Plant, Cell & Environment最新文献

This study investigated the mechanisms of cadmium (Cd) tolerance and root exudate-mediated soil activation in mulberry (Morus alba L.), a promising species for phytoremediation. Hydroponic experiments with Cd-tolerant seedlings exposed to 5 and 50 mg/L Cd revealed a biphasic concentration-dependent response. Low Cd induced negligible biological effects, whereas high Cd triggered substantial disturbances across multiple biological levels, including morphological alterations, physiological dysregulation and disrupted elemental accumulation patterns. Metabolomic profiling indicated that Cd stress significantly altered the secretion patterns of 17 root exudate metabolites in mulberry, exemplified by the upregulation of sucrose, lactose and 4-acetylbutyric acid, and the downregulation of β-alanine and myo-inositol. Further pathway enrichment analysis linked these differential metabolites to 17 metabolic pathways, with carbohydrate and amino acid metabolism as the main Cd-responsive pathways, suggesting their core role in mediating mulberry's Cd resistance. Root exudates enhanced soil Cd mobilisation in a positive concentration-dependent yet negative time-dependent manner. Consequently, mulberry adapts to Cd stress via metabolic reprogramming of root exudates-a strategic trade-off that serves a dual role by enhancing plant tolerance while simultaneously increasing Cd bioavailability in the soil. This insight provides a foundational framework for phytoremediation, centred on exudate management and the selection of stress-tolerant varieties.

Fruit peel colour is a critical quality trait in chayote, directly influencing its commercial value. However, the molecular mechanisms underlying peel colour variation remain poorly understood. In this study, we observed higher chlorophyll content in deep green peel (DGP), green peel (GP), and light green peel (LGP) compared to white peel (WP). Additionally, WP exhibited reduced chloroplast number and structural disorganisation, with metabolomics confirming the reduction of galactolipids (DGDG and MGDG) essential for membrane stability. Integrated transcriptomic, resequencing, and WGCNA analyses identified SeAPRR2 as a candidate gene controlling peel colour, with a ~ 13-kb deletion in WP responsible for the white phenotype. This deletion triggered downregulation of DEGs related to chlorophyll biosynthesis and photosynthesis pathways. DAP-Seq revealed that SeAPRR2 binds to the cis-element (AAT(G/C)ATT) in promoters. Through Y1H, DLR, GUS activity, EMSA, and molecular docking assays, we confirmed that SeAPRR2 activates the transcription of SeHEMA1 and SeLHCB4 via promoter binding. Heterologous overexpression of SeAPRR2, SeHEMA1, and SeLHCB4 in tomato significantly elevated chlorophyll content and increased chloroplast number. Collectively, this study establishes SeAPRR2 as a master regulator of peel colour through the SeAPRR2-SeHEMA1/SeLHCB4 module. The large-fragment deletion mechanism provides novel genetic insights for breeding colour traits in cucurbit crops.

The mechanisms of selenium (Se) oxyanion transformation in endophytic bacteria remain poorly understood, which limits their application in biofortification and phytoremediation. Here, we investigated these mechanisms using the plant-growth-promoting (PGP) endophyte Erwinia sp. PSI-03. Under 2 mM selenite stress, the strain intracellularly and extracellularly produced spherical selenium nanoparticles (SeNPs; ab57 nm average diameter). Multi-omics analyses revealed that these SeNPs were formed through parallel enzymatic (mediated by sulfite reductase, cysI) and non-enzymatic (via glutathione and l-cysteine) reduction pathways. Additionally, γ-glutamyl-Se-methylselenocysteine was identified as a key organo-selenium metabolite. Selenite exposure induced extensive reprogramming of the metabolome and transcriptome, highlighting key roles for glutathione metabolism and stress response systems related to cell wall/membrane maintenance, oxidative phosphorylation, two-component signaling systems, and DNA repair. Intriguingly, selenite stress concurrently stimulated bacterial synthesis of PGP compounds, including the auxin precursor indole-3-pyruvate, the defense hormone salicylic acid, and acetate. Consistent with this, under selenite-free and high-selenite (12 mg kg^-1 Se) conditions, inoculation with Erwinia sp. PSI-03 significantly promoted tea plant growth. Compared to uninoculated controls, the leaf biomass increased by 52.8% and 51.7%, and the total biomass by 82.9% and 49.6%, respectively. These findings establish a paradigm where endophytic bacteria simultaneously detoxify Se and promote plant health, offering a robust strategy for agricultural and environmental Se management.

