Saline–alkaline soils are a major environmental problem that limit plant growth and crop productivity. Plasma membrane H⁺-ATPases and the salt overly sensitive (SOS) signaling pathway play important roles in plant responses to saline–alkali stress. However, little is known about the functional genes and mechanisms regulating the transcription of H⁺-ATPases and SOS pathway genes under saline–alkali stress. In the present study, we identified that the plant AT-rich sequence and zinc-binding (TaPLATZ2) transcription factor are involved in wheat response to saline–alkali stress by directly suppressing the expression of TaHA2/TaSOS3. The knockdown of TaPLATZ2 enhances salt and alkali stress tolerance, while overexpression of TaPLATZ2 leads to salt and alkali stress sensitivity in wheat. In addition, TaWRKY55 directly upregulated the expression of TaPLATZ2 during saline–alkali stress. Through knockdown and overexpression of TaWRKY55 in wheat, TaWRKY55 was shown to negatively modulate salt and alkali stress tolerance. Genetic analyses confirmed that TaPLATZ2 functions downstream of TaWRKY55 in response to salt and alkaline stresses. These findings provide a TaWRKY55–TaPLATZ2–TaHA2/TaSOS3 regulatory module that regulates wheat responses to saline–alkali stress.

Programmed cell death (PCD) is essential for animal and plant development. However, the knowledge of the mechanism regulating PCD in plants remains limited, largely due to technical limitations. Previously, we determined that the protease NtCP14 could trigger PCD in the embryonic suspensor of tobacco (Nicotiana tabacum), providing a unique opportunity to overcome the limitations by creating synchronous two-celled proembryos with ongoing PCD for transcriptome analysis and regulatory factor screening. Here, we performed comparative transcriptome analysis using isolated two-celled proembryos and explored the potential regulatory network underlying NtCP14-triggered PCD. Multiple phytohormones, calcium, microtubule organization, the immunity system, soluble N-ethylmaleimide-sensitive factor attachment protein receptor proteins, long non-coding RNAs and alternative splicing are addressed as critical factors involved in the early stage of suspensor PCD. Genes thought to play crucial roles in suspensor PCD are highlighted. Notably, decreased antioxidant gene expression and increased reactive oxygen species (ROS) levels during suspensor PCD suggest a critical role for ROS signaling in the initiation of NtCP14-triggered PCD. Furthermore, five genes in the regulatory network are recommended as immediate downstream elements of NtCP14. Together, our analysis outlines an overall molecular network underlying protease-triggered PCD and provides a reliable database and valuable clues for targeting elements immediately downstream of NtCP14 to overcome technical bottlenecks and gain deep insight into the molecular mechanism regulating plant PCD.

Plant growth is determined by the production of cells and initiation of new organs. Exploring genes that control cell number and cell size is of great significance for understanding plant growth regulation. In this study, we characterized two wheat mutants, ah and dl, with abnormal growth. The ah mutant is a naturally occurring variant characterized by severe dwarfism, increased tiller number, and reduced grain length, while the dl mutant is derived from an ethyl methane sulfonate (EMS)-mutagenized population and exhibits smaller grain size and slightly reduced plant height. Cytological analyses revealed abnormal cell number, cell morphology and arrangement in the stems and leaves of the ah mutant, along with reduced cell length in the grains of the dl mutant. Map-based cloning identified that both mutants carry mutations in the same gene TavWA1-7D, which encodes a protein with a von Willebrand factor A (vWA) domain. The ah mutant harbors a 174-bp insertion in the 1,402-bp coding sequence (CDS) of TavWA1-7D, causing premature termination of protein translation, while the dl mutant contains a Glu420Lys substitution. Mimicking the TavWA1-7D^ah through clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated nuclease 9-mediated genome editing leads to a severe dwarfism phenotype. The C-terminus of the protein is crucial for its correct subcellular localization and interaction, supporting its critical role for TavWA1-7D function. Proteomic analysis showed that the dwarf phenotype of the ah mutant is associated with impaired photosynthesis, ribosome function, and nucleosome formation. Additionally, TavWA1-7D interacts with an E3 ligase, TaVIP1-3B, the expression levels of which are elevated in both mutants. Overexpression and knockout studies of TaVIP1-3B demonstrated its negative regulatory role in cell length and grain size. Together, our findings suggest that TavWA1-7D plays a vital role in regulating wheat growth and yield-related traits, with the dl mutant's short grain phenotype being associated with TaVIP1-3B expression levels.

