Resumo em Inglês:
Inga cylindrica Trypsin Inhibitor (ICTI) was purified as a single polypeptide chain by one step anion-exchange chromatography from a crude extract of Inga cylindrica (Vell.) Mart. seeds. ICTI is a 19.5 kDa protein presenting a remarkable inhibitory activity against bovine trypsin (EC 3.4.21.4) (Ki = 4.3 nM). Circular dichroism analysis revealed that this inhibitor is a β type protein (40.4% of β-strand; 24.6% of β-turn and 6.7% of α-helix) in accordance with properties displayed in Kunitz type inhibitors. ICTI is a thermal stable protein within a wide range of pH (1.6 to 10.0) exhibiting highest stability at pH 7.0 as indicated by Tm of 70.0 ºC and ΔG25 of 48.5 ± 0.7 kJ.mol-1. The values of ΔG25 at pH 1.6 (22.5 ± 1.2 kJ.mol-1) and pH 10.0 (31.5 ± 1.0 kJ.mol-1) indicate a reduced structural stability of the protein under these conditions. This is likely to result from pKa differences of the acid and basic side chains reflecting the changes in the non-covalent interactions in the folded state.Resumo em Inglês:
Accumulation of salts in irrigated soils is one of the primary factors limiting yield in South Asia. We investigated whether exogenous nitric oxide (NO) supplementation as sodium nitroprusside has any ameliorating effect against NaCl induced oxidative damage in chickpea leaves. NaCl treatment (250 mM) alone and in combination with two concentrations of SNP (0.2 and 1 mM) were given to 50 days old chickpea plants for 2, 4 and 6 days. Salt stress adversely affected the relative membrane injury, lipid peroxidation levels, relative water content (RWC) and H2O2 content. The effect was time dependent. SNP treatments could ameliorate the toxic effect of short term salt stress of 2 days on relative membrane injury and partial amelioration was observed with 4 and 6 day stress treatment. A partial ameliorative effect of SNP was observed with lipid peroxidation levels, H2O2 content and RWC. Salt stress activated the antioxidant system by increasing the activities of SOD, POX, APX and DHAR. However no obvious change was observed in GR activity and CAT activity decreased under salt stress. Both the SNP treatments had a positive effect on antioxidant enzymes SOD, CAT, APX, GR and DHAR under salt stress. NaCl treatment resulted in a decline in the GSH/GSSG and ASC/DHA ratio. SNP treatments increased the reduced form of both the metabolites thus elevating the ratio of GSH/GSSG and ASC/DHA. This study concludes that exogenous application of NO protects chickpea leaves from NaCl induced oxidative stress.Resumo em Inglês:
The aroma and fragrance industry is a billion-dollar world market which grows annually. Essential oils comprise the majority of compounds used by these industries. These sets of metabolites are formed mainly by monoterpenes, which are products of the plants' secondary metabolism. Biosynthesized from mevalonate and methylerythitol phosphate, the essential oil production depends not only on genetic factors and the developmental stage of plants, but also on environmental factors which could result in biochemical and physiological alterations in plants modifying the quantity and quality of the essential oil. These modifications impair aromatic plant production aimed at essential oil by reducing their quality. It is desirable to develop techniques of agronomical management to improve essential oil products and their specific compounds. Among other factors influencing essential oil production are plant growth regulators or plant hormones. Endogenous levels as well exogenous application could affect essential oil production and chemical composition. In this review we will present research in which plant growth regulators or their synthetic analogs were used and their effects on essential oil production.Resumo em Inglês:
