Polyploidy occurs prevalently and plays an important role during plant speciation and evolution. This phenomenon suggests polyploidy could develop novel features that enable them to adapt wider range ...of environmental conditions compared with diploid progenitors. Bread wheat (Triticum aestivum L., BBAADD) is a typical allohexaploid species and generally exhibits greater salt tolerance than its tetraploid wheat progenitor (BBAA). However, little is known about the underlying molecular basis and the regulatory pathway of this trait. Here, we show that the histone acetyltransferase TaHAG1 acts as a crucial regulator to strengthen salt tolerance of hexaploid wheat. Salinity-induced TaHAG1 expression was associated with tolerance variation in polyploidy wheat. Overexpression, silencing, and CRISPR-mediated knockout of TaHAG1 validated the role of TaHAG1 in salinity tolerance of wheat. TaHAG1 contributed to salt tolerance by modulating reactive oxygen species (ROS) production and signal specificity. Moreover, TaHAG1 directly targeted a subset of genes that are responsible for hydrogen peroxide production, and enrichment of TaHAG1 triggered increased H3 acetylation and transcriptional upregulation of these loci under salt stress. In addition, we found the salinity-induced TaHAG1-mediated ROS production pathway is involved in salt tolerance difference of wheat accessions with varying ploidy. Our findings provide insight into the molecular mechanism of how an epigenetic regulatory factor facilitates adaptability of polyploidy wheat and highlights this epigenetic modulator as a strategy for salt tolerance breeding in bread wheat.
Summary
Excess soluble salts in soil are harmful to the growth and development of most plants. Evidence is emerging that the plant cell wall is involved in sensing and responding to salt stress, but ...the underlying mechanisms are not well understood. We reveal that the histone acetyltransferase General control non‐repressed protein 5 (GCN5) is required for the maintenance of cell wall integrity and salt stress tolerance. The levels of GCN5 mRNA are increased in response to salt stress. The gcn5 mutants exhibited severe growth inhibition and defects in cell wall integrity under salt stress conditions. Combining RNA sequencing and chromatin immunoprecipitation assays, we identified the chitinase‐like gene CTL1, polygalacturonase involved in expansion‐3 (PGX3) and MYB domain protein‐54 (MYB54) as direct targets of GCN5. Acetylation of H3K9 and H3K14 mediated by GCN5 is associated with activation of CTL1, PGX3 and MYB54 under salt stress. Moreover, constitutive expression of CTL1 in the gcn5 mutant restores salt tolerance and cell wall integrity. In addition, the expression of the wheat TaGCN5 gene in Arabidopsis gcn5 mutant plants complemented the salt tolerance and cell wall integrity phenotypes, suggesting that GCN5‐mediated salt tolerance is conserved between Arabidopsis and wheat. Taken together, our data indicate that GCN5 plays a key role in the preservation of salt tolerance via versatile regulation in plants.
Significance Statement
The elucidation of plant salt‐stress response mechanisms will provide valuable information for promoting crop productivity. In this study we reveal that the histone acetyltransferase general control non‐repressed protein plays a critical role in maintenance of cell wall integrity and salt tolerance by directly targeting cellulose synthesis genes.
