Yiting Xiao

Cypripedium shanxiense S. C. Chen has high ornamental value; it relies on specific habitats and fungi. Wild C. shanxiense populations need urgent conservation because they are declining rapidly. This study investigated three wild C. shanxiense populations under different canopy densities in the Changbai Mountains, analyzing habitat characteristics and plant morphology. Tissue isolation methods, molecular identification techniques, and metagenomic approaches were applied separately to purify root-colonizing fungi and to investigate the composition and functions of rhizosphere fungi, thereby revealing the diversity of root mycobiome in C. shanxiense. Results revealed that C. shanxiense achieved the best growth when the canopy density was 85.29%, and the lowest growth was under 96.13% canopy density. Soil phosphorus and potassium contents reached their highest levels under 69.33% canopy density, while soil nitrogen and organic matter contents peaked at 85.29%. Soil organic matter and available nitrogen constitute the core nutrient factors for the growth of C. shanxiense. A total of 16 fungal strains were mainly enriched in the roots, all belonging to Ascomycota. Including numerous growth-promoting fungi and pathogenic fungi. The rhizosphere fungi were mainly enriched with Basidiomycota and Ascomycota. Functional genes related to replication, recombination, and repair, and Glycoside Hydrolases. This study clarifies the optimal growth conditions of this species and the dominant rhizosphere and root fungi, providing a scientific basis for the ecological restoration and conservation of rare species.

A Cypripedium plant was discovered in Wangqing County, Changbai Mountain, Jilin Province. This newly discovered plant of Cypripedium not only inhabits the same natural habitat as Cypripedium calceolus L. and Cypripedium × ventricosum Sw. but also has a morphology intermediate between that of C. calceolus and C. × ventricosum. Its dorsal sepals, petals, and synsepal are similar to those of C. calceolus, while the color of its lip is intermediate between that of C. calceolus and C. × ventricosum. For the purpose of distinguishing the newly discovered plant of Cypripedium from other Cypripedium plants, we provisionally named it W1. To further verify the taxonomic status of W1, we introduced three identified forms of C. × ventricosum and conducted molecular biology analyses with W1, C. calceolus, and C. × ventricosum. The analyses further confirmed the relationship between W1 and C. × ventricosum, and the phylogenetic analysis of the nuclear region demonstrated a close relationship between W1 and C. calceolus. Collectively, the morphological and molecular evidence indicates that W1 is a product of the backcross between C. × ventricosum and C. calceolus. Although it shows morphological differences from typical C. × ventricosum, it can still be considered a form of C. × ventricosum. We further investigated the chloroplast genome of this form of C. × ventricosum and determined that its total genome length was 196,850 bp. The genome contains 132 genes, including 87 protein-coding genes, 37 tRNA genes, and 8 rRNA genes. By analyzing the phylogenetic position and chloroplast genome of the form of C. × ventricosum, this study clarified the relationships among Cypripedium taxa with similar morphological characteristics, laying a foundation for research on orchid evolution and species conservation.

The growth and development of Cypripedium macranthos Sw. are affected by environmental factors, such as temperature, humidity, soil type, and its crown density. In this study, its morphological attributes, physiological traits, and interactions with environmental factors were analysed. The results indicate that the growth of C. macranthos was limited by elevated crown density, soil alkaline-hydrolysed nitrogen, and available soil potassium concentration. Moreover, the physiological attributes of C. macranthos were variably suppressed by high crown density and elevated soil alkaline-hydrolysed nitrogen concentration, whereas enhanced available soil potassium concentration promoted these physiological characteristics. At lower crown density, C. macranthos had greater photosynthetic capacity and higher δ¹³C, C, and N, which were more favourable for organic matter accumulation and plant growth and development. Conversely, at higher crown densities, plants relied more heavily on mycorrhizal fungi for nutrient acquisition. In conclusion, crown density, soil alkali-hydrolysed nitrogen, and available soil potassium concentration were the main environmental factors influencing the morphological and functional form of C. macranthos. Optimal growth conditions were identified at a crown density of 0.5–0.7, soil alkali-hydrolysed nitrogen concentration of 155.06–246.98 mg/kg, and available potassium concentration of 432.53–502.87 mg/kg. The results of this study provide a theoretical understanding for developing conservation strategies for C. macranthos to ensure the stability of the wild population and the health of its habitats.

Drought is a major environmental factor limiting plant growth and development. Hemerocallis middendorffii is a perennial herbaceous plant with high drought resistance, and high ornamental and application values. Understanding the mechanism of drought stress resistance in H. middendorffii is helpful for better utilization of plant resources and selection of excellent germplasms. In this study, the phenological and physiological traits of H. middendorffii were comprehensively analyzed under natural drought stress (ND) and PEG-simulated drought stress (PD), and the resistance of H. middendorffii to different levels of drought stress was evaluated. ND was treated using a natural water loss method. PD was treated under drought stress by using PEG-6000. H. middendorffii were able to grow within 15 d of ND and 4 d of 20% PD. Beyond this drought time, H. middendorffii will wilt and lose their ornamental value. Further study showed that H. middendorffii protect themselves from damage and enhance drought resistance mainly by increasing the content of osmoregulatory substances, enhancing the activity of antioxidant enzymes, and inhibiting photosynthesis. Malondialdehyde (MDA) content accumulated rapidly at 15 d of ND and 7 d of PD. Antioxidant enzyme activities peaked at 15 d of ND and 4 d of PD. Photosynthetic parameters decreased at 15 d of ND and 4 d of 20% PD, respectively. Moreover, we identified that the HmWRKY9 gene was up-regulated for expression in the leaves after ND and PD. HmWRKY9 may be involved in regulating the response of H. middendorffii to drought stress.