Effects of the bendazol fungicide on in vitro development of the nim (Azadirachta indica A. JUSS)

Two experiments were conducted to evaluate Bendazol fungicidal effects in neem micropropagation. In these experiments, the nodal segment explants from in vitro plants were used. In the first experiment, the explants remained in DKW culture medium for a period of 30 days containing different concentrations of Bendazol (M1 -50, M2 - 100, M3 - 200, and M4 - 400 mg.L-1). The control treatment (M0) was prepared with DKW medium + BAP (0.225 mg.L-1). In the second experiment, the explants were maintained for only one week in media supplemented with Bendazol or BAP, and then they were transferred and kept in free Bendazol/BAP media for three weeks. In each experiment, the design was completely randomized with five treatments, 10 replicates per treatment, and one explant/cultivation flask.  The variables analyzed included the formation of calluses and roots, lateral bud development, shoot height, contamination and plant death. There was no significant difference in tree variables (shoot, callus formation and shoot height) between treatments in both experiments. There was no death, plant contamination and rooting during the experiment. The results indicate that Bendazol can be used at low doses for in vitro neem cloning thereby replacing BAP and ultimately reducing production costs

Ação da prolina exógena no cultivo in vitro de genótipos de cana-de-açúcar submetidos ao estrese salino

A cana-de-açúcar é um dos principais produtos agrícola no cenário econômico e social brasileiro e sua manutenção, bem como o aumento de produção e produtividade está ligado ao melhoramento genético com seleção de novos genótipos que apresentem características de interesse agronômico. As técnicas de cultura de tecidos podem ser utilizadas em estudos de seleção ou avaliação da tolerância de plantas contribuindo no esclarecimento das alterações provenientes das condições de estresse. A produtividade da cana-de-açúcar sofre influência de diversos fatores ambientais como a salinidade que limita a produção devido aos efeitos osmóticos e de toxidade iônica pela absorção de Na+ e Cl-. O estresse salino aumenta a concentração de espécies reativas de oxigênio (ROS), podendo promover estresse oxidativo e provocar injúrias aos lipídeos, proteínas, carboidratos e DNA. Para minimizar os danos causados pelo acúmulo de ROS, as plantas possuem o sistema antioxidativo de defesa que envolve substâncias de natureza enzimática (catalase-CAT, peroxidase-POD, ascorbato peroxidase-APX e polifenoloxidase-PPO) e não enzimática como a prolina. Os objetivos desse estudo foram avaliar a ação de prolina exógena no cultivo in vitro de genótipos de cana-de-açúcar submetidos ao estresse salino e analisar as alterações bioquímicas que ocorrem nessas condições. Foram utilizadas plantas micropropagadas dos genótipos RB931011 e RB872552. As plantas foram cultivadas, durante 20 dias, na ausência ou presença de 20 mM de prolina associada ou não a 100 mM de NaCl, totalizando cinco tratamentos. Foi utilizado o delineamento inteiramente casualizado com fatorial 2x5 (genótipo x tratamento). Amostras de folhas foram coletadas procedendo-se análises dos teores de prolina endógena e proteínas solúveis totais, porcentagem de extravasamento de eletrólitos, concentração dos íons Na+ e K+ e atividade das enzimas CAT, POD, APX e PPO. Os dados foram submetidos à análise de variância ANOVA, e as médias comparadas pelo teste de Tukey a 5% de probabilidade. Nos tratamentos salinos, ambos os genótipos apresentaram aumento no extravasamento de eletrólitos, causado, possivelmente, pela peroxidação lipídica. As plantas cultivadas sob estresse salino apresentaram redução no teor de proteínas solúveis totais e paralelamente ocorreu uma manutenção ou acréscimo no teor de prolina endógena. O sal também promoveu o aumento na concentração de Na+ e diminuição de K+ gerando, consequentemente, uma elevada relação Na+/K+. A atividade das enzimas CAT, POD, APX e PPO, responsáveis pela eliminação de ROS, aumentaram em função da salinidade em ambos os genótipos. O genótipo RB931011 apresentou uma maior aclimatação ao estresse salino quando comparado ao genótipo RB872552 devido ao maior aumento do teor de prolina endógena e maior atividade das enzimas antioxidantes o que resultou em um menor dano de membrana.Sugarcane is one of the main agricultural products in the economic and social scenario Brazilian and maintenance, as well as increased production and productivity is linked to genetic improvement with selection of new genotypes that have the characteristics of agronomic interest. The techniques of tissue culture can be used in studies of selection or evaluation of the tolerance of plants contributing to clarify the changes from the conditions of stress. The productivity of sugarcane is influenced by several environmental factors such as salinity that limits production due to osmotic effects and ion toxicity by absorption of Na+ and Cl-. Salt stress increase the concentration of reactive oxygen species (ROS), may promote oxidative stress and cause injury to lipids, proteins, carbohydrates and DNA. To minimize the damage caused by the accumulation of ROS, plants possess the antioxidant defense system involving substances of nature enzyme (catalase-CAT, peroxidase-POD, ascorbate peroxidase-APX and polyphenoloxidase, PPO) and not enzyme as the proline. The objectives of this study were to evaluate the effects of exogenous proline in cultivation in vitro of sugarcane submitted to salt stress and analyze the biochemical changes that occur in these conditions. Plants were micropropagated genotypes RB931011 and RB872552. Plants were grown, for 20 days, in the absence or presence of 20 mM proline with or without 100 mM NaCl, totaling five treatments. We used a completely randomized design with 2x5 factorial (genotype x treatment). Leaf samples were collected proceeding to analysis of endogenous levels of proline and total soluble proteins, percentage of electrolyte leakage, concentration of Na+ and K+ and activity of enzymes CAT, POD, APX and PPO. The data were analyzed using ANOVA and means compared by Tukey test at 5% probability. In the saline treatments, both genotypes showed an increase in electrolyte leakage, caused possibly, by lipid peroxidation. Plants grown under salt stress showed a reduced content of total soluble protein and in parallel maintenance or increase in the endogenous proline content. The salt also promoted the increase in the concentration of Na+ and decreased K+ generating thus a high ratio Na+/K+. The activity of CAT, POD, APX and PPO, responsible for the elimination of ROS, increased with increasing salinity in both genotypes. The RB931011 genotype had a greater acclimation compared to genotype RB872552 due to the largest increase in endogenous proline content and increased activity of antioxidant enzymes resulting in minor membrane damage.Conselho Nacional de Pesquisa e Desenvolvimento Científico e Tecnológico - CNP

