Transcriptome analysis of Sesuvium portulacastrum L. uncovers key genes and pathways involved in root formation in response to low-temperature stress

Sesuvium portulacastrum L., a perennial facultative halophyte, is extensively distributed across tropical and subtropical coastal regions. Its limited cold tolerance significantly impacts both the productivity and the geographical distribution of this species in higher-latitude areas. In this study, we employed RNA-Seq technology to delineate the transcriptomic alterations in Sesuvium plants exposed to low temperatures, thus advancing our comprehension of the molecular underpinnings of this physiological adaptation and root formation. Our findings demonstrated differential expression of 10,805, 16,389, and 10,503 genes in the low versus moderate temperature (LT vs. MT), moderate versus high temperature (MT vs. HT), and low versus high temperature (LT vs. HT) comparative analyses, respectively. Notably, the gene categories "structural molecule activity", "ribosome biogenesis", and "ribosome" were particularly enriched among the LT vs. HT-specific differentially expressed genes (DEGs). When synthesizing the insights from these three comparative studies, the principal pathways associated with the cold response mechanism were identified as "carbon fixation in photosynthetic organisms", "starch and sucrose metabolism", "plant hormone signal transduction", "glycolysis/gluconeogenesis", and "photosynthesis". In addition, we elucidated the involvement of auxin signaling pathways, adventitious root formation (ARF), lateral root formation (LRF), and novel genes associated with shoot system development in root formation. Subsequently, we constructed a network diagram to investigate the interplay between hormone levels and pivotal genes, thereby clarifying the regulatory pathways of plant root formation under low-temperature stress and isolating key genes instrumental in root development. This study has provided critical insights into the molecular mechanisms that facilitate the adaptation to cold stress and root formation in S. portulacastrum.