Liliana Cardemil

• University of Chile

Throughout evolution, plants have developed different strategies of responses and adaptations that allow them to survive in different conditions of abiotic stress. Aloe vera (L.) Burm.f. is a succulent CAM plant that can grow in warm, semi-arid, and arid regions. Here, we tested the effects of preconditioning treatments of water availability (100,...

Key message The study determined the tolerance of Aloe vera to high temperature, focusing on the expression of hsp70 , hsp100 and ubiquitin genes. These were highly expressed in plants acclimated at 35 °C prior to a heat shock of 45 °C. Abstract Aloe barbadensis Miller (Aloe vera), a CAM plant, was introduced into Chile in the semiarid IV and III R...

Changes in the starch and protein reserves of Araucaria araucana (Mol.) Koch embryo and megagametophyte tissue during the first 90 h after the start of imbibition have been measured by colorimetric and by chromatographic methods. The starch content (about 30%) of the embryo decreases rapidly until radicle protrusion–germination (40 h) and remains r...

Background:Aloe vera, a plant with crassulacean acid metabolism naturally adapted to water deficit, was introduced in the semi-arid regions of Chile in 1999.Aims: Our objective was to evaluate how A. vera scavenged the superoxide ion (O2 ‐), formed during oxidative stress, induced by water deficit.Methods: Total and specific activity, enzyme accumu...

We analyzed the mitigating effect of NO3 - and salicylic acid (SA) on the detrimental effects of salt stress by studying the water status of plants of maize grown in Hoagland's medium with NaCl 100 mM as the saline component, to which SA and NO3 - were added in different concentrations as mitigating agents. We evaluated water potential Ψw, osmotic...

Aloe barbadensis Miller, known as Aloe Vera, requires limited irrigation depending on the capacity of the soil to retain humidity, since it is a CAM species and thus naturally adapted to conditions of dryness and high temperatures. Therefore, we postulated that plants of Aloe Vera plants under conditions of water deficit should improve their water...

and L. Cardemil. 2010. Mitigating effect of salicylic acid and nitrate on water relations and osmotic adjustment in maize, cv. Lluteño exposed to salinity. Cien. Inv. Agr. 37(3): 71-81. We analyzed the mitigating effect of NO 3 -and salicylic acid (SA) on the detrimental effects of salt stress by studying the water status of plants of maize grown i...

The cultivation of Aloe Vera (Aloe barbadensis Miller) has achieved economic importance due to the products which are obtained from its leaves. However, there is a scarcity of information about its agronomic management and the effect of water availability for its establishment and production. The objective of this study was to evaluate the effect o...

The polysaccharides from the envelopes of heterocysts of Cylindrospermum licheniforme Kütz., and of heterocysts and spores of Anabaena variabilis Kütz., like those from the differentiated cells of Anabaena cylindrica Lemm., have a 1,3-linked backbone consisting of glucosyl and mannosyl residues in a molar ratio of approximately 3:1. As is the case...

The main aim of this research was to compare the photosynthetic responses of two species of Prosopis, Prosopis chilensis (algarrobo) and Prosopis tamarugo (tamarugo) subjected to heat and water stress, to determine how heat shock or water deficit, either individually or combined, affect the photosynthesis of these two species. The photosynthetic ra...

Four cell wall proteins of seedling cotyledons of Prosopis chilensis were characterized by SDS-polyacrylamide gel electrophoresis. The molecular masses of these proteins were 180, 126, 107 and 63 kDa. All of them immuno-crossreacted with polyclonal antibodies raised against extensin from soybean seed coats. Immuno-dot blot analysis demonstrated tha...

At temperatures between 25 and 35°C, 100% of Prosopis chilensis seeds germinated within 24 h. At higher temperatures, the germination rate was reduced; at 50°C, seeds did not germinate. After germination at 25°C, the optimal temperature for seedling growth was 35°C and the seedlings did not grow at a temperature of 50°C. However, when germination w...

The aim of this study was to evaluate the hypothesis that Deschampsiaantarctica Desv., the only grass of the Maritime Antarctic, responds to temperatures higher or lower than its optimum for photosynthesis (13°C), with the accumulation of heat shock proteins. The LT50 was determined in plants acclimated at 4°C (cold-acclimated plants) and in plants...

We determined changes in cell-wall peroxidase activities and isoform patterns in response to wounding in seedlings of Prosopis tamarugo Phil. (an endemic species of the Atacama Desert) and Prosopis chilensis (Mol.) Stuntz (a native species of central Chile), to assess tolerance to predation. In seedlings of both species, the maximal increase in per...

