SnoRNP is essential for thermospermine-mediated development in Arabidopsis thaliana

A Solanum lycopersicum polyamine oxidase contributes to the control of plant growth, xylem differentiation, and drought stress tolerance

Polyamines are involved in several plant physiological processes. In Arabidopsis thaliana, five FAD-dependent polyamine oxidases (AtPAO1 to AtPAO5) contribute to polyamine homeostasis. AtPAO5 catalyzes the back-conversion of thermospermine (T-Spm) to spermidine and plays a role in plant development, xylem differentiation, and abiotic stress tolerance. In the present study, to verify whether T-Spm metabolism can be exploited as a new route to improve stress tolerance in crops and to investigate the underlying mechanisms, tomato (Solanum lycopersicum) AtPAO5 homologs were identified (SlPAO2, SlPAO3, and SlPAO4) and CRISPR/Cas9-mediated loss-of-function slpao3 mutants were obtained. Morphological, molecular, and physiological analyses showed that slpao3 mutants display increased T-Spm levels and exhibit changes in growth parameters, number and size of xylem elements, and expression levels of auxin- and gibberellin-related genes compared to wild-type plants. The slpao3 mutants are also characterized by improved tolerance to drought stress, which can be attributed to a diminished xylem hydraulic conductivity that limits water loss, as well as to a reduced vulnerability to embolism. Altogether, this study evidences conservation, though with some significant variations, of the T-Spm-mediated regulatory mechanisms controlling plant growth and differentiation across different plant species and highlights the T-Spm role in improving stress tolerance while not constraining growth.

Genome-wide identification, characterization, and expression analysis unveil the roles of pseudouridine synthase (PUS) family proteins in rice development and stress response

Pseudouridylation, the conversion of uridine (U) to pseudouridine (Ѱ), is one of the most prevalent and evolutionary conserved RNA modifications, which is catalyzed by pseudouridine synthase (PUS) enzymes. Ѱs play a crucial epitranscriptomic role by regulating attributes of cellular RNAs across diverse organisms. However, the precise biological functions of PUSs in plants remain largely elusive. In this study, we identified and characterized 21 members in the rice PUS family which were categorized into six distinct subfamilies, with RluA and TruA emerging as the most extensive. A comprehensive analysis of domain structures, motifs, and homology modeling revealed that OsPUSs possess all canonical features of true PUS proteins, essential for substrate recognition and catalysis. The exploration of OsPUS promoters revealed presence of cis-acting regulatory elements associated with hormone and abiotic stress responses. Expression analysis of OsPUS genes showed differential expression at developmental stages and under stress conditions. Notably, OsTruB3 displayed high expression in salt, heat, and drought stresses. Several OsRluA members showed induction in heat stress, while a significant decline in expression was observed for various OsTruA members in drought and salinity. Furthermore, miRNAs predicted to target OsPUSs were themselves responsive to variable stresses, adding an additional layer of regulatory complexity of OsPUSs. Study of protein-protein interaction networks provided substantial support for the potential regulatory role of OsPUSs in numerous cellular and stress response pathways. Conclusively, our study provides functional insights into the OsPUS family, contributing to a better understanding of their crucial roles in shaping the development and stress adaptation in rice.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12298-023-01396-4.

RNA pseudouridine modification in plants

Pseudouridine is one of the well-known chemical modifications in various RNA species. Current advances to detect pseudouridine show that the pseudouridine landscape is dynamic and affects multiple cellular processes. Although our understanding of this post-transcriptional modification mainly depends on yeast and human models, the recent findings provide strong evidence for the critical role of pseudouridine in plants. Here, we review the current knowledge of pseudouridine in plant RNAs, including its synthesis, degradation, regulatory mechanisms, and functions. Moreover, we propose future areas of research on pseudouridine modification in plants.