Summary
Common wheat (Triticum aestivum L.) is an important staple food crop worldwide. Lateral roots (LRs), as the major component of root architecture, affect water and nutrient uptake in wheat. ...The phytohormone ethylene is known to affect LR formation; however, the factor(s) modulating ethylene during this process have not yet been elucidated in wheat. Here we identified wheat TaWRKY51 as a key factor that functions in LR formation by modulating ethylene biosynthesis. Wheat TaWRKY51RNA interference lines (TaWRKY51‐RNAi) and the homozygous mutants tawrky51‐2a and tawrky51‐2b all produced fewer LRs than the wild type and negative transgenic plants, whereas the TaWRKY51 overexpression lines (TaWRKY51‐OE) had the opposite phenotype. Transcription analysis revealed that 1‐aminocyclopropane‐1‐carboxylic acid synthase (ACS) genes (TaACS2, TaACS7 and TaACS8) involved in ethylene biosynthesis were downregulated in TaWRKY51‐OE lines but upregulated in TaWRKY51‐RNAi lines. The rate of ethylene production also decreased in TaWRKY51‐OE lines but increased in TaWRKY51‐RNAi lines compared with their respective negative transgenic controls. Electrophoretic mobility shift and transient expression assays revealed that TaWRKY51 inhibits the expression of ACS genes by binding to the W‐box cis‐element present in their promoter region. Moreover, overexpression of ACS2 or exogenous application of 1‐aminocyclopropane‐1‐carboxylic acid reversed the phenotype of enhanced LR number in TaWRKY51‐OE Arabidopsis lines, and overexpression of TaWRKY51 in the ethylene‐overproducing mutant eto1‐1 rescued its LR defect phenotype. In addition, genetic evidence demonstrates that TaWRKY51‐regulated LR formation is also dependent on ethylene and auxin signaling pathways. Our findings reveal a molecular genetic mechanism by which a WRKY gene coordinates ethylene production and LR formation in wheat.
Significance Statement
Ethylene is known to affect lateral root formation, but the factor(s) modulating ethylene during this process have not yet been identified in wheat. In this study we identify wheat WRKY51 as a key factor that functions in lateral root formation by modulating ethylene biosynthesis by directly targeting the ethylene synthesis genes.
To promote the resource utilization of steel slag and improve the production process of steel slag in steelmaking plants, this research studied the characteristics of three different processed steel ...slags from four steelmaking plants. The physical and mechanical characteristics and volume stability of steel slags were analyzed through density, water absorption, and expansion tests. The main mineral phases, morphological characteristics, and thermal stability of the original steel slag and the steel slag after the expansion test are analyzed with X-ray diffractometer (XRD), scanning electron microscope (SEM), and thermogravimetric analysis (TG) tests. The results show that the composition of steel slag produced by different processes is similar. The main active substances of other processed steel slags are dicalcium silicate (C
S), tricalcium silicate (C
S), CaO, and MgO. After the expansion test, the main chemical products of steel slag are CaCO
, MgCO
, and calcium silicate hydrate (C-S-H). Noticeable mineral crystals appeared on the surface of the steel slag after the expansion test, presenting tetrahedral or cigar-like protrusions. The drum slag had the highest density and water stability. The drum slag had the lowest porosity and the densest microstructure surface, compared with steel slags that other methods produce. The thermal stability of steel slag treated by the hot splashing method was relatively higher than that of steel slag treated by the other two methods.
Common wheat (
, BBAADD) is an allohexaploid species combines the D genome from
and with the AB genomes from tetraploid wheat (
). Compared with tetraploid wheat, hexaploid wheat has wide-ranging ...adaptability to environmental adversity such as salt stress. However, little is known about the molecular basis underlying this trait. The plasma membrane Na
/H
transporter Salt Overly Sensitive 1 (SOS1) is a key determinant of salt tolerance in plants. Here we show that the upregulation of
expression is positively correlated with salt tolerance variation in polyploid wheat. Furthermore, both transcriptional analysis and GUS staining on transgenic plants indicated
and
exhibited higher basal expression in roots and leaves in normal conditions and further up-regulated under salt stress; while
showed markedly lower expression in roots and leaves under normal conditions, but significant up-regulated in roots but not leaves under salt stress. Moreover, transgenic studies in Arabidopsis demonstrate that three
homoeologs display different contribution to salt tolerance and
plays the prominent role in salt stress. Our findings provide insights into the subgenomic homoeologs variation potential to broad adaptability of natural polyploidy wheat, which might effective for genetic improvement of salinity tolerance in wheat and other crops.
•Lignin content is closely related to the lodging resistance of common buckwheat.•Uniconazole significantly increased the lignin metabolism of common buckwheat.•Uniconazole significantly increased ...the lodging resistance of common buckwheat.•The best concentration of seed dressing with uniconazole was 200mgkg−1.•The best concentration of foliar spraying with uniconazole was 75mgL−1.
