Determination of ptaquiloside in ten species of Pteris in northwestern Argentina.

The toxic effect of ferns of the genus of Pteris in bovines is caused by ptaquiloside, the main carcinogenic toxin. In this study, ten species of Pteris fern in different phenologic stages and plant conditions were collected in northwest Argentina. The phytochemical analysis showed the presence of Pt in the recent collected samples (adults and young plants) but not in the herbarium specimens. The results show a great variation of Pt concentration that depends on the phenologic stage, plant condition, and collection site. Pt was measured in 6-4326 µg/g concentration, with a mean concentration of 644 µg/g. No Pt was detected in eight species of Pteris collected from herbarium samples; such results may be a false negative. It is important to notice that analysis of herbarium samples for Pt may not be a reliable method to determine its presence. It is important to further understand the potential toxicity caused by these ferns because of their effect on animals, public health, and the environment.

Morphological characteristics and accumulation of arsenic in Argyrochosma formosa (Liebm.) Windham developed in a highly contaminated site with arsenic in Matehuala, SLP, México.

We studied the ability of Argyrochosma formosa growing in an arsenic heavily contaminated site to accumulate this metalloid; morphological characteristics and translocation of arsenic were evaluated in the organs. Population census of wild specimens of A. formosa was done, and 14 samples of ferns and rhizosphere soil were collected randomly. We recorded morphological characteristics with scanning electronic microscopy (SEM); concentrations of As in organs of fern plants (root, rhizome, and fronds) were evaluated with inductively coupled plasma-optic emission spectrometry (ICP-OES). Two hundred ninety-four individuals at different stages of development were identified, indicating the establishment of fern on the site. Morphological characteristics of A. formosa in fern plant organs did not show structural effects, compared with herbarium plants. Arsenic distribution in fern plant tissues was 192.2-763.6 mg/kg, 188-1017 mg/kg, and 113-2008 mg/kg, in roots, rhizomes, and fronds, respectively. The calculated bioaccumulation factor in fronds ranged from 2 to 7 and the translocation factor from 0.6 to 2.1. Our data suggest that A. formosa is an arsenic-tolerant species and propose it for phytoremediation on contaminated sites with As concentrations similar to that of the studied location. Further studies should be performed to evaluate the mechanisms of accumulation of As in plant tissues.

Arsenic removal using Chlamydomonas reinhardtii modified with the gene acr3 and enhancement of its performance by decreasing phosphate in the growing media.

Arsenic contamination of groundwater is a significant problem in countries like Mexico, where San Luis Potosi is among the regions registering severe levels of it. Bioremediation with microalgae capable to absorb and metabolize metals or metalloids like arsenic reduces their toxicity and is a cost-effective approach compared to physical-chemical processes. We evaluated the capability of Chlamydomonas reinhardtii to remove arsenate and compared it with an acr3-modified recombinant strain, which we produced by transforming the wild-type strain with Agrobacterium tumefaciens using the construct pARR1 including a synthetic, optimized acr3 gene from Pteris vittata, a hyper-accumulator of arsenic. We monitored the growth of both strains in media with arsenate, containing a standard or a 10-fold decreased amount of phosphate. Comparing both strains in media initially with 0.5, 1, and 1.5 mg/L of arsenate, the acr3-modified strain removed 1.5 to 3 times more arsenic than the wild-type strain. Moreover, the arsenic uptake rate increased 1.2 to 2.3 times when growing the acr3-modified strain in media with decreased phosphate, while the uptake rate for the wild-type strain scarcely changed under the same conditions. These results confirm the expression of the acr3 gene in C. reinhardtii and its potential application to remove arsenic.

Bovine enzootic haematuria from consumption of Pteris deflexa and Pteris plumula in northwestern Argentina.

Bovine enzootic haematuria (BEH) is caused by prolonged ingestion of toxic principles of bracken fern, essentially by Pteridium spp. In northwestern Argentina, this disease has a great economic impact ant it is attributed a chronic consumption to Pteridium arachnoideum. This paper describes two endemic areas for enzootic hematuria due to the consumption of Pteris deflexa and Pteris plumula. Two areas where P. deflexa and P. plumula are endemic, but free of Pteridium species, were devised and seven farms were visited. The disease was confirmed based on the presence of clinically affected animals. In four necropsies bleeding neoplastic lesions were observed in the mucosa of the urinary bladder. At phytochemical analysis, both ptaquiloside and pterosin B were found in P. deflexa and P. plumula. Thus, the consumption of P. deflexa and P. plumula can also cause BEH.

