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The objective of this study was to observe the effects of brassinosteroid, gibberelin, and auxin application on the development and foliar anatomy of Tabebuia alba (Cham.) Sandw. seedlings. T. alba seedlings were grown in plastic bags with fertilized soil and treated with the following: 1- water (control); 2- brassinolide (BR1) 0.104 mM; 3- BR1 0.208 mM; 4- 3-indoleacetic acid (IAA) 0.2854 mM; 5- IAA 0.5708 mM; 6- GA3 (gibberellin A3) 0.1443 mM; 7- GA3 0.2887 mM; 8- GA3 0.072 mM + IAA 0.1427 mM; 9- GA3 0.1443 mM + IAA 0.2854 mM; 10- GA3 0.072 mM + BR1 0.052 mM; and 11- GA3 0.1443 mM + BR1 0.104 mM. Plant height and petiole length were measured before the treatments and 21 days after application of the growth regulators. These data allowed the calculation of stem and petiole growth rates. The results showed that GA3 + brassinolide produced the highest stem and petiole growth rates and brassinolide application stimulated petiole growth but not stem growth. The anatomical study of leaves showed alterations in blade and petiole thickness, palisade and spongy parenchyma height, and epidermis cells.

Lotus corniculatus, L. tenuis, L. pedunculatus, and L. subbiflorus inoculated with Mesorhizobium loti NZP2037 strain were grown in a growth chamber. The plants dry weight (DW), the nodule fresh weight (FW), the nitrogenase activity, the nodule glutamine synthetase (GS) and glutamate synthase (GOGAT) activities, as well as the leghemoglobin content and the amino acid in the stem were measured 28 days after inoculation. The highest DW of plants was measured in L. tenuis and the highest FW of nodules was measured in L. pedunculatus. Nitrogenase activity in L. tenuis, L. pedunculatus and L. subbiflorus was six fold the activity in L. corniculatus. Nodule GS and GOGAT activities did not follow this same pattern. L. tenuis had the highest values of GS and GOGAT activities in the nodule, and a high nitrogenase activity which is consistent with its high plant DW. The four species of Lotus were compared and no correlation between nitrogen fixation parameters and ammonia assimilation enzymes was found, but the GS/GOGAT ratio has a positive and significant correlation (r²=0.82**) with the amino acid content in stems.

Galactinol synthase (GS) is a key enzyme for the biosynthesis of raffinose oligosaccharides (RO) which are the flatulence factors present in soybean seeds and several other legumes. Understanding of soybean seed GS properties is, therefore, of biotechnological interest. The GS enzyme catalyses formation of galactinol and UDP from UDP-gal and myo-inositol. This enzyme is currently assayed by an isotopic method. We have then idealized a more convenient method for GS assay based on the indirect colorimetric determination of the UDP formed which is then hydrolyzed by exogenous apyrase and the resulting Pi quantified by a modification of the colorimetric method of Fiske & SubbaRow. The color developed is stable, and the method is suitable for detection of very low GS activity. The GS activity profiles of developing soybean seeds determined by the isotopic and the colorimetric methods are closely related. The GS enzyme was partially purified (46-fold) by treatment of seed extract with MnCl2, sequential chromatographies on DEAE-Sepharose, Phenyl-Sepharose CL-4B and Q-Sepharose columns. The crude and the partially purified enzyme showed maximum activity at pH 7.0 and 50 ºC. Dithiothreitol and MnCl2 enhanced considerably the activity of the partially purified enzyme. While UDP-glc could be hydrolyzed by the enzyme at a reative activity corresponding to 49% of that calculated for UDP-gal, UDP-man and sucrose were completely ineffective as alternative substrates.

Avaliou-se o efeito de concentrações crescentes de Cu no crescimento, teores e translocação de metais pesados e nutrientes no eucalipto em solução nutritiva. Mudas de Eucalyptus maculata e Eucalyptus urophylla foram crescidas em vasos de 2L contendo solução nutritiva de Clark, adicionando-se 0, 32, 64, 128 e 192 m M de Cu fornecido como CuSO4. Após cinco semanas de exposição aos tratamentos, as plantas exibiram sintomas típicos de toxidez de Cu como manchas aquosas foliares, clorose e necrose internerval, além do escurecimento das raízes e inibição do crescimento mesmo nas menores concentrações do elemento. A concentração crítica de Cu na solução para reduzir em 10% a matéria seca da parte aérea foi de 8,3 miM e 3,3 miM para E. urophylla e E. maculata, respectivamente. O nível crítico de toxidez na matéria seca da parte aérea foi muito baixo, entre 12 e 13 mg Kg-1 para ambas espécies. E. urophylla mostrou-se menos sensível do que E. maculata, sendo isso relacionado à capacidade dessa em restringir a translocação do Cu das raízes para a parte aérea. Além disso, E. urophylla absorveu mais Fe na presença do excesso de Cu. A translocação de Fe das raízes para a parte aérea foi reduzida, independentemente da espécie, de 27% no controle para apenas 12% na concentração de 192 m M Cu, evidenciando a alta interferência do Cu na translocação do Fe, podendo ser uma das causas da fitotoxidez do Cu para o eucalipto. Altas concentrações de Cu não causaram redução na absorção e translocação de P, K, S, Ca e Mg, não representando, portanto, mecanismo de fitotoxidez desse metal pesado para essas espécies.

