Factores que afectan el enraizamiento adventicio y brotación en estacas de Hyptis australis (Lamiaceae) / Factors affecting adventitious rooting and sprouting in Hyptis australis (Lamiaceae) cuttings

Resumen Hyptis australis es una especie de la familia Lamiaceae, endémica del Bosque Atlántico, cuyo estado de conservación es crítico y se desconoce aún sus beneficios potenciales para el ecosistema y la sociedad. Con fines de rescate y conservación (ex situ/in situ), se plantea como necesidad, generar un protocolo de propagación vegetativa para facilitar y aumentar la disponibilidad de plantas. Con este objetivo, se estudiaron factores como el tipo de sustrato, tipo de estaca y hormona. Se utilizaron plantas de un año de edad, obtenidas de semillas cosechadas de las plantas ubicadas en la región sur de la provincia de Misiones (Argentina). Estacas apicales y subapicales fueron utilizadas en dos ensayos, en el primero se estudió la factibilidad de inducir raíces adventicias en los sustratos corteza de pino, arena y perlita. En el segundo ensayo, se evaluó la inducción de rizogénesis en estacas tratadas durante 30 minutos con una solución de 100 mg.kg -1 de ácido naftalenacetico (ANA) o ácido indolbutirico (AIB) en corteza de pino. Los mejores resultados se obtuvieron en el sustrato arena y en las estacas terminales. El ANA fue la hormona que generó mayor porcentaje de estacas apicales (80.00±14.14 %) y subapicales (84.00±16.73 %) con raíces. En las estacas subapicales el porcentaje de brotación fue mayor en ambos experimentos. La probabilidad de que una estaca de H. australis desarrolle raíces adventicia depende del tipo de sustrato, pero la adicción de ANA mejora notablemente el porcentaje de enraizamiento.

Abstract Hyptis australis is a species of the Lamiaceae family, endemic to the Atlantic Forest, whose conservation status is critical and its potential benefits for the ecosystem and society are still unknown. For rescue and conservation purposes (ex situ/in situ), the need arises to generate a vegetative propagation protocol to facilitate and increase the availability of plants. With this objective, factors such as the type of substrate, type of stake and hormone were studied. One-year-old plants were used, obtained from seeds harvested from plants located in the southern region of the province of Misiones (Argentina). Apical and subapical cuttings were used in two trials, the first studied the feasibility of inducing adventitious roots in pine bark, sand and perlite substrates. In the second test, the induction of rhizogenesis was evaluated in cuttings treated for 30 minutes with a solution of 100 mg.kg-1 of naphthalenacetic acid (ANA) or indole butyric acid (IBA) in pine bark. The best results were obtained in the sand substrate and in the terminal stakes. ANA was the hormone that generated the highest percentage of apical cuttings (80.00±14.14%) and subapical (84.00±16.73%) with roots. In the subapical cuttings the sprouting percentage was higher in both experiments. The probability that an H. australis cuttings will develop adventitious roots depends on the type of substrate, but the addition of ANA notably improves the rooting percentage.

Sumatran fleabane (Conyza sumatrensis [Retz.] E. Walker) control in soybean with combinations of burndown and preemergence herbicides applied in the off-season

Sumatran fleabane (Conyza sumatrensis [Retz.] E. Walker) can be found in many different agricultural environments and impact different crops, such as soybeans and corn. It is believed that the application of burndown and preemergence herbicides in the off-season are effective in controlling Sumatran fleabane in soybean crops. The objective was to evaluate the effectiveness of burndown and preemergence herbicides in the off-season, with one or two applications, in the control of Sumatran fleabane in soybean cultivation. Five field experiments were conducted in Maripá, state of Paraná (PR), Brazil. The treatments consisted of the application of burndown herbicides in combinations with preemergence ones, with one or two applications. Control of Sumatran fleabane and soybean yield were evaluated. With the set of experiments, it is highlighted that the strategy combining more applications, with different herbicides, burndown and preemergence, is more promising in the control of Sumatran fleabane. When comparing synthetic auxins, dicamba and triclopyr stand out. For sequential application, worse performance was observed for diquat. Combinations between burndown and preemergence herbicides were effective in controlling Sumatran fleabane, for pre sowing application in soybean. With emphasis on managements with sequential applications of saflufenacil with glufosinate or glyphosate. The strategy combining more applications, with different herbicides, burndown and preemergence herbicides, is more promising in the control of Sumatran fleabane.

