Establishment of micropropagation and cell suspension culture conditions on Achyrocline flaccida (Weinm.) DC. (Asteraceae)

It is a rich source of flavonoids and other secondary metabolites with antioxidant properties. Their inflorescences are used as remedies in folk medicine for the treatment of a variety of human ailments. In fact, the permanence of this species is threatened by the increased interest of medicinal herb collectors. Thus, techniques which could provide vegetative propagated material for commercial use are necessary, and in vitro-propagation is a valuable method for producing large numbers of genetically uniform, pathogen-free plants in a short time. Moreover, the production of Achyrocline secondary metabolites is crucial for research and commercial large scale production since they are controllable systems and easy to scale up. Besides productive aims, cell culture suspensions are valuable tools to investigate metabolic pathways involved in secondary metabolites synthesis and to discover new bioactive molecules. The aims of this study were the optimization of a method to propagate in vitro plant of A. flaccida and the establishment of cell suspension cultures to determine the optimal culture conditions in order to improve cell growth as a first step toward secondary metabolites production. It was concluded that DKW without growth regulators is the optimal medium for micropropagation of this species. Friable callus formation was optimized in MS supplied with 0.5 mg L Key words: growth regulators, in vitro culture, friable callus Achyrocline flaccida (Weinm.) DC. (Asteraceae), comúnmente conocida como marcela amarilla, es una especie de importancia medicinal debido a su alto contenido de flavonoides y otros metabolitos secundarios con propiedades antioxidantes. Sus inflorescencias son usadas para el tratamiento de un gran número de enfermedades, lo que ha conducido a considerar esta especie en riesgo de extinción debido al gran interés de los colectores de hierbas medicinales. Por esta razón, es muy importante el establecimiento de técnicas de propagación vegetativa con fines comerciales, que permitan la producción de un gran número de plantas, libre de patógenos, y en un corto plazo. Además, la producción directa de metabolitos secundarios de Achyrocline es crucial para la investigación y la producción con fines comerciales ya que son sistemas controlados donde es posible aumentar fácilmente la escala de producción. Además de ser utilizados con fines comerciales, los cultivos de células presentan grandes ventajas como sistema para el estudio de vías metabólicas y el descubrimiento de nuevas biomoléculas. Los objetivos de este trabajo fueron la optimización de métodos de micropropagación in vitro de A. flaccida y el establecimiento de suspensiones celulares para determinar las condiciones óptimas de crecimiento celular como primer paso hacia la producción de metabolitos secundarios. Se determinó que DKW sin reguladores del crecimiento es el medio ade-AGROCIENCIA 2 cuado para la micropropagación de esta especie. La obtención de callos friables se optimizó en medio MS suplementado con 0.5 mg L -1 de 2,4-D mientras que las suspensiones celulares se obtuvieron y mantuvieron en medio DKW suplementado con 1 mg L -1 de 2,4-D. Palabras clave: reguladores del crecimiento, cultivo in vitro, callo friabl

Use of AFLP markers to estimate molecular diversity of Phakopsora pachyrhizi.

AbstractBackgroundAsian soybean rust (SBR) caused by Phakopsora pachyrhizi Syd. & Syd., is one of the main diseases affecting soybean and has been reported as one of the most economically important fungal pathogens worldwide. Knowledge of the genetic diversity of this fungus should be considered when developing resistance breeding strategies. We aimed to analyze the genetic diversity of P. pachyrhizi combining simple sampling with a powerful and reproducible molecular technique.ResultsWe employed Amplified Fragment Length Polymorphism (AFLP) technique for the amplification of P. pachyrhizi DNA extracted from naturally SBR-infected plants from 23 production fields. From a total of 1919 markers obtained, 77% were polymorphic. The high percentage of polymorphism and the Nei's genetic diversity coefficient (0.22) indicated high pathogen diversity. Analysis of molecular variance showed higher genetic variation within countries than among them. Temporal analysis showed a higher genetic variation within a year than between years. Cluster, phylogenetic and principal co-ordinate analysis showed that samples group by year of collection and then by country sampled.ConclusionsThe study proposed combining a simple collection of urediniospore with a subsequent analysis by AFLP was useful to examine the molecular polymorphism of samples of P. pachyrhizi collected and might have a significant contribution to the knowledge of its genetic diversity. Also, AFLP analysis is an important and potent molecular tool for the study of genetic diversity and could be useful to carry out wider genetic diversity studies

Equações de estimativa da fitomassa da parte aérea da alface Equations to estimate shoot phytomass of lettuce

O objetivo deste trabalho foi identificar equações de regressão que expressem o acúmulo de fitomassa a partir de variáveis meteorológicas e índices de crescimento da cultura, com a finalidade de avaliar o crescimento da alface cultivada em estufa plástica e a campo, em diferentes épocas do ano. No estudo, foi utilizada a cultivar "Regina". As variáveis meteorológicas determinadas foram a temperatura, a umidade relativa média do ar e a radiação solar fotossinteticamente ativa acumulada. Os índices de crescimento da alface utilizados foram a fitomassa seca e o índice de área foliar. Independentemente da época do ano, os resultados evidenciaram que as equações de regressão simples, utilizando as variáveis índice de área foliar ou radiação solar fotossinteticamente ativa acumulada, apresentaram melhor desempenho na estimativa da fitomassa (R²>0,88) nos dois ambientes. As equações de regressão múltipla, apesar de englobarem mais variáveis, apresentaram pequeno acréscimo no valor do R².<br>The aim of this paper was to propose regression equations that express the dry matter accumulation in lettuce using meteorological parameters and growth index, to modeling the lettuce growth in greenhouse and in the field, in different growth season. The "Regina" cultivar was utilized. The meteorological variables determined were air temperature and relative humidity average and accumulated photosynthetically active radiation. The growth indexes of lettuce used were dry mass and leaf area index. Independent of the growth season, the results shown that linear regressions utilizing variables leaf area index and accumulated photosynthetically active radiation provided a good estimate of the dry mass (R²>0.88) for both seasons. The multiple regressions need more data, but shown a little increase in R² value