ABSTRACT The effect of plant growth-promoting bacteria inoculation on plant growth and the sugar content in Agave americana was assessed. The bacterial strains ACO-34A, ACO-40, and ACO-140, isolated from the A. americana rhizosphere, were selected for this study to evaluate their phenotypic and genotypic characteristics. The three bacterial strains were evaluated via plant inoculation assays, and Azospirillum brasilense Cd served as a control strain. Phylogenetic analysis based on the 16S rRNA gene showed that strains ACO-34A, ACO-40 and ACO-140 were Rhizobium daejeonense, Acinetobacter calcoaceticus and Pseudomonas mosselii, respectively. All of the strains were able to synthesize indole-3-acetic acid (IAA), solubilize phosphate, and had nitrogenase activity. Inoculation using the plant growth-promoting bacteria strains had a significant effect (p < 0.05) on plant growth and the sugar content of A. americana, showing that these native plant growth-promoting bacteria are a practical, simple, and efficient alternative to promote the growth of agave plants with proper biological characteristics for agroindustrial and biotechnological use and to increase the sugar content in this agave species.

Current protocols for Agave americana L. micropropagation have limited commercial application due to the low number of plants produced by explant. Indirect organogenesis could be an alternative, however is necessary to optimize plant growth regulators for plantlet number maximization. The objective of this work was to optimize 2,4-dicholorophenoxyacetic acid (2,4-D) and 6-benzyl adenine (BA) concentrations on the induction of A. americana embryogenic callus from apical meristem as explant for maximized the number of shoots per callus using a response surface experimental design. MS medium containing 30 g l-1 sucrose amended with 0.11,0.18, 0.45 or 2.26 μM 2,4-D, and 11.0, 22.0, 38.2 or 44.0 μM BA was used. Nine treatments with three repetitions was applied and number of shoots per callus were monitored after 4, 16, 20 and 36 weeks. In vitro rooting of shoot was done in MS medium added with indole butyric acid (IBA). A maximum number of plantlets per explant (74) was obtained with 2.26 μM of 2,4-D and 38.2 μM BA. In conclusion, the indirect organogenesis of A. americana L. could be an alternative for obtain plantlets for propagation commercial purposes.

Los protocolos actuales para la micropropagación de Agave americana L. tienen limitaciones para su aplicación comercial debido al bajo número de plantas producidas por cada explante. La organogénesis indirecta podría ser una alternativa, sin embargo, es necesario optimizar los reguladores de crecimiento vegetal para maximizar el número de plantas. El objetivo del trabajo fue optimizar la concentración de ácido 2,4-diclorofenoxiacetico (2,4-D) y de 6-bencil adenina (BA) sobre la inducción de callos embriogénicos en A. americana usando meristemos apicales como explante para maximizar el número de brotes por callo, utilizando un diseño experimental de superficie de respuesta. Se utilizó el medio Murashige Skoog (MS) adicionado con 30 g l-1 de sacarosa, y con 0,11;0,18; 0,45 o 2,26 μM de 2,4-D, y 11,0; 22,0; 38,2 o 44,0 μM de BA. Se implementaron 9 tratamientos con 3 repeticiones y el número de brotes por callo fue evaluado después de 4, 16, 20 y 36 semanas. Se indujo el enraizamiento in vitro usando medio MS adicionado con ácido indolbutírico (AIB). Se obtuvo un máximo de 74 plántulas por callo, usando 2,26 μM de 2,4-D y 38,2 μM de BA. En conclusión, la organogénesis indirecta podría ser una alternativa para la micropropagación de A. americana L con fines comerciales.

The tropical legume Acaciella angustissima inoculated with or without Sinorhizobium mexicanum ITTG R7T strain was cultivated in an aluminium (Al) spiked soil to study its tolerance towards this metal. Seedlings of A. angustissima were grown in soil with 0, 2, 4 or 6 mg Al kg-1. The effect of Al and inoculation on growth, nodulation, and nitrogen and tannins content in the plants was monitored. Height and total and dry root weight of plantlets decreased significantly when soil was spiked with Al, but increased when inoculated. Al decreased the number of nodules. Inoculum increased total N and tannin content of the plantlets. It was found that Al reduced the growth of the tropical leguminous N2-fixing shrub A. angustissima, while inoculation with S. mexicanum ITTG R7T stimulated its growth and increased its tannin and N content.