Rapid in vitro adventitious rooting and proliferation by leaf and nodal cultures of Momordica cymbalaria Fenzl.

An effective approach for rapid in vitro rooting and proliferation of leaf and nodal cultures of Momordicacymbalaria has been developed. To the ability of induction of rhizogenesis, both leaf and nodal explants wereused in culture on Murashige and Skoog (MS) medium. The effects of auxins such as α-naphthaleneaceticacid (NAA), indole-3-butyric acid (IBA), and indole-3-acetic acid (IAA) at different concentrations have beenstudied. The maximum number of roots was produced from nodal explants containing 1.5 mg/L of NAA (9.3 ±0.61), 1.0 mg/L of IBA (6.5 ± 0.41), and 1.0 mg/L of IAA (3.5 ± 0.66), and in leaf explants containing 1.0 mg/Lof NAA (5.7 ± 0.56), 1.0 mg/L of IBA (6.9 ± 0.61), and 1.5 mg/L of IAA (5.0 ± 0.73) on the half-strength MSmedium. For the root induction, NAA is the very effective auxin in node explants of M. cymbalaria. Moreover,a large amount of quercetin bioactive compound is presented in the roots, which is used in anticancer drugs, andwe have described an effective method for the in vitro rhizogenesis of the M. cymbalaria.

Micropropagation of Stevia rebaudiana plants / Micropropagação de plantas de Stevia rebaudiana

ABSTRACT: The aim of the study was to develop optimum composition of plant growth regulators in media for the propagation and rooting of shoots of stevia (Stevia rebaudiana Bertoni) in in vitro cultures. Single-node shoot fragments obtained from plants propagated on MS medium were placed onto media supplemented with: BAP, 2iP and KIN at concentrations: 0.5, 1, 2 and 5 mg∙dm-3, whereas at the rooting stage with addition of: IAA, IBA and NAA at concentrations 1, 2, 4 and 8 mg∙dm-3. The highest number of shoots and leaves was reported for plants propagated on MS medium enriched with 0.5 mg∙dm-3 BAP. The greatest number of the longest roots was developed by stevia on the MS medium enriched with 1 mg∙dm-3 IAA.

RESUMO: O objetivo do estudo foi desenvolver uma composição ótima de reguladores de crescimento em meios para a propagação e enraizamento de brotos de estévia (Stevia rebaudiana Bertoni) em culturas in vitro. Fragmentos de parte aérea obtidos de plantas propagadas em meio MS foram colocados em meio suplementado com: BAP, 2iP e KIN nas concentrações: 0.5, 1, 2 e 5 mg∙dm-3, enquanto no estádio de enraizamento com adição de: IAA, IBA e ANA nas concentrações 1, 2, 4 e 8 mg∙dm-3.O maior número de brotações e folhas foi encontrado para plantas propagadas em meio MS enriquecido com 0.5 mg∙dm-3 de BAP. O maior número de raízes mais longas foi desenvolvido por estévia no meio MS enriquecido com 1 mg∙dm-3 de IAA.

Somatic embryogenesis in Carica papaya as affected by auxins and explants, and morphoanatomical-related aspects

ABSTRACT The aim of this study was to evaluate somatic embryogenesis in juvenile explants of the THB papaya cultivar. Apical shoots and cotyledonary leaves were inoculated in an induction medium composed of different concentrations of 2,4-D (6, 9, 12, 15 and 18 µM) or 4-CPA (19, 22, 25, 28 and 31 µM). The embryogenic calluses were transferred to a maturation medium for 30 days. Histological analysis were done during the induction and scanning electron microscopy after maturing. For both types of auxin, embryogenesis was achieved at higher frequencies with cotyledonary leaves incubated in induction medium than with apical shoots; except for callogenesis. The early-stage embryos (e.g., globular or heart-shape) predominated. Among the auxins, best results were observed in cotyledonary leaves induced with 4-CPA (25 µM). Histological analyses of the cotyledonary leaf-derived calluses confirmed that the somatic embryos (SEs) formed from parenchyma cells, predominantly differentiated via indirect and multicellular origin and infrequently via synchronized embryogenesis. The secondary embryogenesis was observed during induction and maturation phases in papaya THB cultivar. The combination of ABA (0.5 µM) and AC (15 g L-1) in maturation medium resulted in the highest somatic embryogenesis induction frequency (70 SEs callus-1) and the lowest percentage of early germination (4%).

