Browsing by Author "Riveros, Anibal"

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    A novel pectin methylesterase inhibitor, PMEI3, in common bean suggests a key role of pectin methylesterification in Pseudomonas resistance
    (2024) De la Rubia, Alfonso G.; Largo-Gosens, Asier; Yusta, Ricardo; Sepulveda-Orellana, Pablo; Riveros, Anibal; Centeno, Maria Luz; Sanhueza, Dayan; Meneses, Claudio; Saez-Aguayo, Susana; Garcia-Angulo, Penelope
    The mechanisms underlying susceptibility to and defense against Pseudomonas syringae (Pph) of the common bean (Phaseolus vulgaris) have not yet been clarified. To investigate these, 15-day-old plants of the variety Rinon were infected with Pph and the transcriptomic changes at 2 h and 9 h post-infection were analysed. RNA-seq analysis showed an up-regulation of genes involved in defense/signaling at 2 h, most of them being down-regulated at 9 h, suggesting that Pph inhibits the transcriptomic reprogramming of the plant. This trend was also observed in the modulation of 101 cell wall-related genes. Cell wall composition changes at early stages of Pph infection were associated with homogalacturonan methylation and the formation of egg boxes. Among the cell wall genes modulated, a pectin methylesterase inhibitor 3 (PvPMEI3) gene, closely related to AtPMEI3, was detected. PvPMEI3 protein was located in the apoplast and its pectin methylesterase inhibitory activity was demonstrated. PvPMEI3 seems to be a good candidate to play a key role in Pph infection, which was supported by analysis of an Arabidopsis pmei3 mutant, which showed susceptibility to Pph, in contrast to resistant Arabidopsis Col-0 plants. These results indicate a key role of the degree of pectin methylesterification in host resistance to Pph during the first steps of the attack.
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    Cistanthe longiscapa exhibits ecophysiological and molecular adaptations to the arid environments of the Atacama Desert
    (OXFORD UNIV PRESS INC, 2025) Ossa, Paulina; Moreno, Adrian A.; Orellana, Daniela; Toro, Monica; Carrasco Valenzuela, Tomas; Riveros, Anibal; Meneses Araya, Claudio Antonio; Nilo Poyanco, Ricardo; Orellana, Ariel
    Understanding how plants survive extreme conditions is essential to breeding resilient crops. Cistanthe longiscapa, which flourishes in the Atacama Desert, provides a rare glimpse into plant resilience. To uncover the genetic basis of its stress tolerance, we investigated the ecophysiological and transcriptomic responses of C. longiscapa from 3 sites with low but different precipitation levels. Ecophysiological analyses were performed on samples collected in the field at dusk and dawn, which are crucial stages in crassulacean acid metabolism (CAM), a water-efficient type of photosynthesis. Additional transcriptomic analysis allowed us to evaluate CAM intensity in C. longiscapa and identify changes in the molecular signature of these plants. Our results show that C. longiscapa displays considerable ecophysiological trait response variation across the 3 sites, including variations in markers such as nocturnal acid accumulation, isotopic carbon ratio, and succulence, among others. Analysis of gene expression patterns revealed differences among plants exhibiting varying intensities of CAM photosynthesis and identified key molecular signatures associated with their ecological strategies. Additionally, genes related to stress responses, plastid activities, and circadian rhythm show contrasting expression levels between strong and weak CAM plants, and this expression profile is shared with other CAM plants under stress. Our findings demonstrate that C. longiscapa is a valuable resource for identifying genes involved in the transition between different CAM intensities. This may lead to the discovery of genes that enhance plant tolerance to stressful environments., Cistanthe longiscapa exhibits weak or strong CAM photosynthesis under varying aridity levels in the Atacama Desert, which is associated with contrasting gene expression patterns during dawn and dusk.
