Integrated transcriptome and metabolome analysis reveals antioxidant machinery in grapevine exposed to salt and alkali stress.

Plant acclimation to salt and alkali stress is closely linked to the ability of the antioxidant system to mediate the scavenging of reactive oxygen species (ROS). In this study, we investigated the effects of salt stress and alkali stress on ROS, antioxidant enzymes, transcriptome, and metabolome. The results showed that the levels of superoxide anions, hydrogen peroxide, malondialdehyde, and electrolyte leakage increased under salt and alkali stress, with higher concentrations observed under alkali stress than salt stress. The activities of superoxide dismutase (EC 1.15.1.1), peroxidase (EC 1.11.1.7), catalase (EC 1.11.1.6), ascorbate peroxidase (EC 1.11.1.11), glutathione reductase (EC 1.6.4.2), dehydroascorbate reductase (EC 1.8.5.1), and monodehydroascorbate reductase (EC 1.6.5.4) varied under salt and alkali stress. The transcriptome analysis revealed the induction of signal transduction and metabolic processes and differential expression of genes encoding antioxidant enzymes in response to salt and alkali stress. The metabolome analysis demonstrated increased ascorbic acid and glutathione under salt stress, while most phenolic acids, flavonoids, and alkaloids increased under salt and alkali stress. Integrative analysis of the metabolome and transcriptome data revealed that the flavonoid biosynthesis pathway played a key role in the grapevine's response to salt stress. The total flavonoid content increased under salt and alkali stress, but the accumulation of flavonoids was higher under salt stress than alkali stress. In conclusion, our findings indicate significant differences in the antioxidant defense of grapevines under these two stresses, providing insight into distinct acclimation mechanisms in grapevine under salt and alkali stress.

Efficient Visible-Light-Driven Tetracycline Degradation and Cr(VI) Reduction over a LaNi1-xFexO3 (0 ≤ x ≤ 1)/g-C3N4 Type-II Heterojunction Photocatalyst.

The development of efficient, stable, and visible-light-responsive photocatalysts is crucial to address the pollution of water bodies by toxic heavy metal ions and organic antibiotics. Herein, a series of LaNi1-xFexO3/g-C3N4 heterojunction photocatalysts are prepared by a simple wet chemical method. Moreover, LaNi0.8Fe0.2O3/g-C3N4 composites are characterized by various methods, including structure, morphology, optical, and electrochemical methods and tetracycline degradation and photocatalytic reduction of Cr(VI) under visible light irradiation. Then, the photocatalytic performance of as-prepared LaNi0.8Fe0.2O3/g-C3N4 composites is evaluated. Compared with pure LaNi0.8Fe0.2O3 and g-C3N4, the LaNi0.8Fe0.2O3/g-C3N4 composite photocatalysts exhibit excellent photocatalytic performance due to synergy of doping and constructing heterojunctions. The results show that the doping of Fe ions can increase the concentration of oxygen vacancies, which is ultimately beneficial to the formation of electron traps. Moreover, the type-II heterojunction formed between LaNi0.8Fe0.2O3 and g-C3N4 effectively strengthens the separation and transfer of photoinduced carriers, thereby promoting photocatalytic activity. Furthermore, the photocatalytic activity of the LaNi0.8Fe0.2O3/g-C3N4 photocatalyst remains almost unchanged after three cycles, indicating long-term stability. Ultimately, the photocatalytic mechanism of the LaNi0.8Fe0.2O3/g-C3N4 composites is proposed.

Grapevine (Vitis vinifera) responses to salt stress and alkali stress: transcriptional and metabolic profiling.

