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.

Previous studies have identified numerous transcription factors involved in drought response, each of which play different roles in plants. The objective of the present study was to evaluate the effectiveness of two transcription factors on drought response in Jatropha curcas L., JcNAC1 and JcZFP8. The overexpression of these transcription factors in tobacco (Nicotiana benthamiana L.) improved drought resistance, but JcZFP8 delayed germination and JcNAC1 reduced biomass and yield. By constitutively co-expressing these two genes in tobacco, drought resistance was improved, and the negative effects of each of them were overcome. The transgenic plants with double-gene co-expression showed stronger drought tolerance with 1.76-fold greater accumulation of proline and lower H₂O₂ and malondialdehyde (MDA) content to 43 and 65% of wildtype (WT) levels, respectively. The expression levels of NbbHLH1 and NbbHLH2 genes upregulated linearly with the increased drought tolerance of double genes co-expression plants. In drought conditions, the leaf water contents of bhlh1, bhlh2, and bhlh1bhlh2 deletion mutants obtained by CRISPR-CAS9 knockout technique were maintained at 99%, 97%, and 97% of WT. The bhlh1bhlh2 was found with lower germination rate but with higher reactive oxygen levels (1.64-fold H₂O₂ and 1.41-fold MDA levels). Thus, the co-expression of two transcription factors with different functions overcame the adverse traits brought by a single gene and enhanced the shared drought-tolerant traits, which can provide guidance on theory and selection of gene combinations for the application of multi-gene co-expression in agriculture in the future.

The flavor variation among different tea plant cultivars significantly influences their economic value. ‘Huangjinya’ (HJY), a typical light-sensitive etiolated tea cultivar, is prized for its fresh and mellow taste with low bitterness and astringency, and commands a high market value, serving as excellent germplasm for breeding superior-flavor tea varieties. Previous studies have largely focused on the mechanisms underlying fresh and umami tastes, whereas the regulatory mechanisms underlying bitterness and astringency remain poorly understood. In this study, two tea plant (Camellia sinensis (L.) O. Kuntze) cultivars with distinct bitterness and astringency phenotypes, namely ‘Fuxuan 9’ (FX) and HJY, were used to investigate the formation mechanism of reduced bitterness and astringency through integrated metabolomic and transcriptomic analyses. Metabolomic profiling identified 601 differentially accumulated metabolites between the two cultivars, which were significantly enriched in the flavonoid biosynthesis pathway. Notably, although the total flavonoid content was higher in HJY, the accumulation of non-esterified catechins (C, EC, EGC), which are key contributors to bitterness, was significantly lower than in FX. By contrast, the levels of esterified catechins (EGCG, GCG) showed no marked differences between cultivars. This distinct accumulation pattern provides a metabolic basis potentially associated with the reduced bitterness and astringency in HJY. Transcriptomic analysis revealed that the catechin biosynthetic gene CsLAR was significantly down-regulated in HJY, consistent with the reduced accumulation of non-esterified catechins. Promoter cloning and functional validation confirmed that the CsLAR promoters in both cultivars were active, which differed by only one regulatory element. Under shading treatment, CsLAR expression in HJY was more sensitive to light and decreased more markedly, suggesting that the expression of CsLAR may be regulated by transcription factors. Furthermore, 385 differentially expressed transcription factors were identified, with predicted binding sites in the CsLAR promoter region, implying their potential involvement in modulating catechin accumulation through modulation of CsLAR expression. Together, these multi-omics findings reveal molecular features potentially contributing to the low bitterness and astringency of HJY, providing a theoretical basis and candidate regulators for breeding tea cultivars with improved flavor profiles.