Actividad antimicrobiana in vitro de Pteris vittata L / In vitro antimicrobial activity of Pteris vittata L

Introducción: las hojas de Pteris vittata L (helecho) son utilizadas por la población para el tratamiento de la candidiasis y en enfermedades producidas por bacterias en la piel. Objetivo: identificar preliminarmente las familias de metabolitos secundarios presentes en las hojas de la planta y evaluar su posible actividad antimicrobiana. Métodos: se recolectaron las hojas de Pteris vittata L. El material vegetal fue lavado, desinfectado, secado y seguidamente se procedió a su pulverización. Este polvo se utilizó en la elaboración de los diferentes extractos y tintura. La tintura obtenida se concentró y se fraccionó sucesivamente con n-hexano, cloroformo y acetato de etilo. A estos extractos se les realizó el tamizaje fitoquímico, ensayos microbiológicos y cromatografía de capa fina. Resultados: las pruebas in vitro efectuadas a los extractos obtenidos a partir de la tintura 20 por ciento, demostraron que éstos presentan actividad antimicrobiana frente a Escherichia coli, Staphylococcus aureus, destacándose los resultados obtenidos frente a Candida sp para los extractos de acetato de etilo y clorofórmico. En estas fracciones están presentes en mayor proporción alcaloides y quinonas, que podrían ser los responsables de esta actividad, lo cual se corrobora con la identificación de estos metabolitos secundarios mediante la cromatografía de capa fina y el tamizaje fitoquímico realizado. Conclusiones: el estudio combinado mediante la cromatografía de capa fina y el tamizaje fitoquímico de los extractos hexánico, acetato de etilo y clorofórmico permite inferir que la actividad antimicrobiana puede deberse a la presencia de quinonas y alcaloides(AU)

Introduction: Pteris vittata L. leaves (fern) are used by people on the candidiasis treatment and some skin illnesses caused by bacteria. Objective: to identify preliminarily the secondary metabolites present in the leaves of the plant and to evaluate their possible antimicrobial activity. Methods: Pteris vittata L. leaves were collected. The plant material was washed, disinfected, dried and pulverized. The powder obtained was used to make the various extracts and the tincture. The latter was concentrated and successively fractionated with n-hexane, chloroform, and ethyl acetate. The extracts underwent phytochemical screening, microbiological assays and thin-layer chromatography. Results: in vitro tests performed in the obtained extracts from the 20 percent tincture proved that they have antimicrobial activity against Escherichia coli and Staphylococcus aureus, emphasizing the accomplished results against Candida of the ethyl and chloroform acetate extracts. Alkaloids and quinones, which are found in large proportion in the extracts, would be responsible of the above- mentioned antibacterial activity. This was corroborated by the identification of these secondary metabolites through thin-layer chromatography and phytochemical screening. Conclusions: the combined study through thin-layer chromatography and phytochemical screening of the ethyl and chloroform acetate extracts showed that the antimicrobial activity could be possible due to the alkaloids and quinones presence(AU)

Predicting arsenic bioavailability to hyperaccumulator Pteris vittata in arsenic-contaminated soils.

Using chemical extraction to evaluate plant arsenic availability in contaminated soils is important to estimate the time frame for site cleanup during phytoremediation. It is also of great value to assess As mobility in soil and its risk in environmental contamination. In this study, four conventional chemical extraction methods (water, ammonium sulfate, ammonium phosphate, and Mehlich III) and a new root-exudate based method were used to evaluate As extractability and to correlate it with As accumulation in P. vittata growing in five As-contaminated soils under greenhouse condition. The relationship between different soil properties, and As extractability and plant As accumulation was also investigated. Arsenic extractability was 4.6%, 7.0%, 18%, 21%, and 46% for water, ammonium sulfate, organic acids, ammonium phosphate, and Mehlich III, respectively. Root exudate (organic acids) solution was suitable for assessing As bioavailability (81%) in the soils while Mehlich III (31%) overestimated the amount of As taken up by plants. Soil organic matter, P and Mg concentrations were positively correlated to plant As accumulation whereas Ca concentration was negatively correlated. Further investigation is needed on the effect of Ca and Mg on As uptake by P. vittata. Moreover, additional As contaminated soils with different properties should be tested.