BACKGROUND: Soil salinization and alkalization are widespread environmental problems that limit grapevine (Vitis vinifera L.) growth and yield. However, little is known about the response of grapevine to alkali stress. This study investigated the differences in physiological characteristics, chloroplast structure, transcriptome, and metabolome in grapevine plants under salt stress and alkali stress. RESULTS: We found that grapevine plants under salt stress and alkali stress showed leaf chlorosis, a decline in photosynthetic capacity, a decrease in chlorophyll content and Rubisco activity, an imbalance of Na+ and K+, and damaged chloroplast ultrastructure. Fv/Fm decreased under salt stress and alkali stress. NPQ increased under salt stress whereas decreased under alkali stress. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment showed the differentially expressed genes (DEGs) induced by salt stress and alkali stress were involved in different biological processes and have varied molecular functions. The expression of stress genes involved in the ABA and MAPK signaling pathways was markedly altered by salt stress and alkali stress. The genes encoding ion transporter (AKT1, HKT1, NHX1, NHX2, TPC1A, TPC1B) were up-regulated under salt stress and alkali stress. Down-regulation in the expression of numerous genes in the 'Porphyrin and chlorophyll metabolism', 'Photosynthesis-antenna proteins', and 'Photosynthesis' pathways were observed under alkali stress. Many genes in the 'Carbon fixation in photosynthetic organisms' pathway in salt stress and alkali stress were down-regulated. Metabolome showed that 431 and 378 differentially accumulated metabolites (DAMs) were identified in salt stress and alkali stress, respectively. L-Glutamic acid and 5-Aminolevulinate involved in chlorophyll synthesis decreased under salt stress and alkali stress. The abundance of 19 DAMs under salt stress related to photosynthesis decreased. The abundance of 16 organic acids in salt stress and 22 in alkali stress increased respectively. CONCLUSIONS: Our findings suggested that alkali stress had more adverse effects on grapevine leaves, chloroplast structure, ion balance, and photosynthesis than salt stress. Transcriptional and metabolic profiling showed that there were significant differences in the effects of salt stress and alkali stress on the expression of key genes and the abundance of pivotal metabolites in grapevine plants.

Glucoraphanin and sulforaphane biosynthesis by melatonin mediating nitric oxide in hairy roots of broccoli (Brassica oleracea L. var. italica Planch): insights from transcriptome data.

Glucoraphanin (GRA) is present in the seeds and nutrient organs of broccoli and is the precursor of the anti-cancer compound sulforaphane (SF). The hairy roots obtained by infecting broccoli (Brassica oleracea L. var. Italic Planch) leaves with Agrobacterium rhizogenes (ATCC15834) are phytohormonally autonomous, genetically stable, and can produce large amounts of the anti-cancer substance SF. Melatonin (MT) is a natural hormone widely found in plants. Studies have shown that melatonin can regulate the synthesis of secondary metabolites of downstream targets by mediating the synthesis of signal molecules. However, whether MT regulates the synthesis of NO and H2O2 and mediates the synthesis mechanism of secondary metabolites, GRA and SF, is not yet clear. In this study, the hairy roots of broccoli were treated with 500 µmol/L MT, and the genome of broccoli (Brassica oleracea L. var. botrytis L) was used as the reference genome for transcriptome analysis. By this approach, we found that MT regulates the synthesis of NO and H2O2 and mediates the synthesis of secondary metabolites GRA and SF. GO annotations indicated that DEGs involved in the MT treatment of broccoli hairy roots were mainly related to catalytic activity, cells, and metabolic processes; the KEGG pathway analysis indicated that MT treatment likely affects the hormone signal transduction process in broccoli hairy roots; broccoli hairy roots were treated with 500 µmol/L MT for 0, 6, 12, 20, and 32 h, respectively; compared with 0 h, the yield of GRA and SF increased under the other treatments. The highest yields of GRA and SF occurred at 12 h. The NO content was the highest at 12 h, and the H2O2 content was positively correlated with MT concentration. The content of NO and H2O2 were regulated, and the content of GRA and SF was increased under MT treatment. NO synthase inhibitor (L-NAME and TUN) could effectively inhibit the content of NO in broccoli hairy roots and reduce GRA and SF yield; MT could regulate NO levels by regulating NO synthesis-related enzymes and could alleviate the reduction of NO content in tissue cells caused by NO synthase inhibitor and promote NO synthesis. These results have important theoretical implications for understanding the regulation of GRA and SF synthesis events by NO and H2O2.

Transcriptome analysis of genes related to glucoraphanin and sulforaphane synthesis in methyl jasmonate treated broccoli (Brassica oleracea var. italica) hairy roots.

