Nardeli, S. M. | Search bioRxiv

bioRxiv2024

The Arabidopsis splicing factor PORCUPINE/SmE1 orchestrates temperature-dependent root development via auxin homeostasis maintenance

O_LIAppropriate abiotic stress response is pivotal for plant survival and makes use of multiple signaling molecules and phytohormones to achieve specific and fast molecular adjustments. A multitude of studies has highlighted the role of alternative splicing in response to abiotic stress, including temperature, emphasizing the role of transcriptional regulation for stress response. Here we investigated the role of the core splicing factor PORCUPINE (PCP) on temperature-dependent root development. C_LIO_LIWe used marker lines and transcriptomic analyses to study the expression profiles of meristematic regulators and mitotic markers, and chemical treatments, as well as root hormone profiling to assess the effect of auxin signaling. C_LIO_LIThe loss of PCP significantly alters RAM architecture in a temperature-dependent manner. Our results indicate that PCP modulates the expression of central meristematic regulators and is required to maintain appropriate levels of auxin in the RAM. C_LIO_LIWe conclude that alternative pre-mRNA splicing is sensitive to moderate temperature fluctuations and contributes to root meristem maintenance, possibly through the regulation of phytohormone homeostasis and meristematic activity. C_LI

plant biology↗

bioRxiv2023

Temperature-dependent regulation of Arabidopsis thaliana growth and development by LSM7

Temperature affects plant growth by modulating the expression of genes and subsequent processing of RNAs that govern essential physiological processes. Here, we show that Arabidopsis thaliana Sm-like7 (LSM7), a core component of the splicing and decapping machinery, is indispensable for embryogenesis and development. Hypomorphic lsm7-2 mutants display severe developmental defects that are exacerbated by high temperatures. Transcriptome analysis verified LSM7s extensive role in gene regulation. In particular, we found that the key regulator of thermomorphogenesis, PHYTOCHROME INTERACTING FACTOR 4 (PIF4), and auxin-related genes, including SMALL AUXIN UP-REGULATED (SAUR) genes, are misregulated in lsm7-2. Auxin metabolic profiling confirmed that auxin homeostasis was disturbed in lsm7-2. Importantly, overexpression of the auxin-responsive SAUR19 gene partially restored thermomorphogenesis defects in lsm7-2 under high ambient temperature. Taken together, our research provides mechanistic insights into the interplay between RNA processing, hormone homeostasis, and the response to temperature regulation in plants and elucidates LSM7s essential function in plant temperature acclimation and resilience. Significance StatementGiven their sessile nature, plants cannot escape adverse environmental conditions such as cold or heat. Instead, they continuously adjust their gene expression and RNA processing to regulate growth and physiology in response to their surroundings. In this study, we investigated the role of the core RNA processing factor LSM7 in temperature acclimation in Arabidopsis thaliana. We found that LSM7 knockdown mutants were impaired in thermomorphogenesis and, as a result, were hypersensitive to elevated temperatures. At the molecular level, we demonstrated that this temperature sensitivity was caused by the misregulation of key regulators of thermomorphogenesis, including PIF4, auxin homeostasis and signaling, and SAUR genes. Our findings provide valuable insights into the role of RNA processing in plant temperature acclimation.

plant biology↗