Biology subjects

Vicente-Carbajosa, J.

Publications and source records attributed to Vicente-Carbajosa, J..

3 recordsLinked to original sources

bioRxiv2025

Identification of a novel link connecting indole-3-acetamide with abscisic acid biosynthesis and signaling

Plants regulate their developmental programs and their responses to environmental changes through a complex network of small signaling compounds, known as phytohormones. The role of auxins in promoting plant growth has been extensively investigated. Furthermore, previous studies have demonstrated that the accumulation of indole-3-acetamide (IAM), an auxin precursor, results in the suppression of plant growth, particularly primary root elongation. This observation led to the hypothesis that IAM or an IAM derivative exerts negative growth regulatory effects. However, the molecular mechanism by which IAM inhibits plant growth remains largely unelucidated. To gain deeper insight into the molecular mode of action of IAM, we conducted a comprehensive genome-wide association study (GWAS) using a highly diverse collection of 166 wild Arabidopsis accessions from the Iberian Peninsula. Consequently, we identified several genomic regions associated with a reduced response to IAM under controlled in vitro conditions, which included ABA3 and GA2ox2 as candidate genes. Sequence analyses, transcriptomics studies, and comparison of three-dimensional models generated for ABA3 proteins encoded by the two major natural alleles identified in the collection of wild accessions suggested that IAM-triggered inhibition of primary root elongation is closely associated with the formation of abscisic acid (ABA) in Arabidopsis thaliana seedlings. Finally, physiological characterization of mutants for those candidate genes further corroborated that IAM activates ABA signaling. Our results demonstrate that IAM is intricately linked with ABA biosynthesis and signaling, thereby elucidating a novel node in plant hormone crosstalk.

plant biology↗

bioRxiv2024

The autophagy-related genes AtATG5 and AtATG7 influence reserve mobilisation and responses to ABA during seed germination in Arabidopsis thaliana

Autophagy is an intracellular recycling mechanism that generally degrades cytoplasmic components non-selectively, but it can also target specific substrates under certain conditions. Here, we investigate the impact of autophagy on Arabidopsis seed biology through autophagy-related (ATG) genes AtATG5 and AtATG7, and their role in ABA responses. Seeds of atg5 and atg7 mutants germinate significantly slower than Col-0, especially under ABA, and show transcriptomic differences and histochemical alterations in the organization of lipid droplets and protein storage vacuoles. Notably, immunolocalization of ATG8 is observed in PSV of Col-0, but not in atg mutants. Differentially expressed genes in atg7 compared to Col-0 in response to ABA include reported targets of the transcription factor (TF) ABI5, a master regulator of ABA signalling in the seed. Interestingly, the decrease in ABI5 normally observed in Col-0 seeds after imbibition is delayed in atg mutants, which also show altered accumulation in developing seeds of the bZIP67, an ABI5 homolog that regulates reserve biosynthesis. Yeast two-hybrid and co-immunoprecipitation assays confirmed a direct interaction with the autophagy machinery in vitro and in vivo, mediated through ATG8. Our data highlight the relevance of autophagy in seed reserve mobilization, and seed germination through ABA responses by a TF decay mechanism.

plant biology↗

bioRxiv2024

The endophytic fungus Serendipita indica alters auxin distribution in Arabidopsis thaliana roots through alteration of auxin transport and conjugation to promote plant growth

Plants share their habitats with a multitude of different microbes. This close vicinity promoted the evolution of inter-organismic interactions between plants and many different microorganisms that provide mutual growth benefits both to the plant and the microbial partner. The symbiosis of Arabidopsis thaliana with the beneficial root colonizing endophyte Serendipita indica represents a well-studied system. Co-colonization of Arabidopsis roots with S. indica significantly promotes plant growth. Due to the notable phenotypic alterations of fungus-infected root systems, the involvement of a reprogramming of plant hormone levels, especially that of indole-3-acetic acid, has been suggested earlier. However, until now, the molecular mechanism by which S. indica promotes plant growth remains largely unknown. This study used comprehensive transcriptomics, metabolomics, reverse genetics, and life cell imaging to reveal the intricacies of auxin-related processes that affect root growth in the symbiosis between A. thaliana and S. indica. Our experiments revealed the essential role of tightly controlled auxin conjugation in the plant-fungus interaction. It particularly highlighted the importance of two GRETCHEN HAGEN 3 (GH3) genes, GH3.5 and GH3.17, for the fungus infection-triggered stimulation of biomass production, thus broadening our knowledge about the function of GH3s in plants. Furthermore, we provide evidence for the transcriptional alteration of the PIN2 auxin transporter gene in roots of Arabidopsis seedlings infected with S. indica and demonstrate that this transcriptional adjustment affects auxin signaling in roots, which results in increased plant growth.

plant biology↗