Plant, Cell & Environment最新文献

Salicylic acid (SA) and jasmonic acid (JA) play critical roles in regulating plant disease resistance. However, the underlying molecular mechanisms of their coordinated action against pathogens in woody plants, particularly in peach (Prunus persica), are unknown. In this study, we demonstrate that SA and JA positively regulate resistance to bacterial spot disease induced by Xanthomonas arboricola pv. pruni (Xap) in peach. Two defence-responsive genes, pathogenesis-related protein 2 (PpPR2) and PpPR5, were induced to express during this disease response. A key transcription factor, TGACG-BINDING FACTOR 1 (PpTGA1), functioned as a positive regulator of disease resistance by activating PpPR2 and PpPR5 transcription. Furthermore, nonexpressor of pathogenesis-related gene 1 (PpNPR1), a core component of the SA signalling response pathway, interacted with PpTGA1 to enhance transcriptional activation of PpTGA1 on downstream PR genes, thereby strengthening disease resistance. The JA signalling repressor, JASMONATE ZIM-DOMAIN 1 (PpJAZ1), negatively regulated disease resistance by interacting with PpTGA1 and inhibiting its transcriptional activation on the PRs. In summary, this study reveals an important regulatory network mediated by SA-JA hormone crosstalk for peach resistance to bacterial spot disease, based on the PpNPR1/PpJAZ1-PpTGA1-PpPR2/5 cascade. These findings provide novel insight into the synergistic crosstalk between hormones and the defence mechanisms against bacterial spot disease.

Due to their strong oxidizing potential, rapid membrane permeability, and high reactivity, reactive oxygen species (ROS) play essential roles in plant development and stress responses. Superoxide (O₂ ^•-) is a primary product of molecular oxygen reduction and a crucial source of hydrogen peroxide, representing a ROS species of substantial importance. Its detoxification is mediated by superoxide dismutases (SODs) and non-enzymatic antioxidants such as ascorbate and tocopherol. The inherently unstable and dynamic nature of O₂ ^•- demands tight spatial and temporal control to preserve its signaling and developmental functions. The final O₂ ^•- level and its distribution result from the combinatorial effects of its production and scavenging, which is often mediated by phytohormones such as abscisic acid and auxin. The primary objective of this article is to elucidate the putative mechanisms underlying the coregulation of O₂ ^•- production and decomposition during plant development. We summarize current insights into the ABA and auxin-mediated regulation of its production by NADPH oxidases and highlight the central role of SODs, enzymes responsible for O₂ ^•- detoxification, exploring also their key regulatory mechanisms. Using bioinformatics, we propose potential pathways coordinating O₂ ^•- production and scavenging. Mechanisms such as direct activation of SODs by ROS, transcriptional control, and protein-protein interactions that respond to developmental signals are discussed.

Cadmium (Cd) is a significant environmental pollutant with widespread detrimental effects on living organisms, making it a frequent subject of laboratory studies. However, different types of Cd salts are used to spike media, often without considering the possibility that accompanying anions may influence the effects of metal cations. Using two commonly used Cd salts, CdSO₄ and CdCl₂, we observed distinct toxicity effects on Arabidopsis thaliana development. On a physiological level, 7-day-old seedlings exposed to 50 µM CdSO₄ had shorter roots than those treated with CdCl₂. Proteomic analysis revealed strong downregulation of proteins involved in microtubule organization and primary cell wall synthesis in the root of plants exposed to CdSO₄. Additionally, these plants exhibited higher Cd uptake from the medium and greater Cd accumulation in the shoot, indicating that the SO₄ ^2-, as an accompanying anion, exacerbates Cd toxicity. These findings highlight the critical but often overlooked role of accompanying anions in modulating the toxic effects of heavy metals on plants.

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.

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.

Cadmium toxicity severely restricts plant growth and development. Nuclear transcription factor-YA (NF-YA) plays a critical role in regulating abiotic stress tolerance, but its role in Cd stress remains unknown. We identified AtNF-YA3 transcription factor as a crucial player in Arabidopsis thaliana Cd stress tolerance. AtNF-YA3 overexpression significantly enhances tolerance to Cd stress, while AtNF-YA3 knockout causes heightened sensitivity. Overexpression significantly reduced Cd²⁺ flux in roots and whole-plant Cd accumulation, whereas AtNF-YA3 knockout enhanced Cd²⁺ flux, and Cd and ROS accumulation. Transcriptome analysis revealed that Cd stress disrupted immune responsive pathways in the knockout line relative to wild-type. Moreover, AtWRKY41 transcription factor expression levels decreased by approximately two-fold in the knockout line relative to wild-type. Yeast two-hybrid and luciferase assays demonstrated a direct interaction between AtNF-YA3 and AtWRKY41; yeast one-hybrid and dual-luciferase assays confirmed that AtWRKY41 directly binds to the AtNF-YA3 promoter. Arabidopsis AtWRKY41 knockout lines exhibited significantly increased sensitivity to Cd stress, and increased Cd²⁺ flux rates and Cd and ROS accumulation. Genetic analysis indicated that AtWRKY41 acts upstream of AtNF-YA3 to increase Cd stress tolerance. Together, these findings suggest that AtNF-YA3 is a key regulator of Cd tolerance and a potential target for plant heavy metal phytoremediation research.

Wheat natural resistance-associated macrophage protein 3 (NRAMP3) are manganese (Mn) transporters that can also transport unwanted cadmium (Cd). However, their roles in regulating grain Cd concentration are unknown. Here, we functionally characterised TpNRAMP3-7A and TpNRAMP3-7B cloned from dwarf Polish wheat (Triticum polonicum L., AABB) in them of their expression patterns, transcript localisations, metal transport activities, and associated phenotypes. Both TpNRAMP3-7A and TpNRAMP3-7B were expressed in the epidermis, endodermis, and xylem parenchyma cells of roots, the xylem parenchyma cells and phloem region of nodes and leaf sheaths, and the phloem region of leaf blades. Knockout of TpNRAMP3-7A and/or TpNRAMP3-7B not only limited grain Cd concentration, but also reduced Cd uptake, root-to-shoot translocation, and shoot-to-grain distribution. They also limited grain Mn concentration by inhibiting shoot-to-grain Mn distribution when grown in the field (high-Mn concentration), and decreased Mn uptake and root-to-shoot translocation under low-Mn stress. Position 192F in TpNRAMP3 was the core amino acid determining Cd and Mn transport activity. These results provide a valuable guide and target gene for limiting Cd concentration in wheat grains.