Cysteine is the precursor for the biosynthesis of glutathione, a key stress-protective metabolite, and methionine, which is imperative for cell growth and protein synthesis. The exact mechanism that governs the routing of cysteine toward glutathione or methionine during stresses remains unclear. Our study reveals that under oxidative stress, methionine and glutathione compete for cysteine and that the increased oxidized glutathione (GSSG) levels under stress hinder methionine biosynthesis. Moreover, we find that inhibition occurs as GSSG binds to and accelerates the degradation of cystathionine γ-synthase, a key enzyme in the methionine synthesis pathway. Consequently, this leads to a reduction in the flux toward methionine-derived metabolites and redirects cysteine utilization toward glutathione, thereby enhancing plant protection. Our study suggests a novel regulatory feedback loop involving glutathione, methionine, and cysteine, shedding light on the plant stress response and the adaptive rerouting of cysteine. These findings offer new insights into the intricate balance of growth and protection in plants and its impact on their nutritional value due to low methionine levels under stress.

Rapeseed (Brassica napus L.) exhibits high-sulfur requirements to achieve optimal growth, development, and pathogen resistance. Despite the importance of sulfur, the mechanisms regulating its metabolism and disease resistance are not fully understood. In this study, we found that the zinc finger transcription factors BnaSTOP2s play a pivotal role in sulfur metabolism and Sclerotinia sclerotiorum resistance. Our findings indicate that BnaSTOP2s are involved in sulfur metabolism, as evidenced by extensive protein interaction screening. BnaSTOP2s knockout reduced the content of essential sulfur-containing metabolites, including glucosinolate and glutathione, which is consistent with the significantly lowered transcriptional levels of BnaMYB28s and BnaGTR2s, key factors involved in glucosinolate synthesis and transportation, respectively. Comprehensive RNA-seq analysis revealed the substantial effect of BnaSTOP2s on sulfur metabolism from roots to siliques, which serve as pivotal sources and sinks for sulfur metabolism, respectively. Furthermore, we found that leaf lesion size significantly decreased and increased in the BnaSTOP2-OE and Bnastop2 mutants, respectively, compared with the wild-type during S. sclerotiorum infection, suggesting a vital role of BnaSTOP2s in plant defense response. In conclusion, BnaSTOP2s act as global regulators of sulfur metabolism and confer resistance to S. sclerotiorum infection in B. napus. Thus, they have potential implications for improving crop resilience.

Poplar plantations are often established on nitrogen-poor land, and poplar growth and wood formation are constrained by low nitrogen (LN) availability. However, the molecular mechanisms by which specific genes regulate wood formation in acclimation to LN availability remain unclear. Here, we report a previously unrecognized module, basic region/leucine zipper 55 (PtobZIP55)–PtoMYB170, which regulates the wood formation of Populus tomentosa in acclimation to LN availability. PtobZIP55 was highly expressed in poplar wood and induced by LN. Altered wood anatomical properties and increased lignification were detected in PtobZIP55-overexpressing poplars, whereas the opposite results were detected in PtobZIP55-knockout poplars. Molecular and transgenic analyses revealed that PtobZIP55 directly binds to the promoter sequence of PtoMYB170 to activate its transcription. The phenotypes of PtoMYB170 transgenic poplars were similar to those of PtobZIP55 transgenic poplars under LN conditions. Further molecular analyses revealed that PtoMYB170 directly bound the promoter sequences of lignin biosynthetic genes to activate their transcription to increase lignin concentrations in LN-treated poplar wood. These results suggest that PtobZIP55 activates PtoMYB170 transcription, which in turn positively regulates lignin biosynthetic genes, increasing lignin deposition in the wood of P. tomentosa in the context of acclimation to LN availability.