The aim of this study was to evaluate the effects of H2O2 on germination and acclimation of maize plants subject to salt stress. Three experiments using BRS3003 seeds, a triple hybrid of maize, were carried out in a growth room and in greenhouse. In the first experiment, H2O2 accelerated the germination percentage of seeds at 100 mM, but not at 500 mM. In the second experiment, the pretreatment of seeds was observed to induce a pronounced increase in ascorbate peroxidase (APX) and catalase (CAT) enzyme activity after 30 h of soaking in H2O2. It was also observed that guaiacol peroxidase (GPX) activity was smaller in the seeds soaked in H2O2 for 12, 24, 30, 36 and 42 h, in relation to those soaked in distilled water. The superoxide dismutase (SOD) activity was not affected by the pretreatment of seeds, except for the 24 h treatment. Only one CAT isoform was detected. In the third experiment, seeds were pretreated with 36 h soaking in 100 mM H2O2 solution or in distilled water and later cultivated in Hoagland's nutrient solution or nutrient solution with 80 mM NaCl. The results showed the pretreatment of seeds with H2O2 induced acclimation of the plants to salinity. It decreased the deleterious effects of salt stress on the growth of maize. In addition, the differences in antioxidative enzyme activities may explain the increased tolerance to salt stress of plants originated from H2O2 pretreated seeds.Resumo em Português:
O objetivo deste trabalho foi avaliar o efeito do estresse salino sob o crescimento radicular e a atividade de enzimas antioxidantes em duas cultivares de feijão caupi contrastantes em termos de crescimento e resposta oxidativa de folhas. Plântulas com quatro dias de idade foram expostas a NaCl 100 mM durante dois dias sob condições controladas. A massa seca das raízes foi afetada somente na cultivar Pérola (sensível) enquanto que o comprimento radicular foi mais reduzido na Pitiúba (resistente). O estresse salino não afetou o conteúdo relativo de água, contudo o conteúdo de Na+ nas raízes atingiu níveis tóxicos de acordo com a razão K+/Na+ em ambas as cultivares, indicando que a inibição do crescimento radicular pode ser estar mais relacionada à toxicidade iônica mais do ao estresse osmótico induzido pelo sal. Embora o vazamento de eletrólitos tenha aumentado principalmente na cultivar sensível, a peroxidação de lipídeos decresceu de forma similar em ambas as cultivares. As atividades de APX e SOD foram diminuídas pela salinidade nas duas cultivares, atingindo valores similares, apesar do decréscimo em Pitiúba ter sido maior, em relação aos controles. A atividade de CAT diminuiu significantemente em Pitiúba, mas permaneceu inalterada em Pérola. O decréscimo na atividade de CAT em Pitiúba é, em princípio, incompatível com maior proteção oxidativa. Nossos resultados evidenciam que as atividades de SOD, APX, CAT e POX e a peroxidação de lipídeos em raízes de plântulas de feijão caupi não são compatíveis com tolerância diferencial a salinidade como foi previamente caracterizado por meio do crescimento e resposta oxidativa de folhas de plantas.Resumo em Inglês:
The salt stress effect in root growth and antioxidative response were investigated in two cowpea cultivars which differ in salt tolerance in terms of plant growth and leaf oxidative response. Four-day-old seedlings (establishment stage) were exposed to 100 mM NaCl for two days. The roots of the two cultivars presented distinct response in terms of salt-induced changes in elongation and dry weight. Root dry weight was only decreased in Pérola (sensitive) cultivar while root elongation was mainly hampered in Pitiúba (tolerant). Root relative water content remained unchanged under salinity, but root Na+ content achieved toxic levels as revealed by the K+/Na+ ratio in both cultivars. Then, root growth inhibition might be due to ionic toxicity rather than by salt-induced water deficit. Although electrolyte leakage markedly increased mainly in the Pérola genotype, lipid peroxidation decreased similarly in both salt-stressed cultivars. APX and SOD activities were reduced by salinity in both cultivars reaching similar values despite the decrease in Pitiúba had been higher compared to respective controls. CAT decreased significantly in Pitiúba but did not change in Pérola, while POX increased in both cultivars. The salt-induced decrease in the CAT activity of Pitiúba root is, at principle, incompatible to allow a more effective oxidative protection. Our results support the idea that the activities of SOD, APX, CAT and POX and lipid peroxidation in cowpea seedling roots were not associated with differential salt tolerance as previously characterized in terms of growth rate and oxidative response in plant leaves.Resumo em Português:
