Fernando Teixeira Nicoloso

Cadmium and mineral nutrient accumulation in potato plantlets grown under cadmium stress in two different experimental culture conditions

In order to evaluate the effect of cadmium (Cd(2+)) toxicity on mineral nutrient accumulation in potato (Solanum tuberosum L.), two cultivars named Asterix and Macaca were cultivated both in vitro and in hydroponic experiments under increasing levels of Cd(2+) (0, 100, 200, 300, 400 and 500 microM in vitro and 0, 50, 100, 150 and 200 microM in hydroponic culture). At 22 and 7 days of exposure to Cd(2+), for the in vitro and hydroponic experiment, respectively, the plantlets were separated into roots and shoot, which were analyzed for biomass as well as Cd(2+), and macro (Ca(2+), K(+) and Mg(2+)) and micronutrient (Cu(2+), Fe(2+), Mn(2+) and Zn(2+)) contents. In the hydroponic experiment, there was no reduction in shoot and root dry weight for any Cd(2+) level, regardless of the potato cultivar. In contrast, in the in vitro experiment, there was an increase in biomass at low Cd(2+) levels, while higher Cd(2+) levels caused a decrease. In general, Cd(2+) decreased the macronutrient and micronutrient contents in the in vitro cultured plantlets in both roots and shoot of cultivars. In contrast, the macronutrient and micronutrient contents in the hydroponically grown plantlets were generally not affected by Cd(2+). Our data suggest that the influence of Cd(2+) on nutrient content in potato was related to the level of Cd(2+) in the substrate, potato cultivar, plant organ, essential element, growth medium and exposure time.

Cadmium toxicity causes oxidative stress and induces response of the antioxidant system in cucumber seedlings

In this study, the effects of cadmium (Cd) on lipid peroxidation, electrolyte leakage, protein oxidation, ascorbate peroxidase (APX; E.C. 1.11.1.11), catalase (CAT; E.C. 1.11.1.6) and superoxide dismutase (SOD; E.C. 1.15.1.1) activities, and ascorbic acid, non-protein thiol groups and total soluble protein contents in cucumber seedlings (Cucumis sativus L.) were investigated. Seedlings were grown in vitro in an agar-solidified substrate containing four Cd levels as CdCl2 (0, 100, 400, and 1000 µmol L-1) for 10 d. The lowest Cd level decreased the malondialdehyde concentration. Electrolyte leakage increased only at 1000 µmol Cd L-1, whereas protein oxidation and total soluble protein content were enhanced at 400 and 1000 µmol Cd L-1. Activity of APX was inhibited while the activities of CAT and SOD were increased at all Cd concentrations. Ascorbic acid was enhanced at 400 and 1000 µmol Cd L-1 whereas non-protein thiol groups were increased at all Cd supplies. The results evidence the importance of the enzymatic and non-enzymatic antioxidant system in response to cadmium toxicity in cucumber seedlings.

Behavior and brain enzymatic changes after long-term intoxication with cadmium salt or contaminated potatoes

This study investigated the cadmium (Cd) intoxication on cognitive, motor and anxiety performance of rats subjected to long-term exposure to diet with Cd salt or with Cd from contaminated potato tubers. Potato plantlets were micropropagated in MS medium and transplanted to plastic trays containing sand. Tubers were collected, planted in sand boxes and cultivated with 0 or 10 μM Cd and, after were oven-dried, powder processed and used for diet. Rats were divided into six groups and fed different diets for 5 months: control, potato, potato+Cd, 1, 5 or 25 mg/kg CdCl2. Cd exposure increased Cd concentration in brain regions. There was a significant decrease in the step-down latency in Cd-intoxicated rats and, elevated plus maze task revealed an anxiolytic effect in rats fed potato diet per se, and an anxiogenic effect in rats fed 25 mg/kg Cd. The brain structures of rats exposed to Cd salt or Cd from tubers showed an increased AChE activity, but Na+,K+-ATPase decreased in cortex, hypothalamus, and cerebellum. Therefore, we suggest an association between the long-term diet of potato tuber and a clear anxiolytic effect. Moreover, we observed an impaired cognition and enhanced anxiety-like behavior displayed by Cd-intoxicated rats coupled with a marked increase of brain Cd concentration, and increase and decrease of AChE and Na+,K+-ATPase activities, respectively.