Mycorrhizal association in gametophytes and sporophytes of the fern Pteris vittata (Pteridaceae) with Glomus intraradices

Ferns, which are usually colonizing different environments and their roots frequently present mycorrhization, have two adult stages in their life cycle, the sporophytic and the gametophytic phase. This paper describes the experimental mycorrhizal association between Pteris vittata leptosporangiate fern and a strain of Glomus intraradices during the life cycle of the fern, from spore germination to the development of a mature sporophyte. The aim of this study was to compare the colonization pattern of in vitro cultures of G. intraradices along the fern life cycle with those found in nature. For this, mature spores were obtained from fertile P. vittata fronds growing in walls of Buenos Aires city, Argentina. Roots were stained and observed under the light microscope for arbuscular mycorrhizal colonization. Approximately, 75 fern spores were cultured in each pot filled with a sterile substrate and G. intraradices (BAFC N° 51.331) as inoculum on the surface. After germination took place, samples were taken every 15 days until the fern cycle was completed. In order to determine colonization dynamics each sample was observed under optical and confocal microscope after staining. Gametophyte was classified as Adiantum type. Male and female gametangia were limited to the lower face, mycorrhizal colonization started when they were differentiated and took place through the rhizoids. Spores and vesicles were not found in this cycle stage. Paris-type mycorrhizal colonization was established in the midrib and in the embrionary foot. It was colonized by external mycelium. When the first root was developed soil inoculum colonized de novo this structure and Arum-type colonization was observed. This study proves that the type of colonization is determined by the structure of the host, not by the fungus. Both the gametophyte and embryo foot have determined growth and Paris-type colonization, while, sporophyte roots have undetermined growth and Arum-type colonization. The structures found in vitro cultures were highly similar to those found under natural conditions. Rev. Biol. Trop. 60 (2): 857-865. Epub 2012 June 01.

Los helechos presentan dos etapas en su ciclo de vida, una fase esporofítica y una gametofítica. Estos por lo general pueden colonizar diferentes ambientes y frecuentemente presentan raíces micorrizadas. Este estudio describe la asociación experimental entre Pteris vittata, un helecho leptosporangiado y una cepa de Glomus intraradices durante el ciclo de vida del helecho, desde la germinación de las esporas hasta el desarrollo del esporofito maduro. El objetivo de este estudio fue comparar los patrones de colonización de G. intraradices a lo largo de todo el ciclo de vida del helecho con los tipos encontrados en la naturaleza. Las esporas maduras fueron obtenidas de frondes fértiles de P. vittata que crecen sobre las paredes de la ciudad de Buenos Aires, Argentina. Las raíces se tiñeron y fueron observadas bajo microscopio óptico para el estudio de la colonización micorrízica. Aproximadamente 75 esporas de helecho se cultivaron en macetas con un sustrato estéril y con un inóculo de G. intraradices (N° 51.331 BAFC) en la superficie. Después de la germinación, se tomaron muestras cada 15 días hasta que se completó el ciclo de vida del helecho. Con el fin de determinar la dinámica de la colonización, cada muestra se observó con el microscopio óptico y el microscopio de confocal luego de la tinción correspondiente. El gametofito fue clasificado como del tipo “Adiantum”. Los gametangios femeninos y masculinos se desarrollaron en la cara inferior del mismo. La micorrización comenzó cuando los gametangios estaban ya diferenciados y la colonización se produjo a través de los rizoides. Las esporas y las vesículas no se encontraron en esta fase del ciclo. La micorrizacion tipo Paris se observó sobre la línea de la nervadura central. El pie del esporofito fue colonizado por el micelio externo. Cuando la raíz se desarrolló, se colonizó “de novo”, y se observó una colonización de tipo Arum. Este estudio demuestra que el tipo de colonización está determinado por la estructura del helecho y no por el hongo. Tanto el gametofito como el pie del embrión tienen crecimiento definido y colonización tipo Paris, mientras que las raíces del esporofito presentan un crecimiento indeterminado y una colonización tipo Arum. Las estructuras que se encontraron bajo cultivo coinciden con las que se encontraron en condiciones naturales.

