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.

Polygonatum cyrtonema Hua (Asparagaceae) is a perennial herb widely distributed in China (Chen et al. 2021). The rhizome has antioxidant, anti-inflammatory, and immunomodulatory properties and is traditionally used to treat dizziness, diabetes, and asthma (Lu et al. 2023; Pang et al. 2022). About 3000 P. cyrtonema plants were planted in five fields at the Institute of Medicinal Plant Development (40.04°N, 116.28°E), Beijing, China, where rhizome rot was observed from June to October 2023, with an incidence rate of about 10%. Most cases occurred in low-lying, waterlogged fields. Initially, infected plants had no obvious aboveground symptoms but had brown spots on their rhizomes. In severe cases, plants exhibited aboveground withering and brown rot in rhizomes. A fungus was isolated from symptomatic plants (isolation rate 73%), and single spores were used to grow pure colonies on potato-dextrose-agar (PDA) and incubated for 5 d at 25°C in the dark. Eleven isolates with the same morphology were obtained. The upper surface of the colonies was white, with cottony mycelium and a light purple center. The lower surface of the colonies was hazel in the center. Two representative isolates, C76 and C78, were cultivated on carnation leaf agar medium. Microconidia of the isolates were aseptate, oval, elliptic or clavate, and their dimensions were 4.9 to 12.1 × 1.5 to 4.5 μm (n = 50). Macroconidia were long, slender and thin, rod-shaped or slightly curved, with one to five septa, and their dimensions were 15.3 to 44.9 × 2.7 to 4.5 μm (n = 50). The isolates were classified as Fusarium based on morphology (Leslie and Summerell 2006). To determine the species identity, we sequenced the translation elongation factor (TEF-1α) and partial RNA polymerase second largest subunit (RPB2) of two isolates (i.e., C76 and C78, GenBank access numbers: TEF-1α, PQ550044, PQ285402; RBP2, PQ550045, PQ285403, respectively) (Crous et al 2009) and compared them to other Fusarium species found at Fusarium-ID and GenBank databases. Both isolates exhibited 99.84% (TEF-1α, MT305203) and 100% (RBP2, LT841252) similarity with Fusarium proliferatum. The phylogenetic tree was constructed by combining TEF-1α, and RBP2 using MEGA6, and the two isolates clustered with F. proliferatum. To demonstrate pathogenicity, 2 mL of conidial suspension (1 × 106 conidia/mL) of the isolate of F. proliferatum designed C76 were dropped on the surface of four rhizomes without wounding. For the control, sterile water was applied on two control rhizomes. All treatments were repeated three times. Seedlings were grown at 25°C in moist soil. After 7 d, inoculated roots exhibited similar symptoms to those in the field, while control roots showed no symptoms. The same isolate was reisolated from diseased roots and was identified based on morphological characteristics, fulfilling Koch's postulates. Based on morphology and molecular biology, the isolates were identified as F. proliferatum, a ubiquitous pathogen (Li, et al 2017) that was reported to cause leaf spot on P. cyrtonema (Zhou, et al. 2021). This is the first report of F. proliferatum causing rhizome rot on P. cyrtonema. This research will help develop strategies to manage rhizome rot incited by F. proliferatum.

Perilla frutescens is an important medicinal and edible plant in Asia and was introduced in Europe and North America mainly as a spice plant. The commonly cultivated species is an allotetraploid (AABB). While the identity of its AA diploid donor has been preliminarily clarified, the other donor, BB, has not been discovered yet, and the taxonomic status and characteristics of the BB donor remain unresolved. Based on the published genomes of Perilla spp., we employed a collinearity analysis, gene structure similarity assessment, and multi-level functional annotation to infer the genomic and phenotypic features of the B subgenome. Results suggest that the protein sequences of the B and A subgenomes exhibit the highest similarity, while the protein sequences of Lavandula angustifolia or Ocimum basilicum are less similar to the B subgenome, and two subgenomes also possess the largest number of homologous genes and have similar gene structures. A total of 90 BB progenitor-specific genes were significantly enriched in pathways related to secondary metabolite biosynthesis and environmental stress response. Among these genes, the terpene synthase genes constitute the main genetic basis for the diversity of bioactive components in perilla. The discovery of a homologous gene containing the NB-ARC domain, associated with resistance to late blight, suggests that BB may contribute to key disease-resistant traits. Further gene family analysis revealed that compared with the A subgenome, the B subgenome exhibited fewer genes and lower diversity in the TPS and NB-ARC families. These findings indicate that BB may have originated from an unfound or extinct species within the Perilla spp. The BB donor might be less diversified than AA, possibly adapting to a narrow geographic and climatic range.