Seed composition and reserve mobilization were investigated in wild poinsettia (Euphorbia heterophylla L.). Lipids, around 60% of seed dry mass, are the major reserve. Proteins, including albumins (49%), salt insoluble globulins (30%), salt-soluble globulins (21%) and prolamins (0.3%), comprise about a quarter of seed dry mass. Soluble sugars comprise about 3.6% of seed dry mass, sucrose being the predominant sugar. Starch was not detected in the endosperm of E. heterophylla. Lipid depletion starts after initial imbibition, and is completed between 72 and 96 hours. Protein fractions exhibit different degradation patterns, salt-soluble globulins being continuously degraded after the start of imbibition whereas salt insoluble fractions are degraded between 36 and 72 hours, and albumins between 60 and 84 hours. Globulin depletion is accompanied by an increase in free amino acids in the endosperm whereas intense albumin depletion is not. This result suggests that during albumin depletion there is a rapid transfer of amino acids to the growing embryo. Histochemical studies indicated that light accelerates protein degradation in the micropylar area of the seed. Soluble sugars increase in the embryo with no concomitant decrease in the endosperm, suggesting that sugars are mostly originated from the catabolism of lipids.

A possibilidade de se encontrar genótipos de arroz, gramínea C3, com características anatômico-foliares semelhantes às gramíneas C4 levou ao presente estudo. Genótipos com características C4 seriam superiores fotossinteticamente, mais adaptados ao estresse ambiental e mais produtivos. Nesta pesquisa foi observada a anatomia foliar de 483 exemplares de arroz, sendo 477 da espécie Oryza sativa L. e seis de outras espécies (Oryza glumaepatula, O. glaberrima, O. nivara, O. rufipogon, O. flotante e O. longistaminata). Na pesquisa, observou-se a presença de cloroplastos nas células da bainha vascular da cultivar CNA 6189. Em alguns outros genótipos, foram encontrados apenas vestígios de cloroplastos, e nenhum cloroplasto na maioria dos genótipos, como o IAC 25. Com base nos resultados encontrados, espera-se que por meio de técnicas de biologia molecular, características de plantas C4 venham a ser incorporadas a plantas, como o arroz, melhorando substancialmente as suas potencialidades de adaptação a ambientes menos favorecidos.

ABSTRACT - The mobilization of seed proteins from Pisum arvense L. during germination in the absence of light was studied. The seeds were found to be completely consumed 22 days after germination and seedlings ceased growth after the 18th day. SDS-PAGE indicated that the main protein bands correspond to high molecular mass storage proteins which undergo proteolysis in the initial stages of germination and are not detected after the 7th day of germination. However, the corresponding lectin profiles were detected during the entire germination process, suggesting that these proteins are strongly resistant to seed proteolytic enzymes and should be important for seedling establishment. Furthermore, haemagglutinating activity in cotyledons was detected until 22 days after germination, indicating that the lectins remain active even in senescent cotyledons.

Com o objetivo de estudar a cinética da despolimerização dos microtúbulos e a dinâmica da indução de micronúcleos, usaram-se dois herbicidas com ação antimitótica, amiprofós-metil (APM) e oryzalin (ORY), em células de Helianthus maximiliani. A aplicação de ambos os herbicidas em células com ativo crescimento resultou num elevado número de células com micronúcleos, em virtude das modificações mitóticas causadas pela ausência de microtúbulos. Primeiramente, cromossomos isolados ou grupos de 2 ou mais cromossomos espalharam-se pelo citoplasma. Duas a três horas após a aplicação dos herbicidas, os microtúbulos, estavam despolimerizados e os cromossomos metafásicos condensaram-se, formando diretamente os micronúcleos sem ter havido a divisão do centrômero e a separação das cromátides. A concentração mais eficiente de ORY foi 20 µM, ao passo que para APM foi 60 µM, para um período de incubação de 36 e 48 h respectivamente. O prolongamento do período de tratamento elevou a freqüência de micronúcleos deformados, bem como aumentou a morte celular. A adição de citocalasina-B (CB) (20 µM), após 24 h da aplicação dos herbicidas, aumentou significativamente a micronucleação e estabilização dos micronúcleos nas células. O controle dos microtúbulos de células em suspensão torna-se uma ferramenta eficiente para a indução de micronúcleos, bem como representa um método elegante para a transferência genômica parcial.