Starch is the principal reserve of Araucaria araucana seeds, and it is hydrolysed during germination mainly by α‐amylase. There are several α‐amylase isoenzymes whose patterns change in the embryo and in the megagametophyte from the one observed in quiescent seeds (T0) to a different one observed 90 h after imbibition (T90). The objective of this r...

Photosynthetic parameters were investigated in relation to light intensity (PAR and UV-B) in two Chilean Prosopis sp., Prosopis chilensis and Prosopis tamarugo in their natural habitats. The objective of this work was to compare the photosynthetic responses and to determine the degree of adaptation of both species to visible- and UV-radiation stres...

Relative growth rates, basal and acclimated thermotolerance, membrane damage, fluorescence emission, and relative levels of free and conjugated ubiquitin and HSP70 were compared after 2 h of treatment at different temperatures between Prosopis chilensis and Glycine max (soybean), cv. McCall, to evaluate if the thermotolerance of these two plants wa...

Relative growth rates, basal and acclimated thermotolerance, membrane damage, fluorescence emission, and relative levels of free and conjugated ubiquitin and HSP70 were compared after 2 h of treatment at different temperatures between Prosopis chilensis and Glycine max (soybean), cv. McCall, to evaluate if the thermotolerance of these two plants wa...

Peroxidase enzymes have been found in soluble, ionically bound, and covalently bound forms and have been implicated in several physiological processes in plants. This paper investigates the effect of aphid infestation on soluble and bound-cell wall peroxidase activity and bound-cell wall isoform changes of barley plants. Peroxidase activity was mea...

The purpose of this work was to investigate whether ethylene is involved in the oxidative and defensive responses of barley to the aphids Schizaphis graminum (biotype C) and Rhopalophum padi. The effect of aphid infestation on ethylene production was measured in two barley cultivars (Frontera and Aramir) that differ in their susceptibility to aphid...

Expression of α-amylase (EC 3.2.1.1) isoenzymes present in the embryos and mega-gametophytes of Araucaria araucana seedlings was studied under gibberellic acid (GA3) and abscisic acid (ABA) treatments and after 90 hr of imbibition in 20 mM of β-chloroethyltrimethylammonium (CCC), a GA3 biosynthesis inhibitor. When CCC was used, α-amylase activity i...

The diurnal courses of CO2 assimilation and stomatal conductance in spring were determined in trees of Prosopis chilensis growing in Quebrada San Carlos, Vicuña, 4th Region, Chile. These two parameters along with proline content, and the expression of free and conjugated ubiquitin and the heat shock protein (HSP) Mr 70 K were determined at the same...

We have previously reported the purification and partial characterization of two cationic peroxidases from the cell walls of seeds and seedlings of the South American conifer, Araucaria araucana. In this work, we have studied the amino acid composition and NH2-terminal sequences of both enzymes. We also compare the data obtained from these analyses...

Seven α-amylase isoenzymes present in quiescent seeds of the South American conifer Araucaria araucana were purified by affinity chromatography and partially characterized. The molecular masses of these isoenzymes were 45.7, 47.0, 50.2, 51.2, 52.0, 53.5 and 55.2 kDa. The two main isoforms were separated from each other and from the rest of the isoe...

Surface features, anatomy, and ultrastructure of the floral nectary of Eccremocarpus scaber (Bignoniaceae), pollinated predominantly by the largest-known hummingbird (Patagona gigas gigas), were studied together with nectar sugar content and secretion rate. The annular disk nectary comprises epidermis, secretory and ground parenchyma with intercell...

Surface features, anatomy, and ultrastructure of the floral nectary of Eccremocarpus scaber (Bignoniaceae), pollinated predominantly by the largest-known hummingbird (Patagona gigas gigas), were studied together with nectar sugar content and secretion rate. The annular disk nectary comprises epidermis, secretory and ground parenchyma with intercell...

Four cell wall proteins of cotyledons of Prosopis chilensis seedlings were characterized by PAGE and Western analyses using a polyclonal antibody, generated against soybean seed coat extensin. These proteins had M(r)s of 180,000, 126,000, 107,000 and 63,000, as determined by SDS-PAGE. The proteins exhibited a fluorescent positive reaction with dans...

Two major proteins present in the cell walls of the embryo and megagametophyte tissues of Araucaria araucana seeds were partially purified, characterized and identified as peroxidases. These two proteins have Mrs of 83 and 145 × 103, a pI of 10.5, an optimal pH of 5.0 and a buoyant density of 1.333 g ml−1. Kinetic studies of these peroxidases defin...

Araucaria araucana seeds and seedlings respond to wounding after 48 h with a 3- to 4-fold increase of hydroxyproline-rich glycoproteins (HRGP) in the cell walls of the embryo and with a 15-fold increase in the cell walls of the megagametophyte. The megagametophyte walls accumulate six times more hydroxyproline per μg of cell wall protein than the e...

