The heartwood of Dalbergia odorifera T. Chen has garnered significant attraction due to its high medicinal, aromatic and timber values; however, its formation mechanism remains unexplored. This study utilized the sapwood (N-B), transition zone (N-T), and heartwood (N-H) of the xylem of 15-year-old, naturally heartwood-forming D. odorifera to observe the nuclei of parenchyma cells, revealing that no living cells were specialized in synthesizing the secondary metabolites of heartwood in the N-H. Additionally, analysis of gene expression patterns across different compartments indicated that differentially expressed genes (DEGs) involved in the synthesis of secondary metabolites of heartwood were primarily up-regulated in the N-T, suggesting that the pattern of heartwood formation in D. odorifera follows the Type-I (Robinia-Type) model, wherein secondary metabolites are synthesized in situ in the ray parenchyma cells of the N-T, followed by programmed cell death (PCD) leading to heartwood formation. Furthermore, DEGs related to ethylene biosynthesis and signaling pathways were up-regulated in the N-T, suggesting that ethylene signaling may play a critical role in regulating the heartwood formation process of D. odorifera. Treatment of suspension cells with polyethylene glycol (PEG) and an ethylene synthesis inhibitor (AVG) further confirmed that ethylene acts as a key signaling molecule in the formation of heartwood-like material in D. odorifera. This study provides initial insights into the molecular mechanisms underlying heartwood formation in D. odorifera and offers a foundation for developing heartwood formation and promotion technologies.

Aquilaria sinensis (Lour.) Spreng is a known medicinal plant producing agarwood. To date, studies on the floral biology of A. sinensis have been limited. In this study, the floral micro- and ultra-structures, pollen viability, stigma receptivity, and artificial pollination of A. sinensis were investigated. The results show that the flower’s development can be divided into five stages, including the flower bud differentiation stage (2–7 d), the flower bud stage (7–13 d), the flowering stage (14 d), the pollination stage (14–15 d), and the fruiting stage (15–25 d). The floral organs mainly include: 4–6 split calyces, 10 petals, 10 stamens, and 1 pistil. The anther is oblong, with four pollen sacs the pollen is round, with maximum viability 6 h after flowering; and stigma receptivity is at its best 6 h before flowering. Artificial pollination is successful in the field. These findings will provide useful information for producing and breeding A. sinensis.

Perilla frutescens(L.) Britt. (P. frutescens) is an important medicinal and aromatic plant, whose leaf color and chemotype strongly influence its medicinal quality and economic value. All the previously discovered perillene (PL)-type P. frutescens are double-sided green, and whether the PL-type trait is tightly linked with the green-leaf trait in genetics remains to be clarified. This study aimed to address this question and attempt to create purple-leaf PL-type germplasm through perillaldehyde (PA) × PL hybridization. Three parallel experiments were conducted using purple-leaf PA-type P. frutescens as male parents and green-leaf PL-type P. frutescens as female parents. Chemotypes were identified by gas chromatography (GC). Association analyses between leaf color and chemotype were performed in segregating F₂ populations. Genes involved in leaf color formation and PL biosynthesis were mapped onto the published Hoko-3 reference genome to provide genomic evidence for the genetic relationship between the two traits. All F₁ individuals were uniformly PA-type. The three F₂ populations exhibited distinct leaf color–chemotype association patterns: Z01 (n = 118) showed a strong association (Fisher’s exact p = 9.13 × 10⁻¹⁰; φ = 0.564), Z02 (n = 117) showed no detectable association (p = 0.9; φ = 0.012), and Z03 (n = 88) showed a moderate association (p = 0.00669; φ = 0.289). Importantly, purple-leaf PL-type recombinants were obtained in F₂ populations and stably maintained through subsequent generations (F₃–F₅), demonstrating that the PL-type trait is not tightly linked with the green-leaf trait in P. frutescens. Genomic mapping genes related to leaf color and PL biosynthesis are distributed across multiple chromosomes and usually present as multiple loci, which is consistent with the pattern of incomplete linkage. The PL-type trait is recessive and not genetically tightly linked to the green-leaf traits in P. frutescens. The successful creation of a purple-leaf PL-type germplasm breaks the historical phenotypic constraint and provides a novel material for further dissection of the molecular mechanisms regulating secondary metabolism and organ coloration in P. frutescens.