Banca de QUALIFICAÇÃO: ISABELLA PERES DE OLIVEIRA
Uma banca de QUALIFICAÇÃO de MESTRADO foi cadastrada pelo programa.DISCENTE : ISABELLA PERES DE OLIVEIRA
Data: 27/02/2026
HORA: 14:00
LOCAL: Sala 210 do Bloco Zeta do Campus de São Bernardo do Campo da Universidade Federal do ABC
TÍTULO:
Deciphering the structure and diversity of core components in the abscisic acid signaling pathway of monocot species.
PÁGINAS: 100
RESUMO:
Global climate change has introduced major challenges to agriculture, particularly by the temperature rises and altering precipitation patterns. Monocotyledons, a key plant clade widely used for food and biomass production, are strongly affected by water deficit, reinforcing the need to expand knowledge of their physiological and molecular responses to drought. Abscisic acid (ABA) plays a pivotal role in drought adaptation by regulating stomatal closure and the expression of stress-responsive genes. Canonical ABA signaling involves PYR/PYL/RCAR receptors, clade A PP2C phosphatases, and SnRK2 kinases, which interact via reversible phosphorylation to mediate ABA-dependent responses. Despite its importance, the evolutionary and functional diversity of these components remains poorly characterized in several non-model monocot species. This study investigated the gene organization, phylogenetic relationships, and structural variation of PYR/PYL/RCAR, PP2C, and SnRK2 genes monocots of commercial interest: Agave tequilana, Saccharum spp., Miscanthus sinensis, Panicum hallii, Panicum virgatum, and Urochloa fusca. We identified 135, 174, and 153 putative genes encoding PYR/PYL/RCAR, PP2C, and SnRK2 proteins, respectively. Phylogenetic reconstructions classified these genes into three PYL subfamilies and three SnRK2 subclasses, providing functional inferences based on evolutionary relationships with well-characterized homologs from Arabidopsis thaliana and Oryza sativa. Subcellular localization analysis revealed that most PYL, PP2C, and SnRK2 proteins are predicted to localize to the nucleus (75%, 42%, and 93%, respectively), consistent with their roles in transcriptional regulation. A substantial fraction of PYL and PP2C proteins were also predicted to localize to chloroplasts (23% and 40%, respectively), suggesting potential coordination between hormone production and downstream signaling. Functional and transcriptomic analyses in Megathyrsus maximus cv. Tamani under contrasting water regimes revealed a coordinated activation of ABA-dependent signaling cascades. Pairwise comparisons among irrigation treatments identified several transcripts differentially expressed (TDEs) encoding core ABA signaling components and downstream effectors, including PP2Cs, SnRK kinases, and multiple transcription factor families. Together, these results indicate that drought stress in M. maximus triggers a multilayered ABA-centered regulatory network integrating phosphorylation-dependent signaling, ROS-mediated responses, and transcriptional control. This regulatory plasticity, potentially enhanced by polyploidy-driven gene family expansion and subfunctionalization, may contribute to the robustness of drought adaptation mechanisms in this forage species. By integrating comparative genomics across monocots with functional and physiological analyses in M. maximus, this study provides a multiscale view of ABA signaling evolution, compartmentalization, and stress responsiveness. The observed expansion, subcellular diversification, and differential regulation of ABA pathway components—potentially reinforced by polyploidy-driven gene family expansion and subfunctionalization—suggest a molecular basis for regulatory plasticity under drought. These findings not only advance fundamental understanding of ABA signaling in non-model grasses but also establish a foundation for the development of molecular markers and biotechnological strategies aimed at improving drought resilience in forage and bioenergy crops under future climate scenarios.
MEMBROS DA BANCA:
Presidente - Interno ao Programa - 3292611 - MILCA RACHEL DA COSTA RIBEIRO LINS
Membro Titular - Examinador(a) Interno ao Programa - 3065803 - WAGNER RODRIGO DE SOUZA
Membro Titular - Examinador(a) Externo à Instituição - LEANDRO FRANCISCO DE OLIVEIRA - USP
Membro Suplente - Examinador(a) Interno ao Programa - 1601025 - MARCELLA PECORA MILAZZOTTO
Membro Suplente - Examinador(a) Externo ao Programa - 1544372 - HANA PAULA MASUDA