Lizbeth A. Castro-Concha

Centro de Investigación Científica de Yucatán, Ciudad de Mérida, Yucatán, Mexico

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Publications (11)14.52 Total impact

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    ABSTRACT: In chili pepper’s pods, placental tissue is responsible for the synthesis of capsaicinoids (CAPs), the compounds behind their typical hot flavor or pungency, which are synthesized from phenylalanine and branched amino acids. Placental tissue sections from Habanero peppers (Capsicum chinense Jacq.) were immobilized in a calcium alginate matrix and cultured in vitro, either continuously for 28 days or during two 14-day subculture periods. Immobilized placental tissue remained viable and metabolically active for up to 21 days, indicating its ability to interact with media components. CAPs contents abruptly decreased during the first 7 days in culture, probably due to structural damage to the placenta as revealed by scanning electron microcopy. CAPs levels remained low throughout the entire culture period, even though a slight recovery was noted in subcultured placentas. However, doubling the medium’s nitrate content (from 40 to 80 mM) resulted in an important increment, reaching values similar to those of intact pod’s placentas. These data suggest that isolated pepper placentas cultured in vitro remain metabolically active and are capable of metabolizing inorganic nitrogen sources, first into amino acids and, then, channeling them to CAP synthesis.
    01/2015; 2015:1-6. DOI:10.1155/2015/794084
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    ABSTRACT: In the past few years, there has been a renewed interest in studying a wide variety of food products that show beneficial effects on human health. Capsicum is an important agricultural crop, not only because its economic importance, but also for the nutritional values of its pods, mainly due to the fact that they are an excellent source of antioxidant compounds, and also of specific constituents such as the pungent capsaicinoids localized in the placental tissue. This current study was designed to evaluate the antioxidant capacity and total phenolic contents from fruits tissues of two Capsicum chinense accessions, namely, Chak k'an-iik (orange) and MR8H (red), at contrasting maturation stages. Results showed that red immature placental tissue, with a Trolox equivalent antioxidant capacity (TEAC) value of 55.59 μ mols TE g(-1) FW, exhibited the strongest total antioxidant capacity using both the 2,2-diphenyl-1-picrylhydrazyl (DPPH) and the CUPRAC methods. Placental tissue also had the highest total phenolic content (27 g GAE 100 g(-1) FW). The antioxidant capacity of Capsicum was directly related to the total amount of phenolic compounds detected. In particular, placentas had high levels of capsaicinoids, which might be the principal responsible for their strong antioxidant activities.
    The Scientific World Journal 02/2014; 2014:809073. DOI:10.1155/2014/809073 · 1.73 Impact Factor
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    ABSTRACT: The activities of primary ammonia assimilation enzymes were analyzed in isolated placentas of habanero peppers (Capsicum chinense Jacq.). The placentas were cultured in vitro and exposed to conditions promoting capsaicinoid accumulation, such as treatments with salicylic acid (SA) and methyl jasmonate (MeJa). Although exposure to both inducers resulted in increased accumulation of capsaicinoids, the induction by SA was more pronounced. Glutamine synthetase (GS) activity, which incorporates ammonia into glutamine, increased more than six fold under such conditions, suggesting GS participation in fulfilling the demand for amino acids required to support the increase in capsaicinoid synthesis. Glutamate dehydrogenase (GDH), which has been involved in nitrogen assimilation in non-photosynthetic tissues such as placentas, was apparently not involved; its activity decreased in tissues exposed to the inducers. Thus, under the conditions tested, the activation of secondary metabolism required activation of basal nitrogen metabolism.
    Plant Cell Tissue and Organ Culture 06/2013; 113(3). DOI:10.1007/s11240-012-0282-y · 2.61 Impact Factor
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    ABSTRACT: Three accessions of habanero pepper (Capsicum chínense Jacq.), differing in the color of the fruits throughout the maturation process, were analyzed for antioxidants, namely carotenoids, ascorbate and glutathione. The mature fruits from the three accessions contained high levels of the above mentioned antioxidants. Accession MR8H presented the highest content of red carotenoids, while in SBN01, the ascorbate level was the maximal found regardless of the maturation stage.
    Journal of the Mexican Chemical Society 03/2012; 56(1):15-18. · 0.55 Impact Factor
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    ABSTRACT: An overview of the methods for assessing cell viability is presented. Different protocols of the most commonly used assays are described in detail so that the readers may be able to determine which assay is suitable for their own projects in plant biotechnology.
    Methods in molecular biology (Clifton, N.J.) 01/2012; 877:49-56. DOI:10.1007/978-1-61779-818-4_5 · 1.29 Impact Factor
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    ABSTRACT: The effects of nitrate (NO₃⁻) on the root system are complex and depend on several factors, such as the concentration available to the plant, endogenous nitrogen status and the sensitivity of the species. Though these effects have been widely documented on Arabidopsis and cereals, no reports are available in the Capsicum genus. In this paper, we have determined the effect of an exogenous in vitro application of this nutrient on root growth in habanero pepper (Capsicum chinense Jacq.). Exposure to NO₃⁻ inhibited primary root growth in both, dose- and time-dependent manners. The highest inhibition was attained with 0.1 mM NO₃⁻ between the fourth and fifth days of treatment. Inhibition of primary root growth was observed by exposing the root to both homogeneous and heterogeneous conditions of the nutrient; in contrast, ammonium was not able to induce similar changes. NO₃⁻-induced inhibition of primary root growth was reversed by treating the roots with IAA or NPA, a polar auxin transport inhibitor. Heterogeneous NO₃⁻ application stimulated the formation and elongation of lateral roots in the segment where the nutrient was present, and this response was influenced by exogenous phytohormones. These results demonstrate that habanero pepper responds to NO₃⁻ in a similar fashion to other species with certain particular differences. Therefore, studies in this model could help to elucidate the mechanisms by which roots respond to NO₃⁻ in fluctuating soil environments.
