Fruitlet abscission frequently occurs in Areca catechu L. and causes considerable production loss. However, the inducement mechanism of fruitlet abscission remains mysterious. In this study, we observed that the cell architecture in the abscission zone (AZ) was distinct with surrounding tissues, and varied obviously before and after abscission. Transcriptome analysis of the “about-to-abscise” and “non-abscised” AZs were performed in A. catechu, and the genes encoding the plant-specific DOF (DNA-binding with one finger) transcription factors showed a uniform up-regulation in AZ, suggesting a role of the DOF transcription in A. catechu fruitlet abscission. In total, 36 members of the DOF gene family distributed in 13 chromosomes were identified from the A. catechu genome. The 36 AcDOF genes were classified into nine subgroups based on phylogenic analysis. Six of them showed an AZ-specific expression pattern, and their expression levels varied according to the abscission process. In total, nine types of phytohormone response cis-elements and five types of abiotic stress related cis-elements were identified in the promoter regions of the AcDOF genes. In addition, histochemical staining showed that lignin accumulation of vascular bundles in AZ was significantly lower than that in pedicel and mesocarp, indicating the specific characteristics of the cell architecture in AZ. Our data suggests that the DOF transcription factors might play a role in fruitlet abscission regulation in A. catechu.

The camellia flower is a famous woody plant with a long-cultivated history and high ornamental value. It is extensively planted and utilized around the world and owns a massive germplasm resource. Camellia ‘Xiari Qixin’ belongs to one of the typical cultivars in the four seasons camellia hybrids series. Due to its long flowering period, this kind of cultivar is identified as a precious resource of camellia flowers. In this study, the complete chloroplast genome sequence of C. ‘Xiari Qixin’ was first reported. Its whole chloroplast genome is 157,039 bp in length with an overall GC content of 37.30%, composed of a large single copy region (LSC, 86,674 bp), a small single copy region (SSC, 18,281 bp), and a pair of inverted repeat regions (IRs, 26,042 bp each). A total of 134 genes were predicted in this genome, including 8 ribosomal RNA genes, 37 transfer RNA genes, and 89 protein-coding genes. In addition, 50 simple sequence repeats (SSRs) and 36 long repeat sequences were detected. By comparing C. ‘Xiari Qixin’ and seven Camellia species on the chloroplast genome, seven mutation hotspot regions were identified, including psbK, trnS (GCU)-trnG(GCC), trnG(GCC), petN-psbM, trnF(GAA)-ndhJ, trnP(UGG)-psaJ, and ycf1. Phylogenetic analysis of 30 chloroplast genomes showed that the genetic relationship between C. ‘Xiari Qixin’ and Camellia azalea is quite close in evolution. These results could not only provide a valuable database for determining the maternal origin of Camellia cultivars, but also contribute to the exploration of the phylogenetic relationship and utilization of germplasm resources for Camellia.

Flexistyly in Plagiostachys was first reported by Takano et al., while they provided no detailed study on pollination biology and breeding system. In this study, we tested this suspicion in one species of Plagiostachys (Plagiostachys austrosinensis). Field observations suggested that flexistyly was present in this species, and stigmatic behavior was similar to that reported for Alpinia and Amomum species. Two phenotypes (anaflexistylous and cataflexistylous) occurred in a ratio of 1:1 in natural populations. Anthesis began around 1530–1600 h and lasted for about 24 h. Pollen viability and stigma receptivity remained high throughout the flowering process. Mean nectar volume (4.15–11.30 μL) and mean sugar concentration (>32%) also remained at a high level during the flowering process. No fruit set occurred in unpollinated bagged plants. Two pollinators (Bombus pyrosoma and Vespidae spp.) and one pollen robber (Mutillidae spp.) were found as flower visitors. Fruit set following self-pollination and cross-pollination did not differ significantly in the cataflexistylous morph. Partial self-incompatibility was apparent in the anaflexistylous morph. These results provide the concrete evidence of flexistyly in Plagiostachys and a more thorough understanding of its evolutionary origin in gingers.

Camellia osmantha is a new species of the Camellia genus discovered in Nanning, Guangxi, China, in 2012. It can be used as an excellent woody oil crop. There is little related research on this species in China and abroad, and its genome information is still lacking. In this study, the complete chloroplast genome sequence of C. osmantha was first reported (GenBank number: MZ128138). The whole chloroplast genome is 156,981 bp in length with a GC content of 37.28%, and it is composed of a large single copy (LSC) region of 86,647 bp, a small single copy (SSC) region of 18,284 bp, and a pair of inverted repeat (IR) regions of 26,025 bp each. The genome contains a total of 135 functional genes, including 37 transfer RNA genes, 90 protein-coding genes, and 8 ribosomal RNA genes. The maximum likelihood analysis based on 21 chloroplast genomes showed that C. osmantha and C. oleifera (MF541730.2) were the most closely related.

Camellia gigantocarpa Hu et T. C. Huang, belonging to the Theaceae family, is an excellent landscape tree species with high ornamental value. It is also an important woody oil-bearing plant with high economic value. This study reports the first complete chloroplast genome sequence of C. gigantocarpa (GenBank accession number: MZ054232). Its whole chloroplast genome is 156,953 bp long with an overall GC content of 37.31%, which is composed of a large single copy region (86,631 bp), a small single copy region (18,402 bp), and a pair of inverted repeat regions (25,960 bp each). A total of 135 genes were predicted in this genome, namely eight ribosomal RNA genes, 37 transfer RNA genes, and 90 protein-coding genes. Based on maximum likelihood analysis results, we found that the Camellia species are clustered into a distinct branch, and the phylogenetic relationships among C. gigantocarpa, C. crapnelliana, and C. kissii were the closest.

Between 2023 and 2024, a type of green alga was observed for the first time settling on Oil-tea Camellia leaves and branches in the eastern Oil-tea Camellia planting area of Hainan Island, forming a layer of gray-green moss with a rough surface that seriously interfered with the leaves’ normal photosynthesis. To further research the issue, this study used the plant photosynthesis measurement system and the paraffin sectioning technique to compare and analyze the changes in photosynthetic characteristics and anatomical structure of healthy and green algal-covered Oil-tea Camellia leaves. At the same time, the algal strain was effectively separated and purified using the plate delineation method, and its species classification was determined by combining morphological observation and molecular identification based on SSU-ITS sequences. The results of the study demonstrated that the coating of green alga facilitated the lignification of the leaf’s epidermal cell walls. After being covered by the green alga, the intercellular CO₂ concentration (Ci) increased significantly by 21.5%, while the net photosynthetic rate (Pn), transpiration rate (Tr), and stomatal conductance (Gs) all significantly decreased by 72.8%, 30.4%, and 24.9%, respectively. More specifically, the green alga that covers the leaves of Oil-tea Camellia was identified as Desmodesmus armatus of Chlorophyta. Notably, the green alga had a long growth cycle, did not undergo a decline phase within one month, had an optimal growth pH of 11.0, and could flourish in excessively alkaline conditions. In conclusion, this study not only reported for the first time the phenomena of D. armatus infesting Oil-tea Camellia leave, but also showed its unique physiological and ecological properties, providing a foundation for future research on relevant prevention and control approaches.