Biology subjects

Ortiz-Garcia, P.

Publications and source records attributed to Ortiz-Garcia, P..

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↗

bioRxiv2025

Comparative genomics-driven design of virus-delivered short RNA inserts triggering robust gene silencing

Engineered RNA viruses can downregulate target genes through virus-induced gene silencing (VIGS). Largely optimized using the model plant Nicotiana benthamiana, current VIGS protocols rely on viral vectors engineered to deliver 200-400 nt inserts with homology to a target gene, often located in less conserved regions to ensure specificity. Given the N. benthamiana allopolyploidy and functional redundancy, we leveraged enhanced genomics and transcriptomics resources to obtain curated locus annotations, which guided the design of virus-delivered short RNA inserts (vsRNAi) for simultaneous targeting of homeologous gene pairs. Our results showed that quantitative silencing phenotypes could be obtained using 24-, 28-, and 32-nt vsRNAi that targeted conserved regions of functionally redundant gene pairs. vsRNAi triggered informative transcriptome-wide changes, and target transcript downregulation was linked to gene-pair-specific production of 21- and 22-nt sRNAs. The portability of vsRNAi to crops was confirmed in tomato (Solanum lycopersicum) and scarlet eggplant (Solanum aethiopicum). Overall, our results support the usefulness of vsRNAi-based approaches in functional genomics and trait reprogramming of the model species N. benthamiana, as well as of crops that contribute to global and local food provisions. HIGHLIGHTS O_LIComparative genomics enables design of virus-delivered short RNA inserts (vsRNAi) C_LIO_LI32-, 28-, and 24-nt vsRNAi resulted in quantitative gene silencing phenotypes C_LIO_LIvsRNAi trigger transcriptome-wide changes for gene functional characterization C_LIO_LIvsRNAi elicit production of 21- and 22-nt small RNAs and gene downregulation C_LIO_LIvsRNAi approaches assist functional genomics and phenotypic alteration in crops C_LI

plant biology↗

bioRxiv2020

Perturbations of the AMI1 IAM-amidohydrolase expression trigger plant stress responses in Arabidopsis thaliana

The evolutionary success of plants relies to a large extent on their extraordinary ability to adapt to changes in their environment. These adaptations require that plants balance their growth with their stress responses. Plant hormones are crucial mediators orchestrating the underlying adaptive processes. However, whether and how the growth-related hormone auxin and the stress-related hormones jasmonic acid (JA), salicylic acid, and abscisic acid (ABA) are coordinated remains largely elusive. Here, we analyze the physiological role of AMIDASE 1 (AMI1) in plant growth and its possible connection to plant adaptations to abiotic stresses. AMI1 contributes to cellular auxin homeostasis by catalyzing the conversion of indole-acetamide into the major plant auxin indole-3-acetic acid. Functional impairment of AMI1 increases the plants stress status rendering mutant plants more susceptible to abiotic stresses. Transcriptomic analysis of ami1 mutants disclosed the reprogramming of a considerable number of stress-related genes, including JA and ABA biosynthesis genes. The ami1 mutants exhibit only moderately repressed growth, but an enhanced ABA accumulation, which suggests a role for AMI1 in the crosstalk between auxin and ABA. Altogether, our results suggest that AMI1 is involved in coordinating the trade-off between plant growth and stress responses, balancing auxin with ABA homeostasis. HIGHLIGHTThe IAM amidohydrolase AMI1 catalyzes the conversion of IAM into IAA in vivo. Expression of AMI1 is specifically repressed by osmotic stress conditions, which triggers ABA biosynthesis through the induction of NCED3, thereby linking auxin homeostasis with plant stress responses.

plant biology↗