Plants have mechanisms to transport secondary metabolites from where they are biosynthesized to the sites where they function, or to sites such as the vacuole for detoxification. However, current research has mainly focused on metabolite biosynthesis and regulation, and little is known about their transport. Tanshinone, a class diterpenoid with medicinal properties, is biosynthesized in the periderm of Salvia miltiorrhiza roots. Here, we discovered that tanshinone can be transported out of peridermal cells and secreted into the soil environment and that the ABC transporter SmABCG1 is involved in the efflux of tanshinone ⅡA and tanshinone Ⅰ. The SmABCG1 gene is adjacent to the diterpene biosynthesis gene cluster in the S. miltiorrhiza genome. The temporal–spatial expression pattern of SmABCG1 is consistent with tanshinone accumulation profiles. SmABCG1 is located on the plasma membrane and preferentially accumulates in the peridermal cells of S. miltiorrhiza roots. Heterologous expression in Xenopus laevis oocytes demonstrated that SmABCG1 can export tanshinone ⅡA and tanshinone Ⅰ. CRISPR/Cas9-mediated mutagenesis of SmABCG1 in S. miltiorrhiza hairy roots resulted in a significant decrease in tanshinone contents in both hairy roots and the culture medium, whereas overexpression of this gene resulted in increased tanshinone contents. CYP76AH3 transcript levels increased in hairy roots overexpressing SmABCG1 and decreased in knockout lines, suggesting that SmABCG1 may affect the expression of CYP76AH3, indirectly regulating tanshinone biosynthesis. Finally, tanshinone ⅡA showed cytotoxicity to Arabidopsis roots. These findings offer new perspectives on plant diterpenoid transport and provide a new genetic tool for metabolic engineering and synthetic biology research.

Insects secret chemosensory proteins (CSPs) into plant cells as potential effector proteins during feeding. The molecular mechanisms underlying how CSPs activate plant immunity remain largely unknown. We show that CSPs from six distinct insect orders induce dwarfism when overexpressed in Nicotiana benthamiana. Agrobacterium-mediated transient expression of Nilaparvata lugens CSP11 (NlCSP11) triggered cell death and plant dwarfism, both of which were dependent on ENHANCED DISEASE SUSCEPTIBILITY 1 (EDS1), N requirement gene 1 (NRG1) and SENESCENCE-ASSOCIATED GENE 101 (SAG101), indicating the activation of effector-triggered immunity (ETI) in N. benthamiana. Overexpression of NlCSP11 led to stronger systemic resistance against Pseudomonas syringae DC3000 lacking effector HopQ1-1 and tobacco mosaic virus, and induced higher accumulation of salicylic acid (SA) in uninfiltrated leaves compared to another effector XopQ that is recognized by a Toll-interleukin-1 receptor (TIR) domain nucleotide-binding leucine-rich repeat receptor (TNL) called ROQ1 in N. benthamiana. Consistently, NlCSP11-induced dwarfism and systemic resistance, but not cell death, were abolished in N. benthamiana transgenic line expressing the SA-degrading enzyme NahG. Through large-scale virus-induced gene silencing screening, we identified a TNL protein that mediates the recognition of CSPs (RCSP), including aphid effector MP10 that triggers resistance against aphids in N. benthamiana. Co-immunoprecipitation, bimolecular fluorescence complementation and AlphaFold2 prediction unveiled an interaction between NlCSP11 and RCSP. Interestingly, RCSP does not contain the conserved catalytic glutamic acid in the TIR domain, which is required for TNL function. Our findings point to enhanced ETI and systemic resistance by a TNL protein via hyperactivation of the SA pathway. Moreover, RCSP is the first TNL identified to recognize an insect effector.