respectivamente; L. rotundifolia (flores e folhas):-pineno (8,7% e 1,8%), mirceno (5,1% e 3,6%), limoneno (26,0% e 7,9 %), cis-pinocanfona (4,5% e 3,1%) e mirtenal (22,3% e 16,7%), respectivamente. Os óleos essenciais de L. lacunosa apresentaram um forte e agradável aroma de manga, que foi relacionado à presença de mirceno e mircenona. Diferenças fundamentais na composição química de seus óleos essenciais podem representar uma poderosa ferramenta na classificação botânica das espécies.Lippia lacunosa and L. rotundifolia (Verbenaceae) are two Brazilian species of complex taxonomic delimitation. The composition of the essential oils from leaves and flowers of these plants was investigated by gas chromatography (GC) and gas chromatography coupled with mass spectrometry (GC-MS) analysis. The major components of the essential oils of flowers and leaves of L. lacunosa were: myrcene (14.7% and 11.9%), myrcenone (45.2% and 64.2%), Z-ocimenone (5.7% and 5.2%), and E-ocimenone (14.7% and 4.1%), respectively; whereas in L. rotundifolia (flowers and leaves) were -pinene (8.7% and 1.8%), myrcene (5.1% and 3.6%), limonene (26.0% and 7.9 %), cis-pinocamphone (4.5% and 3.1%) and myrtenal (22.3% and 16.7%), respectively. The essential oils from L. lacunosa exhibited a strong and pleasant mango aroma, which was related to the presence of myrcene and myrcenone. The marked differences in the chemical composition of their essential oils may represent a powerful tool for the botanical classification. Keywords: Lippia lacunosa, Lippia rotundifolia, myrcene, myrcenone, (E)-ocimenone, limonene, myrtenal, GC, GC-MS IntroductionThe genus Lippia (Verbenaceae) comprises about 200 species occurring mainly in Central and South America, as also in some areas of Tropical Africa.1 One of the main diversity centers of the genus Lippia is located at the "Cadeia do Espinhaço" Mountains, in the State of Minas Gerais, Brazil. 2There are some taxonomical controversies on the number of Lippia species. Moldenke 3 compared the descriptions given by various authors to this genus, and presumably all the authors Leitão et al. 1389 Vol. 19, No. 7, 2008 included Acantholippia, Aloysia and Phyla in their concept of Lippia. 3,4 Some species, like L. alba and L. graveolens are largely used in folk medicine and culinary.1 As part of our continuing study on Lippia species occurring in Brazil, L. lacunosa Mart. & Schauer and L. rotundifolia Cham. were selected for investigation. Included in the Section Corymbosae, they form a complex of very difficult...

Polyploidy is widely recognized as a major evolutionary force in plants and has been reported in the genus Lippia (Verbenaceae). Lippia alba, the most studied species, has been documented as a polyploid complex involving at least four ploidal levels. L. alba presents remarkable chemical and genetic variation and represents a model for understanding genome organization. Although the economic and medicinal importance of the species has been widely described, no established polyploid induction protocol has been reported so far. Here, we describe the production of synthetic polyploid plants of L. alba using colchicine. The ploidal levels were estimated by flow cytometry and chromosome counting. In addition, FISH and molecular markers approaches were used to confirm the stability of the synthetic polyploids. The major component of the essential oils was estimated by GCMS to compare with the natural individuals. Tetraploids and triploids were produced providing new opportunities for investigating medicinal, pharmacological, and economic applications as well as addressing intrinsic questions involved in the polyploidization process in tropical plants.

This study aimed to evaluate the variation in the levels of proline, oxidative metabolism and photosynthetic pigments in plants of Pitcairnia encholirioides grown in vitro under different conditions and after acclimatization. The analyses were performed after 150 days of in vitro cultivation in MS media supplemented with 10 µM GA 3 or 0.2 µM NAA, sucrose at 15 or 30 g L -1 , in test tubes which allowed gas exchange or in a hermetically sealed system, and 180 days after acclimatization. The in vitro maintenance in hermetically sealed flasks, with GA 3 and 15 g L -1 sucrose had adverse metabolic effects, which was demonstrated by the lower proline and photosynthetic pigments accumulation and by the increase in antioxidant enzymes activities. After acclimatization, differences for proline and photosynthetic pigments were no longer found and the enzymatic activities ranged unevenly. The results suggest that the in vitro cultivation in media with 0.2 µM NAA and 30 g L -1 sucrose, in test tubes capped with closures which allowed gas exchange, is more suitable for micropropagation of P. encholirioides, providing a prolonged maintenance of in vitro cultures and plantlets with superior quality for ex vitro development.Keywords: enzymatic activity, oxidative stress, micropropagation, proline. Niveis de prolina, do metabolismo oxidativo e dos pigmentos fotossintéticos durante o crescimento in vitro e aclimatização de Pitcairnia encholirioides L.B. Sm. (Bromeliaceae) ResumoEste trabalho objetivou avaliar a contribuição da prolina, do metabolismo oxidativo e dos pigmentos fotossintéticos na propagação in vitro e aclimatização de Pitcairnia encholirioides, uma bromélia criticamente ameaçada de extinção. As análises foram realizadas após 150 dias de cultivo in vitro em meio MS suplementado com 10 µM de GA 3 ou 0,2 µM de ANA, 15 ou 30 g L -1 de sacarose, em tubos de ensaio que permitiam trocas gasosas ou em sistema hermeticamente vedado, e também 180 dias após aclimatização. A manutenção in vitro em frascos hermeticamente fechados, com GA 3 e 15 g L -1 de sacarose apresentou efeito metabólico adverso, demonstrado pelo menor acúmulo de prolina e pigmentos fotossintéticos e também pelo aumento das atividades de enzimas antioxidantes. Após aclimatização, as diferenças para prolina e pigmentos fotossintéticos não foram mais encontradas e as atividades enzimáticas variaram de maneira desuniforme. Os resultados sugerem que o cultivo in vitro em meio com 0,2 µM de ANA e 30 g L -1 de sacarose, em tubos fechados com tampas que permitem trocas gasosas, é mais adequado para a micropropagação de P. encholirioides, proporcionando uma manutenção prolongada das culturas in vitro e plântulas com qualidade superior para o desenvolvimento ex vitro.Palavras-chave: atividade enzimática, estresse oxidativo, micropropagação, prolina.