Mycorrhizal association in gametophytes and sporophytes of the fern Pteris vittata (Pteridaceae) with Glomus intraradices.

A Ferns, which are usually colonizing different environments and their roots frequently present mycorrhization, have two adult stages in their life cycle, the sporophytic and the gametophytic phase. This paper describes the experimental mycorrhizal association between Pteris vittata leptosporangiate fern and a strain of Glomus intraradices during the life cycle of the fern, from spore germination to the development of a mature sporophyte. The aim of this study was to compare the colonization pattern of in vitro cultures of G. intraradices along the fern life cycle with those found in nature. For this, mature spores were obtained from fertile P. vittata fronds growing in walls of Buenos Aires city, Argentina. Roots were stained and observed under the light microscope for arbuscular mycorrhizal colonization. Approximately, 75 fern spores were cultured in each pot filled with a sterile substrate and G. intraradices (BAFC No 51.331) as inoculum on the surface. After germination took place, samples were taken every 15 days until the fern cycle was completed. In order to determine colonization dynamics each sample was observed under optical and confocal microscope after staining. Gametophyte was classified as Adiantum type. Male and female gametangia were limited to the lower face, mycorrhizal colonization started when they were differentiated and took place through the rhizoids. Spores and vesicles were not found in this cycle stage. Paris-type mycorrhizal colonization was established in the midrib and in the embrionary foot. It was colonized by external mycelium. When the first root was developed soil inoculum colonized de novo this structure and Arum-type colonization was observed. This study proves that the type of colonization is determined by the structure of the host, not by the fungus. Both the gametophyte and embryo foot have determined growth and Paris-type colonization, while, sporophyte roots have undetermined growth and Arum-type colonization. The structures found in vitro cultures were highly similar to those found under natural conditions.

[Gametophytes and young sporophytes of four species of the fern genus Pteris (Pteridaceae) naturalized in the American continent]. / Gametófitos y esporófitos jóvenes de cuatro especies de helechos del género Pteris (Pteridaceae) naturalizadas en América.

The pantropical fern genus Pteris L. has about 250 species of which 60 occur in the American continent. We studied the morphogenesis of the gametophyte, and the morphology of the young sporophytes of four species: P. cretica, P. ensiformis, P. multifida and P. vittata, together with a palynological analysis that includes the ability of spores to germinate. Gametophytes were obtained trough in vitro culture techniques with agar-gellified Knudson medium. Young sporophytes were placed in earth-sand (3:1) sterile substrate. We used light and SEM microscopy. Triletes spores predominate, but monolete, tetralete, and other types of apertura are often found. The viability of spores is not affected by the variation, so the term spore polymorphism is applied to the condition occurring among these species. Spore polymorphism is similar in P. cretica and P. multifida. Germination occurs following the Vittaria type, 3-7 days after the sowing. Filamentous, 3-5 celled gametophytes were found in P. cretica, P. multifida and P. vittata, and 7-9 celled in P. ensiformis. Development of gametophytes takes place following Adiantum type and Ceratopteris type. The symmetry of the laminae differ in gametophytes, those of P. ensiformis and P. multifida are similar and differ from the other two species, P. cretica and P. vittata. Gametophytes of P. ensiformis, P. multifida and P. vittata are bisexual and protandric, while male gametophytes were found in P. cretica. Antheridia correspond to the common leptosporangiate type; they are cylindric in P. vittata and ovoid in the other three species. Archegonia necks have 4 rows of 4 cells each. The sporophytes complete their development 3 months after sowing, and have indument close to the adult plants. P. cretica shows obligated apogamy.