Efecto de Dicamba y de ácido 2,4 diclorofenoxiacético sobre la embriogénesis somática en caña de azúcar / Effect of Dicamba and 2,4 dichlorophenoxiacetic acid on sugarcane somatic embryogenesis

El cultivo in vitro de la caña de azúcar ha sido establecido en muchas variedades comerciales con el propósito de producir material libre de enfermedades microbianas, conservar germoplasma, detectar resistencia a enfermedades y plagas, etc. En este sentido, el objetivo de este trabajo fue analizar la efectividad de las auxinas sintéticas ácido 2,4-diclorofenoxiacético (2,4D) y ácido 3,6-dicloro-2-metoxibenzoico (Dicamba), en la inducción del proceso de embriogénesis somática y la regeneración de vitroplántulas de distintas variedades de caña de azúcar (C26670, RB855546, V99245, V756, V781, V0050, CC8592, CC8475). Para esto se cultivaron discos de hojas en fase de macollamiento, de 1 cm de diámetro y 2 mm de grosor, en medio Murashige-Skoog, 1962 (MS) suplementado con 50 ml.l-1 agua de coco, 30 g.l-1 sacarosa y dos tratamientos diferentes: 3 mg.l-1 2,4-D ó 6.63 mg.l-1 Dicamba, ambos en completa oscuridad a 25ºC, durante 1 mes. Los callos obtenidos se colocaron en medio de regeneración, conteniendo ½ sales MS, 200 ml.l-1 agua de coco y 60 g.L-1 sacarosa, incubándose bajo luz continua, 25ºC, por 2 meses. El mayor porcentaje de callo embriogénico se obtuvo en medios suplementados con Dicamba un promedio de 70,83 % de callo embriogénico por variedad ; mientras que en los medios con 2,4D se obtuvo 62,08 % de callo embriogénico por variedad. Se obtuvo un promedio de 89,00 % de plantas regeneradas a partir de los callos obtenidos en medios con Dicamba y 66,12 % de plantas a partir de callos obtenidos en medios con 2,4D. Con el uso de Dicamba se estableció un sistema eficiente de embriogénesis somática para estas variedades de caña de azúcar.

In order to conserve sugarcane germplasm, produce microbial disease-free material, detect resistance to diseases and pests, etc., in vitro propagation of sugarcane has been established in many commercial varieties. In this sense, the aim of this work was to analyze the efficiency of 2,4-dichlorophenoxyacetic acid (2,4D) and 3,6-dichloro -2- methoxybenzoic acid (Dicamba) to induce somatic embryogenesis and regeneration of plantlets from sugarcane varieties C26670, RB855546, V99245, V756, V781, V0050, CC8592, CC8475. For induction of embryogenic callus, leaf discs in tillering stage of 1 cm diameter and 2 mm thick, were inoculated on Murashige-Skoog, 1962 medium (MS), supplemented with 50 ml.l-1 coconut water, 30 g.l-1sucrose and two different treatments: 3 mg.l-1 2,4D or 6.63 mg.l-1 Dicamba, both of them in total darkness at 25 °C, during 1 month. For plant regeneration, embryogenic calli were transferred to ½ MS salts supplemented with coconut water 200 ml.l-1 and sucrose 60 g.l-1 and incubated under continuous light, 25 °C, for 2 months. The highest percent of embryogenic callus induction was obtained in media supplemented with Dicamba, an average of 70.83 % of embryogenic callus by variety, while in media with 2,4-D, 62.08 % of embryogenic callus was obtained by variety. An average of 89,00 % of plantlets was obtained from calli induced on media with Dicamba and an average of 66.12% of plantlets was obtained from calli induced on media supplemented with 2,4D. Using Dicamba it was possible to establish an efficient somatic embryogenesis protocol for these sugarcane varieties.