Lodging is one of the major factors contributing to common buckwheat (Fagopyrum esculentum M.) yield and quality reduction. This study was conducted to determine whether lignin metabolism and lodging resistance of culm in common buckwheat could be affected by uniconzole. Two common buckwheat cultivars, Youqiao2 (lodging-tolerant cultivar; YQ2) and Ukraine daliqiao (lodging-susceptible cultivar; UD), were used to investigate the effects of uniconzole on the common buckwheat lodging behavior, lignin metabolism in culm and its relation to lodging resistance. In one experiment, seed dressing with uniconazole at the rate of 0 (CK1), 100 (P1), 200 (P2), and 300 (P3)mgkg−1 were applied. In the second experiment, foliar spraying with uniconazole at the rate of 0 (CK2), 25 (S1), 50 (S2), 75 (S3), and 100 (S4)mgL−1 were applied at the four-leaf stage. Results showed that the lignin content was significantly and positively correlated with culm snapping resistance, while significantly and negatively correlated with lodging index and lodging percentage. The lodging index and lodging percentage decreased and then increased with the increase of the concentration of uniconazole, and their minimum values appeared in the P2 and S3 treatments. The yield, culm snapping resistance, lignin content, and the enzyme activities of phenylalanine ammonia-lyase (PAL), 4-coumarate:CoA ligase (4CL), cinnamyl alcohol dehydrogenase (CAD), and peroxidase (POD) increased and then decreased with the increase of the concentration of uniconazole, and their maximum values appeared in the P2 and S3 treatments. These results suggested that the lignin content is closely related to the lodging resistance of common buckwheat, and higher lignin content could strengthen the lodging resistance of common buckwheat. Uniconazole significantly decreased the risk of lodging occurred by increasing the lignin content and its related enzymes activities of culm, and the concentrations which showed the greatest effects were 200mgkg−1 with seed dressing and 75mgL−1 with foliar spraying.
•The grain yield of common buckwheat was significantly correlated with photosynthetic capacity, and agronomic traits.•N fertilizer and planting density had significant effects on the photosynthetic ...capacity, agronomic traits, and yield of common buckwheat.•The combination of N fertilizer of 45 kg ha−1 and 90 plants m−2 is recommended for enhancing the yield of common buckwheat.
Nitrogen fertilizer and planting density are two crucial factors that affect the yield of common buckwheat (Fagopyrum esculentum M.). Youqiao2, a common buckwheat cultivar with high photosynthetic capacity and planted widely in local production was used to investigate the effects of nitrogen fertilizer and planting density on the leaf photosynthetic characteristics, agronomic traits, and grain yield in common buckwheat by a split plot design. The main plots were assigned to three nitrogen fertilizer rates: 0, 45, and 90 kg ha−1, and the subplots were assigned to three planting densities: 60, 90, and 120 plants m−2. Results showed that the grain yield was significantly and positively correlated with net photosynthesis rate (Pn), stomatal conductance (Gs), transpiration rate (Tr), stomatal limitation value (Ls), chlorophyll content (SPAD value), leaf area index (LAI), plant height, stem diameter, branch number, internode number, grain number per plant, and 1000-grain weight, while significantly and negatively correlated with intercellular CO2 concentration (Ci) and water-use efficiency (WUE). The Pn, Gs, Tr, Ls, SPAD, LAI, grain yield, stem diameter, branch number, internode number, grain number per plant, and 1000-grain weight increased and then decreased with the increase of nitrogen fertilizer and planting density, and their maximum values appeared in the nitrogen fertilization of 45 kg ha−1 and planting density of 90 plants m−2 treatment. The Ci and WUE decreased and then increased with the increase of nitrogen fertilizer and planting density, and their minimum values appeared in the nitrogen fertilization of 45 kg ha−1 and planting density of 90 plants m−2 treatment. The plant height increased with the increase of nitrogen fertilizer, while decreased with the increase of planting density. These results suggested that nitrogen fertilizer and planting density had significant effects on the leaf photosynthetic capacity, agronomic traits, and grain yield of common buckwheat, and the combination of nitrogen fertilization of 45 kg ha−1 and planting density of 90 plants m−2 is recommended for common buckwheat planting.