Com este trabalho objetivou-se investigar a aquisição da capacidade germinativa e o estabelecimento da dormência em sementes em desenvolvimento de Bixa orellana L. (urucum). Foram caracterizados 7 estádios de desenvolvimento das sementes, baseados nas características morfológicas, massa fresca, massa seca e teor de umidade dos frutos e das sementes. Sementes imaturas de B. orellana não germinaram durante os estádios iniciais de seu desenvolvimento. As sementes adquiriram a capacidade germinativa máxima quando os níveis de umidade declinaram para valores em torno de 60%. Nessa fase, as sementes apresentaram acúmulo máximo de massa seca. A dormência foi estabelecida quando as sementes exibiam um conteúdo de água em torno de 10%.

Leaf lipoxygenases (LOX) are involved with important physiological processes such as plant growth and development, senescence, biosynthesis of regulatory molecules, and response to pathogens and insects. We did a biochemical evaluation of the LOX pathway of soybean leaves submitted to wounding in a normal genotype (IAC-100) and its counterpart lacking seed LOX (IAC-100 TN). Our results indicate that LOX activities in the different pHs and temperatures tended to be higher in the wounded plants compared to their respective controls. The K M app values at 168 h after wounding reached a minimum in both genotypes indicating that the plants respond by changing the leaf LOX pool. There was an increase on protease inhibitor levels in all time points after wounding, for both cultivars. The levels of hexanal and total aldehydes are similar for the wounded plants at different times after wounding and their respective controls for both genotypes. Our results strongly suggest that the LOX pathway is activated during the wound response leading to jasmonate by the initial action of hydroperoxide cyclase. In addition, the results show that the genetic removal of seed LOX does not interfere with the plant’s ability to respond to wound via the LOX pathway.

Citric and malic acid excretion in the medium and malic acid accumulation in seedling roots and embryo-derived calli as possible mechanisms of aluminum (Al) resistance and the effects of a 17-h Al stress period on root growth in Oryza sativa have been studied. Four-day-old seedlings and embryo-derived calli of Al-resistant (IRAT 112 and IR6023) and Al-sensitive (Aiwu and IKP) cultivars were treated with 250 and 500 µM {Al2(S04)3.18H20 }of total aluminum or without Al for 36 hours. After 3 to 36 hours of stress, seedlings and calli were removed from the flasks and concentration of citric and malic acids was estimated in the Al and control solutions. Malic acid was also assayed in roots tips and in callus tissues. After 17-h of Al stress, inhibition of root growth was a typical effect of Al in rice and the extent of the inhibition depended on both cultivar and Al concentration. At 500 µM of Al, strong reduction of root elongation occurred in all cultivars while at 250 µM of Al, only IRAT was unaffected, when compared to their control. In the absence of Al, all varieties excreted comparable amounts of citric and malic acid. Al treatments, were without effect upon citrate excretion in both Al-resistant and Al-sensitive cultivars. Al treatment, for periods from 3 to 24h, slightly stimulated the excretion of malic acid from seedlings, in all cultivars. Malic acid concentrations in root apices, in the presence or absence of aluminum, were not correlated with aluminum resistance. No differences in malic excretion and internal concentrations were detected between Al-treated and untreated rice calli of the same four cultivars. It is therefore concluded that, in our experimental conditions, differences in Al resistance in our rice cultivars cannot be attributed to citric and malic acids. Further research needs to be carried out to examine other possible mechanisms of Al-resistance in rice and to determine whether organic acids such as succinic and oxalic acid are implicated.