Oxidative stress is an early symptom triggered by aluminum in Al-sensitive potato plantlets.

The objective of this study was to evaluate whether the oxidative stress caused by aluminum (Al) toxicity is an early symptom that can trigger root growth inhibition in Macaca (Al-sensitive) and SMIC148-A (Al-tolerant) potato clones. Plantlets were grown in a nutrient solution (pH 4.00) with 0, 100 and 200mg Al L(-1). At 24, 72, 120 and 168h after Al addition, root length and biochemical parameters were determined. Regardless of exposure time, root length of the Macaca clone was significantly lower at 200mg Al L(-1). For the SMIC148-A clone, root length did not decrease with any Al treatments. Al supply caused lipid peroxidation only in Macaca, in both roots (at 24, 72, 120 and 168h) and shoot (at 120 and 168h). In roots of the Macaca, catalase (CAT) and ascorbate peroxidase (APX) activity decreased at 72 and 120h, and at 24, 72 and 120h, respectively. At 168h, both activities increased upon addition of Al. In roots of the SMIC148-A, CAT activity increased at 72 and 168h, whereas APX activity decreased at 72h and increased at 24, 12 and 168h. The Macaca showed lower root non-protein thiol group (NPSH) concentration at 200mg Al L(-1) in all evaluations, but the SMIC148-A either did not demonstrate any alterations at 24 and 72h or presented higher levels at 120h. This pattern was also observed in root ascorbic acid (AsA) concentration at 24 and 120h. The cellular redox status of these potato clones seems to be affected by Al. Therefore, oxidative stress may be an important mechanism for Al toxicity, mainly in the Al-sensitive Macaca clone.

Copper uptake, accumulation and physiological changes in adult grapevines in response to excess copper in soil

AimsThis study investigated Cu uptake and accumulation as well as physiological and biochemical changes in grapevines grown in soils containing excess Cu.MethodsThe grapevines were collected during two productive cycles from three vineyards with increasing concentrations of Cu in the soil and at various growth stages, before and after the application of Cu-based fungicides. The Cu concentrations in the grapevine organs and the macronutrients and biochemical parameters in the leaf blades were analyzed.ResultsAt close to the flowering stage of the grapevines, the concentration and content of Cu in the leaves were increased. However, the Cu concentrations in the roots, stem, shoots and bunches did not correlate with the metal concentrations in the soil. The application of Cu-based fungicides to the leaves increased the Cu concentrations in the shoots, leaves and rachis; however, the effect of the fungicides on the Cu concentration in the berries was not significant. The biochemical analyses of the leaf blades demonstrated symptoms of oxidative stress that correlated with the Cu concentrations in soil.ConclusionsThe increased availability of Cu in soil had a slight effect on the levels and accumulation of Cu in mature grapevines during the productive season and did not alter the nutritional status of the plant. However, increased Cu concentrations were observed in the leaves. The evidence of oxidative stress in the leaves correlated with the increased levels of Cu in soil.

Aluminum-induced oxidative stress in cucumber.