Response to in vitro salt stress in sugarcane is conditioned by concentration and condition of exposure to NaCl

Salinity is one of the major environmental stress factors that affect crop productivity, as well as interfering with plant growth and development, resulting in reduced production quality. Given this, we highlight the importance of research in response to plants subjected to salt stress in order to assess the physiological and biochemical behavior of genotypes, with the objective of selecting the more tolerant. One way to ensure the uniformity of the response of the plants is through in vitro cultivation, which allows control of the cultivation conditions. Therefore, the objective of this work was to evaluate the response of two commercial varieties of sugar cane exposed to saline stress in different conditions (gradual and abrupt). Two varieties of sugarcane (RB931011 and RB872552) were subjected to in vitro salt stress by NaCl (56 mM and 112 mM), either gradually or suddenly. The responses of the enzymatic antioxidant system (catalase, peroxidases and ascorbate peroxidase) and free proline, as well as the Na+ and K+ contents, were assessed 30 days after the beginning of the treatments. Differences were observed in the responses of the varieties as a function of the induction mode of salt stress, graded or by shock, rather than as a function of the NaCl concentrations in the culture medium. The stress response is therefore conditioned not only by salt concentration, but also by the form of exposure to salt

ANTIOXIDANT ENZYMES ACTIVITY IN EMBRYOGENIC AND NON-EMBRYOGENIC TISSUES IN SUGARCANE

The objective of this work was to induce direct somatic embryogenesis from segments of immature leaves of the RB872552 variety of sugarcane and to correlate this morphogenic event with oxidative stress. Two previously described protocols were utilized for the induction of somatic embryogenesis in sugarcane with different supplementations of the culture medium and different incubation conditions. For the conversion of embryos into plants was used MS medium without phytoregulators. Histological analyses and activity of antioxidant enzymes were also conducted for the embryogenic and non-embryogenic tissues. The formation of somatic embryos was obtained in 81 % of the explants with the combination of regulators 2,4-D (2,4-dichlorophenoxyacetic acid)and BAP (6-benzylaminopurine) when incubated under 16 h photoperiod. With regards to the antioxidant enzymes, there was increased activity of peroxidase and an increase in the soluble protein content in embryogenic tissues, whereas lower activities of polyphenol oxidase and catalase appeared in these tissues compared to nonembryogenic tissues. It could be inferred that oxidative stress plays an important role in the induction of somatic embryogenesis in sugarcane

Response to in vitro salt stress in sugarcane is conditioned by concentration and condition of exposure to NaCl

