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

Nitrate reductase BoNIA2b responds to nitric oxide to positively regulate the accumulation of Glucoraphanin and Sulforaphane in broccoli hairy roots

Glucoraphanin (GRA) and sulforaphane (SF) are potent anticancer compounds. Understanding their accumulation mechanisms is crucial for increasing their levels in broccoli. This study aimed to investigate the role of nitric oxide (NO) in GRA and SF accumulation and identify key genes involved in this process. Low NO concentrations were found to promote GRA and SF accumulation. Transcriptome sequencing and Weighted Gene Co-expression Network Analysis (WGCNA) identified BoNIA2b, a nitrate reductase (NR) gene, as a key regulator of NO-mediated GRA and SF accumulation. Silencing BoNIA2b reduced endogenous NO levels and NR activity in hairy roots, while exogenous treatment with sodium nitroprusside (SNP) restored NO levels without affecting NR activity. Overexpression of BoNIA2b increased NO content and NR activity. Silencing BoNIA2b decreased GRA content, but SF levels remained unaffected. SNP treatment enhanced both GRA and SF accumulation, with GRA being more dependent on BoNIA2b. In BoNIA2b-overexpressing roots, both GRA and SF levels were significantly higher than in controls. Moreover, the interaction between BoNIA2b and BoMYB28 protein was confirmed through Y2H and luciferase complementation assays. These findings underscore BoNIA2b's role in NO-mediated regulation of GRA and SF accumulation in broccoli hairy roots, offering insights to enhancing the production of these anticancer compounds.

In vitro strategy to enhance the production of bioactive polyphenols and caffeoylputrescine in the hairy roots of Physalis peruviana L

The Rhizobium rhizogene-transformed root culture from Physalis peruviana L. (P. peruviana) may be a promising and novel source of valuable phenolics, including caffeoylputrescine (CP), which is known for antioxidant, antidiabetic, insect-resistant, disease-resistant, and neuroprotective properties. In this study, to improve the production efficiency of phytochemical components in P. peruviana hairy root cultures, we optimized various culture conditions, including the inoculum size, liquid volume, culture media type, carbon source, sucrose concentration, initial pH, and application of elicitors, to enhance the total phenolic content and CP yield in these hairy root cultures. The findings indicate that the use of sucrose as carbon source resulted in the highest biomass (13.28 g DW/L), total phenolic content (6.26 mg/g), and CP yield (2.40 mg/L). The White medium excelled in enhancing the total phenolic content (9.35 mg/g), whereas the B5 medium was most effective for the biomass (13.38 g DW/L) and CP yield (6.30 mg/L). A sucrose concentration of 5% was best for the biomass (18.40 g DW/L), whereas a sucrose concentration of 4% was ideal for the CP yield. Optimal culture conditions were as follows: an inoculum size of 0.5 g/100 mL, a liquid volume of 100 mL in a 250-mL flask, B5 medium, 4% sucrose, and a pH of 5.5. Among the tested elicitors, methyl jasmonate (MeJA) at 100 µM significantly increased the biomass (21.3 g/L), total phenolic content (23.34 mg/g), and CP yield (141.10 mg/L), which represent 0.96-, 2.12-, and 13.04-fold increases, respectively, over the control after 8 days. The optimized HR culture of P. peruviana provides a promising system to enhance the production of CP for pharmaceutical applications.

Transcriptome analysis revealed the role of moderate exogenous methyl jasmonate treatments in enhancing the metabolic pathway of L-borneol in the Blumea balsamifera

Introduction

Blumea balsamifera L. (Ainaxiang) DC. is a perennial herb of the compositae family. It is also the primary source of natural borneol. Endo-borneol, the principal medical active element in B. balsamifera, is anti-inflammatory, antioxidant, and analgesic; enhances medicine absorption; refreshes; and is used as a spice and in cosmetic. Industrialization of B. balsamifera is limited by its low L-borneol concentration. Thus, understanding the accumulation pattern of the secondary metabolite endo-borneol and its synthesis process in secondary metabolism is critical for increasing B. balsamifera active ingredient content and cultivation efficiency.

Methods

In this work, B. balsamifera was treated with varying concentrations (1.00 and 10.00 mmol/L) of methyl jasmonate (MeJA) as an exogenous foliar activator. The physiological parameters and L-borneol concentration were then assessed. Transcriptome sequencing of B. balsamifera-induced leaves was used to identify key genes for monoterpene synthesis.

Results

The treatment effect of 1 mmol/L MeJA was the best, and the leaves of all three leaf positions accumulated the highest L-borneol after 120 h, correspondingly 3.043 mg·g-1 FW, 3.346 mg·g-1 FW, and 2.044 mg·g-1 FW, with significant differences from the control. The main assembly produced 509,285 transcripts with min and max lengths of 201 and 23,172, respectively. DEG analysis employing volcano blots revealed 593, 224, 612, 2,405, 1,353, and 921 upregulated genes and 4, 123, 573, 1,745, 766, and 763 downregulated genes in the treatments D1_1vsCK, D1_10vsCK, D2_1vsCK, D2_10vsCK, D5_1vsCK, and D5_10vsCK. Interestingly, when exposed to MeJA treatments, the MEP pathway's unigenes express themselves more than those of the MVA route. Finally, when treated with 1 mmol/L, the genes DXR, DXS, and GPS showed increased expression over time. At the same time, a 10 mmol/L therapy resulted in elevated levels of ispH and GGPS.

Discussion

Our preliminary research indicates that exogenous phytohormones can raise the level of L borneol in B. balsamifera (L.) DC when given in the appropriate amounts. The most significant discovery made while analyzing the effects of different hormones and concentrations on B. balsamifera (L.) DC was the effect of 1 mmol/L MeJA treatment.

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.