Aluminum (Al) is one of the most abundant elements of the planet and exposure to this metal can cause oxidative stress and lead to various signs of toxicity in plants. Plants are essential organisms for the environment as well as food for humans and animals. The toxic effect of aluminum is the major cause of decreased crop productivity. Thus, the objective of the present study was to analyze the effects of aluminum on the activity of antioxidant enzymes such as catalase (CAT - E.C. 1.11.1.6), superoxide dismutase (SOD - E.C.1.15.1.1) and ascorbate peroxidase (APX - E.C. 1.11.1.11), and on lipid peroxidation, electrolyte leakage percentage (ELP) and chlorophyll and protein oxidation levels in Cucumis sativus L. (cv. Aodai). Seedlings were grown at different concentrations of aluminum ranging from 1 to 2000 microM for 10 days. The increase in ELP and H(2)O(2) production observed in the seedlings may be related to the decreased efficiency of the antioxidant system at higher aluminum concentrations. The antioxidant system was unable to overcome toxicity resulting in negative effects such as lipid peroxidation, protein oxidation and a decrease in the growth of Cucumis seedlings. Aluminum toxicity triggered alterations in the antioxidant and physiological status of growing cucumber seedlings.

Influência da posição da estaca no ramo sobre o enraizamento de Pfaffia glomerata (Spreng.) Pedersen em dois substratos

Pfaffia glomerata (Spreng.) Pedersen is a medicinal herb that has been used in the Brazilian folk medicine against several illnesses, such as inflammations and reumatism. It has also been playing the role of a ginseng-like tonic herb, helping to fight fatigue and combat stress. Therefore, wild resources have been exploited considerably and informations about suitable methods for its propagation are needed. The aim of this work was to evaluate the suitability of vegetative propagation via cuttings, the shoot cutting position effect, and the substrate on rooting process of Pfaffia cuttings. The treatments followed a 4 x 2 factorial scheme, involving four positions of cuttings in the shoot (basal, middle-basal, middle-apical, and apical) and two substrates (sand + carbonized rice husk and soil + carbonized rice husk, 1:1 v/v). The cuttings, ranged from 15 to 20cm length, were obtained by sucessive cuts of the shoot from the base to the tip. The experimental design was completely randomized with five replications, and 20 cuttings per experimental unity. The experiment was installed on July 17th,1997 and last for 90 days under ambient temperature. The results allowed to indicate that vegetative propagation via cuttings is a feasible method, cuttings taken from the shoot basis and the shoot middle positions show the best physiological features to rooting, and the combination of soil + carbonized rice husk is a suitable substrate for rooting and for the growth of the plantlet in the field.

Effect of cadmium on growth, micronutrient concentration, and δ-aminolevulinic acid dehydratase and acid phosphatase activities in plants of Pfaffia glomerata

Plântulas de Pfaffia glomerata (Spreng.) Pedersen foram cultivadas em cinco niveis (0, 20, 40, 60 e 80 μM) de cadmio (Cd) em um sistema hidroponico durante 7 d, visando-se analisar o crescimento, as concentracoes de micronutrientes, clorofilas e carotenoides, bem como as atividades da desidratase do acido δ-aminolevulinico (ALA-D; E.C.4.2.1.24) e fosfatase acida (AP; E.C.3.1.3.2) nas plantas. A concentracao de Cd, na parte aerea e raizes, aumentou com o incremento dos niveis de Cd. A concentracao de Cd nas raizes foi, em media, 12 vezes maior do que na parte aerea. O comprimento das raizes nao foi afetado pelos tratamentos de Cd. Em contraste, a biomassa seca da parte aerea e raizes aumentou significativamente pela adicao de 20 e 40 μM Cd. Alem disso, a biomassa seca total das plantas somente diminuiu no nivel de 80 μM Cd em relacao a das plantas-controle. Por outro lado, a biomassa radicular diminuiu significativamente pela adicao de Cd a niveis superiores a 40 μM. Constatou-se resposta dependente do orgao e do micronutriente a toxicidade de Cd. As concentracoes de Zn e Cu na parte aerea e raizes nao foram alteradas pela presenca de Cd. A absorcao de Mn foi diminuida pelo estresse de Cd, porem sua translocacao nao foi alterada. Um efeito sinergistico do Cd na concentracao de Fe nas raizes foi observado nos niveis de 20 e 80 μM Cd. As atividades da ALA-D e AP foram diminuidas com o incremento dos niveis de Cd, porem a ALA-D foi mais afetada. Naquelas concentracoes de Cd, a concentracao de clorofila tambem foi diminuida. Houve uma correlacao positiva entre as concentracoes de carotenoides e clorofila. Os resultados indicam que a P. glomerata parece ter algum grau de tolerância ao Cd.

