ABSTRACT
Gynura (Gynura bicolor DC.) is a perennial herbaceous plant in the family Compositae. It is an important Chinese vegetable, and is commonly used as a Chinese herbal medicine. In 2010, a severe leaf spot disease was observed on gynura grown in the main production areas in Tong Nan County, Chongqing City, China. Some farms experienced 60% disease incidence. Symptoms usually began on the lower leaves, as circular to elliptical or irregular spots with concentric rings. Individual spots were dark brown with grayish centers, sometimes coalescing and leading to extensive necrosis. The fungus associated with lesions was characterized as follows: Conidiophores were single or in clusters, straight or flexuous, unbranched, percurrent, cylindrical, pale to dark brown, 87.5 to 375.0 µm long and 5.0 to 10.5 µm wide. Conidia were solitary or catenate, straight to slightly curved, obclavate to cylindrical, 3 to 14 pseudoseptate, 82.8 to 237.5 µm long and 7.0 to 7.8 µm wide, and pale brown. The morphological characteristics of the conidia and conidiophores agreed with the descriptions for Corynespora cassiicola (1). To isolate the causal pathogen, surface-sterilized tissue at the margin of lesions was immersed in 75% ethanol for 30 s, rinsed in sterile water, dried in a laminar flow bench, transferred to PDA, and incubated at 28°C. Four single-spore cultures of the isolates were obtained and named from ZBTK10110637 to ZBTK10110640. All strains were identified as C. cassiicola. The isolate ZBTK10110637 was selected as representative for molecular identification. Genomic DNA was extracted by CTAB (2). The internal transcribed spacer (ITS) region of the rDNA was amplified using primers with ITS1 (5'-TCCGATGGTGAACCTGCGG-3') and ITS4 (5'-TCCTCCGCTTATTGATATGC-3'). Amplicons were 433 bp (GenBank Accession No. JX867272) and shared 100% similarity with that of C. cassiicola (NRC2-1 No. AB539285.1). To confirm pathogenicity, four isolates were used to inoculate 12 gynura plants (6 weeks old) by mist spray-inoculation with 108 spores/ml suspension in sterile distilled water on the leaves. Control plants were misted with sterile distilled water. After inoculation, all plants were incubated in a greenhouse maintained at 20 to 28°C with relative humidity of 80 to 85%. Five days after inoculation, dark brown spots with a grayish center typical of field symptoms were observed on all inoculated plants. No symptoms were seen on water-treated control plants. The fungus was re-isolated from inoculated plants. The morphological characteristics of isolates were identical with the pathogen recovered originally. This is the first report of C. cassiicola on gynura. References: (1) M. B. Ellis. CMI Mycological Papers 65(9):1-15, 1957. (2) T. J. White et al. Page 315 in: PCR Protocols: A Guide to Methods and Applications. Academic Press, San Diego, CA, 1990.
ABSTRACT
INTRODUCTION: Teacher-centred education dominates dental education in China. Student-centred education has recently been introduced in the School of Stomatology, Wuhan University, and the effectiveness of such methods needs to be tested. The purpose of this study is to compare the learning outcomes of case-based learning (CBL) and lecture-based education (LBE) in an oral medicine curriculum. MATERIALS AND METHODS: We chose oral leukoplakia as the learning subject for dental students. Forty fourth-year dental students participated in the study. First, they were presented to basic knowledge of oral leukoplakia and related oral mucosal diseases. Then, they were divided into a CBL group (n=20) and an LBE group (n=20) by random numbers. The groups experienced the remaining course in separate groups. All students answered a questionnaire on their satisfaction with the education and the same standardised written test to analyse their learning outcomes. RESULTS: Both CBL and LBE courses were well accepted by students according to the satisfactory scores of the questionnaire. The test scores of the CBL group (90.00±6.69) were significantly higher (P<0.01) than those of the LBE group (83.00±6.77). The percentage of high test score (test score≥85) of the CBL group (85%) was also significantly higher (P<0.01) than that of the LBE group (45%). CONCLUSIONS: In this example, CBL was found to be more effective than LBE to teach dental students. These findings suggest that CBL should be added in our future oral medicine curriculum for dental students.