Mutants of Anabaena sp. strain PCC 7120 unable to grow aerobically on dinitrogen were isolated by mutagenesis with UV irradiation, followed by a period of incubation in yellow light and then by penicillin enrichment. A cosmid vector, pRL25C, containing replicons functional in Escherichia coli and in Anabaena species was constructed. DNA from wild-t...

alpha-Amylase is one of the major enzymes present in the seeds of both Araucaria species of South America and it initiates starch hydrolysis during germination and early seedling growth. The pattern of the multiple forms of alpha-amylase of the two Araucaria species was investigated by electrophoresis and isoelectrofocusing of the native enzyme in...

As starch is the main seed reserve material in both species of Araucaria of South America, A. araucana and A. angustifolia, it is important to understand starch breakdown in both embryo and megagametophyte tissues of Araucaria seeds. Sugar analysis by thin layer chromatography indicates that sucrose is the main sugar produced in both tissues. Enzym...

Root tips of both Araucaria araucana (Mol.) Koch and Araucaria angustifolia (Bert.) O. Ktze. were used as sources of mitotic chromosomes. Both species have 26 chromosomes as the diploid number, consisting of 13 pairs of homologues. In both species 10 pairs of chromosomes are metacentric, and 3 pairs are submetacentric with slight differences in the...

Starch is the main reserve in Araucaria araucana (Mol.) Koch seeds. In an attempt to understand the regulation of starch mobilization during seed germination, amylase activity was characterized and its levels were measured for the first 90 h after the start of seed imbibition. Amylase is present in both the embryo and megagametophyte when seeds are...

The female gametophyte of Araucaria araucaria (Mol.) Koch consists of large haploid cells, about 180 (μm in diameter, that include many starch grains and several nuclei. Segments of megagametophyte, with and without embryonic tissue, were cultured at 25 °C in Murashige and Skoog media, supplemented with 10 mg · l-1 of NAA and 1 mg · l-1 of kinetin....

The polysaccharides from the envelopes of heterocysts of Cylindrospermum licheniforme Kutz., and of heterocysts and spores of Anabaena variabilis Kutz., like those from the differentiated cells of Anabaena cylindrica Lemm., have a 1,3-linked backbone consisting of glucosyl and mannosyl residues in a molar ratio of approximately 3:1. As is the case...

Isolated heterocysts, incubated for 1 h at 30 degrees C [14C]mannose, synthesize [14C]arabinose and [14C]glucose, and incorporate the three 14C-labeled sugars into their envelopes with glycosidic linkages characteristic of their envelope polysaccharide. In extracts of metabolic intermediates with hot 80% methanol, [14C]mannose is associated with th...

The carbohydrate portion of fraction I of the Neurospora crassa cell wall has been analyzed for sugar composition by gas-liquid chromatography and colorimetric methods. The analysis was performed comparatively in a wild-type strain (RL 3-8A) and three morphological mutants: scumbo (FGSC 49), peak-2a (a mutant known to be allelic to biscuit), and ra...

The polysaccharides from the envelopes of heterocysts and spores of Anabaena cylindrica consist of repeating units containing 1 mannosyl and 3 glucosyl residues, all linked by beta(1 yields 3) glycosidic bonds, with glycosidic bonds, with glucose, xylose, galactose, and mannose present in side branches. Degradation of the polysaccharides with speci...

The polysaccharides from the envelopes of heterocysts and spores of Anabaena cylindrica consist of repeating units containing 1 mannosyl and 3 glucosyl residues, all linked by ..beta..(1 ..-->.. 3) glucosidic bonds, with glucose, xylose, galactose, and mannose present in side branches. Degradation of the polysaccharides with specific glycosidases h...

Lindberg's combined gas chromatography-mass spectrometry techniques for the analysis of partially methylated alditol acetate sugar derivatives were used to study the structures of polysaccharides from the envelopes of heterocysts and spores of Anabaena cylindrica. Polysaccharides from both envelopes are highly branched. Glucose, mannose, galactose,...

Mutants of Anabaena PCC7120 capable of aerobic growth with NOâ⁻ but not Nâ, and capable of microaerobic reduction of CâHâ, were isolated by penicillin enrichment after UV irradiation. Heterocysts of two mutants lack the principal envelope glycolipid, those of EF116 have a non-cohesive envelope polysaccharide, and those of other strains have other...

Seeds of Prosopis chilensis, a leguminous tree from semi-arid regions of Central Chile, were germinated at temperatures of 25-30-35-40-45 and 50°C. Germination was 100% between 25 and 40°C, being faster at 35°C. The best temperature for root growth was also 35°C. There was not germination at 50°C. However, seedlings coming from seeds germinate...