Browsing by Author "Alvarez, Jose Miguel"

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    NAC072 Interacts with HB12, HAT9, and MYBR1 in a Temporal Regulatory Network Controlling Peach Fruit Development
    (2023) Nunez-Lillo, Gerardo; Zabala, Jose; Lillo-Carmona, Victoria; Alvarez, Jose Miguel; Pedreschi, Romina; Meneses, Claudio
    Fruit development is a complex process that involves the interplay of different biological processes carefully coordinated to control fruit quality traits. The peach fruit development consists in four recognized growth stages (S1-S4). The second stage (S2) is characterized by the endocarp hardening process and is followed by the second exponential growth phase (S3), where an increase in fruit size is produced by a rapid cell expansion. A nectarine genotype incapable of ripening and described as a slow ripening phenotype was identified and selected as a good model for studying peach fruit development. Slow ripening fruit remained firm, green, and exhibited no rise in CO2 or ethylene production rates blocking fruit development at S3 stage. The transcription factor NAC072 has been proposed as a key regulatory element involved in both the slow ripening and the harvest date phenotypes. However, the regulatory mechanisms by which NAC072 produces these phenotypic changes are still unknown. Using a transcriptomic approach between normal and slow ripening individuals with a transcription factor-gene target interaction database, a NAC072 regulatory network was constructed, identifying putative direct and indirect NAC072 fruit development-related elements. Three transcription factors were identified along with NAC072 in early stages of fruit development, two homeobox-leucine zippers (HB12 and HAT9), and one MYB transcription factor (MYBR1). In addition, we determined that the NAC072 transcriptional regulatory network promotes phenylpropanoids biosynthesis and cell wall remodeling to develop fruit growth, seed development, and softening, probably through hormonal signaling pathways involving abscisic acid and gibberellic acid.
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    The copper-dependent ACE1 transcription factor activates the transcription of the mco1 gene from the basidiomycete Phanerochaete chrysosporium
    (2008) Canessa, Paulo; Alvarez, Jose Miguel; Polanco, Ruben; Bull, Paulina; Vicuna, Rafael
    We have previously identified and functionally characterized the transcription factor ACE1 (Pc-ACE1) from Phanerochaete chrysosporium. In Saccharomyces cerevisiae, ACE1 activates the copper-dependent transcription of target genes through a DNA sequence element named ACE. However, the possible target gene(s) of Pc-ACE1 were unknown. An in silico search led to the identification of putative ACE elements in the promoter region of mco1, one of the four clustered genes encoding multicopper oxidases (MCOs) in P. chrysosporium. Since copper exerts an effect at the transcriptional level in MCOs from several organisms, in this work we analysed the effect of copper on transcript levels of the clustered MCO genes from P. chrysosporium, with the exception of the transcriptionally inactive mco3. Copper supplementation of cultures produced an increment in transcripts from genes mco1 and mco2, but not from mco4. Electrophoretic mobility-shift assays revealed that Pc-ACE1 binds specifically to a probe containing one of the putative ACE elements found in the promoter of mco1. In addition, using a cell-free transcription system, we showed that in the presence of cuprous ion, Pc-ACE1 induces activation of the promoter of mco1, but not that of mco2.