Enraizamento in vitro de catuaba (Anemopaegma arvense (Vell. ) Stell. ex de Souza), uma planta medicinal do Cerrado / Study on the in vitro rooting of Anemopaegma arvense (Vell. ) Stell. ex de Souza, a medicinal plant of the Brazilian Cerrado

Este trabalho foi realizado com o objetivo de otimizar o protocolo para enraizamento in vitro de Anemopaegma arvense, planta medicinal do Cerrado em risco de extinção e conhecida popularmente como catuaba, a qual é amplamente utilizada na medicina popular. Brotações cultivadas in vitro foram inoculadas em meio de cultura MS/2 liquido e MS sólido suplementado com diferentes concentrações de auxinas, poliaminas ou dithiothreitol (DTT). As avaliações foram realizadas quanto à porcentagem de enraizamento, número e comprimento das raízes. A presença de NAA (Ácido naftaleno acético) no meio de cultura foi essencial para promover a indução de raízes adventícias nas brotações. A maior porcentagem de enraizamento, 50%, foi obtida no tratamento 2 mg L-1 de NAA com tempo de permanência de 15 dias nesta auxina. No experimento com poliaminas o melhor tratamento foi MS/2 + 5 mg L-1 de putrescina, com 27% de brotações enraizadas. Na presença de DTT (Dithiothreitol), 23% das brotações enraizaram em 0,10 mg L-1 de DTT. A presença da auxina NAA e a alternância no tempo de permanência foi a melhor condição para promover o enraizamento in vitro da de A. arvense. .

This work was carried out in order to optimize an efficient protocol for the in vitro rooting of Anemopaegma arvense, a medicinal plant of the Brazilian Cerrado in danger of extinction, popularly known as Catuaba in Portuguese and widely used in folk medicine. Shoots cultivated in vitro were inoculated in liquid MS/2 and solid MS culture medium supplemented with different concentrations of auxins, polyamines or dithiothreitol (DTT). Evaluations were performed for the rooting percentage and for the number and length of roots. The presence of NAA (naphthaleneacetic acid) in the culture medium was essential to promote the induction of adventitious roots. Higher rooting percentage (50%) was obtained in the treatment with 2 mg L-1 NAA and duration of stay of 15 days in this auxin. In the experiment with polyamines, the best treatment was MS/2 + 5 mg L-1 putrescine with 27% of shoots rooted. In the presence of DTT (dithiothreitol), 23% of shoots rooted at 0.10 mg L-1 DTT. The presence of the auxin NAA and the alternation in length of stay was the best condition to promote in vitro rooting of A. arvense. .

Producción de attisueros para la detección de áido indolacético en cultivos dee bacterias promotoras del crecimiento vegetal / Antisera Production to Detect Indoleacetic Acid in Cultures of Plant-Growth Promoting Bacteria

Se obtuvieron antisueros en conejo utilizando como antígeno el AIA adherido a membranas de nitrocelulosa que mostraron un elevado título y especificidad. Mediante la técnica de inmunoadsorción por manchas marcadas con oro coloidal se detectó la producción de esta auxina por cepas de los géneros Gluconacetobacter, Herbaspirillum, Azospirillum, Pseudomonas, Burkholderia y Bacillus empleando como antígenos los sobrenadantes de los cultivos. Para cuantificar la producción de AIA y corroborar los datos obtenidos se empleó la técnica colorimétrica derivada de Salkowski. Los resultados muestran que todos los géneros bacterianos estudiados tienen la capacidad de producir AIA y se demuestra la factibilidad del uso de este antisuero policlonal para la detección de este metabolito. Teniendo en cuenta las potencialidades de estas bacterias, resulta de gran importancia la utilización de antisueros y técnicas serológicas para la detección rápida y sencilla de este tipo de metabolitos en bacterias asociadas a cultivos de interés económico.

Rabbit polyclonal antisera against indoleacetic acid (IAA) bound to nitrocellulose membrane were obtained, which exhibited a high titer and specificity. The dot immunobinding technique with colloidal gold was used to detect auxin production by several strains belonging to Gluconacetobacter, Herbaspirillum, Azospirillum, Pseudomonas, Burkholderia and Bacillus genera, using culture supernatants as antigens. Moreover, auxin production was quantified by the Salkowski's method to corroborate the previous results. It was found that that all the studied microorganisms produce IAA and the feasibility of using these antisera to detect the metabolite was confirmed. Taking into account the potentialities of plant growth promoting bacteria as biofertilizers, the use of these antisera for a rapid and easy detection of IAA in bacteria associated with important crops is thus recommended.