    Plant Physiology and Biochemistry 12/2011; 49(12):1456-64. DOI:10.1016/j.plaphy.2011.09.003 · 2.35 Impact Factor
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    ABSTRACT: The accumulation of reactive oxygen species (ROS) and concomitant oxidative stress have been considered deleterious consequences of aluminum toxicity. However, several lines of evidence suggest that ROS can function as important signaling molecules in the plant defense system for protection from abiotic stress and the acquisition of tolerance. The role of ROS-scavenging enzymes was assayed in two different coffee cell suspension lines. We treated L2 (Al-sensitive) and LAMt (Al-tolerant) Coffea arabica suspension cells with 100 μM AlCl(3) and observed significant differences in catalase activity between the two cell lines. However, we did not observe any differences in superoxide dismutase or glutathione reductase activity in either cell line following Al treatment. ROS production was diminished in the LAMt cell line. Taken together, these results indicate that aluminum treatment may impair the oxidative stress response in L2 cells but not in LAMt cells. We suggest a possible role for Al-induced oxidative bursts in the signaling pathways that lead to Al resistance and protection from Al toxicity.
    Journal of inorganic biochemistry 11/2011; 105(11):1523-8. DOI:10.1016/j.jinorgbio.2011.09.031 · 3.27 Impact Factor
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    ABSTRACT: Zinniol, a non-host selective phytotoxin commonly produced by fungi of the Alternaria genus, has been reported as the metabolite responsible for the phytotoxicity of the lipophilic fraction of A. tagetica. While both the lipophilic fraction and zinniol have been shown to produce necrosis on leaves of susceptible marigold (Tagetes erecta) plants, the true role of zinniol in the infectious process remains uncertain. Using marigold cell cultures as a model, we evaluated the effects of zinniol and the lipophilic fraction at the cellular level and showed that pure zinniol is not markedly phytotoxic at concentrations known to induce necrosis in leaves of T. erecta. Moreover, the effects of zinniol on cell membranes and DNA fragmentation are less intense than those caused by the lipophilic fraction. These results suggest that zinniol may not play a significant role in the A. tagetica–T. erecta interaction and, consequently, its classification as a non-host selective phytotoxin is questionable. Keywords Alternaria tagetica -Host-selective phytotoxins-Non-host selective phytotoxins-Programmed cell death-Reactive oxygen species- Tagetes erecta
    Journal of General Plant Pathology 04/2010; 76(2):94-101. DOI:10.1007/s10327-010-0222-9 · 0.71 Impact Factor
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    ABSTRACT: Lipid peroxidation in plants is an important feature of hypersensitive cell death during incompatible or non-host interactions of plants with pathogens. Malondialdehyde is a marker of oxidative lipid injury. The 1- methyl-2-phenylindole colorimetric assay has been considered specific for the quantitation of malondialdehyde in animal systems, but its applicability to plant tissues remains unknown. In here, we report its utilization in cell cultures of Tagetes erecta L. (cempasúchil) treated with hydrogen peroxide. Our results suggest a close relationship between the extent of membrane damage that resulted from lipid peroxidation and cell viability.
    01/2010; 28(2):165-167.
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    ABSTRACT: Alternaria tagetica, a fungus that causes early blight in marigold (Tagetes erecta), produces two groups of phytotoxic metabolites: one hydrophilic and the other lipophilic that show phytotoxic activity when tested by the leaf-spot assay in T. erecta. We evaluated the cellular effects of the phytotoxic culture filtrate of A. tagetica and the hydrophilic and lipophilic fractions, then determined whether the filtrate or the fractions differentially induced pathogenesis-related mechanisms in the plant. The culture filtrate and the phytotoxic fractions had adverse effects on cell viability, fresh mass, and the number of cells, and induced ROS accumulation, lipid peroxidation and DNA damage on T. erecta cell suspension cultures, and these effects are related to pathogenic mechanisms attributed to phytotoxins. However, although exposure of marigold cells to the phytotoxic culture filtrate of A. tagetica triggered programmed cell death, the hydrophilic and the lipophilic phytotoxic fractions induced death that was more related to a toxic effect leading to necrosis. This study presents a complementary perspective in the search for the roles of metabolites, including phytotoxins, produced by phytopathogenic fungi during plant infection.
    Journal of General Plant Pathology 10/2009; 75(5):331-339. DOI:10.1007/s10327-009-0184-y · 0.71 Impact Factor
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    ABSTRACT: An overview of the methods for assessing cell viability in in vitro cultures is presented. The protocols of four of the most commonly used assays are described in detail, so the readers may be able to determine which assay is suitable for their own projects using plant cell cultures.
    Methods in Molecular Biology 02/2006; 318:71-6. · 1.29 Impact Factor