The actual (A) and potential (Apot) photosynthetic rates of C3 and C4 tropical crop species grown under greenhouse conditions was compared. The following species were investigated: Oryza sativa, Phaseolus vulgaris, Glycine max, Helianthus annuus, Gossypium hirsutum, Manihot esculenta, Theobroma cacao, Coffea arabica, Hevea brasiliensis, and Eucalyptus urophylla × E. grandis, all from the C3 group, and Amaranthus sp., Panicum maximum, Pennisetum purpureum, Zea mays and Saccharum officinarum, from the C4 group. A, determined under non-limiting light at ambient temperature and CO2, was measured with an infrared gas analyser, whilst Apot, determined under saturating light and CO2 at an optimal temperature (35 ºC for all species), was gauged with a gas-phase oxygen electrode. On an area basis, A varied from 5.0 up to 26.3 mumol CO2 m-2 s-1, whilst Apot was very similar in 14 of the 15 species, with an average rate of 35.0 ± 2.4 mumol O2 m-2 s-1. The value of Apot in T. cacao was approximately half the mean of the remaining species. On a mass basis, variations in A were much larger, and differences in Apot, although not large, emerged. The overall mean Apot per unit mass in the four tree species was 28.0 ± 2.2 mumol O2 g-1 min-1 against 44.6 ± 5.8 mumol O2 g-1 min-1 in the remaining species. As a whole, the results evidenced a conservative behaviour of the photosynthetic apparatus to fix CO2 amongst the species investigated, despite the large differences in A among them.

It has been reported that Coffea arabica seeds contain as the main reserve protein, a legumin-like protein, constituted of two subunits, alpha and beta, of approximately 35 and 20 kDa. In this work the seed proteins of several coffee species and varieties were investigated by SDS-PAGE and gel filtration. No differences were observed in the electrophoretic profiles among varieties of C. arabica, however, marked differences were observed among species, or even among individuals of some species. In general, the molecular weight of the subunits alpha and beta accounted for a monomer of 48 to 62 kDa. However, native molecular weight obtained by gel filtration showed that for most of the species there is association of 6 of such proteins, in a hexamer. The most marked difference was observed for C. canephora and C. racemosa. The former clearly showing isoforms of the subunits, and the later showing absence of the beta subunit. The influence of proteases in this observations is discussed.

Two-dimensional gel electrophoresis analysis was performed on adventitious and storage root in cassava (Manihot esculenta Crantz). Adventitious root lacking swelling formation and swelled storage root were obtained from the accession WU104 grown in the green house of the Department of Biology in Washington University in St. Louis (MO-USA). Saline buffer-soluble proteins were extracted, separated in a high-resolution 2-D electrophoresis system, visualized with silver staining gel procedure, and digital image generate for further analysis. Quantitative and qualitative protein spots analysis was performed with a computer assisted image software system. Results revealed large variation in the complexity of the gel protein profile between the two root systems. About 90% of the protein spots appeared in the pI range value of 4.0 to 6.5 and between 14 to 80 Kda of molecular mass. Detailed computer assisted analysis of this gel allowed us to establish 5 distinct classes of protein based on spot quantification that could be associated with swelling and non-swelling roots. Variation in the complexity of protein pattern was related with different type of root. Whereas the adventitious root showed a more simple profile related to primary growth, the storage root showed to be a more complex profile related to secondary growth and starch accumulation.

In order to evaluate the influence of photoperiod on the accumulation of allantoin in comfrey (Symphytum officinale L.), a well known medicinal plant, an experiment was conducted during July and August, 1998. Cuttings obtained from 90 day old plants were submitted to four photoperiods (8, 12, 16 and 20 hours). After 60 days, allantoin content in roots and rhizomes was evaluated. The results showed that increases in photoperiod promoted an increment in the average content of allantoin in roots (0.06%, 0.303%, 1.213% and 4.78%). On the other hand, in rhizomes, allantoin accumulation decreased (9.65%, 7.14%, 0.55%) when the photoperiod was increased from 8 to 12 and 16 hours, respectively, stabilizing on a 20-hour photoperiod (0.53%). Plants cultivated under field conditions presented 2.55% and 2.63% allantoin content in rhizomes and roots, respectively. Based on the fact that in comfrey the roots are considered to be sites of allantoin synthesis, the results demonstrated that photoperiod could influence both the synthesis of allantoin in these organs as well as its accumulation in the rhizomes.

