Sunan He

Vacuolar H⁺-ATPases play crucial roles in plant ion homeostasis and stress adaptation, yet the functional characterization of their subunit genes in purslane remains limited. In this study, PoVHA-a3, encoding a tonoplast-localized V-ATPase a3 subunit, was identified as a key salt-responsive gene through transcriptomic analysis. Integrated bioinformatic analysis and molecular docking simulations predicted specific binding of NAC3, MYB1, and bHLH62 to the PoVHA-a3 promoter, suggesting their synergistic role in regulating PoVHA-a3 expression. Under salt stress, PoVHA-a3 transgenic Arabidopsis lines exhibited elevated endogenous abscisic acid levels and upregulation of signaling genes (AtNCED3, AtRD29A, AtCOR15A), while the brassinosteroid signaling pathway was suppressed, as indicated by the reduced expression of AtBZR1 and AtEXPA8. Meanwhile, the transgenic lines demonstrated enhanced ATP levels, respiratory rate, and V-ATPase activity. In addition, PoVHA-a3 expression led to greater accumulation of osmoprotectants (proline, soluble sugars and proteins), higher activities of antioxidant enzymes, and reduced levels of oxidative stress indices. Furthermore, a significantly lower shoot Na⁺/K⁺ ratio was observed in transgenic plants, indicating improved ion homeostasis. In conclusion, this study demonstrates that PoVHA-a3 acts as a pivotal positive regulator of salt tolerance in purslane, providing a valuable genetic resource for enhancing salt tolerance in crops through genetic engineering.

Mitogen-Activated Protein Kinases (MAPKs) play crucial roles in plant stress signaling, but the mechanisms of MAPK genes in Portulaca oleracea remain functionally uncharacterized. In this study, transcriptomic screening of P. oleracea under salt stress identified PoMPK3 as a candidate gene, showing significant root-specific upregulation. Phylogenetic analysis classified it as a Group A MAPK protein, and subcellular localization confirmed its membrane association. Heterologous expression of PoMPK3 in Arabidopsis thaliana significantly enhanced salt tolerance, as evidenced by improved seed germination rates, longer primary roots, increased biomass, and reduced stress symptoms. Mechanistically, PoMPK3 expression activated ABA signaling, leading to increased ABA levels and upregulation of AtNCED3, AtPYR1, and AtABF3. Furthermore, it strengthened the antioxidant defense, as evidenced by elevated antioxidant enzyme activity, leading to a reduction in oxidative stress. The transgenic lines also demonstrated enhanced osmotic adjustment through osmolytes accumulation and ionic homeostasis, evidenced by tissue-specific Na⁺/K⁺ ratios (low in shoots, high in roots) resulting from the concerted upregulation of AtSOS1, AtNHX1, and AtHKT1. In addition, gene co-expression network analysis and molecular docking predicted phosphorylation of WRKY transcription factors, suggesting a novel mechanism for transcriptome reprogramming. Collectively, our findings not only advance the understanding of salt tolerance mechanisms in purslane but also identify PoMPK3 as a key genetic determinant, thereby laying the foundation for its use in breeding programs aimed at enhancing salt stress resilience in crops.

Saline–alkali land is a critical factor limiting agricultural production and ecological restoration. Utilizing salt-tolerant plants for bioremediation represents an environmentally friendly and sustainable approach to soil management. This study employed the highly salt-tolerant crop Portulaca oleracea L. cv. “Su Ma Chi Xian 3” as the test material. A plot experiment was established in coastal saline soils with planting P. a- oleracea (P) and no planting (CK) under three blocks with the different salt levels (S1: 2.16 g/kg; S2: 4.08 g/kg; S3: 5.43 g/kg) to systematically evaluate its salt accumulation capacity and effects on soil physicochemical properties. The results demonstrated that P. oleracea exhibited adaptability across all three salinity levels, with aboveground biomass following the trend PS2 > PS3 > PS1. The ash salt contents removed through harvesting were 1.29, 2.03, and 1.74 t/ha, respectively, in PS1, PS2, and PS3. Compared to no planting, a significant reduction in bulk density was observed in the 0–10 and 10–20 cm soil layers (p < 0.05). A significant increase in porosity by 9.72%, 16.29%, and 12.61% was found under PS1, PS2, and PS3, respectively, in the 0–10 cm soil layer. Soil salinity decreased by 34.20%, 50.23%, and 48.26%, in the 0–10 cm soil layer and by 14.43%, 32.30%, and 26.42% in the 10–20 cm soil layer under PS1, PS2, and PS3, respectively. The pH exhibited a significant reduction under the planting treatment in the 0–10 cm layer. A significant increase in organic matter content by 13.70%, 12.44%, and 13.55%, under PS1, PS2, and PS3, respectively, was observed in the 0–10 cm soil layer. The activities of invertase and urease were significantly enhanced in the 0–10 and 10–20 cm soil layers, and the activity of alkaline phosphatase also exhibited a significant increase in the 0–10 cm layer under the planting treatment. This study indicated that cultivating P. oleracea could effectively facilitate the improvement of coastal saline soils by optimizing soil structure, reducing salinity, increasing organic matter, and activating the soil enzyme system, thereby providing theoretical and technical foundations for ecological restoration and sustainable agricultural utilization of saline–alkali lands.

Sesbania cannabina (Retz.) Pers., as a legume, has strong waterlogging tolerance, but the lack of genomic information limits the exploration of key genes and molecular mechanisms. In this study, single-molecule real-time technology was used to sequence stems RNA of two Sesbania varieties at five time points under waterlogging stress through the PacBio Iso-Seq platform. The full-length transcriptome information contained 42 Gb raw data, 32,503 transcripts with an average length of 1912.28 nt, N50 length of 2059 nt and GC content of 42.69%. A total of 32,143 coding sequences (CDSs), 1745 transcription factors (TFs), 282 long non-coding RNAs (LncRNAs), 7497 simple sequence repeats (SSRs) and 202 alternative splicing (AS) events were identified through sequence alignment and software analysis. The analysis showed that 10,075 transcripts were enriched in 137 KEGG pathways, and 519 transcripts were included in plant hormone signal transduction, of which 103 and 123 transcripts were, respectively, involved in the ethylene and auxin pathways. The assembly and annotation of full-length transcriptome data of Sesbania provided reliable and accurate genomic information for the exploration of key genes and the study of molecular mechanisms in stem response to waterlogging stress.