Browsing by Author "Martínez Barradas, Vera Isabel"

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    Autopolyploidization and  in vitro regeneration of three blueberry cultivars from leaves and microstems
    (2024) Jarpa Tauler, Gabriela Teresa; Martínez Barradas, Vera Isabel; Romero Romero, Jesús 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 analysed 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 the MYB60 Gene of Phaseolus vulgaris and its Role in Regulating Stomatal Aperture
    (2024) Martínez Barradas, Vera Isabel; Arce Johnson, Jorge Patricio; Pontificia Universidad Católica de Chile. Facultad de Ciencias Biológicas; Pontificia Universidad Católica de Chile. Facultad de Agronomía e Ingeniería Forestal
    In this thesis the Phaseolus vulgaris MYB60 gene was characterized, and it is pointed as a promising candidate to improve its tolerance to drought stress. The specific objectives were: Characterize the ‘Zorzal’ cultivar physiological and yield response to drought stress in greenhouse. Identify, clone, and characterize the MYB60 gene of Phaseolus vulgaris orthologous to Arabidopsis thaliana including its coding region and promoter. Establish an in vitro regeneration protocol for the “Zorzal” common bean cultivar and design gRNAs that can be furtherly used for its edition. Zorzal presented physiological traits associated with drought tolerance. However, these traits are insufficient to maintain a stable yield under severe drought stress at the pre-flowering stage.Phaseolus vulgaris has a PvMYB60 ortholog gene to the MYB60 of Arabidopsis thaliana, with stomata-specific expression that is involved in promoting stomatal aperture.An in vitro regeneration method was developed that allows successful fertile plant regeneration of ‘Zorzal’ common bean by direct organogenesis from embryonic axis and embryonic apical meristem explants, with regeneration rates of 58.3 and 21.1% respectively, that together with the designed gRNAs provide a potential tool for genetic manipulation of Zorzal cultivar and common bean in general.
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    PvMYB60 gene, a candidate for drought tolerance improvement in common bean in a climate change context
    (2024) Martínez Barradas, Vera Isabel; Galbiati, Massimo; Barco Rubio, Francisco Antonio; Paolo, Dario; Espinoza, Carmen; Cominelli, Eleonora; Arce Johnson, Patricio
    Background: Common bean (Phaseolus vulgaris) is one of the main nutritional resources in the world, and a low environmental impact source of protein. However, the majority of its cultivation areas are affected by drought and this scenario is only expected to worsen with climate change. Stomatal closure is one of the most important plant responses to drought and the MYB60 transcription factor is among the key elements regulating stomatal aperture. If targeting and mutating the MYB60 gene of common bean would be a valuable strategy to establish more drought-tolerant beans was therefore investigated. Results: The MYB60 gene of common bean, with orthology to the Arabidopsis AtMYB60 gene, was found to have conserved regions with MYB60 typical motifs and architecture. Stomata-specific expression of PvMYB60 was further confirmed by q-RT PCR on organs containing stomata, and stomata-enriched leaf fractions. Further, function of PvMYB60 in promoting stomata aperture was confirmed by complementing the defective phenotype of a previously described Arabidopsis myb60-1 mutant. Conclusions: Our study finally points PvMYB60 as a potential target for obtaining more drought-tolerant common beans in the present context of climate change which would further greatly contribute to food security particularly in drought-prone countries.