Search

Lipopeptides, a class of compounds consisting of a peptide ring and a fatty acid chain, are secondary metabolites produced by Bacillus spp. As their hydrophilic and oleophilic properties, lipopeptides are widely used in food, medicine, environment and other industrial or agricultural fields. Compared with artificial synthetic surfactants, microbial lipopeptides have the advantages of low toxicity, high efficiency and versatility, resulting in urgent market demand and broad development prospect of lipopeptides. However, due to the complex metabolic network and precursor requirements of synthesis, the specific and strict synthesis pathway, and the coexistence of multiple homologous substances, the production of lipopeptides by microorganisms has the problems of high cost and low production efficiency, limiting the mass production of lipopeptides and large-scale application in industry. This review summarizes the types of Bacillus-produced lipopeptides and their biosynthetic pathways, introduces the versatility of lipopeptides, and describes the methods to improve the production of lipopeptides, including genetic engineering and optimization of fermentation conditions. [ABSTRACT FROM AUTHOR]

SUMMARY: Chilling stress causes banana fruit softening disorder and severely impairs fruit quality. Various factors, such as transcription factors, regulate fruit softening. Herein, we identified a novel regulator, MaC2H2‐IDD, whose expression is closely associated with fruit ripening and softening disorder. MaC2H2‐IDD is a transcriptional activator located in the nucleus. The transient and ectopic overexpression of MaC2H2‐IDD promoted "Fenjiao" banana and tomato fruit ripening. However, transient silencing of MaC2H2‐IDD repressed "Fenjiao" banana fruit ripening. MaC2H2‐IDD modulates fruit softening by activating the promoter activity of starch (MaBAM3, MaBAM6, MaBAM8, MaAMY3, and MaISA2) and cell wall (MaEXP‐A2, MaEXP‐A8, MaSUR14‐like, and MaGLU22‐like) degradation genes. DLR, Y1H, EMSA, and ChIP‐qPCR assays validated the expression regulation. MaC2H2‐IDD interacts with MaEBF1, enhancing the regulation of MaC2H2‐IDD to MaAMY3, MaEXP‐A2, and MaGLU22‐like. Overexpressing/silencing MaC2H2‐IDD in banana and tomato fruit altered the transcript levels of the cell wall and starch (CWS) degradation genes. Several differentially expressed genes (DEGs) were authenticated between the overexpression and control fruit. The DEGs mainly enriched biosynthesis of secondary metabolism, amino sugar and nucleotide sugar metabolism, fructose and mannose metabolism, starch and sucrose metabolism, and plant hormones signal transduction. Overexpressing MaC2H2‐IDD also upregulated protein levels of MaEBF1. MaEBF1 does not ubiquitinate or degrade MaC2H2‐IDD. These data indicate that MaC2H2‐IDD is a new regulator of CWS degradation in "Fenjiao" banana and cooperates with MaEBF1 to modulate fruit softening, which also involves the cold softening disorder. Significance Statement: MaC2H2‐IDD/MaEBF1 complex modulates banana fruit softening by regulating genes related to starch and cell wall degradation. Chilling stress severely represses the activation of softening‐related genes, causing fruit ripening disorder and impairing the texture quality. [ABSTRACT FROM AUTHOR]

As zinc finger protein transcription factors (TFs), the molecular mechanism of Cys-Cys-Cys-His (CCCH) TFs in regulating plant development, growth and stress response has been well studied. However, the roles of CCCH TFs in fruit ripening are still obscure. Herein, we report that MaCCCH33-like2 TF and its associated proteins modulate the fruit softening of 'Fenjiao' bananas. MaCCCH33-like2 interacts directly with the promoters of three genes: isoamylase2 (MaISA2), sugar transporter14-like (MaSUR14-like) and β- d -xylosidase23 (MaXYL23), all of which are responsible for encoding proteins involved in the degradation of starch and cell wall components. Additionally, MaCCCH33-like2 forms interactions with abscisic acid–insensitive 5 (ABI5)-like and ethylene F-box protein 1 (MaEBF1), resulting in enhanced binding and activation of promoters of genes related to starch and cell wall degradation. When MaCCCH33-like2 is transiently and ectopically overexpressed in 'Fenjiao' banana and tomato fruit, it facilitates softening and ripening processes by promoting the degradation of cell wall components and starch and the production of ethylene. Conversely, the temporary silencing of MaCCCH33-like2 using virus-induced gene silencing (VIGS) inhibits softening and ripening in the 'Fenjiao' banana by suppressing ethylene synthesis, as well as starch and cell wall degradation. Furthermore, the promoter activity of MaCCCH33-like2 is regulated by MaABI5-like. Taken together, we have uncovered a novel MaCCCH33-like2/MaEBF1/MaABI5-like module that participates in fruit softening regulation in bananas. [ABSTRACT FROM AUTHOR]