Biology subjects

Oliveira, T. R.

Publications and source records attributed to Oliveira, T. R..

3 recordsLinked to original sources

bioRxiv2025

Uncovering the Molecular Regulation of Seed Development and Germination in Endangered Legume Paubrasilia echinata Through Proteomic and Polyamine Analyses

Understanding the molecular regulation of seed maturation and germination is essential for plant conservation and agricultural applications. Here, we provide novel insights into the proteomic and polyamine dynamics of seeds from Paubrasilia echinata, an endangered legume, at 4, 6, and 8 weeks after anthesis. Using a sequential protein extraction approach combined with a species-specific protein database, we identified over 2,000 proteins, uncovering key regulators of maturation, stress tolerance, and germination. Seeds that reached maturity at 6 weeks displayed a high accumulation of proteasome components, translation machinery, and stress-associated proteins, notably late embryogenesis abundant (LEA) and heat shock proteins (HSPs), underscoring their role in seed development. Polyamine profiling showed that high putrescine levels were associated with early development and reduced germination, while spermidine and spermine were correlated with maturation, tolerance to desiccation, and germination. The decreases in certain proteins and polyamines during the transition to germination reveal dynamic regulatory shifts essential for the establishment of seedlings. These molecular signatures reveal dynamic metabolic and regulatory changes that facilitate the transition from seed development to germination. These findings reveal previously uncharacterized mechanisms of seed maturation and early germination in P. echinata and provide information on seed biology, ex situ conservation, and propagation strategies for endangered legumes.

plant biology↗

bioRxiv2022

Plant age-dependent dynamics of annatto pigment (bixin) biosynthesis in Bixa orellana L.

Age affects the production of secondary metabolites, but how developmental cues regulate secondary metabolism remains poorly understood. Annatto (Bixa orellana L.) is a source of bixin, an apocarotenoid used in the worlds food industry worldwide. Understanding how age-dependent mechanisms control bixin biosynthesis is of great interest for plant biology and for pharmaceutical, cosmetic, and textile industries. Here, we used genetic and molecular tools to unravel the role of the annatto age regulated miRNA156 (miR156) targeted SQUAMOSA PROMOTER BINDING PROTEIN LIKE (BoSPL) genes in secondary metabolism. Low expression of several BoSPL genes in miR156 overexpressing annatto plants (OE::156) impacted leaf ontogeny, reducing bixin production and increasing abscisic acid (ABA) levels. Modulation of BoCCD4;4 and BoCCD1 expression, key genes in lycopene cleavage, was associated with diverting the carbon flux from bixin to ABA, whereas upregulation of lycopene {beta} cyclase genes implies the xanthophyll biosynthetic pathway acted as a carbon sink in OE::156 plants. Proteomic analyses revealed low accumulation of most secondary metabolite-related enzymes in OE::156 plants, suggesting that miR156 targeted BoSPLs are required to activate several annatto secondary metabolic pathways. Our findings suggest that carbon flux in B. orellana OE::156 leaves was redirected from bixin to ABA production, indicating an age-dependent leaf dynamics of bixin biosynthesis. Importantly, our study opened a new venue to future annatto breeding programs aiming to improve bixin output.

plant biology↗

bioRxiv2019

Mitochondrial ascorbate synthesis acts as a pro-oxidant pathway and down-regulate energy supply in plants

Attempts to improve the ascorbate (AsA) content of plants are still dealing with the limited understanding of why exists a wide variability of this powerful anti-oxidant molecule in different plant sources, species and environmental situations. In plant mitochondria, the last step of AsA synthesis is catalyzed by the enzyme L-galactone-1,4-lactone dehydrogenase (L-GalLDH). By using GalLDH-RNAi silencing plant lines, biochemical and proteomic approaches, we here discovered that, in addition to accumulate this antioxidant, mitochondria synthesize AsA to down-regulate the respiratory activity and the cellular energy provision. The work reveals that the AsA synthesis pathway within mitochondria is a branched electron transfer process that channels electrons towards the alternative oxidase, interfering with conventional electron transport. It was unexpectedly found that significant hydrogen peroxide is generated during AsA synthesis, which affects the AsA level. The induced AsA synthesis shows proteomic alterations of mitochondrial and extra-mitochondrial proteins related to oxidative and energetic metabolism. The most identified proteins were known components of plant responses to high light acclimation, programmed cell death, oxidative stress, senescence, cell expansion, iron and phosphorus starvation, different abiotic stress/pathogen attack responses and others. We propose that changing the electron flux associated with AsA synthesis might be part of a new mechanism by which the L-GalLDH enzyme would adapt plant mitochondria to fluctuating energy demands and redox status occurring under different physiological contexts.

plant biology↗