Pré-tratamento com água e doses de ácido indolbutírico para estaquia herbácea de pitangueiras / Pre-treatments with water and indole butyric acid dosis for herbaceous cuttings of Surinam cherry

No Brasil, a maioria dos pomares de pitangueira (Eugenia uniflora) é formada por mudas do tipo pé-franco, o que torna os plantios com baixa uniformidade genética. A propagação vegetativa via estaquia é uma alternativa viável para propagação de diversas espécies frutíferas, podendo ser utilizada também com as espécies nativas, proporcionando a formação de pomares homogêneos, com a produção de mudas com alta sanidade, além de antecipar a produção. Nesse contexto, conduziu-se um estudo visando à multiplicação vegetativa da pitangueira, em que se testou a estaquia herbácea a partir de estacas coletadas de plantas matrizes jovens e adultas, submetidas a três períodos de imersão em água (0, 24 ou 48 horas), além da aplicação de doses de ácido indolbutírico (0, 2000, 4000 e 6000mg L-1). Foram avaliadas a sobrevivência ( por cento), a retenção e a emissão foliar (n° folhas/ estaca), a calogênese ( por cento) e enraizamento das estacas ( por cento). Ao final do experimento, avaliou-se massa fresca e seca de parte aérea e raiz, número de folhas e área foliar. O delineamento experimental foi o completamente casualizado, com três repetições de dez plantas por tratamento para os parâmetros não destrutivos e três repetições de cinco plantas por tratamento para os parâmetros destrutivos. A estaquia herbácea foi eficiente para produzir mudas de pitangueira, especialmente quando utilizadas estacas oriundas de plantas jovens sem necessidade de pré-lavagem nem adição de auxinas exógenas.

In Brazil, most of the Surinam cherry (Eugenia uniflora) orchards is formed by ungrafted plants, which makes the plantations have low genetic uniformity. The vegetative minicutting propagation is a viable alternative for the propagation of several fruit species, and can also be used with native species providing the formation of orchards with homogeneous populations of plants, with production of seedlings with high health and accelerated propagation process. In this context, a study for the multiplication of Surinam cherry was conduced with herbaceous cuttings, taken from young and adult mother plants, immersed in indole butyric acid doses (0, 2000, 4000 and 6000mg L-1), in three different water periods (0, 24 or 48 hours). Survival rate ( percent), leaf retention and emission (No. leaves /cutting), callus rate ( percent) and rooting ( percent) were evaluated. At the end of the experiment, were also evaluated fresh and dry weight of shoot and root, leaf number and leaf area. The experiment has a completely randomized design with three replications of ten plants per treatment for nom destructive and three replications of five plants per treatment for the destrutive parameters. The herbaceous cuttings were efficient to produce seedlings of Surinam cherry, particularly when using cuttings derived from seedlings in the absence of the immersion in water and exogenous auxin.

Propagação vegetativa de jambeiro vermelho [Syzygium malaccense (L.) Merr. & L.M. Perry] / Vegetative propagation of malay apple [Syzygium malaccense (L.) Merr. & L.M. Perry]

O jambeiro vermelho [Syzygium malaccense (L.) Merr. & L.M. Perry] se apresenta como opção ao fruticultor por apresentar frutos atrativos e bem aceitos pelo consumidor. A dificuldade de cultivo dessa espécie reside no fato de que a planta possui um porte demasiadamente alto e longo período juvenil quando propagada por semente, com isso, é desejável sua multiplicação vegetativa visando a antecipar o período produtivo e diminuir seu porte. Foi estudada a possibilidade de clonagem dessa espécie pelas técnicas de estaquia, alporquia e enxertia. No experimento por estaquia, testaram-se três doses de ácido indolbutírico (AIB) (0, 1.000 3.000 e 5.000 mg L-1) em dois comprimentos de estacas herbáceas (15 e 25 cm). No experimento de alporquia, avaliaram-se duas épocas de realização do alporque (verão e outono) e quatro doses de AIB (0, 1.000, 4.000, 7.000 e 10.000 mg kg-1). Na enxertia, analisou-se a compatibilidade do jambeiro vermelho (S. malaccense) sobre o jambeiro rosa [Syzygium jambos (L.) Alston] com dois diâmetros de porta-enxertos (0,5 e 0,8 cm) em duas épocas (inverno e verão), pelo método de enxertia de topo em fenda cheia. A estaquia obteve até 20 por cento de enraizamento, independentemente da dose de AIB, exceto na dose de 5.000 mg L-1, que apresentou efeito negativo ao enraizamento entre estacas de 15 cm; não houve sucesso para alporquia e enxertia, nas condições estudadas.