Salinity is one of the major environmental stress factors that affect crop productivity, as well as interfering with plant growth and development, resulting in reduced production quality. Given this, we highlight the importance of research in response to plants subjected to salt stress in order to assess the physiological and biochemical behavior of genotypes, with the objective of selecting the more tolerant. One way to ensure the uniformity of the response of the plants is through in vitro cultivation, which allows control of the cultivation conditions. Therefore, the objective of this work was to evaluate the response of two commercial varieties of sugar cane exposed to saline stress in different conditions (gradual and abrupt). Two varieties of sugarcane (RB931011 and RB872552) were subjected to in vitro salt stress by NaCl (56 mM and 112 mM), either gradually or suddenly. The responses of the enzymatic antioxidant system (catalase, peroxidases and ascorbate peroxidase) and free proline, as well as the Na+ and K+ contents, were assessed 30 days after the beginning of the treatments. Differences were observed in the responses of the varieties as a function of the induction mode of salt stress, graded or by shock, rather than as a function of the NaCl concentrations in the culture medium. The stress response is therefore conditioned not only by salt concentration, but also by the form of exposure to salt

EFFECT OF EXOGENOUS PROLINE IN TWO SUGARCANE GENOTYPES GROWN IN VITRO UNDER SALT STRESS

<p class="TextosemFormatao1">Sugarcane production is influenced by various abiotic stresses including salt stress. Salinity can induce oxidative stress, which in turn damages biomolecules and cellular structures. However, such damage can be avoided or minimized by the enzymatic and non-enzymatic defense systems of plants. The aim of the study was to determine the effect of exogenous proline on Na⁺ and K⁺ content and on the activity of catalase, ascorbate peroxidase and peroxidase in two sugarcane genotypes (RB931011 and RB872552) grown <em>in vitro</em> under salt stress. The plants were grown for 20 days with or without 100 mM NaCl and exposed to 20 mM proline for varying period of time. The data were subjected to ANOVA factorial (two genotypes and five treatments), and the mean values were compared by Tukey test at a 5% probability. Under salinity stress, both genotypes exhibited membrane integrity reduction, reduced total soluble protein content and unaltered or increased endogenous proline content. Exogenous proline reduced Na⁺ accumulation in a manner proportional to the exposition period at the amino acid. In both genotypes, antioxidant enzymes activity increased with the addition of NaCl. In conclusion, RB931011 genotype showed higher proline accumulation and increased in activity of the antioxidant enzymes, indicating better salt stress tolerance than in RB872552 genotype.</p

INDUÇÃO DE CALOS EMBRIOGÊNICOS NAS CULTIVARES BRS ARARIPE E BRS SERIDÓ DO ALGODOEIRO

The callus culture facilitates the study of factors involved in somatic embryogenesis, technique that allows the production of embryos in vitro from somatic tissue, making the propagation possible of elite plants and constituting an important tool in breeding programs. The objective was to analyze the influence of growth regulators on the formation of callus on cotton cultivars BRS Araripe and BRS Seridó. In the Laboratory of Tissue Culture of Embrapa Algodão, for the induction and proliferation of callus, hypocotyledonary segments were cultured on MS medium supplemented with phytoregulators NAA, KIN and 2,4-D. For the induction of embryogenic callus, it was used redifferentiation medium, with no phytoregulators. Data were analyzed according to the nonparametric chi-square test, being verified high number of potentially embryogenic callus, with a friable consistence and cream-greenish coloration. In the treatment with addition of NAA and KIN was observed the formation of embryogenic callus of BRS Seridó. The dependence of the genotype is a major problem for the low frequency of somatic embryogenesis in cotton that has been achieved in a few cultivars; it is necessary to study in other varieties for the definition of appropriate protocols in this process

MORPHOMETRIC STUDIES AND ANALYSES OF GERMINABILITY IN CENOSTIGMA MACROPHYLLUM TUL. IN AN URBAN-RURAL GRADIENT IN TERESINA-PI, BRAZIL

Urbanization can alter environmental factors that affect the morphological and germinative characteristics of seeds. We evaluated the influence of an urban-rural gradient on the morphometrics of the fruits and seeds of Cenostigma macrophyllum Tul. (Fabaceae) and on seed germinability in the region near Teresina, Piaui State, Brazil. One hundred fruits were collected in the urban zone and 100 in the rural area, and the lengths, widths, thicknesses, and weights of both the fruits and seeds were measured, as well as the numbers of seeds per fruit. The seeds were then used in greenhouse germination experiments (during two months) to calculate the percentages of emergence (E%) and survival (S%), the emergence rate index (ERI), synchronization index (Z), and Timson’s index (T). The results showed significant statistical differences between the two areas in terms of the biometric patterns of the fruits and seeds as well as seed germination, with higher values in the urban zone. As such, urbanization was found to affect the morphologies and germination processes of plant species