The Ginkgo biloba microRNA160-ERF4 module participates in terpene trilactone biosynthesis.

Terpene trilactones (TTLs) are important secondary metabolites in ginkgo (Ginkgo biloba); however, their biosynthesis gene regulatory network remains unclear. Here, we isolated a G. biloba ethylene response factor 4 (GbERF4) involved in TTL synthesis. Overexpression of GbERF4 in tobacco (Nicotiana tabacum) significantly increased terpenoid content and upregulated the expression of key enzyme genes (3-hydroxy-3-methylglutaryl-CoA reductase [HMGR], 3-hydroxy-3-methylglutaryl-CoA synthase [HMGS], 1-deoxy-D-xylulose-5-phosphate reductoisomerase [DXR], 1-deoxy-D-xylulose-5-phosphate synthase [DXS], acetyl-CoA C-acetyltransferase [AACT], and geranylgeranyl diphosphate synthase [GGPPS]) in the terpenoid pathway in tobacco, suggesting that GbERF4 functions in regulating the synthesis of terpenoids. The expression pattern analysis and previous microRNA (miRNA) sequencing showed that gb-miR160 negatively regulates the biosynthesis of TTLs. Transgenic experiments showed that overexpression of gb-miR160 could significantly inhibit the accumulation of terpenoids in tobacco. Targeted inhibition and dual-luciferase reporter assays confirmed that gb-miR160 targets and negatively regulates GbERF4. Transient overexpression of GbERF4 increased TTL content in G. biloba, and further transcriptome analysis revealed that DXS, HMGS, CYPs, and transcription factor genes were upregulated. In addition, yeast 1-hybrid and dual-luciferase reporter assays showed that GbERF4 could bind to the promoters of the HMGS1, AACT1, DXS1, levopimaradiene synthase (LPS2), and GGPPS2 genes in the TTL biosynthesis pathway and activate their expression. In summary, this study investigated the molecular mechanism of the gb-miR160-GbERF4 regulatory module in regulating the biosynthesis of TTLs. It provides information for enriching the understanding of the regulatory network of TTL biosynthesis and offers important gene resources for the genetic improvement of G. biloba with high contents of TTLs.

Genome-wide analysis of NAC transcription factors and exploration of candidate genes regulating selenium metabolism in Broussonetia papyrifera.

MAIN CONCLUSION: Genome-wide identification revealed 79 BpNAC genes belonging to 16 subfamilies, and their gene structures and evolutionary relationships were characterized. Expression analysis highlighted their importance in plant selenium stress responses. Paper mulberry (Broussonetia papyrifera), a deciduous arboreal plant of the Moraceae family, is distinguished by its leaves, which are abundant in proteins, polysaccharides, and flavonoids, positioning it as a novel feedstock. NAC transcription factors, exclusive to plant species, are crucial in regulating growth, development, and response to biotic and abiotic stress. However, extensive characterization of the NAC family within paper mulberry is lacking. In this study, 79 BpNAC genes were identified from the paper mulberry genome, with an uneven distribution across 13 chromosomes. A comprehensive, genome-wide analysis of BpNACs was performed, including investigating gene structures, promoter regions, and chromosomal locations. Phylogenetic tree analysis, alongside comparisons with Arabidopsis thaliana NACs, allowed for categorizing these genes into 16 subfamilies in alignment with gene structure and motif conservation. Collinearity analysis suggested a significant homologous relationship between the NAC genes of paper mulberry and those in Morus notabilis, Ficus hispida, Antiaris toxicaria, and Cannabis sativa. Integrating transcriptome data and Se content revealed that 12 BpNAC genes were associated with selenium biosynthesis. Subsequent RT-qPCR analysis corroborated the correlation between BpNAC59, BpNAC62 with sodium selenate, and BpNAC55 with sodium selenite. Subcellular localization experiments revealed the nuclear functions of BpNAC59 and BpNAC62. This study highlights the potential BpNAC transcription factors involved in selenium metabolism, providing a foundation for strategically breeding selenium-fortified paper mulberry.

The long noncoding RNAs lnc10 and lnc11 regulating flavonoid biosynthesis in Ginkgo biloba.

Although long non-coding RNAs have been recognized to play important roles in plant, their possible functions and potential mechanism in Ginkgo biloba flavonoid biosynthesis are poorly understood. Flavonoids are important secondary metabolites and healthy components of Ginkgo biloba. They have been widely used in food, medicine, and natural health products. Most previous studies have focused on the molecular mechanisms of structural genes and transcription factors that regulate flavonoid biosynthesis. Few reports have examined the biological functions of flavonoid biosynthesis by long non-coding RNAs in G. biloba. Long noncoding RNAs associated with flavonoid biosynthesis in G. biloba have been identified through RNA sequencing, but the function of lncRNAs has not been reported. In this study, the expression levels of lnc10 and lnc11 were identified. Quantitative real-time polymerase chain reaction analysis revealed that lnc10 and lnc11 were expressed in all detected organs, and they showed significantly higher levels in immature and mature leaves than in other organs. In addition, to fully identify the function of lnc10 and lnc11 in flavonoid biosynthesis in G. biloba, lnc10 and lnc11 were cloned from G. biloba, and were transformed into Arabidopsis and overexpressed. Compared with the wild type, the flavonoid content was increased in transgenic plants. Moreover, the RNA-sequencing analysis of wild-type, lnc10-overexpression, and lnc11-overexpression plants screened out 2019 and 2552 differentially expressed genes, and the transcript levels of structural genes and transcription factors associated with flavonoid biosynthesis were higher in transgenic Arabidopsis than in the wild type, indicating that lnc10 and lnc11 activated flavonoid biosynthesis in the transgenic lines. Overall, these results suggest that lnc10 and lnc11 positively regulate flavonoid biosynthesis in G. biloba.

LILRB4 knockdown inhibits aortic dissection development by regulating pyroptosis and the JAK2/STAT3 signaling pathway.

Aortic dissection (AD) is a life-threatening condition with a high mortality rate and without effective pharmacological therapies. Our previous study illustrated that leukocyte immunoglobulin-like receptor B4 (LILRB4) knockdown promoted the contractile phenotypic switch and apoptosis of AD cells. This study aimed to further investigate the role of LILRB4 in animal models of AD and elucidate its underlying molecular mechanisms. Animal models of AD were established using 0.1% beta-aminopropionitrile and angiotensin II and an in vitro model was developed using platelet-derived growth factor BB (PDGF-BB). The effects of LILRB4 knockdown on histopathological changes, pyroptosis, phenotype transition, extracellular matrix (ECM), and Janus kinase 2 (JAK2)/signal transducers and activators of transcription 3 (STAT3) pathways were assessed using a series of in vivo and in vitro assays. The effects of the JAK2 inhibitor AG490 on AD cell function, phenotypic transition, and ECM were explored. LILRB4 was highly expressed in AD and its knockdown increased survival rate, reduced AD incidence, and alleviated histopathological changes in the AD mouse model. Furthermore, LILRB4 knockdown promoted contractile phenotype switch, stabilized the ECM, and inhibited pyroptosis. Mechanistically, LILRB4 knockdown inhibited the JAK2/STAT3 signaling pathway. JAK2 inhibitor AG490 inhibited cell viability and migration, enhanced apoptosis, induced G0/G1 cell cycle arrest, and suppressed S-phase progression in PDGF-BB-stimulated human aortic smooth muscle cells. LILRB4 knockdown suppresses AD development by inhibiting pyroptosis and the JAK2/STAT3 signaling pathway.