Jasmonate (JA) signaling plays a pivotal role in plant stress responses and secondary metabolism. Many studies have demonstrated that JA effectively induce the expressions of alkaloid biosynthetic genes in various plants, which rendered to the accumulation of alkaloid to counteract stresses. Despite the multiple roles of JA in the regulation of plant growth and different stresses, less studied involved in the regulatory role of JA in Dendrobium officinale alkaloids. A strategy for the rapid identification of alkaloid and the intermediates of D. officinale was established based on a solid-phase extraction coupled with high-performance liquid chromatography tandem mass spectrometry method. By using SPE-LC-MS/MS method, the potential compounds were tentatively identified by aligning the accurate molecular weight with the METLIN and Dictionary of Natural Products databases. The chemical structures and main characteristic fragments of the potential compounds were further confirmed by retrieving the multistage mass spectra from the MassBank and METLIN databases. The Mass Frontier software was used to speculate the fragmentation pathway of the identified compounds. Seven alkaloids were separated and identified from D. officinale, which were mainly classified into five types (tropane alkaloids, tetrahydroisoquinoline alkaloids, quinolizidine alkaloids, piperidine alkaloids, and spermidine alkaloids). Besides the alkaloids, forty-nine chemical substances, including guanidines, nucleotides, dipeptides, sphingolipids and nitrogen-containing glucosides, were concurrently identified. These findings gives the composition of chemicals currently found in D. officinale, which could provide the scientific method for the identification of alkaloids in other Dendrobium plants.

Platycodon grandiflorum (P. grandiflorum) is a commonly used medicinal plant in China. Transcriptome sequencing studies of different tissues of P. grandiflorum have been widely conducted. However, studies on transcriptome sequencing and expression patterns of key genes in the saponin synthesis pathway of Tongcheng P. grandiflorum, a high-quality medicinal resource of different years, are relatively limited. This study involved transcriptome sequencing and bioinformatics analysis of the roots from annual, biennial, and triennial P. grandiflorum in the Tongcheng area. After data filtering and assembly, we obtained 111.44 Gb of clean base data, including 742,880616 clean reads. We identified 5,156 differential expression unigenes between at least two sample groups, with differences noted among annual, biennial, and triennial P. grandiflorum plants. GO enrichment analysis annotated 3509, 1819, and 1393 DEGs in comparison TC1vsTC2, TC1vsTC3, and TC2vsTC3, respectively. Furthermore, KEGG enrichment analysis identified 16 genes encoding key enzymes in the terpene skeleton biosynthesis, sesquiterpene and triterpene biosynthesis pathways, including SE, AACT, FPPS, DXR, HMGR, HMGS, and DXS. The results of qRT-PCR experiments showed that most of the genes were most highly expressed in annual P. grandiflorum. The present study provided transcriptomic data from the roots of Tongcheng P. grandiflorum of different years, which provides critical bioinformatics data on the growth and development of P. grandiflorum, laying a foundation for further research on saponins and identifying key enzymes involved in this process across different growth stages.

Phenylalanine ammonia lyase (PAL) plays an important role in the biosynthesis of secondary metabolites regulating plant growth response. To date, the evolutionary history of the PAL family in Rosaceae plants remains unclear. In this study, we identified 16 PAL homologous genes in five Rosaceae plants (Pyrus bretschneideri, Fragaria vesca, Prunus mume, Prunus persica, and Malus × domestica). We classified these PAL genes into three categories based on phylogenetic analysis，and all PAL genes were distributed on 13 chromosomes. Subsequently, we track gene replication events and perform sliding window analysis. These results revealed the evolution of PAL genes in five Rosaceae plants. We predicted the promoter of the PbPAL genes by PLANTR CARE online software, and found that the 5'regulatory region of both PbPAL1 and PbPAL3 has at least one AC element motif. The results of qRT-PCR analysis found that PbPAL1 and PbPAL2 were highly expressed in the stem and root , while expression level of PbPAL3 was relatively low in different tissues. The expression of PbPAL1 and PbPAL2 genes increased firstly and then decreased at different developmental periods of pear fruit. Among them, the expression of PbPAL1 reached the highest level 55 days after flower. Three PbPAL genes were induced by abiotic stress to varying degrees. We transfected PbPAL1 and PbPAL2 genes into Arabidopsis thaliana, resulting in lignin content increased significantly and thick cell wall of intervascular fibers and xylem cells. In summary, This study laid a foundation for better understanding the molecular evolution of PAL genes in five Rosaceae plants. Furthermore, the present study revealed the role of PbPAL genes in lignin synthesis, and provided basic data for regulating lignin synthesis and stone cell development of pear.