Browsing by Author "Reyes-Diaz, Marjorie"

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    Biochemical and molecular changes in response to aluminium-stress in highbush blueberry (Vaccinium corymbosum L.)
    (2011) Inostroza-Blancheteau, Claudio; Reyes-Diaz, Marjorie; Aquea, Felipe; Nunes-Nesi, Adriano; Alberdi, Miren; Arce-Johnson, Patricio
    Aluminium (Al) stress is an important factor limiting crop yields in acid soils. Despite this, very little is known about the mechanisms of resistance to this stress in woody plants. To understand the mechanisms of Al-toxicity and response in blueberries, we compared the impact of AI-stress in Al-resistant and AI-sensitive genotypes using Vaccinium corymbosum L. (Ericaceae) as a plant model. We investigated the effect of Al-stress on the physiological performance, oxidative metabolism and expression of genes that encode antioxidant enzymes in two V. corymbosum cultivars maintained hydroponically with AlCl3 (0 and 100 mu M). Microscopic analyses of AI-treated root tips suggested a higher degree of Al-induced morphological injury in Bluegold (sensitive genotype) compared to Brigitta (resistant genotype). Furthermore, the results indicated that Brigitta had a greater ability to control oxidative stress under Al-toxicity, as reflected by enhancement of several antioxidative and physiological properties (radical scavenging activity: RSA, superoxide dismutase: SOD and catalase: CAT; maximum quantum yield: Fv/Fm, effective quantum yield: 04)511, electron transport rate: ETR and non-photochemical quenching: NPQ). Finally, we analyzed the expression of genes homologous to GST and ALDH, which were identified in a global expression analysis. In the resistant genotype, the expression of these genes in response to Al-stress was greater in leaves than in roots. (C) 2011 Elsevier Masson SAS. All rights reserved.
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    RESISTANCE MECHANISMS OF ALUMINUM (Al3+) PHYTOTOXICITY IN CEREALS: PHYSIOLOGICAL, GENETIC AND MOLECULAR BASES
    (2008) Inostroza-Blancheteau, Claudio; Soto, Braulio; Ulloa, Pilar; Aquea, Felipe; Reyes-Diaz, Marjorie
    Aluminum (Al) toxicity is one of the main factors limiting crop productivity in acid soils around the world. In cereals, this problem can affect between 30 and 40% of crop yields. One way to reduce the toxic effect of Al is to neutralize the acidity with calcareous amendments. However, this practice is demanding and not very effective. An alternative is the search for genetic variability in the genome of cropping grasses and/or their wild relatives to resist Al. The development of biotechnology and molecular genetics approach has facilitated the understanding of the physiological, genetic and molecular bases in the process of ameliorating these species. This review presents the main physiological mechanisms of Al resistance and the genetic and molecular bases that explain the degree of resistance between different cereals species.
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    Vegetation drives the response of the active fraction of the rhizosphere microbial communities to soil warming in Antarctic vascular plants
    (2022) Parada-Pozo, Genesis; Bravo, Leon A.; Saez, Patricia L.; Cavieres, Lohengrin A.; Reyes-Diaz, Marjorie; Abades, Sebastian; Alfaro, Fernando D.; De la Iglesia, Rodrigo; Trefault, Nicole
    In the Antarctic Peninsula, increases in mean annual temperature are associated with the coverage and population density of the two Antarctic vascular plant species-Deschampsia antarctica and Colobanthus quitensis-potentially modifying critical soil processes. In this study, we characterized the diversity and community composition of active microorganisms inhabiting the vascular plant rhizosphere in two sites with contrasting vegetation cover in King George Island, Western Antarctic Peninsula. We assessed the interplay between soil physicochemical properties and microbial diversity and composition, evaluating the effect of an in situ experimental warming on the microbial communities of the rhizosphere from D. antarctica and C. quitensis. Bacteria and Eukarya showed different responses to warming in both sites, and the effect was more noticeable in microbial eukaryotes from the low vegetation site. Furthermore, important changes were found in the relative abundance of Tepidisphaerales (Bacteria) and Ciliophora (Eukarya) between warming and control treatments. Our results showed that rhizosphere eukaryal communities are more sensitive to in situ warming than bacterial communities. Overall, our results indicate that vegetation drives the response of the active fraction of the microbial communities from the rhizosphere of Antarctic vascular plants to soil warming.