The dried root of Salvia miltiorrhiza is a renowned traditional Chinese medicine that was used for over 1000 years in China. Salvianolic acid B (SalB) is the main natural bioactive product of S. miltiorrhiza. Although many publications described the regulation mechanism of SalB biosynthesis, few reports simultaneously focused on S. miltiorrhiza root development. For this study, an R2R3-MYB transcription factor gene (SmMYB52) was overexpressed and silenced, respectively, in S. miltiorrhiza sterile seedlings. We found that SmMYB52 significantly inhibited root growth and indole-3-acetic acid (IAA) accumulation, whereas it activated phenolic acid biosynthesis and the jasmonate acid (JA) signaling pathway. Quantitative real-time polymerase chain reaction (qRT-PCR) analyses revealed that SmMYB52 suppressed the transcription levels of key enzyme-encoding genes involved in the IAA biosynthetic pathway and activated key enzyme-encoding genes involved in the JA and phenolic acid biosynthesis pathways. In addition, yeast one-hybrid (Y1H) and dual-luciferase assay showed that SmMYB52 directly binds to and activates the promoters of several key enzyme genes for SalB biosynthesis, including SmTAT1, Sm4CL9, SmC4H1, and SmHPPR1, to promote the accumulation of SalB. This is the first report of a regulator that simultaneously affects root growth and the production of phenolic acids in S. miltiorrhiza.

Introduction: Paeonia lactiflora contains diverse active constituents and exhibits various pharmacological activities. However, only partial identification of biologically active substances from P. lactiflora has been achieved using low-throughput techniques. Here, the roots of P. lactiflora, namely, Fenyunu (CK), Dafugui (DFG), and Red Charm (HSML), were studied. The primary and secondary metabolites were investigated using ultrahigh-performance liquid chromatography-electrospray ionization-tandem mass spectrometry (UPLC-ESIMS/MS). Methods: The chemical compounds and categories were detected using broadly targeted UPLC–MS/MS. Principal component analysis (PCA), orthogonal partial least-squares discriminant analysis (OPLS-DA), and hierarchical clustering analysis (HCA) were carried out for metabolites of different varieties of P. lactiflora. Results: A total of 1237 compounds were detected and classified into 11 categories. HCA, PCA, and OPLS-DA of these metabolites indicated that each variety of P. lactiflora was clearly separated from the other groups. Differential accumulated metabolite analysis revealed that the three P. lactiflora varieties contained 116 differentially activated metabolites (DAMs) involved in flavonoid, flavone, and flavonol metabolism. KEGG pathway analysis revealed that, in 65 pathways, 336 differentially abundant metabolites (DMs) were enriched in the CK and DFG groups; moreover, the type and content of terpenoids were greater in the CK group than in the DFG group. The CK and HSML groups contained 457 DMs enriched in 61 pathways; the type and amount of flavonoids, terpenoids, and tannins were greater in the CK group than in the HSML group. The DFG and HSML groups contained 497 DMs enriched in 65 pathways; terpenoids and alkaloids were more abundant in the HSML variety than in the DFG variety. Conclusions: A total of 1237 compounds were detected, and the results revealed significant differences among the three P. lactiflora varieties. Among the three P. lactiflora varieties, phenolic acids and flavonoids composed the largest and most diverse category of metabolites, and their contents varied greatly. Therefore, CK is suitable for medicinal plant varieties, and DFG and HSML are suitable for ornamental plant varieties. Twelve proanthocyanidin metabolites likely determined the differences in color among the three varieties.

In order to learn the retrotransposons expression profiles in rice implanted by low-energy ion beam and the effects on these retrotransposons adjacent genes, we analyzed expression features of the retrotransposons in rice with exposure to the nitrogen ion beam implantation(6×1017 N+/cm2), using the Agilent Rice Oligo Microarray(4×44K)Genome Array. Rice seeds were implanted by the nitrogen ion beam with 40Kev energy in dose 6×1017 N+/cm2. Total RNA, from the seedlings 96 h after the germination, was used to genechip analysis. The vigor index was measured at 10 days after the germination. The results showed that the vigor index increased obviously than control. We also found that there were 43 retrotransposons transcripts detected by the chip, 4 out of these transcripts were up or down-regulated (≥2fold), including the gag, pol, and int. The differentially expressed genes (detected by the same gene chip), in the frame from up 1MB to down 1MB in the chromosomes at the differentially expressed retrotranscription, represented the same up or down regulated case. These findings suggested that the differential expression of retrotransposons in rice were related with the response to N+ ion beam implantation through the regulation of their adjacent genes.

Trichomes are specialized epidermal structures that play pivotal roles in plant defense against biotic and abiotic stresses. Inositol polyphosphate kinase 2 (IPK2) is a key enzyme in inositol phosphate metabolism with diverse functions in eukaryotic cellular processes. However, its involvement in trichome development remains uncharacterized. Here, we systematically analyzed the function of a rice inositol polyphosphate kinase gene (OsIPK2) in trichome development using transgenic rice lines and heterologously expressing Arabidopsis lines. Scanning electron microscopy (SEM) analysis revealed that OsIPK2 acts as an organ-specific modulator of trichome development in rice. Its overexpression repressed macrohair initiation and microhair elongation in leaves, while promoting trichome development on the glumes. Metabolomic profiling revealed that OsIPK2 overexpression reprogrammed cuticular wax metabolism in transgenic rice leaves, shifting fatty acid flux toward long-chain wax precursors and increasing soluble carbohydrate levels. Transcriptomic and qPCR analysis confirmed that OsIPK2 modulated the expression of genes involved in cuticular wax biosynthesis, auxin homeostasis, and the core trichome regulatory cascade in rice. Conversely, heterologous overexpression of OsIPK2 in Arabidopsis strongly suppressed trichome initiation and branching, resulting in drastically reduced trichome density and fewer trichome branches. These phenotypes were associated with the downregulation of the MYB-bHLH-WD40 (MBW) transcriptional complex and its downstream target genes. Collectively, our findings suggest that OsIPK2 modulated trichome development through organ- and species-specific mechanisms. In rice, it coordinated wax metabolism and the OsSPL10-OsSCR1/2-OsWOX3B-OsHL6 cascade to affect organ-specific trichome formation. In Arabidopsis, it inhibited trichome development by repressing the MBW complex. These results uncover a novel role of OsIPK2 in plant epidermal cell fate specification and advance our understanding of the molecular mechanisms underlying organ- and species-specific regulation of trichome development.