Physiological and oxidative stress responses of four potato clones to aluminum in nutrient solution

Aluminum toxicity is a serious problem in Brazilian soils and selecting potato clones is an important strategy to produce this crop on these kinds of soils. Potato clones, Macaca, SMIC148-A, Dakota Rose, and Solanum microdontum, were grown in a nutrient solution (pH 4.0) with 0, 50, 100, 150 and 200 mg Al L-1. After 7 d, Al concentration in both root system and shoot of all clones increased linearly with increasing Al levels. Based on relative root growth, S. microdontum and SMIC148-A were considered Al-tolerant clones, whereas Macaca and Dakota Rose were considered Al-sensitive. Shoot growth in Macaca linearly decreased with increasing Al levels. Root H2O2 concentration in both Al-sensitive clones increased with increasing Al supply, whereas in Al-tolerant clones it either decreased (SMIC148-A) or demonstrated no alteration (S. microdontum). Shoot H2O2 concentration increased linearly in Macaca, whereas for Dakota Rose it showed a quadratic relationship with Al levels. On the other hand, shoot H2O2 concentration in the Al-tolerant clones either demonstrated no alteration (S. microdontum) or presented lower levels (SMIC148-A). Root catalase (CAT) activity in both Al-sensitive clones increased with increasing Al levels, whereas in Al-tolerant clones it either demonstrated no alteration (SMIC148-A) or presented lower levels (S. microdontum). Shoot CAT activity in the S. microdontum increased curvilinearly with increasing Al levels. In all potato clones, chlorophyll concentration showed a curvilinear response to Al supply, where in Al-sensitive clones it decreased upon addition of Al exceeding 100 mg L-1, but in SMIC148-A it increased at levels between approximately 100 and 150 mg L-1, and decreased in S. microdontum regardless of the Al level. Carotenoid concentrations in the Al-sensitive clones were linearly decreased with increasing Al levels. Aluminum supply caused root lipid peroxidation only in the Al-sensitive clones, whereas in the shoot it increased linearly in the Al-sensitive clones and in S. microdontum it only increased at around 50 mg L-1. Most of root protein oxidation was only observed in the Al-sensitive clones. However, shoot protein oxidation was increased with increasing Al levels for all potato clones. These results indicate that oxidative stress caused by Al in potato may harm several components of the cell, mainly in Al-sensitive clones.

COMPRIMENTO DA ESTACA DE RAMO NO ENRAIZAMENTO DE GINSENG BRASILEIRO (Pfaffia glomerata)

Pfaffia glomerata (Spreng.) Pedersen is among several species known as Brazilian ginsengs and it is used as medicinal plant. The aim of this work was to evaluate the length of the shoot cuttings on rooting of P. glomerata. Treatments consisted of three length of cuttings (10, 15, and 20cm; ± 1cm of variation). Cuttings were obtained from the 70cm of the basal portion from shoots of 80 to 140cm of length, from two-year-old plants grown in the Botanical Garden at State University of Santa Maria, RS, Brazil. Treatments were distributed in a completely randomized block design with three replicates and 30 cuttings per plot. Each experimental block consisted of a plastic tray with capacity for 36 liters of nutrient solution. The experiment was installed on July 15th, 1998 and lasted for 44 days under controlled atmospheric condition (temperature, light and air humidity). Results indicated that (i) the cutting length does not affect the rooting percentage, the leaves and root dry matter. On the other hand, the seedlings obtained from cuttings of 10cm length show greater shoot number, shoot length, stalk dry weight, and total dry weight accumulated per cutting than of cuttings of 20cm; and (ii) the use of cuttings of 10cm is suitable and, therefore, allows to increase the number of cuttings per shoot.