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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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Fusarium wilt caused by Fusarium oxysporum f. sp. cubense (Foc), is one of the most devastating diseases in bananas resulting in significant loss of Cavendish bananas production worldwide. Here we show the agronomic traits and the resistance of 'Guijiao 9′ in the field trials from 2012 to 2017. And then we dissect and compare the transcriptome response from these two cultivars (cv. 'Guijiao 9′ and cv. Williams) in an attempt to understand the molecular basis that contribute to the enhanced Foc tropical race 4 (Foc -TR4) resistance. 'Guijiao 9′ is a Cavendish cultivar with strong resistance to Foc -TR4, which was reflected in a lower disease severity and incidence in glasshouse and field trails, when compared to the susceptible cultivar Williams. Gene expression profiles of 'Guijiao 9′ and Williams were captured by performing RNA-Seq analysis on 16 biological samples collected over a six day period post inoculation with Foc -TR4. Transcriptional reprogramming in response to Foc -TR4 was detected in both genotypes but the response was more drastic in 'Guijiao 9′ than in Williams. Specific genes involved in plant-pathogen interaction and defense signaling including MAPK, calcium, salicylic acid, jasmonic acid and ethylene pathways were analyzed and compared between 'Guijiao 9′ and Williams. Genes associated with defense-related metabolites synthesis such as NB-LRR proteins, calmodulin-binding protein and phenylpropanoids biosynthesis genes were significantly up-regulated in 'Guijiao 9′ resistant to Foc -TR4 infection. Taken together, this study highlights the important roles of plant hormone regulation and defense gene activation in mediating resistance in 'Guijiao 9'. • A new breeding banana cultivar 'Guijiao 9′ showed good resistance to Fusarium wilt. • Transcriptional reprogramming in response to the fungus was more drastic in 'Guijiao 9′. • Defense-related genes were significantly up-regulated in 'Guijiao 9′. • The plant hormone regulation and defense gene activation in mediating resistance in 'Guijiao 9′. [ABSTRACT FROM AUTHOR]