Hairy roots obtained by infecting broccoli (Brassica oleracea var. italica) leaves with Agrobacterium rhizogenes (ATCC15834) have the characteristics of phytohormone autonomy, genetic stability and can produce a large amount of the anti-cancer substance Sulforaphane (SF) and the biosynthetic precursor Glucoraphanin (GRA). Under the induction of the exogenous signaling molecule methyl jasmonate (MeJA), the production of SF in broccoli hairy roots was significantly increased. However, the molecular mechanism of GRA and SF synthesis in hairy roots of broccoli treated with MeJA has not been reported. In this study, according to the yield of GRA and SF, the best concentration of MeJA treatment for hairy roots of broccoli was selected. After 18 days of growth, broccoli hairy roots were treated with 10 mmol L-1 MeJA for 0, 3, 6, 9 and 12 h. Compared with 0 h, the yield of GRA and SF increased under other treatments. The highest yield of GRA and SF occurred at 9 h, which were 2.22-fold and 1.74-fold higher than those at 0 h. Brassica oleracea var. botrytis was used as reference genome, and 5,757 differentially expressed genes (DEG) were observed at 0, 3, 6, 9 and 12 h under 10 mmol L-1 MeJA treatment, of which 4,673 were down-regulated and 1084 were up-regulated. The key genes regulating GRA synthesis, CYP79F1, CYP83A1, UGT74B1, FMOGS-OX5 and GSL-OH, were up-regulated at 0 and 3 h, and down-regulated the rest of the time; BCAT2 was up-regulated at 6, 9, 12 h, and at 0, 3 h expression was down-regulated, transcription factors MYB28 and MYB29 were down-regulated by exogenous MeJA treatment. A pathway of GRA biosynthesis and transformation pathways in MeJA-treated broccoli hairy roots was simulated and the molecular mechanism of GRA biosynthesis and SF accumulation in broccoli hairy roots under MeJA treatment was revealed.

Transcriptome analysis of melatonin regulating the transformation of glucoraphanin to sulforaphane in broccoli hairy roots.

Sulforaphane (SF) is one of the most effective natural products in preventing and fighting cancer, found in cruciferous plants. In this study, broccoli hairy roots grown for 20 d were used as the experimental material, and it was treated with 500 µmol/L melatonin (MT) for 0, 12 and 32 h to explore the effect of MT on the conversion of glucoraphanin (GRA) to SF. Results showed that the yields of GRA and SF were the largest under MT treatment for 12 h, which were 1.53 and 1.93-fold, respectively, compared to 0 h. However, Myrosinases activity was the highest under MT treatment for 32 h, which was 1.42-fold compared to that of the 0 h. The differential expression of key genes involved in GRA conversion to SF in broccoli hairy roots was identified transcriptome sequencing, and the path of the transformation from GRA to SF was simulated, which provided a theoretical basis for establishing an efficient transformation system from GRA to SF.

Identification and expression analysis of chlorophyll a/b binding protein gene family in grape (Vitis vinifera).

In higher plants, light capture of chlorophyll a/b binding protein (Lhc) plays a crucial role in the plant's response to adverse environment. So far, the family has not been systematically identified in grapes. In this study, 20 VvLhcs were identified in the grape genome, which were distributed in 13 of 19 grape chromosomes and divided into 7 developing branches. The results of gene duplication analysis showed that 6 VvLhcs formed fragment duplication events, while there was no tandem duplication in VvLhcs. Exon-intron structure analysis showed that they had a wide number of exons. Protein conserved motif analysis showed that VvLhcs contained more similar motif structures in the same phylogenetic branch. The cis-acting elements in the VvLhcs promoter region mainly respond to light, plant hormones and abiotic stresses. In addition, qRT-PCR results showed that different proportions of salt stress and red-blue light affected the expression of VvLhcs and the expression patterns of genes in different grape varieties were different. The results for further study on different grape varieties in different combinations of red and blue light of the Lhc provide a theoretical basis. Supplementary Information: The online version contains supplementary material available at 10.1007/s12298-022-01204-5.

Exogenous Melatonin Promotes Glucoraphanin Biosynthesis by Mediating Glutathione in Hairy Roots of Broccoli (Brassica oleracea L. var. italica Planch).

