Browsing by Autor "Jorge A. N. Quezada"

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A Chloroplast COR413 Protein From Physcomitrella patens Is Required for Growth Regulation Under High Light and ABA Responses
(Frontiers Media, 2020) Cecilia Ruibal; Alexandra Castro; Andrea L. Fleitas; Jorge A. N. Quezada; Gastón Quero; Sabina Vidal
COR413 genes belong to a poorly characterized group of plant-specific cold-regulated genes initially identified as part of the transcriptional activation machinery of plants during cold acclimation. They encode multispanning transmembrane proteins predicted to target the plasma membrane or the chloroplast inner membrane. Despite being ubiquitous throughout the plant kingdom, little is known about their biological function. In this study, we used reverse genetics to investigate the relevance of a predicted chloroplast localized COR413 protein (PpCOR413im) from the moss Physcomitrella patens in developmental and abiotic stress responses. Expression of PpCOR413im was strongly induced by abscisic acid (ABA) and by various environmental stimuli, including low temperature, hyperosmosis, salinity and high light. In vivo subcellular localization of PpCOR413im-GFP fusion protein revealed that this protein is localized in chloroplasts, confirming the in silico predictions. Loss-of-function mutants of PpCOR413im exhibited growth and developmental alterations such as growth retardation, reduced caulonema formation and hypersensitivity to ABA. Mutants also displayed altered photochemistry under various abiotic stresses, including dehydration and low temperature, and exhibited a dramatic growth inhibition upon exposure to high light. Disruption of PpCOR413im also caused altered chloroplast ultrastructure, increased ROS accumulation, and enhanced starch and sucrose levels under high light or after ABA treatment. In addition, loss of PpCOR413im affected both nuclear and chloroplast gene expression in response to ABA and high light, suggesting a role for this gene downstream of ABA in the regulation of growth and environmental stress responses. Developmental alterations exhibited by PpCOR413im knockout mutants had remarkable similarities to those exhibited by hxk1, a mutant lacking a major chloroplastic hexokinase, an enzyme involved in energy homeostasis. Based on these findings, we propose that PpCOR413im is involved in coordinating energy metabolism with ABA-mediated growth and developmental responses.
Biología reproductiva de tres especies de Polylepis (P. neglecta, P. incarum y P. pacensis), con énfasis en su comportamiento germinativo
(2018) Cecilia K. Vega; C. Gabriela Villegas; Paola A. Rocabado; Jorge A. N. Quezada; M. Y. López; Ana W. Quevedo
Reproductive biology of three Polylepis species (P. neglecta, P. incarum and P. pacensis), with emphasis on their germinative behavior. With the purpose of contributing to the knowledge on the sexual reproduction of native species of Bolivia of the genus Polylepis (P. neglecta, P. incarum and P. pacensis), as a base for the production of seedlings destined for reforestation, different germination studies were developed. To obtain seeds, potential seed trees were identified both in natural populations (P. pacensis and P. incarum) as well as in green areas of the Municipality of La Paz (P. neglecta). At the same time a fruit an seed morpho anatomical characterization by species was developed. In relation to the physical quality, depending on the sample, 100 g of seeds per species, a high degree of impurities was found, which made it difficult to obtain pure seed for sowing. The percentage of humidity of seeds was low: 10% in P. incarum, 8% in P. pacensis and 6% in P. neglecta; as in consequence, they could be considered as orthodox seeds (i.e., can be stored for a long time without losing the germinative power). A germination of 10% (P. neglecta), 8% (P. pacensis) and 2% (P. incarum) was obtained. On the other hand, the germinative response of seeds of these Polylepis species under greenhouse conditions showed the highest percentage of germination (19%) in the substrate sand+peat 1:1. The species with the highest percentage of germination was P. neglecta (10 to 15%), while P. pacensis and P. incarum showed 8 and 2%, respectively. Despite the low germination percentage known for the genus Polylepis, having a good amount of seeds and adequate conditions for their development (i.e., humidity, substrate, temperature) makes possible to spread these species massively under greenhouse conditions, with optimal results in terms of quantity and quality of plants.https://doi.org/10.25260/EA.18.28.1.1.703
Bracken fern does not diminish arbuscular mycorrhizal fungus inoculum potential in tropical deforested areas
(Springer Science+Business Media, 2021) Cecilia L. López; César Mayta; Kazuya Naoki; Jorge A. N. Quezada; Isabell Hensen; Silvia C. Gallegos
Pollen limitation and reproductive incompatibility system in a critically endangered tree, Polylepis incarum (Bitter) M. Kessler & Schmidt-Leb (Rosaceae)
(Taylor & Francis, 2021) Cecilia L. López; Alejandra I. Domic; César Mayta; Emilia García; Jorge A. N. Quezada; Silvia C. Gallegos
Anemophilous species depend on wind for sexual reproduction. When plants do not receive enough pollen and/or pollen has poor quality, they may experience pollen limitation. This can reduce the production of fruits and seeds with negative consequences on population dynamics. The self-compatibility system also plays an important role on the likelihood of a species suffering pollen limitation as it determines if plants can produce fruits and seeds in the absence of compatible mates. Here, we studied the breeding system of the Andean anemophilous tree Polylepis incarum, a critically endangered species endemic to Lake Titicaca. We conducted controlled experimental pollination experiments and florescence microscopy analysis to assess whether pollen limitation and the incompatibility system constrain fruit and seed production. Results showed that the seed set is limited by pollen availability, that P. incarum exhibits a pre-zygotic compatibility system and early inbreeding depression manifested during seed development. Therefore, self-pollination is a factor that could be partially associated with the production of non-viable seeds.