Establishment of an efficient in vitro propagation protocol for Sumac (Rhus coriaria L.) and confirmation of the genetic homogeneity.

The conventional reproduction methods are not efficient for regeneration of Sumac (Rhus coriaria L.). The purpose of this work was to study the micropropagation of R. coriaria using lateral buds as explant in Murashige and Skoog (MS) medium with different concentrations of plant growth regulator (PGRs). Four concentrations of Benzylaminopurine (BAP) in combination with three concentrations of indol-3-butyric acid (IBA) and 1.0 mg/L gibberellic acid (GA3) were tested for establishment and shoot multiplication. For root induction, IBA was used at four levels combined with 0, 0.5 and 1 mg/L of naphthalene acetic acid (NAA) in full and half strength of MS medium. BAP at 2 mg/L with 1 mg/L IBA was best, with 88.88% of establishment. The highest shoot proliferation (12.30 ± 0.30) was obtained in medium fortified with 2 mg/L BAP plus 0.5 mg/L IBA and the highest shoot length (8.50 cm) was obtained at 3 mg/L BAP plus 1 mg/L IBA. The highest rooting (100%) was observed in 1/2-strength MS medium containing 1 mg/L IBA with 0.5 mg/L NAA. In conclusion, an efficient protocol with high rate of proliferation and rooting is described for R. coriaria, which can be used in massive propagation.

Accumulation of uranium and heavy metals in the soil-plant system in Xiazhuang uranium ore field, Guangdong Province, China.

Plants that have grown for many years in the special environmental conditions prevailing in mining areas are naturally screened and show strong capacity to adapt to their environment. The present study investigated the enrichment characteristics of U and other heavy metals (As, Cu, Pb, Mn, Mo, Zn, Cd, Co, and Ni) in the soil-plant system in Xiazhuang uranium mine. Four dominant plants (Castanopsis carlesii, Rhus chinensis, Liriodendron chinense, and Sapium discolor) and soil samples were collected from the mined areas, unmined areas, and background areas away from the ore field. U, As, Cu, Pb, Mn, Mo, Zn, Cd, Co, and Ni concentrations were analyzed by ICP-MS. The results demonstrate that (1) The highest concentrations of U (4.1-206.9 mg/kg) and Pb (43.3-126.0 mg/kg) with the geoaccumulation index (Igeo) greater than 1 show that they are the main soil pollutants in the research area. (2) The biological accumulation coefficient (LBAC) values for Cd, Mn, and Cu are greater than zero in S. discolor, L. chinense, and C. carlesii and these three plants indicate that they can be used for remediation of the soil in the ore field. (3) R. chinensis inhibits the accumulation of heavy metals and shows sensitive pigment responses to the accumulation of U in the leaves. L. chinense has the strongest enrichment effect on heavy metals but exhibits weak biochemical responses under U stress. C. carlesii demonstrates strong adaptation to U and can maintain healthy pigment characteristics in case of high U enrichment. (4) S. discolor, L. chinense, C. carlesii and R. chinensis have strong tolerance to U toxicity and different biochemical responses.

Bioaccumulation and detoxification mechanisms for lead uptake identified in Rhus chinensis Mill. seedlings.

A greenhouse experiment was conducted to assay the bioaccumulation and tolerance characteristics of Rhus chinensis Mill. to lead (Pb). The effects of exposing R. chinensis Mill seedlings to increasing Pb concentrations (0, 250, 500, 100mgkg-1) in the soil were assessed by measuring Pb accumulation, subcellular distribution, ultrastructure, photosynthetic characteristics, antioxidative enzyme activity, malondialdehyde content, and phytochelatin content. The majority of Pb taken up by R. chinensis Mill was associated with the cell wall fraction in the roots, where the absorption of Ca increased to maintain cell wall stability, and Pb deposits were found in the intercellular space or in the cell wall structures. In leaves, Pb was primarily stored in the cell wall, while it was compartmentalized into the vacuolar structures in the stem. Pb concentrations adversely affected the morphology of Rhus chinensis Mill cellular substructures. Furthermore, increased Peroxidase (POD) and catalase (CAT) activity was observed in plants grown in Pb-amended soil, and this may have led to reduced ROS to maintain the function of the membrane. Changes in phytochelatin levels (PCs) that were observed in Pb treated plants suggest that PCs formed complexes with Pb in the cytoplasm to reduce Pb2+ toxicity in the metabolically active cellular compartment. This mechanism may allow for the plant to accumulate higher concentrations of toxic Pb and survive for a longer period of time. Our study provides a better understanding of how Rhus chinensis Mill detoxifies Pb.

