Browsing by Author "Martinez-Barradas, Vera"

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    Autopolyploidization and in vitro regeneration of three highbush blueberry (Vaccinium corymbosum L.) cultivars from leaves and microstems
    (SPRINGER, 2024) Jarpa-Tauler, Gabriela; Martinez-Barradas, Vera; Romero-Romero, Jesus Lucina; Arce-Johnson, Patricio
    Blueberries are a fruit with an increasing global demand due to their phytochemical and bioactive compounds content. They are promoted worldwide because of their health benefits. For optimal growth and productivity, blueberry crops need acidic soil pH, specific chilling hours, and an adequate atmospheric temperature. This delicate production equilibrium is under severe threat from climate change, potentially leading to reduced yields and increased cultivation costs unless new cultivars are developed for each edafoclimatic zone. Therefore, considering varietal replacements with more productive cultivars offering higher quality and better adaptability to local conditions is imperative. In this study, we employ polyploidization and in vitro tissue culture to promote variability and lay the foundation for new cultivar development. We report the successful induction of octoploids in three blueberry cultivars, namely 'Biloxi', 'Legacy', and 'Duke', through whole-genome duplication. Leaves and microstem explants were exposed to 0.1% colchicine for 24 and 48 hours in in vitro culture. After analyzing the polyploid level of 160 regenerated shoots using DNA flow cytometry, we obtained a total of 18 mutants, consisting of 8 mixoploids and 10 octoploids. The number of chloroplasts in the stomata was analyzed by fluorescence microscopy, revealing the duplication of these organelles in the induced octoploid plants. To our knowledge, this represents the first successful induction of octoploids in three blueberry cultivars -'Biloxi,' 'Legacy,' and 'Duke'- achieved by exposing leaves and microstem explants to colchicine in in vitro culture. This technique holds promise as a valuable tool for the development of improved blueberry cultivars.
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    Characterization of physiological and antioxidant responses in Run1Ren1 Vitis vinifera plants during Erysiphe necator attack
    (2022) Sosa-Zuniga, Viviana; Martinez-Barradas, Vera; Espinoza, Carmen; Tighe-Neira, Ricardo; Vidal Valenzuela, Alvaro; Inostroza-Blancheteau, Claudio; Arce-Johnson, Patricio
    Grapevine is a fruit crop of major significance worldwide. Fungal attacks are one of the most relevant factors affecting grapevine yield and fruit quality, and powdery mildew caused by Erysiphe necator is one of the most harmful fungal diseases for this fruit-bearing species. Incorporating resistance genes such as Run1 and Ren1 in new vine selections offers a sustainable alternative to control the disease. These combined loci produce an immune response that prevents the development of the disease. However, to date studies are lacking concerning whether this response generates alterations in the physiological and antioxidant parameters of resistant plants in the presence of the fungus or if it has an associated energy cost. Therefore, the main goal of our research was to determine if Run1Ren1 plants present alterations in their physiological and biochemical parameters in the presence of the fungus. To achieve this target, a previously characterized resistant Run1Ren1 genotype and the susceptible Carmenere cultivar were analyzed. We evaluated photochemical parameters (Fv'/Fm', phi PSII and ETR), net photosynthesis (Pn), photosynthetic pigments, transpiration (E), stomatal conductance (g(s)), oxidative stress parameters (MDA), antioxidant activity, and phenols. Our results show that the physiological parameters of Run1Ren1 plants were not negatively affected by the fungus at 10 days post-inoculation, contrasting with alterations observed in the susceptible plants. Therefore, we propose that the resistance response triggered by Run1Ren1 is physiologically and biochemically advantageous to grapevines by preventing the development of powdery mildew infection.
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    Drought Tolerance Evaluation of 'Zorzal,' the Most Cultivated Common Bean in Chile, a Country Facing Desertification
    (2024) Martinez-Barradas, Vera; Inostroza-Blancheteau, Claudio; Tighe-Neira, Ricardo; Romero-Romero, Jesus Lucina; Schwember, Andres R.; Arce-Johnson, Patricio
    During the last decades, water distribution around the globe has been affected by climate change. Particularly, in Chile, the last decade has been marked by a mega-drought period, which has severely impacted agriculture. In this scenario, common bean (Phaseolus vulgaris L.) has been seriously affected due to its dependence on irrigation. In this work, we studied how 'Zorzal,' the most sown cultivar in Chile copes with drought stress and the mechanisms used to deal with it. A greenhouse experiment was performed during the 2019-2020 growing season. Plants were subjected to a severe drought stress suspending irrigation at the pre-flowering stage. Photosynthetic parameters, chlorophyll concentration, relative leaf water content (RWC) and lipid peroxidation were analyzed at 7 and 21 days after water suspension, yield was analyzed at the end of the growing season, and those parameters were compared to a susceptible cultivar of the same gene pool 'Arroz Tuscola.' 'Zorzal' stood out for having diverse treats associated with drought tolerance, as maintaining stable RWC during drought stress, a better reactive oxygen species scavenging system than 'Arroz Tuscola,' and stable root biomass during the drought condition. However, seed production was significantly reduced. Our results evidence that 'Zorzal,' the most widely cultivated cultivar of common bean in Chile, has good physiological and anatomical treats for plant survivance under drought stress conditions. However, our study suggests that these characteristics may not be enough to maintain a stable seed production.