Summary
Plants have evolved a two‐branched innate immune system to detect and cope with pathogen attack, which are initiated by cell‐surface and intracellular immune receptors leading to ...pattern‐triggered immunity (PTI) and effector‐triggered immunity (ETI), respectively. A core transducer including PAD4‐EDS1 node is proposed as the convergence point for a two‐tiered immune system in conferring pathogen immunity. However, the transcriptional regulatory mechanisms controlling expression of these key transducers remain largely unknown.
Here, we identified histone acetyltransferase TaHAG1 as a positive regulator of powdery mildew resistance in wheat. TaHAG1 regulates expression of key transducer gene TaPAD4 and promotes SA and reactive oxygen species accumulation to accomplish resistance to Bgt infection.
Moreover, overexpression and CRISPR‐mediated knockout of TaPAD4 validate its role in wheat powdery mildew resistance. Furthermore, TaHAG1 physically interacts with TaPLATZ5, a plant‐specific zinc‐binding protein. TaPLATZ5 directly binds to promoter of TaPAD4 and together with TaHAG1 to potentiate the expression of TaPAD4 by increasing the levels of H3 acetylation.
Our study revealed a key transcription regulatory node in which TaHAG1 acts as an epigenetic modulator and interacts with TaPLATZ5 that confers powdery mildew resistance in wheat through activating a convergence point gene between PTI and ETI, which could be effective for genetic improvement of disease resistance in wheat and other crops.
Cold injury is a major environmental stress affecting the growth and yield of crops. Brassinosteroids (BRs) and salicylic acid (SA) play important roles in plant cold tolerance. However, whether or ...how BR signaling interacts with the SA signaling pathway in response to cold stress is still unknown. Here, we identified an SA methyltransferase, TaSAMT1, that converts SA to methyl SA (MeSA) and confers freezing tolerance in wheat (Triticum aestivum). TaSAMT1 overexpression greatly enhanced wheat freezing tolerance, with plants accumulating more MeSA and less SA, whereas Tasamt1 knockout lines were sensitive to freezing stress and accumulated less MeSA and more SA. Spraying plants with MeSA conferred freezing tolerance to Tasamt1 mutants, but SA did not. We revealed that BRASSINAZOLE-RESISTANT 1 (TaBZR1) directly binds to the TaSAMT1 promoter and induces its transcription. Moreover, TaBZR1 interacts with the histone acetyltransferase TaHAG1, which potentiates TaSAMT1 expression via increased histone acetylation and modulates the SA pathway during freezing stress. Additionally, overexpression of TaBZR1 or TaHAG1 altered TaSAMT1 expression and improved freezing tolerance. Our results demonstrate a key regulatory node that connects the BR and SA pathways in the plant cold stress response. The regulatory factors or genes identified could be effective targets for the genetic improvement of freezing tolerance in crops.
The most significantly enriched classes of these genes were those responsible for nucleosome organization, which was consistent with the role of TaHAG1 in histone modification (Figure 1o). ......cellular component of plasma membrane and thylakoid was greatly enriched, indicating the membrane and photosynthetic system of TaHAG1-OE might be better adapted to HS treatment, which was further supported by lower electrolytic leakage and higher chlorophyll content in TaHAG1-OE plants. ...this suggested that elevated Fv/Fm may be part of the thermotolerance mechanism mediated by TaHAG1 overexpression. Transient transactivation assay showed that TaNACL was able to activate the expression of TaG1 and TaPSBR1 promoter-driven luciferase (LUC) reporters. ...coexpression TaHAG1 with TaNACL led to a significant increase in TaG1 and TaPSBR1 promoter activation compared with the expression of each single effector (Figure 1v).
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