Gametófitos y esporófitos jóvenes de cuatro especies de helechos del género Pteris (Pteridaceae) naturalizadas en América

Gametophytes and young sporophytes of four species of the fern genus Pteris (Pteridaceae) naturalized in the American continent. The pantropical fern genus Pteris L. has about 250 species of which 60 occur in the American continent. We studied the morphogenesis of the gametophyte, and the morphology of the young sporophytes of four species: P. cretica, P. ensiformis, P. multifida and P.vittata, together with a palynological analysis that includes the ability of spores to germinate. Gametophytes were obtained trough in vitro culture techniques with agar-gellified Knudson medium. Young sporophytes were placed in earth-sand (3:1) sterile substrate. We used light and SEM microscopy. Triletes spores predominate, but monolete, tetralete, and other types of apertura are often found. The viability of spores is not affected by the variation, so the term spore polymorphism is applied to the condition occurring among these species. Spore polymorphism is similar in P. cretica and P. multifida. Germination occurs following the Vittaria type, 3-7 days after the sowing. Filamentous, 3-5 celled gametophytes were found in P. cretica, P. multifida and P. vittata, and 7-9 celled in P. ensiformis. Development of gametophytes takes place following Adiantum type and eratopteris type. The symmetry of the laminae differ in gametophytes, those of P. ensiformis and P. multifida are similar and differ from the other two species, P. cretica and P. vittata. Gametophytes of P. ensiformis, P. multifida and P. vittata are bisexual and protandric, while male gametophytes were found in P. cretica. Antheridia correspond to the common leptosporangiate type; they are cylindric in P. vittata and ovoid in the other three species. Archegonia necks have 4 rows of 4 cells each. The sporophytes complete their development 3 months after sowing, and have indument close to the adult plants. P. cretica shows obligated apogamy. Rev. Biol. Trop. 58 (1): 89-102. Epub 2010 March 01.

El género pantropical Pteris L. tiene 250 especies de la cuales 60 están en el continente Americano. Se estudió la morfogénesis de los gametófitos, y la morfología de los esporófitos jóvenes de cuatro especies: P. cretica, P. ensiformis, P. multifida y P.vittata, junto con un análisis palinológico que incluye la capacidad de las esporas de germinar. Los gametófitos se obtuvieron mediante técnicas de cultivo in vitro. Los esporófitos jóvenes se trasladaron a sustrato estéril de tierra y arena (3:1). Se usó el microscopio de luz y el de barrido (SEM). Se encontraron esporas con diferentes tipos de aperturas. La germinación ocurre entre 3-7 días y corresponde al tipo Vittaria. Se encontraron gametófitos filamentosos formados por 3-5 células en P. cretica, P. multifida y P. vittata y por 7-9 células en P. ensiformis. El desarrollo gametofítico ocurre de dos formas: tipo Adiantum y tipo Ceratopteris. Los gametófitos de P. ensiformis, P. multifida y P. vittata son monoicos y protándricos. P. cretica desarrolla gametófitos anteridiados. Los anteridios corresponden al tipo común de los helechos leptosporangiados, son cilíndricos en P. vittata y ovoides en las otras tres especies. Los cuellos de los arquegonios tienen 4 hileras con 4 células cada una. Los esporófitos se desarrollan después de los 3 meses de su siembra y su indumento es semejante a las plantas adultas. P. cretica presenta apogamia obligada.

Rhizosphere characteristics of two arsenic hyperaccumulating Pteris ferns.

Better understanding of the processes controlling arsenic bioavailability in the rhizosphere is important to enhance plant arsenic accumulation by hyperaccumulators. This greenhouse experiment was conducted to evaluate the chemical characteristics of the rhizosphere of two arsenic hyperaccumulators Pterisvittata and Pterisbiaurita. They were grown for 8 weeks in rhizopots containing arsenic-contaminated soils (153 and 266 mg kg(-1) arsenic). Bulk and rhizosphere soil samples were analyzed for water-soluble As (WS-As) and P (WS-P), pH, and dissolved organic carbon (DOC). Comparing the two plants, P.vittata was more tolerant to arsenic and more efficient in arsenic accumulation than P.biaurita, with the highest frond arsenic being 3222 and 2397 mg kg(-1). Arsenic-induced root exudates reduced soil pH (by 0.74-0.92 units) and increased DOC concentrations (2-3 times) in the rhizosphere, resulting in higher WS-P (2.6-3.8 times higher) compared to the bulk soil. Where there was no difference in WS-As between the rhizosphere and bulk soil in soil-153 for both plants, WS-As in the rhizosphere was 20-40% higher than those in bulk soil in soil-266, indicating that the rate of As-solubilization was more rapid than that of plant uptake. The ability to solubilize arsenic via root exudation in the rhizosphere and the ability to accumulate more P under arsenic stress may have contributed to the efficiency of hyperaccumulator plants in arsenic accumulation.