Perilla frutescens, commonly known as "ZI SU", is an herbaceous plant known for its culinary and medicinal properties and is distributed throughout China (Igarashi and Miyazaki, 2013). In October 2023, wilt symptoms were observed on P. frutescens plants in Shaowu (27.34°N, 117.49°E), Fujian province, China (incidence rate: 30%). The stems first showed discoloration, which transitioned from green to dark brown or black. The leaves drooped and often curled, eventually drying out. Fifteen typical symptomatic stems were randomly selected and samples were taken from the margins of the lesions and cut into 5 × 5-mm pieces. The samples were surface sterilized with 5% sodium hypochlorite solution for 1 min, rinsed with sterile water three times, and dried. Samples were incubated on potato dextrose agar (PDA) medium for 5 d at 25°C in the dark, then transferred using monospore isolation to new PDA plates and incubated for another 5 d at 25°C in the dark. Thirteen of the 20 isolates obtained had similar colony morphology (isolation rate 65%). The front of colonies exhibited a flat, cottony texture. The reverse side of the colonies was pale yellow. Two representative isolates, 1380 and 1383, were cultivated on carnation leaf agar (CLA) medium. Microconidia of the isolates were oval, cylindrical or ovate, and were 5.56 to 15.26 × 2.82 to 4.49 μm (n = 50). Macroconidia had 2 to 5 septa, usually 3 septa, and were straight or slightly curved, 2.6 to 5.47 × 20.8 to 42.4 μm (n = 50). Chlamydospores were roundish, terminal or intercalary. The morphological characteristics were consistent with the description of Fusarium (Leslie and Summerell 2006). DNA was extracted from the two isolates using the cetyltrimethylammonium bromide (CTAB) method. The partial internal transcribed spacer (ITS) region, the translation elongation factor (TEF-1α) and partial RNA polymerase second largest subunit (RPB2), were amplified (GenBank accession numbers for TEF-1α were PV057161 and PV057162, for RBP2 were PV057159 and PV057160, and for ITS were PV639174 and PV639175 for 1380 and 1383, respectively) (Crous et al 2009). When compared with other Fusarium species in GenBank, both isolates exhibited 99.85% (TEF-1α, MN417200), 99.90% (RBP2, AB986568), and 100% (ITS, OR753367) similarity with Fusarium oxysporum. A phylogenetic tree which combined ITS, TEF-1α and RPB2 was constructed using MEGA6 with the maximum likelihood method (Xu et al 2022), and the two isolates clustered with F. oxysporum with 99% bootstrap values. To test pathogenicity, a conidial suspension of 1383 with a concentration of 1 × 106 conidia/mL was sprayed on three stems of one-month-old P. frutescens seedlings. For the control, sterile water was sprayed on two control stems and there were 3 biological replicates. Seedlings were covered with plastic film for 24 h and kept in a culture room at 25°C, and inoculated stems exhibited similar symptoms to those in the field 4 days' post inoculation, while control stems had no symptoms. Koch's postulates were fulfilled by reisolating the same isolate from diseased stems based on morphological characteristics. The morphology and molecular biology results confirm that the isolates were F. oxysporum. This is the first report of F. oxysporum causing wilt on P. frutescens. China is the main cultivation and export country of P. frutescens, and this disease poses a threat and damage to production. Since F. oxysporum has a wide host range, strategies to manage it should be developed.