First Report of Root Rot caused by Coniella fragariae on Paeoniae radix Rubra in China.

Paeoniae radix Rubra is a traditional Chinese herbal medicine, which has the effect of clearing heat and cooling blood, activating blood and removing stasis. It has become popular in the Chinese market in recent years due to its extremely high medicinal value and showy flower color. In May 2021, typical symptoms of root rot were observed in a field (35°7'12″ N, 103°58'48″ E) in Dingxi, Gansu province, China. Approximately 10% of the plants in the field had typical root rot symptoms, and the root of each affected plant is at least 5% severe. The roots of the naturally infected plants in the field discolored and decayed with black brown spots on the surface of the root bark, the root bark detached from the phloem，and some leaves were chlorosis, shrunken and smaller, and the branches were dead and underdeveloped. In the transverse section, the xylem was black diffusion and abnormal odor. Three diseased plants with typical symptoms were chosen at random and brought back to the lab. Small pieces cut from the margins of lesions were surface disinfested with 75% ethanol for 15 s, and 0.5% NaClO solution for 30 s, rinsed three times in sterile distilled water, dried on sterile filter paper, plaed onto potato dextrose agar (PDA), and incubated at 25 ± 1℃ for 7 days in the dark. The pure cultures were obtained by single-spore isolation. All isolates produced wavy on the surface, radial from the inside out, initially white or milky white to orange colonies with abundant black brown oily conidiomata pycnidia on PDA at 25 ± 1℃ after 15 days in the dark. The conidiomata pycnidia is spherical to irregularly spherical, 231.5 to 512.4 µm, initially transparent with age turning brown, with a dark brown internal conidial mass inside, and with a 13.1 to 45.4 µ m wide ostiole central. Young conidia (n=100) developed from conidiogenous cells, which were simple, tapering, hyaline, smooth, and 12.3 to 18.0 × 2.5 to 4.6 µm, 1.0 to 1.5 µm wide at apex. Mature conidia (n=100) were ellipsoid, apices tapering, subobtusely rounded, brown, and 6.5 to 11.0 × 4.1 to 7.5 µm. The morphological characteristics of the isolates were consistent with previous descriptions of the genus Coniella (Crous et al., 2014). A representation isolate CS-1 was deposited in the Institute of Plant Protection, Gansu Academy of Agricultural Sciences and used for further studies. To confirm the identity of the causal fungus, the internal transcribed spacer (ITS), 28S large subunit of nuclear ribosomal RNA (LSU) and partial translation elongation factor 1-alpha (TEF1-α) gene of the representative isolate CS-1 were amplified and sequenced using primers ITS1/ITS4 (White et al., 1990), LROR/LR7 (Chethan et al., 2017) and EF1-728F/EF1-986R (Carbone and Kohn, 1999), respectively, and deposited on GenBank with accession numbers OP824764 (ITS), OP824767 (LSU)/span>and OP903926 (TEF1-α). Blastn analysis of all sequences resulted in E-value of 0.0 (ITS and LSU) and nearly 0.0 (TEF1-α), with Query cover values of 90% to 99% identity with C. fragariae, confirming the hypothesis based on morphological features examination. To conduct a pathogenicity test, three root segments of healthy plants were wounded using sterilized needles and inoculated by pipetting 10 µL of conidial suspension (1×107 conidia/mL) onto each wound, and controls were inoculated with 10 µL sterile distilled water. These root segments were kept in a moist chamber at 25°C in the dark. The experiment was repeated three times. After 14 days, root rot symptoms were observed on all of the inoculated root segments and identical to those observed in the field, whereas control root segments did not develop symptoms. The pathogen was re-isolated from the lesions of inoculated root segments, fulfilling Koch's postulates. To the best of our knowledge, this is the first report of C. fragariae causing root rot on P. radix Rubra in China. This identification can aid in the selection of appropriate management measures for this disease.

Genetic diversity of Venturia inaequalis isolates from the scabs in apple trees in Gansu Province, China, using AFLP markers.

Apple scab is a serious disease that restricts the growth of cultivated apples. The objective of this study is to investigate the genetic variations and genetic structure of Venturia inaequalis in Gansu Province, China. 108 isolates of the pathogen V. inaequalis from the Jingning, Lingtai, Jingchuan, Xifeng, Ning and Maiji regions were collected, and their genetic diversity was analyzed using AFLP molecular marker technique. The results showed that genetic diversity was present among the isolates but was not statistically significant. Genetic distance values ranged from 0.0095 to 0.0762. Cluster analysis results showed that the 108 isolates could be divided into two clusters using a similarity coefficient of 0.69. A total of 104 isolates were contained in cluster I while four isolates were contained in Cluster II. From the AMOVA analysis, 98% of variations were observed within the same region, while 2% were observed across different regions. The analysis of population structure showed that 108 isolates had two common ancestors, with the Jingning isolates mainly being derived from the red ancestor. PCoA analysis showed that the Jingning isolates were independent to a certain extent. The different geographical location caused the genetic difference of the isolates. The genetic diversity of apple scab in Gansu Province is greatly aided by this work, which also offers a theoretical foundation for the use of molecular markers in assisted breeding to create novel resistant types.

Epithelial Cell Rests of Malassez Provide a Favorable Microenvironment for Ameliorating the Impaired Osteogenic Potential of Human Periodontal Ligament Stem Cells.

Human periodontal ligament stromal/stem cells (PDLSCs) are ideal candidates for periodontal regeneration and are of significant importance in clinical practice. However, PDLSCs derived from diseased microenvironments exert impaired behavior, which leads to the failure of periodontal regeneration. The epithelial cell rests of Malassez (ERM), which are involved in periodontal homeostasis, are residual cells from Hertwig's epithelial root sheath (HERS). However, the function of ERM remains largely unknown. Therefore, the aim of this study was to evaluate the effect of ERM on the osteogenic potential of PDLSCs from an impaired microenvironment. PDLSCs from healthy donors (H-PDLSCs), periodontitis donors (P-PDLSCs) and human ERM were harvested. Osteogenic evaluation showed a lower osteogenic potential of P-PDLSCs compared to that of H-PDLSCs. Then, we co-cultured ERM with P-PDLSCs, and the data showed that ERM promoted the expression of osteogenic genes and proteins in P-PDLSCs. In addition, we collected the PDLSCs from aged donors (A-PDLSCs) and analyzed the osteogenesis capacity of the A-PDLSCs and A-PDLSCs + ERM groups, which displayed similar results to P-PDLSCs. Finally, we evaluated the Wnt pathway, which is associated with osteogenic differentiation of stromal/stem cells, in A-PDLSCs + ERM and P-PDLSCs + ERM groups, which indicated that suppression of the Wnt pathway may result in an increase in the osteogenic properties of A-PDLSCs + ERM and P-PDLSCs + ERM groups. Taken together, the above findings shed new light on the function of ERM and provide a novel therapeutic for optimizing PDLSCs-based periodontal regeneration.