The Malay Apple [Syzygium malaccense (L.) Merr. & L.M. Perry] is an option for the producer as its fruits are attractive and well accepted by the consumer. The difficulty of culture of this species is that the plant is very tall and has a long juvenile period when propagated by seed, making its vegetative propagation necessary to anticipate the productive period and decrease its size. The possibility of vegetative propagation of this species was studied by cutting, layering, and grafting. In the cutting experiment, three doses of indolbutyric acid (IBA) (0, 1,000, 3,000, and 5,000 mg L-1) were tested in two lengths of herbaceous cuttings (15 and 25 cm). In the layering experiment, two periods of layering (summer and autumn) and four doses of IBA (0, 1,000, 4,000, 7,000, and 10,000 mg kg-1) were evaluated. For grafting, the compatibility between S. malaccense and S. jambos (L.) Alston as rootstock was studied with two diameters (0.5 and 0.8 cm) and in two periods (winter and summer), by method of full graft. For cuttings, the percentage of rooting was 20 percent, independently of the IBA doses, except for 5,000 mg L-1 that showed negative effect on 15 cm cuttings; layering and grafting were not successful in the studied conditions.

Estaquia de Ginkgo biloba L. utilizando três substratos / Ginkgo biloba L. cutting using three substrates

Ginkgo biloba é arbórea, decídua, cuja folhagem se torna amarelada no outono antes da queda das folhas, o que a torna valorizada em jardinagem. A estaquia é um método de propagação vegetativa baseado na capacidade das células em retomarem o processo de divisão celular, formando raízes em estacas destacadas de ramos provenientes de plantas matrizes. O presente trabalho teve como objetivos verificar a influência de diferentes substratos, assim como, a aplicação da auxina sintética o ácido indol butírico (AIB) no enraizamento de estacas de Ginkgo biloba. No inverno de 2005, ramos foram coletados e transportados até o Laboratório de Macropropagação, onde foram confeccionadas estacas sem folhas, com 10-12 cm de comprimento. Os tratamentos com regulador vegetal (T) foram T1- 0 mg L-1 AIB em solução; T2- 4000 mg L-1 AIB em solução; T3- 8000 mg L-1 AIB em solução; T4- 0 mg kg-1 AIB em talco; T5- 4000 mg kg-1 AIB em talco e T6- 8000 mg kg-1 AIB em talco. Para cada tratamento foram utilizados três diferentes substratos (S), S1- areia, S2- fibra de casca de coco (coxim) e S3- casca de arroz carbonizada. Após 120 dias da instalação, foram avaliadas as porcentagens de estacas enraizadas, vivas, com calos e mortas; o número de raízes por estaca e o comprimento das três maiores raízes por estaca. Os melhores resultados no enraizamento foram obtidos com estacas tratadas com 4000 e 8000 mg kg-1 AIB em talco, utilizando o coxim como substrato (45,00 e 46,25 por cento de enraizamento, respectivamente).

Ginkgo biloba is an arboreal and deciduous species, the foliage of which becomes yellowish in the autumn, before leaf drop, increasing its value for gardening. Cutting is a method of vegetative propagation based on the capacity of cells to recover the cell division process, originating roots in cuttings detached from branches of stock plants. This study aimed to verify the influence of different substrates, as well as the application of the synthetic auxin indole-3-butyric acid (IBA) in Ginkgo biloba cutting rooting. In the winter of 2005, branches were collected and sent to the Macropropagation Lab, where cuttings of 10-12cm length were made without leaves. The treatments with plant growth regulator (T) were T1- 0 mg L-1 IBA solution, T2- 4000 mg L-1 IBA solution, T3- 8000 mg L-1 IBA solution, T4- 0 mg kg-1 IBA in talc, T5- 4000 mg kg-1 IBA in talc, T6- 8000 mg kg-1 IBA in talc. Each treatment was planted in three substrates (S), S1- sand, S2- coir and S3- carbonized rice hull. After 120 days, the percentages of cuttings that were rooted, alive, with callus and dead were evaluated, besides the number of roots per cutting and the length of the three highest roots per cutting. The best results regarding rooting were obtained for cuttings treated with 4000 and 8000 mg kg-1 IBA in talc, by using coir as substrate (45.00 and 46.25 percent rooting, respectively).