Global climate warming has significantly increased plant diseases prevalence. In subtropical regions, high temperature frequently co-occurs with bacterial wilt caused by Ralstonia solanacearum, creating compound stress conditions that severely compromise eggplant productivity. However, the molecular mechanisms governing eggplant's response to combined heat and pathogen stress remain poorly characterized. In this study, we conducted the temperature analyses of Guangzhou, China, and isolated a thermotolerant strain PSS219-GZ under high temperatures in eggplant. Phenotypic analysis of eggplants inoculated with PSS219-GZ at different temperature, indicated that PSS219-GZ have maximal pathogenicity at 37°C. SmWRKY6 is a WRKY transcription factor activated by both high temperatures and Ralstonia solanacearum infection. Genetic evidence from silencing of SmWRKY6 via VIGS in eggplants and overexpression of SmWRKY6 in tomato demonstrated that SmWRKY6 is essential for enhancing resistance to Ralstonia solanacearum under high-temperature stress. SmWRKY6 directly binds to and transcriptionally activates the SmPR1b promoter, forming a key regulatory node in bacterial wilt resistance pathways. This study provides novel insights into plant responses to combined heat and R. solanacearum stress and highlights potential resistance genes for mitigating compound stress effects.

Rice (Oryza sativa L.) features a unique inflorescence organ known as the spikelet, comprising floret, lemma/palea, sterile lemmas, and rudimentary glumes, of which the molecular regulation underlying sterile lemma identity remains elusive. Here, we isolated the G1 locus for sterile lemma specification using an F₂ population developed by crossing between Nipponbare and LG7, a variety with a lemma-like-sterile lemma (lsl). An SNP (+323 G/A) in G1 alleles causes a serine to asparagine (S108N) substitution, leading to the lsl phenotype. Mechanistically, we found that G1 transactivates the expressions of both OsMADS34 and TGW2, two genes known to regulate sterile lemma identity and grain size, through binding to the YACTGTW and CArG-box motifs within their promoters, respectively. Subsequently, we reveal that the transactivation activity of G1^NIP (allele from Nipponbare) is further enhanced through interactions with either OsMADS34 or TGW2. Furthermore, we demonstrated that G1 specifies sterile lemma identity via OsMADS34 and controls grain size through TGW2. Our results reveal two transcriptional circuits (G1-OsMADS34 and G1-TGW2) that are crucial for determining sterile lemma identity and grain size of rice, providing insights into genetic improvement for breeding programs.

Most Proteaceae and some Fabaceae species produce specialised cluster roots (CRs), and are abundant in severely phosphorus (P)-impoverished soils in southwest Australia. Two types of CRs, compound and simple, have been identified. However, the difference in their P-mining strategies remains unclear. Therefore, we conducted glasshouse and field experiments to compare the P-acquisition strategies among 18 CR-producing species in Proteaceae and Fabaceae. Proteaceae produced a significantly larger mass of CRs than Fabaceae. Particularly, Banksia species produced the largest mass of compound CRs and exhibited the greatest net plant-absorbed P in pots and consistently higher mature leaf manganese concentration in the field. In contrast, Hakea and Grevillea species produced less mass of simple CRs but three times as much soil adhered to their CRs per CR dry weight, resulting in greater absorbed P per CR weight. All plants depleted similar P compounds from soil and accessed c. 52% of P that was not extracted by a NaOH-EDTA solution, suggesting that both CRs shared a common physiological function for mining scarcely available P. This study highlights two divergent P-acquisition strategies: greater biomass investment in compound CRs versus greater P-acquisition efficiency in simple CRs.