Acid invertase localization in leaves of the fern Pteris deflexa link.

The localization of invertase, a key enzyme in plant carbohydrate metabolism, has been established in several higher plants, but there are no reports of it in ferns. The aim of the present work was to establish the localization of the previously reported acid invertase activity of Pteris deflexa in fronds tissues and to compare the findings with invertase localization in higher plants. Acid invertase, localized by immuno-histochemical and histochemical techniques on fresh tissues, was evident in vascular tissue, mainly in phloem. It was also detected in parenchymatic, sclerenchymatic and epidermic cells of petiole, rachis and rachis branches as well as in veins of leaf blades. Our results demonstrate that P. deflexa acid invertase localization is the same to that of higher plants. Hence, potential roles of the fern enzyme in relation to the storage and utilization of sucrose and to control carbon flux could be the same of those proposed to higher plants.

Timing of phosphate application affects arsenic phytoextraction by Pteris vittata L. of different ages.

The effects of timing in phosphate application on plant growth and arsenic removal by arsenic hyperaccumulator Pteris vittata L. of different ages were evaluated. The hydroponic experiment consisted of three plant ages (A45d, A90d and A180d) and three P feeding regimens (P200+0, P134+66 and P66+134) growing for 45 d in 0.2-strength Hoagland-Arnon solution containing 145 microg L(-1) As. While all plants received 200 microM P, P was added in two phases: during acclimation and after arsenic exposure. High initial P-supply (P200+0) favored frond biomass production and plant P uptake, while split-P application (P134+66 and P66+134) favored plant root production. Single P addition favored arsenic accumulation in the roots while split-P addition increased frond arsenic accumulation. Young ferns (A45d) in treatment P134+66 were the most efficient in arsenic removal, reducing arsenic concentration to below 10 microg L(-1) in 35 d. The results indicated that the use of young ferns, coupled with feeding of low initial P or split-P application, increased the efficiency of arsenic removal by P. vittata.

Phytoextraction by arsenic hyperaccumulator Pteris vittata L. from six arsenic-contaminated soils: Repeated harvests and arsenic redistribution.

This greenhouse experiment evaluated arsenic removal by Pteris vittata and its effects on arsenic redistribution in soils. P. vittata grew in six arsenic-contaminated soils and its fronds were harvested and analyzed for arsenic in October, 2003, April, 2004, and October, 2004. The soil arsenic was separated into five fractions via sequential extraction. The ferns grew well and took up arsenic from all soils. Fern biomass ranged from 24.8 to 33.5 g plant(-1) after 4 months of growth but was reduced in the subsequent harvests. The frond arsenic concentrations ranged from 66 to 6,151 mg kg(-1), 110 to 3,056 mg kg(-1), and 162 to 2,139 mg kg(-1) from the first, second and third harvest, respectively. P. vittata reduced soil arsenic by 6.4-13% after three harvests. Arsenic in the soils was primarily associated with amorphous hydrous oxides (40-59%), which contributed the most to arsenic taken up by P. vittata (45-72%). It is possible to use P. vittata to remediate arsenic-contaminated soils by repeatedly harvesting its fronds.

Una especie nueva de helecho del género Pteris (Pteridaceae) endémica de Costa Rica / A new species of fern of the genus Pteris (Filicales: Pteridaceae) endemic to Costa Rica

The new fern species Pteris herrerae A. Rojas & M. Palacios, endemic to Costa Rica, is described. It differs from P. decurrens C. Presl in basal segments reduced to 1/5-1/2 of the next segment (vs. 2/3-3/4), basal pinnae not bifurcated (vs. bifurcated), pinnae apex mucronate (vs. acuminate) and segment apex undulate (vs. dentate). It differs from Pteris consanguinea in the elliptic pinnae (vs. oblong), two segments reduced on the base (vs. lack), segments entire to undulate (vs. dentate), basal pinnae without basiscopic lobes (vs. with basiscopic lobes) and segment apex entire to undulate (vs. dentate).