In vitro plant regeneration system for tropical butternut squash genotypes (Cucurbita moschata) / Sistema de regeneración vegetal in vitro para genotipos de calabaza moscada tropical (Cucurbita moschata)

An efficient and reproducible method for regeneration of commercial and pure lines of tropical butternut squash (Cucurbita moschata) plants via somatic embryogenesis was developed. The influence of genotype, explant source, N6-benzylaminopurine (BAP), 2,4-dichlorophenoxyacetic acid (2,4-D) and 2,4,5-trichlorophenoxyacetic acid (2,4,5-T) concentration on somatic embryogenesis induction was investigated. Friable embryogenic calli was produced from zigotic embryos (53-56%) and cotyledons from seedlings (70%) of C. moschata cv. Sello de Oro cultured on callus induction medium (CIM) supplemented with 0.5 mg/l or 3.5 mg/l 2,4-D. No embryogenic calli was obtained from leaf segments of C. moschata cv. Sello de Oro cultured on CIM supplemented with different concentrations of BAP and 2,4-D and cotyledons from seedlings of C. moschata cv. PVG 04 cultured on CIM with BAP and 2,4,5-T. Embryogenic calli induction was achieved in 75% C. moschata pure lines evaluated and calli percentage frequency range from 5% to 34%. Successful acclimatization of squash in vitro plants was achieved in the greenhouse and in the field. Regenerated plants appeared morphologically normal and set flowers and fruits with seeds that could germinate normally. Rev. Biol. Trop. 57 (Suppl. 1): 119-127. Epub 2009 November 30.

En este estudio se desarrolló un método eficiente y reproducible para la regeneración de líneas puras de la planta tropical Cucurbita moschata mediante la vía de embriogénesis somática. Además se investigó acerca de la influencia del genotipo, transplante, y la concentración de N6-benzylaminopurina (BAP), 2,4-diclorofenoxyacetico ácido (2,4-D) y 2,4,5-triclorofenoxyacetico ácido (2,4,5-T) en la inducción de embriogénesis somática. Los callos embriogenéticos viables fueron producidos de embriones zigóticos (53-56%) y cotiledones de semillas (70%) de C. moschata cv. Sello de Oro cultivados en un medio de inducción de callos (CIM) suplementado con 0.5 mg/l o 3.5 mg/l 2,4-D. Los callos no embriogénicos fueron obtenidos de segmentos de hojas de C. moschata cv. Sello de Oro cultivados con CIM suplementado con diferentes concentraciones de BAP y 2,4-D y cotiledones de semillas de C. moschata cv. PVG 04 cultivado con CIM con BAP y 2,4,5-T. La inducción de callos embriogenéticos fue exitosa en un 75% de las líneas puras evaluadas de C. moschata y el porcentaje de frecuencia de los callos fue de 5% a 34%. Se logró una adecuada aclimatización de las plantas in vitro tanto en el invernadero como en el campo. Las plantas regeneradas fueron normales morfológicamente, y las flores y frutos poseen semillas que pueden germinar normalmente.

Relación de la fijación de nitrógeno y la producción de auxinas en cepas de Gluconacetobacter dizotrophicus / Relationships between nitrogen fixation and auxins production in Gluconacetobacter diazotrophicus strains from different crops

Se determinó la capacidad de fijar nitrógeno mediante la actividad reductora de acetileno para 8 cepas de G. diazotrophicus aisladas de diferentes ecosistemas empleando el medio LGI-P. Además, se determinó la producción de auxinas a través del método de Salkowski y se analizó la influencia del aminoácido triptófano y del AIA en la actividad de la nitrogenasa. El triptófano, al igual que otros aminoácidos y las diferentes concentraciones de AIA, inhiben en distinta medida la actividad de la enzima solo parcialmente. Se demostró que las condiciones de nitrofijación no afectan la producción de AIA en esta bacteria. Esta relación entre ambas capacidades fisiológicas beneficiosas para los cultivos agrícolas pudiera tener gran importancia ya que pueden desarrollarse paralelamente, y potenciar la acción beneficiosa hacia la planta, basada en la dinitrofijación y la producción de auxinas estimuladoras del crecimiento vegetal.