La leguminosa tropical Acaciella angustissima inoculada con o sin la cepa Sinorhizobium mexicanum ITTG R7T fue cultivada en un suelo tratado con (Al) para estudiar la tolerancia a este metal. Las plantas de A. angustissima fueron crecidas en el suelo con 0, 2, 4 y 6 mg de Al kg-1. Se hizo un seguimiento del efecto de Al e inoculación en el crecimiento, la nodulación, el contenido de nitrogeno y el contenido de taninos en las plantas. La altura, el peso seco total y el peso seco de la raíz de las plantas decrementó significativamente cuando el suelo fue tratado con Al, pero incrementó cuando fue inoculado. El Al disminuyó el número de nódulos. El inóculo incrementó el N total y el contenido de taninos de las plantas. En este experimento fue encontrado que el Al reduce el crecimiento de la leguminosa arbustiva tropical fijadora de N2 A. angustissima, mientras la inoculación con S. mexicanum ITTG R7T estimula el crecimiento e incrementa el contenido de taninos y nitrógeno.

The effects of different inorganic fertilizers and rhizobial inoculation on shoot height, total shoot and root dry weight, nodule number, total shoot nitrogen, nitrogenase activity and tannic acid content of Acaciella angustissima (Mill.) Britton & Rose were investigated in the laboratory. Seedlings were grown in a climate chamber in glass tubes containing sterilized mixture of vermiculite and peat moss, and treated with combinations of nitrogen (N) at 45 mg plant¹, phosphorus (P) at 30 mg plant¹, potassium (K) at 20 mg plant¹ and inoculated with the bacterium Sinorhizobium mexicanum. The combined applications of N, P or K to uninoculated plants increased shoot height and dry weight as compared to the unamended plantlets. The tannin content in uninoculated plants was highest when amended with P+K. Treatment had a significant effect on plant growth, nodulation and tannin content varied. The plants treated with P + K + S. mexicanum had significantly longer shoot height, total shoot and root dry weight, nodule number, total shoot nitrogen, nitrogenase activity and tannic acid content in comparison with unamended plants. It was found that N reduced number of nodules, tannin content and nitrogenase activity of A. angustisisma. As such, farmers should refrain from applying N fertilizer, but could apply P and K to maximize tannin production in A. angustissima.

Se investigaron en el laboratorio los efectos de diferentes fertilizantes inorgánicos y la inoculación rizobial sobre la altura de planta, peso seco total de planta, peso seco de raíz, el número de nodulos, el nitrógeno total de la planta, la actividad de la nitrogenasa y el contenido de ácido tánico de Acaciella angustissima (Mili.) Britton & Rose. Las plántulas fueron crecidas en una cámara climática en tubos de vidrio conteniendo una mezcla de vermiculita y turba, y tratadas con las combinaciones de nitrógeno (N) en 45 mg planta"¹, fósforo (P) en 30 mg planta"¹, potasio (K) en 20 mg planta"¹ e inoculado con la bacteria Sinorhizobium mexicanum. La combinación de las aplicaciones de N, P o K en plantas sin inocular incrementa la altura y el peso seco de planta en comparación con las plantas sin tratamiento. El contenido de taninos en plantas no inoculadas fue el más alto cuando suplementamos con P+K. El tratamiento tuvo un efecto significativo sobre el crecimiento de planta, modulación y el contenido de tanino variado. Las plantas tratadas con P + K + S. mexicanum tuvieron significativamente mayor altura de planta, peso seco total de planta, peso seco de raíz, el número de nodulos, nitrógeno total de planta, actividad de la nitrogenasa y contenido de taninos en comparación con las plantas sin suplementar. Fue encontrado que el N reduce el número de nodulos, el contenido de taninos y la actividad de la nitrogenasa de A. angustisisma. Como tal, los agricultores deberían abstenerse de aplicar el fertilizante de N, pero podrían aplicar P y K para maximizar la producción de tanino en A. angustissima.

Até o momento, pouco se conhece sobre a relação entre história demográfica e a presente estrutura genética da A. Angus Como uma primeira tentativa em transpor esta deficiência, dados de microssatélites coletados em seis populações e freqüências alélicas de isoenzimas publicadas para 11 populações naturais desta espécie foram analisadas com o objetivo de acessar assinaturas moleculares da história demográfica populacional. Assinaturas de gargalos genéticos foram capturadas em todas as populações analisadas provenientes do Sudeste do Brasil. Entre as populações do Sul, assinaturas de pequeno tamanho populacional efetivo foram observadas em somente três entre 13 populações. Populações do Sul provavelmente apresentaram uma rápida recuperação do tamanho efetivo após a migração para os planaltos. Em acordança, a presente diversidade genética das populações do Sul apresenta evidências de uma rápida recuperação do tamanho populacional. Em geral, a história demográfica da A. Angus concorda com as dinâmicas climáticas do Sul e Sudeste do Brasil durante o Pleistoceno e o Holoceno. Estudos palinológicos e reconstrução de dinâmicas climáticas do Sul e Sudeste do Brasil suportam a hipótese de diferentes dinâmicas de recuperação do tamanho populacional em populações destas regiões.

