Browsing by Author "Hasbun, Rodrigo"

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    Global Methylation Analysis Using MSAP Reveals Differences in Chilling-Associated DNA Methylation Changes during Dormancy Release in Contrasting Sweet Cherry Varieties
    (2022) Narvaez, Gabriela; Munoz-Espinoza, Claudia; Soto, Esteban; Rothkegel, Karin; Bastias, Macarena; Gutierrez, Jose; Bravo, Soraya; Hasbun, Rodrigo; Meneses, Claudio; Miyasaka Almeida, Andrea
    Dormancy is an adaptive strategy developed by temperate perennial crops to protect overwinter tissues from unfavorable environmental conditions. Sweet cherry (Prunus avium L.), a member of the Rosaceae family, requires chilling to overcome dormancy. The time of harvest is directly correlated with chilling requirements in sweet cherries. Consequently, early and late season varieties have low and high chilling requirements, respectively. There is evidence that the expression of dormancy-related genes is regulated by DNA methylation. In this work, methylation-sensitive amplified polymorphism (MSAP) was applied to study genome-wide DNA methylation changes associated with dormancy in two low-chill varieties, 'Royal Dawn' and 'Glen Red', and one high-chill variety, 'Kordia'. Our primary results suggest that the occurrence of progressive DNA demethylation is associated with chilling accumulation during dormancy in the three varieties, independent of their chilling requirements. Genes were identified with different methylation status changes, detected by MSAP, related to cell wall remodeling and energy metabolism. Several MSAP profiles among the varieties were observed, suggesting that fine epigenetic control is required to coordinate hormonal and environmental signals that induce dormancy and its release.
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    Phenotypic and genetic analysis of a peach and a Japanese plum core collection for pre-breeding and distinctness assessment
    (2022) Carrasco, Basilio; Ramirez, Cesar; Gebauer, Marlene; Meisel, Lee A.; Hasbun, Rodrigo; Silva, Herman
    To know the relationships between phenotypic and genetic variables in a germplasm collection of fruit crops is useful a pre-breeding and cultivar distinctness. A core collection of 23 peaches/nectarines (Prunus persica (L.) Batsch), and 16 Japanese plum (Prunus salicina Lindl. var. salicina) cultivars were evaluated for 33 and 29 characteristics (botanical/ productive) respectively during two growing seasons. Also, eight specific simple sequence repeats (SSRs) markers were analyzed in both species. Principal components analyses revealed seven characteristics (related to the size of the fruit and the firmness of the pulp) as the most important for the 23 peach/nectarine cultivars and four characteristics (yield, fruit size, soluble solids, and harvest time) for the 16 Japanese plum cultivars. These analyses revealed three cultivars of peaches (Diamond Princess, Dixon, and Dr. Davis) and three of nectarines (Ruby diamond, Artic sweet, Summer fire) with the highest values for fruit size and pulp firmness. Four Japanese plum cultivars (Angeleno, Flavor Rich, Red Heart, and Pink Delight) showed the highest values of yield, fruit size, soluble solids, and harvest time. Elite germplasms to carry out a breeding program were identified from both the phenotypic and genetic analysis. Additionally, cultivar-specific SSR alleles were identified and are a relevant tool for cultivar distinctness.
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    The impact of Pleistocene glaciations and environmental gradients on the genetic structure of Embothrium coccineum
    (2022) Sepulveda-Espinoza, Francisco; Bertin-Benavides, Ariana; Hasbun, Rodrigo; Toro-Nunez, Oscar; Varas-Myrik, Antonio; Alarcon, Diego; Guillemin, Marie-Laure
    The South American temperate forests were subjected to drastic topographic and climatic changes during the Pliocene--Pleistocene as a consequence of the Andean orogeny and glacial cycles. Such changes are common drivers of genetic structure and adaptation. Embothrium coccineum (Proteaceae) is an emblematic tree of the South American temperate forest (around 20 degrees S of latitude) that has strongly been affected by topographic and climatic events. Previous studies have shown a marked genetic structure in this species, and distinct ecotypes have been described. Yet, little is known about their adaptive genetic responses. The main goal of this study was to investigate the effects of historical and contemporary landscape features affecting the genetic diversity and connectivity of E. coccineum throughout its current natural distribution. Using over 2000 single nucleotide polymorphisms (SNPs), we identified two genetic groups (a Northern and a Central--Southern group) that diverged around 2.8 million years ago. The level of genetic structure was higher among populations within the Northern genetic group than within the Central--Southern group. We propose that these differences in genetic structure may be due to differences in the assemblages of pollinators and in the evolutionary histories of the two genetic groups. Moreover, the data displayed a strong pattern of isolation by the environment in E. coccineum, suggesting that selection could have led to adaptive divergence among localities. We propose that in the Chilean temperate forest, the patterns of genetic variation in E. coccineum reflect both a Quaternary phylogenetic imprint and signatures of selection as a consequence of a strong environmental gradient.