Discovery of gene regulation mechanisms associated with uniconazole-induced cold tolerance in banana using integrated transcriptome and metabolome analysis.

BACKGROUND: The gibberellic acid (GA) inhibitor, uniconazole, is a plant growth regulator commonly used in banana cultivation to promote dwarfing but also enhances the cold resistance in plants. However, the mechanism of this induced cold resistance remains unclear. RESULTS: We confirmed that uniconazole induced cold tolerance in bananas and that the activities of Superoxide dismutase and Peroxidase were increased in the uniconazole-treated bananas under cold stress when compared with the control groups. The transcriptome and metabolome of bananas treated with or without uniconazole were analyzed at different time points under cold stress. Compared to the control group, differentially expressed genes (DEGs) between adjacent time points in each uniconazole-treated group were enriched in plant-pathogen interactions, MAPK signaling pathway, and plant hormone signal transduction, which were closely related to stimulus-functional responses. Furthermore, the differentially abundant metabolites (DAMs) between adjacent time points were enriched in flavone and flavonol biosynthesis and linoleic acid metabolism pathways in the uniconazole-treated group than those in the control group. Temporal analysis of DEGs and DAMs in uniconazole-treated and control groups during cold stress showed that the different expression patterns in the two groups were enriched in the linoleic acid metabolism pathway. In addition to strengthening the antioxidant system and complex hormonal changes caused by GA inhibition, an enhanced linoleic acid metabolism can protect cell membrane stability, which may also be an important part of the cold resistance mechanism of uniconazole treatment in banana plants. CONCLUSIONS: This study provides information for understanding the mechanisms underlying inducible cold resistance in banana, which will benefit the production of this economically important crop.

Transcriptomic and metabolomic differences between banana varieties which are resistant or susceptible to Fusarium wilt.

Background: Fusarium wilt, caused by Fusarium oxysporum f. sp. cubense race 4 (Foc4), is the most lethal disease of bananas in Asia. Methods: To better understand the defense response of banana to Fusarium wilt, the transcriptome and metabolome profiles of the roots from resistant and susceptible bananas inoculated with Foc4 were compared. Results: After Foc4 inoculation, there were 172 and 1,856 differentially expressed genes (DEGs) in the Foc4-susceptible variety (G1) and Foc4-resistant variety (G9), respectively. In addition, a total of 800 DEGs were identified between G1 and G9, which were mainly involved in the oxidation-reduction process, cell wall organization, phenylpropanoid biosynthesis, and lipid and nitrogen metabolism, especially the DEGs of Macma4_08_g22610, Macma4_11_g19760, and Macma4_03_g06480, encoding non-classical arabinogalactan protein; GDSL-like lipase; and peroxidase. In our study, G9 showed a stronger and earlier response to Foc4 than G1. As the results of metabolomics, lipids, phenylpropanoids and polyketides, organic acids, and derivatives played an important function in response to Fusarium wilt. More importantly, Macma4_11_g19760 might be one of the key genes that gave G9 more resistance to Foc4 by a lowered expression and negative regulation of lipid metabolism. This study illustrated the difference between the transcriptomic and metabolomic profiles of resistant and susceptible bananas. These results improved the current understanding of host-pathogen interactions and will contribute to the breeding of resistant banana plants.

Integrated metabolomic and transcriptomic analyses of regulatory mechanisms associated with uniconazole-induced dwarfism in banana.

