Bletilla striata (Thunb.) Rchb. f. (Orchidaceae), known as a traditional Chinese herb, has been widely used as hemostatic and anti-microbial. In May 2017, a leaf spot disease was observed on 20–30% of B. striata in commercial fields located in Ziyuan County, Guangxi, China. Small, circular, brown spots were early observed on leaves, enlarging and developing into irregular dark brown and necrotic lesions. Necrotic lesions caused leaf abscission and occurred frequently during the plant’s life cycle. Three symptomatic leaves from three individual plants were surface sterilized in 1% sodium hypochlorite for 2 min, rinsed 3 times in sterile water, plated on potato dextrose agar (PDA) medium and then incubated at 26°C for 3 days. Seven isolates recovered from diseased plants and the colonies were villose and regular, pale grey, secreting scarlet pigment to the media. After 15 days of incubation, subspheroical chlamydospores were observed, which were brown to black, with verrucose surface. Unicellular chlamydosp...

Crassulacean acid metabolism (CAM), one of three kinds of photosynthesis, is a water-use efficient adaptation to an arid environment. CAM is characterized by CO₂ uptake via open stomata during the nighttime and refixation CO₂ via the Calvin cycle during the daytime. Facultative CAM plants can shift the photosynthesis from C₃ to CAM and exhibit greater plasticity in CAM expression under different environments. Though leaf thickness is an important anatomical feature of CAM plants, there may be no anatomical feature changes during the C₃–CAM transition for all facultative CAM plants. The shift from C₃ photosynthesis to CAM in facultative CAM plants is accompanied by significant changes in physiology including stomata opening, CO₂ gas exchange and organic acid fluxes; the activities of many decarboxylating enzymes increase during the shift from C₃ to CAM; the molecular changes occur during the photosynthesis C₃–CAM shift involved DNA hypermethylation, transcriptional regulation, post-transcriptional regulation and protein level regulation. Recently, omics approaches were used to discover more proceedings underling the C₃–CAM transition. However, there are few reviews on the mechanisms involved in this photosynthetic shift in facultative CAM plants. In this paper, we summarize the progress in the comparative analysis of anatomical, physiological, metabolic and molecular properties of facultative CAM plants between C₃ and CAM photosynthesis. Facultative CAM plants also show the potential for sustainable food crop and biomass production. We also discuss the implications of the photosynthesis transition from C₃ to CAM on horticultural crops and address future directions for research.

Many Dendrobium species, which hold a high status and value in traditional Chinese medicine, grow on barks and rocks in the wild, often encountering harsh environments and facing droughts. However, the molecular mechanisms underlying the shift in the photosynthetic pathway induced by drought remain unclear. To address this issue, three Dendrobium species with different photosynthetic pathways were selected for sequencing and transcriptome data analysis after drought treatment. The findings included 134.43 GB of sequencing data, with numerous Differentially Expressed Genes (DEGs) exhibiting different response mechanisms under drought stress. Gene Ontology (GO)–KEGG-based enrichment analysis of DEGs revealed that metabolic pathways contributed to drought tolerance and alterations in photosynthetic pathways. Phosphoenolpyruvate Carboxylase (PEPC) was subjected to phylogenetic tree construction, sequence alignment, and domain analysis. Under drought stress, variations were observed in the PEPC gene structure and expression among different Dendrobium species; the upregulation of Dc_gene2609 expression may be caused by dof-miR-384, which resulted in the shift from C₃ photosynthesis to CAM, thereby improving drought tolerance in Dendrobium. This study revealed the expression patterns and roles of PEPC genes in enhancing plant drought tolerance and will provide an important basis for in-depth research on Dendrobium’s adaptation mechanisms in arid environments.

Many species of the Dendrobium genus are traditional Chinese herbal medicine and ornamental plants. Flower fragrance is one of the most important horticultural ornamental characters and plays a crucial role in the ecology, economy, and aesthetics of plants. However, the volatile constituents and key regulatory genes related to floral biosynthesis are poorly understood. In this experiment, the flowers from two species of Dendrobium with high-scent smells, Dendrobium moniliforme (L.) Sw. (D. moniliforme), and light-scent smells, Dendrobium nobile “H1” (D. “H1”), were selected. The aim of this study was to explore the key gene expression profiles of floral biosynthesis by combining volatile constituent determination and transcriptome analysis in two different Dendrobium species. Physiological determination results showed that 60 volatile compounds were identified in D. moniliforme and 52 volatile compounds were identified in D. ‘H1’ flowers in four flowering stages, and the full bloom stage was the most complicated stage because there were 41 and 33 volatile compounds, respectively. These compounds belong to terpenes, aromatics, fatty acids, nitrogenous compounds, ketones, alcohols, and alkanes, respectively. The components identified in the gynandrium and petals revealed that the petals were probably the most important sites affecting the release of volatiles. The relative content of terpene compounds was the highest, with 77.25% (D. moniliforme) and 50.38% (D. “H1”), respectively. Transcriptome analysis showed that differentially expressed genes (DEGs) were highly enriched in terpenoid backbone biosynthesis and that four linalool synthetase (LIS) genes were up-regulated in high-scent smell species. This study is helpful to explore the key genes of flower fragrance and provides a theoretical basis for further understanding of the regulatory molecular functions of floral synthesis and release, as well as for the cultivation of new aromatic species.