To investigate the mechanism of melatonin (MT)-mediated glutathione (GSH) in promoting glucoraphanin (GRA) and sulforaphane (SF) synthesis, the gene expression pattern and protein content of hairy broccoli roots under MT treatment were analyzed by a combination of RNA-seq and tandem mass spectrometry tagging (TMT) techniques in this study. Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis revealed that both proteins and mRNAs with the same expression trend were enriched in the "Glutathione metabolism (ko00480)" and "Proteasome (ko03050)" pathways, and most of the differentially expressed genes (DEGs) and differentially abundant proteins (DAPs) regulating the two pathways were downregulated. The results showed that endogenous GSH concentration and GR activity were increased in hairy roots after MT treatment. Exogenous GSH could promote the biosynthesis of GRA and SF, and both exogenous MT and GSH could upregulate the expression of the GSTF11 gene related to the sulfur transport gene, thus promoting the biosynthesis of GRA. Taken together, this study provides a new perspective to explore the complex molecular mechanisms of improving GRA and SF synthesis levels by MT and GSH regulation.

Molybdenum disulfide loading on a Z-scheme graphitic carbon nitride and lanthanum nickelate heterojunction for enhanced photocatalysis: Interfacial charge transfer and mechanistic insights.

Interfacial design and the co-catalyst effect are considered to be effective to achieve separation and transport of photogenerated carriers in composite photocatalysts. In this study, a Z-scheme heterojunction was successfully combined with a co-catalyst to achieve a highly efficient LaNiO3/g-C3N4/MoS2 photocatalyst. MoS2 flakes were loaded on a hybrid material surface, which was formed by LaNiO3 nanocubes embedded on layered g-C3N4, and a good heterostructure with multiple attachment sites was obtained. Experimental studies confirmed that the Z-scheme heterojunction completely preserves the strong redox ability of the photogenerated electrons and holes. As a cocatalyst, MoS2 further promoted interfacial charge separation and transport. The synergistic effect of the Z-scheme heterojunction and co-catalyst effectively realized the transfer of photogenerated carriers from "slow transfer" to "high transfer" and promoted water decomposition and pollutant degradation. Results revealed that under simulated sunlight irradiation, LaNiO3/g-C3N4/MoS2 composites exhibit superior hydrogen evolution of 45.1 µmol h-1, which is 19.1 times that of g-C3N4 and 4.9 times that of LaNiO3/g-C3N4, respectively. Moreover, the LaNiO3/g-C3N4/MoS2 Z-scheme photocatalyst exhibited excellent photocatalytic performance for antibiotic degradation and heavy-metal ion reduction under visible light. This study might provide some insights into the development of photocatalysts for solar energy conversion and environmental remediation.

Transcriptomics analysis of genes induced by melatonin related to glucosinolates synthesis in broccoli hairy roots.

Glucoraphanin (GRA) is found in the seeds and vegetative organs of broccoli (Brassica oleracea L. var. italica Planch) as the precursor of anti-carcinogen sulforaphane (SF). The yield of GRA obtained from these materials is weak and the cost is high. In recent years, the production of plant secondary metabolites by large-scale hairy roots culture in vitro has succeeded in some species. Melatonin (MT) is a natural hormone which existed in numerous organisms. Studies have demonstrated that MT can improve the synthesis of secondary metabolites in plants. At present, it has not been reported that MT regulates the biosynthesis of glucoraphanin in broccoli hairy roots. In this study, the broccoli hairy roots that grew for 20 d were respectively treated by 500 µM MT for 0, 6, 12, 20 and 32. To explore the reason of changes in secondary metabolites and reveal the biosynthetic pathway of glucoraphanin at transcriptional level. Compared with 0 h, the yield of GRA under other treatments was increased, and the overall trend was firstly increased and then decreased. The total yield of GRA reached the highest at 12 h, which was 1.22-fold of 0 h. Then, the genome of broccoli as the reference, a total of 13234 differentially expressed genes (DEGs) were identified in broccoli hairy roots under treatment with 500 µM MT for 0, 6, 12, 20 and 32 h, respectively. Among these DEGs, 6266 (47.35%) were upregulated and 6968 (52.65%) were downregulated. It was found that the pathway of 'Glucosinolates biosynthesis (ko00966)' was enriched in the 16th place by Kyoto Encyclopedia of Genes and Genomes pathway enrichment analysis of the upregulated DEGs. The expression of key genes in the GRA biosynthesis pathway was upregulated at all time points, and a deduced GRA biosynthesis pathway map was constructed for reference.