A partir de ramos semilenhosos de porta-enxerto de pêssego e ameixa (Prunus cerasifera E.) cv. MRS 2/5, porta-enxerto de ameixa (Prunus cerasifera x P. salicina) x (P. cerasifera x P. persica) cv. Ishtarà e oliveira (Olea europaea L.) cv. Frantoio, foram confeccionadas estacas que foram tratadas com 0 mg.L-1 e 2,500 mg.L-1 de ácido indol butírico (IBA) por imersão na base das estacas. Após 60 dias de plantio, as cultivares MRS 2/5, Ishtarà e Frantoio apresentaram diferença significativa com relação à indução do enraizamento pela aplicação de ácido indol butírico (27.5, 47.5 e 41.25 %, respectivamente), promovendo um maior número de raízes por estaca, sem no entanto aumentar significativamente o comprimento das mesmas. Nas estacas enraizadas das três cultivares, os níveis de ascorbato variaram em decorrência da consistência da estaca de cada espécie, todavia demostram uma correlação positiva entre o aumento do enraizamento e o aumento dos níveis de ascorbato na forma reduzida.Resumo em Inglês:
Starting from semihardwood branches of peach and plum rootstocks (Prunus cerasifera E.) cv. MRS2/5, plum rootstocks (Prunus cerasifera × P. salicina) × (P. cerasifera × P. persica) cv. Ishtarà and olive tree (Olea europaea L.) cv. Frantoio, cuttings were collected and treated with 0 mg.L-1 and 2500 mg.L-1 of indolebutyric acid (IBA) by immersion in the base of the cuttings. After 60 days of planting, the cultivars MRS 2/5, Ishtarà and Frantoio presented a significative difference with relation to the rooting induction by application of the indolebutyric acid (27.5, 47.5 and 41.25 %, respectively), inducing a higher number of roots per cutting without at the same time significantly increasing the length of the roots themselves. The levels of ascorbate and dehydroascorbate in the rooted and non-rooted cuttings of the three cultivars were determined. These parameters varied in function of the consistency of the cuttings from each species, but showed a positive correlation between the increase of the rooting and the increase of the ascorbate in the reduced form.Resumo em Inglês:
A greenhouse experiment was conducted to investigate the effect of flooding on two tomato cultivars and two wild related species. Forty days old tomato plants were subjected to a continuous flooding stress of different durations: 0, 2, 4 and 8 days. Plant pots were placed inside larger plastic pots; they were irrigated with excessive quantity of tap water at 25ºC so that the level of water above the surface of soil was 15 cm throughout the flooding period. At the bottom of each plastic pot a drilled hole allowed complete drainage of the pot after flooding. Parameters studied include plant height, number of leaves, leaf length, chlorophyll fluorescence, chlorophyll content, wilting, leaf senescence, adventitious root formation, number of flowers and fruits from cluster 2 to 6, average weight per fruit, fruit length and width, total fruit weight from cluster 2 to 6, total yield per plant. LA1579 genotype was more subjected to the deleterious effect of flooding on almost all the parameters studied. Therefore LA1579 genotype is flooding sensitive. Genotypes CLN2498E, and CA4 showed high tolerance to flooding while LA1421 genotype was tolerant to some extent. This experiment provides information that could help in the identification of physiological and agronomical parameters associated with flood-tolerance in vegetables.Resumo em Inglês:
The effect of several environmental factors on germination of medicinal herb Centella asiatica was investigated. Freshly harvested seeds of C. asiatica did not germinate even after gibberellic acid (GA3) treatment and exposure to different treatments with light qualities, while two-three months old seeds exhibited germination (82%) without pre-treatment at warm environment (25 -30ºC). GA3 treatment induced germination by two weeks earlier than in control. Germination was significantly (p=0.001) higher in red and white light than in blue and far red light. In addition, germination of C. asiatica was sensitive towards the salt stress and was significantly inhibited at 6500 ppm NaCl. The leaf leachates from invasive weeds Chromolaena odorata, Ageratum conyzoides, Parthenium hysterophorus and Xanthium strumarium showed inhibitory effects on seed germination of C. asiatica. Parthenium hysterophorus had significant effect (p<0.001) on seed germination. These data contribute for the establishing of an efficient protocol for C. asiatica cultivation.