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San Miguel de Tucumán, Argentina

Coll Araoz M.V.,PROIMI Biotecnologia | Mercado M.I.,Institute Morfologia Vegetal | Catalan C.A.N.,National University of Tucuman
Chemoecology | Year: 2016

According to theory, variation in plant secondary metabolism against herbivores is driven by variation in biotic and abiotic conditions interacting with plants genotype to determine the expression of resistance traits. Particularly, it has been long postulated that plants growing along latitudinal gradients experience changes in biotic and abiotic interactions, specifically leading to a decrease of plant toxicity towards the poles. We tested this hypothesis using the asteraceous species Smallanthus macroscyphus. Smallanthus species are known to contain sesquiterpene lactones (STLs), bitter compounds with a broad spectrum of biological activities, including deterrence to herbivores. S. macroscyphus showed a decrease in chemical diversity of STLs when investigating populations growing from the tropical regions to less tropical ones. Populations from lower latitudes were found to be more chemically diverse with enhydrin, uvedalin and fluctuanin as main components, while populations southward were chemically fairly uniform, with polymatin A as the main and largely dominant STL. The STL chemistry of S. macroscyphus is in agreement with the hypothesis that plants of tropical forests have a greater diversity of secondary metabolites when compared to their temperate counterparts. © 2016 Springer International Publishing Source

Socolsky C.,CONICET | Hernandez M.A.,Institute Morfologia Vegetal | Bardon A.,CONICET
Studies in Natural Products Chemistry | Year: 2012

Acylphloroglucinols are derivatives of benzene-1,3,5-triol, a compound also known as phloroglucinol. In ferns, phloroglucinols are usually made of two or more rings linked together through methylene bridges. The occurrence of acylphloroglucinols in ferns has been associated with the presence of secreting glands located in their rhizomes. Several phloroglucinol derivatives from ferns display different biological activities including anthelmintic, molluscicidal, and antibacterial effects. This chapter covers in detail not only the distribution of acylphloroglucinols in ferns but also their location in the plant, detection and isolation procedures, structure, and biological activity. © 2012 Elsevier B.V. Source

Martinez J.G.,CONICET | Ponessa G.,Institute Morfologia Vegetal
Quaternary International | Year: 2013

The main objective is to present the discovery of a wild species of the Amaranthus genus found within an archaeological site whose general context corresponds with hunter-gatherer settlements dated between ca. 7910 and 7270BP. Numerous seeds were collected at various stratigraphic layers of Peñas de la Cruz 1.1 site (PCz1.1), a rockshelter located in the Southern Argentinian Puna, in Antofagasta de la Sierra (Catamarca, NW Argentina). The implications of the findings are assessed in relation to the subsistence for these groups traditionally known as camelid hunters. In the overall context of the South-central Andes, the presence of these seeds might indicate early practices in the handling of wild plant species intended for human consumption during the initial mid-Holocene. © 2013 Elsevier Ltd and INQUA. Source

Varela R.O.,Institute Ecologia | Varela R.O.,National University of Chilecito | Albornoz P.L.,Institute Morfologia Vegetal | Albornoz P.L.,National University of Tucuman
Revista de Biologia Tropical | Year: 2013

Seed biology is a relevant aspect of tropical forests because it is central to the understanding of processes of plant establishment, succession and natural regeneration. Anadenanthera colub-rina var. cebil is a timber tree from South America that produces large seeds with thin weak teguments, which is uncommon among legumes. This study describes the morphology and anatomy of the seed coat, the viability, imbibition, and germination in this species. Seeds used during the essays came from 10 trees that grow naturally in Horco Molle, province of Tucumán, Argentina. Seed morphology was described from a sample of 20 units. The seed coat surface was examined with a scanning electron microscope. Transverse sections of hydrated and non-hydrated seeds were employed to describe the histological structure of the seed coat. Hydration, viability and germination experiments were performed under laboratory controlled conditions; and the experimental design consisted of 10 replicas of 10 seeds each. Viability and germination tests were conducted using freshly fallen seeds and seeds stored for five months. Morphologically the seeds of A. colubrina var. cebil are circular to subcircular, laterally compressed, smooth, bright brown and have a horseshoe fissure line (=pleurogram) on both sides. The seed coat comprises five tissue layers and a double (external and internal) cuticle. The outer cuticle (on the epidermis) is smooth and interrupted by microcracks and pores of variable depth. The epidermis consists of macroesclereids with non-lignified secondary walls. This layer is separated from the underlying ones during seed hydration. The other layers of internal tissues are comprised of osteosclereids, parenchyma, osteo-sclereids, and macrosclereids. The percentage of viable seeds was 93%, decreasing to 75% in seeds with five months old. Seed mass increased 76% after the first eight hours of hydration. Germination percentage was 75% after 76 hours. Germination of seeds stored for five months decreased to 12%. The results showed that seeds of A. colubrina var. cebil are highly permeable and germinate directly without a dormant period. Source

Hernandez M.A.,Institute Morfologia Vegetal | Teran L.,Institute Morfologia Vegetal | Mata M.,Institute Morfologia Vegetal | Martinez O.G.,National University of Salta | Prado J.,Institute Botanica
American Fern Journal | Year: 2014

The occurrence of helical cell wall thickenings in fern roots is not well investigated and there are few records about it in the literature. To assess the presence of thickenings and their chemical composition, we studied all species of Polypodiaceae, which grow in northwestern Argentina, using light microscopy, scanning electron microscopy, and fluorescence microscopy. Twenty of the twenty-one species studied showed the thickening in the roots. Only in Melpomene peruviana are helical cell wall thickenings absent. All thickenings have cellulose as the main compound. The structure of the thickening may be classified as simple, furcate, or anastomosing. All data presented in this paper corroborate the same structure and chemical composition of thickenings previously reported for Aspleniaceae. © 2014, American Fern Society. Source

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