Tamizaje fitoquímico de tres especies del desierto del sahara occidental / Phytochemical screening of three species of western sahara

INTRODUCCIÓN: las plantas que crecen en el desierto requieren de características especiales para adaptarse a las condiciones adversas de esta región. Dentro de estos se destacan los géneros Pergularia, Hammada y Rhus, al poseer estructuras y mecanismos que les confieren una gran versatilidad en cuanto a sus usos medicinales. Las investigaciones encaminadas al estudio de su composición química y actividad biológica son limitadas. OBJETIVO: determinar la composición química preliminar de extractos de diferente polaridad de las especies Pergularia tomentosa L. (Apocynaceae), Hammada scoparia I. (Amaranthaceae) y Rhus tripartita L. (Anarcadiaceae). MÉTODOS: los materiales vegetales empleados fueron las hojas y las ramas de las especies. En el momento de la colecta no existía ni floración, ni fructificación en estas especies vegetales. Se realizó un proceso de extracción por maceración, se empleó etanol. A partir de éste extracto se efectuó un fraccionamiento preliminar y se usó disolventes de diferente polaridad; el hexano, acetato de etilo, metanol y butanol. A todas estas fracciones se le realizó un tamizaje fitoquímico. RESULTADOS: los metabolitos secundarios encontrados en la identificación preliminar de las tres especies fueron; los alcaloides, azúcares reductores, compuestos con agrupamientos lactónicos y compuestos fenólicos. CONCLUSIONES: en las tres especies, las fracciones metanólicas fueron las que mostraron una mayor variedad de metabolitos secundarios.

INTRODUCTION: plants growing in deserts require special characteristics to survive under the extreme conditions of these regions. Inside these groups of plants are the genus Pergularia, Hammada and Rhus having a great versatility of medical uses. Investigations about chemical composition and biological activities of these genuses are limited. OBJECTIVE: to determine the preliminary chemical composition of extracts from different polarity of Pergularia tomentosa L. (Apocynaceae), Hammada scoparia (Amaranthaceae) and Rhus tripartita L. (Anarcadiaceae). METHODS: plant materials used were the leaves and branches of the species. At the time of collection there was not flowering or fruiting in these plants. Extraction procedure was carried out by maceration with methanol. From this extract preliminary fractionation was done using solvents with different polarity: hexane, ethyl acetate, methanol and buthanol. All these fractions were phytochemical screened. RESULTS: the secondary metabolites found in the preliminary identification of the three species were: alkaloids, reducing sugars, compounds with lactone groups and phenolic compounds. CONCLUSIONS: in the three species, the methanolics fractions showed the most variety of secondary metabolites.

Do xylem fibers affect vessel cavitation resistance?

Possible mechanical and hydraulic costs to increased cavitation resistance were examined among six co-occurring species of chaparral shrubs in southern California. We measured cavitation resistance (xylem pressure at 50% loss of hydraulic conductivity), seasonal low pressure potential (P(min)), xylem conductive efficiency (specific conductivity), mechanical strength of stems (modulus of elasticity and modulus of rupture), and xylem density. At the cellular level, we measured vessel and fiber wall thickness and lumen diameter, transverse fiber wall and total lumen area, and estimated vessel implosion resistance using (t/b)(h)(2), where t is the thickness of adjoining vessel walls and b is the vessel lumen diameter. Increased cavitation resistance was correlated with increased mechanical strength (r(2) = 0.74 and 0.76 for modulus of elasticity and modulus of rupture, respectively), xylem density (r(2) = 0.88), and P(min) (r(2) = 0.96). In contrast, cavitation resistance and P(min) were not correlated with decreased specific conductivity, suggesting no tradeoff between these traits. At the cellular level, increased cavitation resistance was correlated with increased (t/b)(h)(2) (r(2) = 0.95), increased transverse fiber wall area (r(2) = 0.89), and decreased fiber lumen area (r(2) = 0.76). To our knowledge, the correlation between cavitation resistance and fiber wall area has not been shown previously and suggests a mechanical role for fibers in cavitation resistance. Fiber efficacy in prevention of vessel implosion, defined as inward bending or collapse of vessels, is discussed.