Publication details
ROLE OF THE AUXIN RESPONSE FACTOR5 AND MICRORNA390 IN EMBRYOGENIC TRANSITION IN ARABIDOPSIS THALIANA
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| Year of publication | 2025 |
| Type | Conference abstract |
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| Description | Somatic embryogenesis (SE) is a process through which somatic plant cells acquire the capacity to initiate an embryonic developmental program. This remarkable form of cellular reprogramming is widely used in plant biotechnology for mass micropropagation, biodiversity preservation, and the production of transgenic plants. Despite its broad applications, the molecular mechanisms underlying SE initiation remain incompletely understood. The plant hormone auxin plays a central role in SE, acting through key transcriptional regulators such as AUXIN RESPONSE FACTOR 5 (ARF5), also known as MONOPTEROS (MP). Auxin signaling, transport, and metabolism are essential for embryogenic reprogramming in Arabidopsis thaliana and other plant species. MP is strongly expressed during SE, and loss-of-function mutants show impaired embryogenic potential, highlighting its critical role. Our study focuses on the function of MP11ir, a splice isoform of ARF5 characterized by intron retention. This alternative transcript encodes a truncated MP protein lacking the PB1 domain necessary for dimerization with Aux/IAA proteins, making it potentially insensitive to auxin repression. We found that MP11ir accumulates significantly during both auxin-dependent and auxin-independent SE induction. Functionally, MP11ir partially rescues the embryogenic potential in the mpS319 mutant background. However, overexpression of ?ARF5, the truncated MP protein, disrupts somatic embryo formation and promotes callus development instead. This phenotype is associated with altered expression of auxin biosynthesis genes, resulting in disturbed auxin homeostasis and disrupted local and global auxin levels. Taken together, this project aims to unravel the regulatory interplay between ARF5, auxin biosynthesis (via YUCCA genes), and auxin signaling (via MIR390) in controlling SE. Through a multidisciplinary approach—including CRISPR/Cas9 mutagenesis, MIR390 sensor development, dual-luciferase assays, gene expression profiling, hormonal analysis, and the green-CUT&RUN technique—we seek to clarify how ARF5 and its isoforms coordinate embryogenic transitions. These findings will contribute to a better understanding of auxin-driven developmental plasticity and improve protocols for plant regeneration and genetic transformation. |
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