Soil salinization is a major environmental stress that causes crop yield reductions worldwide. Therefore, the cultivation of salt-tolerant crops is an effective way to sustain crop yield. Tomatoes are one of the vegetable crops that are moderately sensitive to salt stress. Global market demand for tomatoes is huge and growing. In recent years, the mechanisms of salt tolerance in tomatoes have been extensively investigated; however, the molecular mechanism through which non-coding RNAs (ncRNAs) respond to salt stress is not well understood. In this study, we utilized small RNA sequencing and whole transcriptome sequencing technology to identify salt-responsive microRNAs (miRNAs), messenger RNAs (mRNAs), and circular RNAs (circRNAs) in roots of M82 cultivated tomato and Solanum pennellii (S. pennellii) wild tomato under salt stress. Based on the theory of competitive endogenous RNA (ceRNA), we also established several salt-responsive ceRNA networks. The results showed that circRNAs could act as miRNA sponges in the regulation of target mRNAs of miRNAs, thus participating in the response to salt stress. This study provides insights into the mechanisms of salt tolerance in tomatoes and serves as an effective reference for improving the salt tolerance of salt-sensitive cultivars.

To explore the function of phosphatidylinositol 4-phosphate 5-kinase (PIP5K) in tomatoes, members of the tomato PIP5K family were identified and characterized using bioinformatic methods, and their expression patterns were also analyzed under salt stress and in different tissues. Twenty-one PIP5K members—namely, SlPIP5K1–SlPIP5K21—were identified from ten chromosomes, and these were divided into three groups according to a phylogenetic analysis. Further bioinformatic analysis showed four pairs of collinear relationships and fragment replication events among the SlPIP5K family members. To understand the possible roles of the SlPIP5Ks, a cis-acting element analysis was conducted, which indicated that tomato PIP5Ks could be associated with plant growth, hormones, and stress responses. We further validated the results of the in silico analysis by integrating RNA-seq and qRT-PCR techniques for salt- and hormone-treated tomato plants. Our results showed that SlPIP5K genes exhibited tissue- and treatment-specific patterns, and some of the SlPIP5Ks exhibited significantly altered expressions after our treatments, suggesting that they might be involved in these stresses. We selected one of the SlPIP5Ks that responded to our treatments, SlPIP5K2, to further understand its subcellular localization. Our results showed that SlPIP5K2 was located on the membrane. This study lays a foundation for the analysis of the biological functions of the tomato SlPIP5K genes and can also provide a theoretical basis for the selection and breeding of new tomato varieties and germplasm innovation, especially under salt stress.

The mitochondrial calcium uniporter (MCU) is a key channel controlling mitochondrial Ca²⁺ homeostasis, yet its role in plant stress responses remains unclear. Using the tomato pan-genome, this study identified 66 MCU genes across 12 tomato species and grouped them into two distinct evolutionary subfamilies. Phylogenetic, collinearity, and selection pressure analyses revealed that MCU genes are evolutionarily conserved and have undergone strong purifying selection. In addition, one MCU gene located on chromosome 6 appears to have originated before the divergence of monocots and dicots, indicating an ancient evolutionary trajectory. Gene structure and conserved motif analyses confirmed their structural conservation, while promoter cis-element analysis suggested that MCU genes are widely involved in light and hormone responsiveness. Expression profiling under salt stress showed that multiple MCU genes are differentially regulated in a time-dependent manner: SolycMCU1 and SolycMCU2 respond rapidly at early stages, whereas SolycMCU5 and SolycMCU6 are upregulated during middle and late phases. These results highlight the functional diversification of MCU genes in tomato under salt stress. This study provides the first comprehensive evolutionary and functional analysis of the tomato MCU gene family, offering insights into their stress-regulatory mechanisms and potential use in breeding salt-tolerant tomatoes.

As one of the most important vegetable crops in the world, the production of tomatoes was restricted by salt stress. Therefore, it is of great interest to analyze the salt stress tolerance genes. As the non-coding RNAs (ncRNAs) with a length of more than 200 nucleotides, long non-coding RNAs (lncRNAs) lack the ability of protein-coding, but they can play crucial roles in plant development and response to abiotic stresses by regulating gene expression. Nevertheless, there are few studies on the roles of salt-induced lncRNAs in tomatoes. Therefore, we selected wild tomato Solanum pennellii ( S. pennellii ) and cultivated tomato M82 to be materials. By high-throughput sequencing, 1044 putative lncRNAs were identified here. Among them, 154 and 137 lncRNAs were differentially expressed in M82 and S. pennellii , respectively. Through functional analysis of target genes of differentially expressed lncRNAs (DE-lncRNAs), some genes were found to respond positively to salt stress by participating in Abscisic Acid (ABA) signaling pathway, brassinosteroid (BR) signaling pathway, ethylene (ETH) signaling pathway and anti-oxidation process. We also construct a salt-induced lncRNA-mRNA co-expression network to dissect the putative mechanisms of high salt tolerance in S. pennellii . We analyze the function of salt-induced lncRNAs in tomato roots at the genome-wide levels for the first time. These results will contribute to understanding the molecular mechanisms of salt tolerance in tomatoes from the perspective of lncRNAs.

Long non-coding RNAs (lncRNAs) have emerged as important regulatory molecules in plants, but their potential roles during modern maize breeding remain largely unexplored. This study systematically characterized lncRNA expression dynamics using transcriptome data from 137 maize inbred lines from different breeding eras in China. We identified 18,023 lncRNAs transcripts, grouped by expression trends across historical breeding eras. Comparative analysis revealed 2228 differentially expressed lncRNAs transcripts (DElncRNAs) between modern (CN2000&10s) and early (CN1960&70s) accessions. By integrating WGCNA and cis-target analysis, we identified candidate lncRNAs and putative lncRNA-PCG associations that may be associated with maize plant architecture-related processes. Further, 771 DElncRNAs were predicted to be associated with 810 protein-coding genes, and these associated genes were significantly enriched in plant hormone signal transduction. Dual-luciferase reporter assays provided preliminary experimental support that lncrna.33063 and lncrna.33068 can repress the promoter activity of ZmPIF5.2 in a heterologous transient expression system. Furthermore, we constructed a putative ceRNA-related candidate interaction network consisting of lncRNA–miRNA–mRNA triplets that include 317 candidate miRNA-lncRNA pairs and 8325 candidate miRNA-mRNA pairs, with the associated mRNAs enriched in biological processes such as morphogenesis, stimulus response, and hormone metabolism. These findings provide a set of candidate lncRNAs and lncRNA-PCG associations for future functional validation and may offer useful clues for understanding the possible roles of lncRNAs in agronomic trait-related biological processes and maize molecular breeding. Overall, this study provides candidate genetic resources and a framework for future investigation of lncRNA-associated relationships potentially related to agronomic trait variation in maize.