A leucena (Leucaena leucocephala (Lam.) de Wit), quando usada como cobertura no solo, apresenta a propriedades de controlar plantas daninhas, sendo esse efeito resultante da presença de aleloquímicos, principalmente mimosina, encontrados na parte aérea da planta. A maioria dos estudos em alelopatia refere-se apenas ao efeito do aleloquímico sobre a germinação e o crescimento da planta-teste, sem considerar os eventos celulares relacionados às mudanças fisiológicas. Com este trabalho objetivou-se avaliar o efeito do extrato aquoso da leucena sobre o desenvolvimento, índice mitótico radicular e atividade da peroxidase e suas isoformas na parte aérea e raízes de plântulas de milho. Os bioensaios foram conduzidos em casa-de-vegetação utilizando-se sementes de milho híbrido desenvolvidas nas concentrações 0; 0,4; 0,8; 1,6; 3,2 e 6,4 % do extrato aquoso de leucena. Verificaram-se inibição do crescimento de raízes e redução do índice mitótico proporcional ao incremento na dose do extrato, não sendo observada divisão celular a partir da concentração de 1,6 %. A atividade da peroxidase, tanto em raízes como em folhas, cresceu com o aumento da concentração do extrato, sem, contudo, apresentar diferença nos zimogramas de suas isoformas. A maior atividade dessa enzima, nas raízes, foi correlacionada com a presença das isoformas aniônicas, pI 4,99 e 4,86, o que possivelmente esteja contribuindo para maior espessamento das raízes, o que foi verificado nas doses elevadas do extrato. As análises por HPLC revelaram teor de mimosina crescente com aumentos na concentração do extrato, sugerindo o envolvimento desse aleloquímico no desenvolvimento das plântulas.

Active vegetative and reproductive growth in field-grown trees of Coffea arabica L. in Viçosa (20º45’S, 650 m altitude), south-eastern Brazil, occur concurrently. The overall patterns of branch growth and leaf area gain were to a certain extent altered by fruit removal, with growth rates being remarkably greater in de-fruited trees. The content of N-NO3 was not affected by fruiting, whilst that of amino-N was greater in de-fruited than fruiting trees most of the time, but the differences were not large enough to have significantly contributed to the increased growth rates in de-fruited trees. Leaf nitrate reductase activity was greater in plants bearing fruit than in non-bearing ones most of the time; activity was roughly inversely associated with growth. Although the roots contained much more nitrate than the leaves, the root nitrate reductase activity was much lower and not affected by fruiting. Much of the restrictive effects of fruiting on vegetative growth appeared to be associated to starch exhaustion, in addition to the outstanding effect of supra-optimum temperatures per se.

Young sexually and assexually propagated Barbados cherry plants were submitted to water deficit (20 days without irrigation). During this period the accumulation of proline, water potential of branches, osmotic potential, the relative water content of leaves, the leaf diffusive resistance, the transpiration rate and leaf temperature in the cuvette were determined. In addition, photosynthetically active radiation (PAR) and vapor pressure deficit (VPD) were measured in the porometer cuvette. The concentration of proline for both types of plants began to increase on the fifth day without watering, and reached 38.1 times the concentration in the control plants grown from seeds and 26.4 times the concentration in grafted plants on the tenth day without watering. The lowest levels of leaf water potential in the plants suffering from severe water stress varied from -4.5 to -5.7 MPa, the lowest values being observed in the sexually propagated plants. These plants also showed the highest values for transpiration (0.9 mmol.m-2.s-1) and proline concentration (20.42 mg.g-1 DM), the lowest for relative water content of the leaves (38.4%) and diffusive resistance (940 s.m-1) at the end of the experiment. The Barbados cherry plants developed strategies for surviving drought, with differences between various characteristics, resulting from prolonged stress, which significantly influenced the parameters evaluated, with the exception of leaf temperature.

The possibility of improving nitrogen use efficiency in maize was investigated using S1 endogamic families of the populations Sol da Manhã NF and Catetão. A simple 10 X 10 lattice design was adopted and the trials carried out at the experimental field of MITLA AGRÍCOLA LTDA, in Uberlândia, State of Minas Gerais, during the 1994/95 planting season. Based on grain production figures, the three best and three worst performing S1 endogamic families were selected for this study. These were pooled to form four sub-populations denominated NFB, NFR (the best and worst families, respectively, of the Sol da Manhã NF variety), CATB and CATR (the best and worst families, respectively, of the Catetão variety). Each of these sub-populations was evaluated under greenhouse conditions. The experimental design was factorial with treatments arranged in randomized blocks. Sample replicates consisted of pots with four plants. Feeding with modified Hoagland’s nutrient solution began on the seventh day after sowing. The study involved four nitrogen regimes, where varying proportions of NO3- and NH4+ were formulated, such that the nutrient solution contained the following mixtures: 75% NO3- : 25% NH4+; 25% NO3- : 75% NH4+; 50% NO3- : 50% NH4+ (all high N mixtures) and 5% NO3- : 5% NH4+ (low N mixture). Twenty-five days after planting, the activities of the enzymes nitrate reductase and glutamine synthetase (transferase and synthetase assays) were determined for the leaves using the third topmost expanded leaf of the four plants in each pot. The data show that glutamine synthetase (transferase assay) and nitrate reductase activities were efficient in discriminating the S1 endogamic families and could therefore be useful biochemical parameters in breeding programs seeking nitrogen use efficiency.