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    Photosynthetic and Genetic Adaptations Underpinning the Resilience of Cistanthe longiscapa in the Atacama Desert
    (2024) Sandoval-Ibáñez, O.; Tapia-Reyes, P.; Riveros, Anibal; Yusta, R.; Chang, S.; Ossa, P.; Nilo-Poyanco, R.; Moreno, A.A.; Miquel, A.; Almeida, A.M.; Zurita-Silva, A.; Orellana, D.; Baeza, C.; Blanco-Herrera, F.; Genova, A.D.; Allende, M.L.; González, M.; Maass, A.; Gutierrez Alliende, Rodrigo Hernan; Meneses Araya, Claudio Antonio
    The Atacama Desert is one of the most hostile environments for life. However, the plant species Cistanthe longiscapa (C. longiscapa) completes its life cycle in the Atacama Desert after sporadic rainfall. Physiological analyses under controlled environmental conditions revealed superior photosynthetic performance, better light acclimation mechanisms, and larger accumulation of photosystem II in C. longiscapa compared to its mesophilic sister species. C. longiscapa shows evolutionary expansions in gene families related to DNA repair, photosynthesis, and protein homeostasis. In addition, we observed substantial gene duplication and polymorphic variations between coastal and inland populations in the Atacama Desert. Finally, our assembled mitochondrial genome provides genetic information for all DNA-containing compartments of C. longiscapa. Diurnal oscillations of malic acid and time-resolved transcriptome analyses of plants harvested in the Atacama Desert indicate that C. longiscapa engages in CAM metabolism. We observed significant differences in transcripts encoding plastid-localized proteins, including those involved in carbon metabolism, light harvesting, and photoprotection, highlighting the critical role of chloroplasts in the adaptation of C. longiscapa to the Atacama Desert. Our study provides physiological and genetic evidence for the adaptations of C. longiscapa and advances our understanding of how plants can cope with extreme environmental conditions.
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    Response Mechanisms of "Hass" Avocado to Sequential 1-methylcyclopropene Applications at Different Maturity Stages during Cold Storage
    (2022) Olivares, Daniela; Garcia-Rojas, Miguel; Ulloa, Pablo A.; Riveros, Anibal; Pedreschi, Romina; Campos-Vargas, Reinaldo; Meneses, Claudio; Defilippi, Bruno G.
    1-Methylcyclopropene (1-MCP) is used for extending the postharvest life of the avocado during storage. Evaluated the effect of 1-MCP application at different times after harvest, i.e., 0, 7, 14, and 21 d at 5 degrees C, to identify the threshold of the ethylene inhibition response in "Hass" avocado. Our results showed that fruits from two maturity stages at harvest: low dry matter (20-23%) and high dry matter (27%). Changes in ethylene production rates and transcript accumulation of genes involved in ethylene metabolism were measured at harvest and during storage. 1-MCP treated fruit up to 14 d of storage showed similar values of firmness and skin color as fruit treated at harvest time. In contrast, when the application was performed after 21 d, the fruit showed ripening attributes similar to those of the untreated ones. To further understand the molecular mechanisms responsible for the lack of response to 1-MCP at 21 d of storage, transcriptomic analysis was performed. Gene ontology analyses based on the DEG analysis showed enrichment of transcripts involved in the 'response to ethylene' for both maturity stages. All genes evaluated showed similar expression profiles induced by cold storage time, with a peak at 21 d of storage and an increased softening of the fruit and peel color. This was a two-year field study, and results were consistent across the two experimental years. Our results should help growers and markets in selecting the optimal timing of 1-MCP application in "Hass" avocados and should contribute to a deeper understanding of the molecular mechanisms of the avocado ripening process.
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    Transcriptome and Gene Regulatory Network Analyses Reveal New Transcription Factors in Mature Fruit Associated with Harvest Date in Prunus persica
    (2022) Nunez-Lillo, Gerardo; Perez-Reyes, Wellasmin; Riveros, Anibal; Lillo-Carmona, Victoria; Rothkegel, Karin; Miguel Alvarez, Jose; Blanco-Herrera, Francisca; Pedreschi, Romina; Campos-Vargas, Reinaldo; Meneses, Claudio
    Harvest date is a critical parameter for producers and consumers regarding agro-industrial performance. It involves a pleiotropic effect controlling the development of other fruit quality traits through finely controlling regulatory mechanisms. Fruit ripening is a process in which various signals and biological events co-occur and are regulated by hormone signaling that produces the accumulation/degradation of multiple compounds. However, the regulatory mechanisms that control the hormone signaling involved in fruit development and ripening are still unclear. To investigate the issue, we used individuals with early, middle and late harvest dates from a peach segregating population to identify regulatory candidate genes controlling fruit quality traits at the harvest stage and validate them in contrasting peach varieties for this trait. We identified 467 and 654 differentially expressed genes for early and late harvest through a transcriptomic approach. In addition, using the Arabidopsis DAP-seq database and network analysis, six transcription factors were selected. Our results suggest significant hormonal balance and cell wall composition/structure differences between early and late harvest samples. Thus, we propose that higher expression levels of the transcription factors HB7, ERF017 and WRKY70 in early harvest individuals would induce the expression of genes associated with the jasmonic acid pathway, photosynthesis and gibberellins inhibition. While on the other hand, the high expression levels of LHY, CDF3 and NAC083 in late harvest individuals would promote the induction of genes associated with abscisic acid biosynthesis, auxins and cell wall remodeling.