The capacity to fix nitrogen of 8 strains of G. diazotrophicus from different ecosystems was determined by acetylene reduction assay using LGIP medium. Moreover, auxins production was determined by Salkowski’s method and the influence of triptophan and indoleacetic acid (IAA) in the nitrogenase activity were analyzed. The triptophan as other aminoacids and different concentrations of IAA, inhibit at different levels the nitrogen fixation only partially. There were demonstrated that the nitrogen fixation conditions do not affect the auxins production of this bacteria. This relationship between both crop beneficial physiological capacities should be a great importance since they may be parallely developed, and enhance the beneficial action to the plant, based on dinitrogen fixation and stimulating plant growth auxins production.

Peroxidase production from hairy root cultures of red beet (Beta vulgaris)

The genetically transformed roots of red beet have been shown, for the first time, to produce very high levels of peroxidase (POD; EC 1.11.1.7) accounting for 1.21 x 10(6) Units L-1. Of the ten clones established using different strains of Agrobacterium rhizogenes, one was that from the strain LMG-150, three each from A 2/83, A 20/83 and A4. All the clones showed true integration of T-DNA when tested by PCR and Southern hybridization methods. Each clone differed significantly from the others in growth, hormone dependency and POD production where LMG-150 produced highest biomass (140 g FW L-1) as well as POD (ranging from 8000-9000 U g-1 FW and 1.18 x 10(6) U L-1 with a specific activity of 600 U mg-1 protein) on hormone-free medium, both in shake-flask as well as in bioreactor with a further enhancement to 1.21 x 10(6) U L-1 upon the addition of extra calcium chloride (5 mM). PAGE with active staining showed 4 distinct bands of Rm 0.06, 0.16, 0.25, 0.38 and 0.46 in the biomass and bands at Rm 0.06, 0.16, 0.25 and one extra band of Rm 0.575 in the spent medium where isozymes of Rm 0.38 and 0.46 were totally absent. The pH optima and other properties were grossly comparable with the standard horse-radish POD (HRP) with better thermal stability than HRP and therefore, the present source appears to offer a cheaper and additional alternative for the commercial production of POD.

Micropropagation of selected somaclones of Begonia and Saintpaulia.

Begonia x elatior plantlets which regenerated from leaf disk callus showed variations in plant morphology, number of flowers per plant, and flower size. Variations in flowering period, number of flowers per plant, and flower morphology were observed in Saintpaulia ionantha L. plants directly regenerated from leaf disk explants. The cytokinins, benzylaminopurine and zeatin, tested in the culture medium did not affect the basic plant characteristics including flower colour which remained stable in both species. Micropropagation of selected somaclones having the desirable trait of high number of flowers per plant was stable in the MV2 and MV3 generations.

War of hormones over resource allocation to seeds: Strategies and counter–strategies of offspring and maternal parent.

It is suggested that maternal parent and offspring have conflicting interests over the extent of resource allocation to developing seeds. While maternal parent would be selected to allocate her resources optimally among her offspring, the latter would be selected to demand more. In animals, offspring are known to demand additional resources either visibly (through intense vocal calls) or subtly through the production of hormones. In plants though parent offspring conflict over resource allocation has been invoked, the mechanism through which the parent and offspring interact in regulating resource allocation into developing seeds is not yet clear. In this paper, we propose that the strategies and counter–strategies of the offspring and mother during the development of seeds might be manifested through the production of appropriate growth hormones. Accordingly, we predict (i) hormones that mobilize resources into seeds (e.g. auxins and gibberellic acid) shall be synthesized exclusively by the offspring tissue and (ii) hormones that inhibit resource flow in to seeds (e.g. abscisic acid) be produced exclusively by the maternal tissue. We show that these predictions are supported by existing literature on the temporal dynamics and source of production of growth hormones during seed development. Finally, we suggest that such analysis viewing the production of different hormones during early seed development, as strategies and counter–strategies of mother and offspring tissue, helps ofer a meaningful interpretation of the otherwise complex dynamics of hormone fluxes.