BACKGROUND: Uniconazole is an effective plant growth regulator that can be used in banana cultivation to promote dwarfing and enhance lodging resistance. However, the mechanisms underlying banana dwarfing induced by uniconazole are unknown. In uniconazole-treated bananas, gibberellin (GA) was downregulated compared to the control groups. An integrative analysis of transcriptomes and metabolomes was performed on dwarf bananas induced by uniconazole and control groups. The key pathways involved in uniconazole-induced dwarfism in banana were determined according to the overlap of KEGG annotation of differentially expressed genes and (DEGs) differential abundant metabolites (DAMs). RESULTS: Compared with the control groups, the levels of some flavonoids, tannins, and alkaloids increased, and those of most lipids, amino acids and derivatives, organic acids, nucleotides and derivatives, and terpenoids decreased in uniconazole-treated bananas. Metabolome analysis revealed the significant changes of flavonoids in uniconazole-treated bananas compared to control samples at both 15 days and 25 days post treatment. Transcriptome analysis shows that the DEGs between the treatment and control groups were related to a series of metabolic pathways, including lignin biosynthesis, phenylpropanoid metabolism, and peroxidase activity. Comprehensive analysis of the key pathways of co-enrichment of DEGs and DAMs from 15 d to 25 d after uniconazole treatment shows that flavonoid biosynthesis was upregulated. CONCLUSIONS: In addition to the decrease in GA, the increase in tannin procyanidin B1 may contribute to dwarfing of banana plants by inhibiting the activity of GA. The increased of flavonoid biosynthesis and the change of lignin biosynthesis may lead to dwarfing phenotype of banana plants. This study expands our understanding of the mechanisms underlying uniconazole-induced banana dwarfing.

Antifungal mechanism of Bacillus amyloliquefaciens strain GKT04 against Fusarium wilt revealed using genomic and transcriptomic analyses.

The application of endophytic bacteria, particularly members of the genus Bacillus, offers a promising strategy for the biocontrol of plant fungal diseases, owing to their sustainability and ecological safety. Although multiple secondary metabolites that demonstrate antifungal capacity have been identified in diverse endophytic bacteria, the regulatory mechanisms of their biosynthesis remain largely unknown. To elucidate this, we sequenced the entire genome of Bacillus amyloliquefaciens GKT04, a strain isolated from banana root, which showed high inhibitory activity against Fusarium oxysporum f. sp. cubense race 4 (FOC4). The GKT04 genome consists of a circular chromosome and a circular plasmid, which harbors 4,087 protein-coding genes and 113 RNA genes. Eight gene clusters that could potentially encode antifungal components were identified. We further applied RNA-Seq analysis to survey genome-wide changes in the gene expression of strain GKT04 during its inhibition of FOC4. In total, 575 upregulated and 242 downregulated genes enriched in several amino acid and carbohydrate metabolism pathways were identified. Specifically, gene clusters associated with difficidin, bacillibactin, and bacilysin were significantly upregulated, and their gene regulatory networks were constructed. Our work thereby provides insights into the genomic features and gene expression patterns of this B. amyloliquefaciens strain, which presents an excellent potential for the biocontrol of Fusarium wilt.

Overcoming matrix effects: GC method development for the determination of triethylamine and dimethyl sulfoxide in a drug substance.

A direct injection gas chromatography method was developed for the determination of triethylamine and dimethyl sulfoxide (DMSO) in a drug substance (ML-189). Matrix effects were found to result in the overestimation of DMSO when methanol was used as diluent. Multiple approaches to eliminate matrix effects were unsuccessful; these included changes in sample size, split ratio, injector temperature and injector liner (e.g., deactivated liner). Ultimately, matrix effects were eliminated after the diluent was changed from methanol to acetone. A mechanism was proposed and discussed.

[Follow-up of chronic filariasis patients in Jinshan District, Shanghai from 2009 to 2011].

OBJECTIVE: To understand the prognosis of chronic filariasis patients who were nursed with the care methods recommended by WHO in Jinshan District, Shanghai. METHODS: The chronic filariasis patients who were nursed with the care methods recommended by WHO were followed up in Jinshan District from 2009 to 2011. The patients of Level 1 were followed up once a year; the patients of Level 2 and Level 3 were followed up twice a year. All the results were recorded into the standard questionnaires and analyzed statistically. RESULTS: By the end of 2011, there were 264 chronic filariasis patients, including 106 males and 158 females. There were 201 patients aged between 70 and 85 years old, accounting for 76.14% of the patients. Lymphedema was the most common symptom in the patients and 76.51% of the patients had it. From 2009 to 2011, the conducting rates of sanitary cleaning the limbs, elevation of the limbs, and exercises were 89.02%, 83.71% and 72.08%, respectively. The improvement rates were 6.54%, 10.95% and 14.77% each year, which had a statistically significant difference (chi2 = 18.359, P < 0.01). CONCLUSION: The care methods of chronic filariasis patients recommend by WHO really benefit the relief of lymphedema, and should be popularized.