Up to date, little is known about the relationship between historical demography and the current genetic structure of A. Angus As a first effort towards overcoming this lack, microsatellite data scored in six populations and isozyme allele frequencies published for 11 natural stands of this species were analysed in order to assess molecular signatures of populations' demographic history. Signatures of genetic bottlenecks were captured in all analysed populations of southeastern Brazil. Among southern populations, signatures of small effective population size were observed in only three out of 13 populations. Southern populations likely experienced faster recovery of population size after migration onto highlands. Accordingly, current genetic diversity of the southern populations gives evidence of fast population size recovery. In general, demographic history of A. Angusmatches climatic dynamics of southern and southeastern Brazil during the Pleistocene and Holocene. Palynological records and reconstruction of the past climatic dynamics of southeastern and southern Brazil support the hypothesis of different population size recovery dynamics for populations from these regions.

En Chiapas, México, una amplia variedad de plantas tienen potencial para uso industrial. Timbre (Acaciella angustissima) es una leguminosa arbustiva que acumula taninos en su corteza, y se usa para curtir pieles. En la Depresión Central y en la Meseta Comiteca se seleccionaron ocho sitios para estudiar sus características biológicas y su hábitat, así como evaluar su rendimiento cortical. Los resultados indicaron que A. angustissima es una leguminosa muy versátil que crece en diferentes tipos de suelos, en zonas con temperaturas, precipitaciones y altitudes variables. Los arbustos estudiados no presentaron diferencias morfológicas, pero las plantas que crecen en la Meseta Comiteca tuvieron mayor altura que las de la Depresión Central. El sitio experimental Lomas presentó la mayor densidad de arbustos (15 390 plantas ha-1), observándose que 100% de la población estaba conformada por plantas adultas y que registraron el mayor rendimiento cortical en 4 años (176.0 t corteza ha-1) en comparación con los otros sitios estudiados. Sin embargo, la variación en la densidad poblacional del Timbre indica que no hay condiciones para su aprovechamiento. Por tanto, es necesario implementar un programa de reforestación para el aprovechamiento racional de este recurso biótico.

A wide variety of plants in Chiapas, Mexico, have potential for industrial use. Acaciella angustissima, whose local name is Timbre, is a leguminous shrub that accumulates tannins in its bark, which is used to tan leather. In the Central Depression and the Comitec Plateau eight sites were selected to study its biological characteristics and its habitat and to assess bark yield. The results indicated that A. angustissima is a very versatile legume that grows in different types of soils, in areas with varying temperatures, rainfall and altitudes. The shrubs studied were not morphologically different, but the specimens that grow on the Comitec Plateau are taller than those of the Central Depression. In the Lomas experimental site shrub population was denser (15 390 plants ha-1) than in the other sites and 100% of this population was composed of adult plants. The highest bark yield was recorded at 4 years of age (176.0 t bark ha"¹) at this site. However, the variation in population density indicates that there are no conditions for its use. Therefore, it is necessary to implement a reforestation program to assure rational use of this natural resource.

The Edinger-Westphal nucleus (EWN) is a central preganglionic parasympathetic cell group that gives rise to cholinergic input to the ciliary ganglion, thereby regulating several neurovegetative ocular functions. Recently, the supposed presence of the neuropeptide urocortin (UCN) has been reported in EWN neurons in rodent brain. The purpose of the present study was to examine the distribution of UCN in avian brain and to investigate by immunohistochemical analysis the possible use of this substance as an EWN marker in a non-mammalian class of vertebrates. Brain tissue of pigeons was incubated with a specific antibody against UCN and the results showed labeling of many small neurons, forming a double wing in the dorsal mesodiencephalic transition area. Their size and shape, however, differed from those of EWN neurons, and they were preferentially located rostral to the EWN. Double-label experiments employing an antibody against the enzyme choline acetyltransferase (ChAT) showed that UCN is not localized to the cholinergic cells of the EWN and confirmed the rostral distributionof UCN never overlapping the ChAT+ EWN cells. Taken together, these results suggest that, at least in pigeons, the UCN+ population does not belong to the traditionally defined EWN.