Se describe Pteris herrerae A. Rojas & M. Palacios, endémica de Costa Rica. Esta es diferente de P. decurrens C. Presl por segmentos basales reducidos a 1/5-1/2 del tamaño de los siguientes (vs. 2/3-3/4), pinnas basales no bifurcadas (vs. bifurcadas), ápice de las pinnas mucronado (vs. acuminado) y ápice de los segmentos ondulado (vs. dentado). También es diferente de Pteris consanguinea Mett. ex Kuhn por pinnas deltado-lanceoladas (vs. oblongas), con un par de segmentos reducidos en la base (vs. sin ellos), pinnas basales sin lóbulos basicópicos alargados (vs. con lóbulos basiscópicos) y segmentos enteros a ondulados (vs. dentados).

[A new species of fern of the genus Pteris (Filicales: Pteridaceae) endemic to Costa Rica]. / Una especie nueva de helecho del género Pteris (Pteridaceae) endémica de Costa Rica.

The new fern species Pteris herrerae A. Rojas & M. Palacios, endemic to Costa Rica, is described. It differs from P. decurrens C. Presl in basal segments reduced to 1/5-1/2 of the next segment (vs. 2/3-3/4), basal pinnae not bifurcated (vs. bifurcated), pinnae apex mucronate (vs. acuminate) and segment apex undulate (vs. dentate). It differs from Pteris consanguinea in the elliptic pinnae (vs. oblong), two segments reduced on the base (vs. lack), segments entire to undulate (vs. dentate), basal pinnae without basiscopic lobes (vs. with basiscopic lobes) and segment apex entire to undulate (vs. dentate).

Proteinaceous inhibitor versus fructose as modulators of Pteris deflexa invertase activity.

An acid invertase from the fern Pteris deflexa Link was purified and the effect of reaction products on enzyme activity was studied. Fructose and glucose were competitive and non-competitive inhibitors of the enzyme, respectively. Since proteins suppressed glucose and fructose inhibition of the enzyme, an invertase modulation by reaction products is unlikely; nevertheless, an invertase proteinaceous inhibitor previously reported could have a role in this respect. The purified enzyme was an heterodimer Mr 90,000 Daltons composed of subunits of 66,000 and 30,000 Daltons. The enzyme had beta-fructofuranosidase activity and hydrolyzed mainly sucrose but also raffinose and stachyose, with Km of 3.22, 10.80 and 38.50 mM, respectively. Invertase activity with an optimum pH at 5.0 was present in almost every leaf fern tissue. Pinnas (sporophyll leaflets) had the higher enzyme levels. Invertase histochemical and immunochemical localization studies showed the enzyme mainly in phloem cells. Epidermis, collenchyma and parenchyma cells also showed invertase protein.

An invertase inhibitory protein from Pteris deflexa link fronds.

Plant invertases play important roles in sucrose metabolism. Cell wall invertase was reported to participate in phloem loading and unloading. Soluble invertases would be involved in hexose level regulation in mature tissues and in stored sucrose utilization within vacuoles. Invertase inhibitory proteins were described as one of the possible mechanisms for invertase activity regulation in some plant species; nevertheless, these proteins were found only in sink tissues, suggesting that this mechanism would not be relevant in the sucrose turnover of leaves. This report describes the purification of invertase from Pteris deflexa fronds and the occurrence of an invertase inhibitory protein in this fern organ, as well as its purification and invertase-inhibitor interactions. The Mr of the invertase and of its inhibitory protein were 90,000 and 18,000, respectively. SDS-PAGE in the presence of 2-mercaptoetanol gave two subunits for the enzyme (Mr=66,000 and 30,000) and only one for the inhibitor. The inhibitor protein is a glycoprotein (12% w/w of neutral sugars) that did not show agglutinating activity like some others, and also showed a high heat stability at pH 5.0. The optimum pH of invertase activity is 5.0, while invertase inhibitory protein caused maximal inhibition at the same pH value. Invertase-inhibitor complex formation occurs in an immediate manner and a protease activity was discarded. The inhibition is non-competitive (Ki=1.5 x 10(-6) M) without interactions among the binding sites. The complex is slightly dissociable and sucrose was able to partially reduce the inhibitory effect. Up to the present, invertase inhibitory proteins have been found solely in heterotrophic tissues. In this work we demonstrate that this protein is also present in an autotrophic tissue of a lower vascular plant.