Evaluation of a loop-mediated isothermal amplification assay based on hrpZ gene for rapid detection and identification of Pseudomonas syringae pv. lachrymans in cucumber leaves.

AIMS: Cucumber angular leaf spot caused by Pseudomonas syringae pv. lachrymans (Psl) is an important and destructive disease worldwide, and no effective technique has been developed for the control of the pathogen. Detection of infection or latent in cucumber plants is critical to evaluate disease progress and strengthening management to avoid a serious epidemic in the fields. In this paper, we developed a rapid and sensitive method for detection of Psl using an isothermal method known as loop-mediated amplification (LAMP). METHODS AND RESULTS: A set of six primers was designed to amplify the gene coding for the hrpZ, and conditions for detection were optimized to complete in 60 min at 67°C, and the amplification were confirmed through gel electrophoresis or visually inspected using calcein stain. The specificity of LAMP primers set was widely validated on Psl and nontarget strains. In sensitivity testing, LAMP allowed detection as low as 104  CFU per ml bacterial cells without DNA extraction. The novel method was also applied for detecting Psl in infected cucumber leaves, and even the early onset of disease can be detected by the assay. CONCLUSIONS: This study confirmed that the novel developed LAMP assay is an easy, rapid and sensitive method for the detection of Psl in infected leaves. SIGNIFICANCE AND IMPACT OF THE STUDY: The method is suitable for direct detection of Psl without strain enrichment and complex DNA extraction from samples in the field, and hence it has the capability to be used for on-site disease diagnosis and field surveys.

First Report of Myrothecium roridum Causing Leaf Spot on Zantedeschia aethiopica in China.

Zantedeschia aethiopica (L.) Spreng. (calla lily), belonging to family Araceae, is a popular ornamental plant in China. In the summer of 2010, leaves of calla lily with typical symptoms of necrotic lesions were observed in a commercial glasshouse in Beijing, China (116°20' E, 39°44' N). The initial symptoms were circular to subcircular, 1 to 3 mm, and dark brown lesions on the leaf lamina. Under high humidity, lesions expanded rapidly to 5 to 10 mm with distinct concentric zones and produced black sporodochia, especially on the backs of leaves. Later, the infected leaves were developing a combination of leaf lesions, yellowing, and falling off; as a result, the aesthetic value of the plant was significantly impacted. Leaf samples were used in pathogen isolation. Symptomatic leaf tissues were cut into small pieces and surface sterilized with 70% ethanol for 30 s and then in 0.1% mercuric chloride solution for 1 to 3 min. After being washed in sterile distilled water three times, the pieces were plated on potato dextrose agar (PDA) and incubated at 25°C in darkness for 7 days (5). Initial colonies of isolates were white, floccose mycelium and developed dark green to black concentric rings that were sporodochia bearing viscid spore masses after incubating 5 days. Conidiophores branched repeatedly. Conidiogenous cells were hyaline, clavate, and 10.0 to 16.0 × 1.4 to 2.0 µm. Conidia were hyaline, cylindrical, both rounded ends, and 6.0 to 8.2 × 1.9 to 2.4 µm. Morphological characteristics of the fungus were consistent with the description of Myrothecium roridum Tode ex Fr. (3,4). To confirm the pathogenicity, three healthy plants of calla lily were inoculated with a conidial suspension (1 × 106 conidia per ml) brushed from a 7-day-old culture of the fungus. Control plants were sprayed with sterile water. The inoculated plants were individual with clear plastic bags and placed in a glass cabinet at 25°C. After 7 days, all inoculated leaves developed symptoms similar to the original samples, but control plants remained disease free. Re-isolation and identification confirmed Koch's postulates. For molecular identification, genomic DNA of a representative isolate (MTL07081001) was extracted by modified CTAB method (1), and the rDNA-ITS region was amplified by using primers ITS1 (5-TCCGTAGGTGAACCTGCGG-3) and ITS4 (5-TCCTCCGCTTATTGATATGC-3). The 465-bp amplicon (GenBank Accession No. KF761293) was 100% identity to the sequence of M. roridum (JF724158.1) from GenBank. M. roridum has an extensive host range, covering 294 host plants (2). To our knowledge, this is the first record of leaf spot caused by M. roridum on calla lily in China. References: (1) F. M. Ausubel et al. Current Protocols in Molecular Biology. John Wiley & Sons Inc, New York, 1994. (2) D. F. Farr and A. Y. Rossman, Fungal Databases. Syst. Mycol. Microbiol. Lab., ARS, USDA. Retrieved from http://nt.ars-grin.gov/fungaldatabases/ , October 2013. (3) M. T. Mmbaga et al. Plant Dis. 94:1266, 2010. (4) Y. X. Zhang et al. Plant Dis. 95:1030, 2011. (5) L. Zhu et al. J. Phytopathol. 161:59, 2013.

First Report of Colletotrichum capsici Causing Anthracnose on Hosta plantaginea in China.

Fragrant plantain lily [Hosta plantaginea (Lam.) Aschers.] is an easily grown herbaceous perennial plant valued for its decorative foliage and dainty colorful flowers. From 2009 to 2011, a leaf spot disease of H. plantaginea was observed in Yuyuantan Park in Beijing, China (116°25' E, 39°55' N). The leaf spots began as small, irregular, circular, brown lesions in the middle or on the margin of leaves, which enlarged gradually up to 1 to 20 mm in diameter and were circular or irregular and brown to dark brown surrounded by yellowish borders. Occasionally, some spots cracked under dry conditions. Symptomatic leaf tissues were surface-sterilized in 1% NaOCl for 2 min, washed three times with distilled water, and then placed on potato dextrose agar (PDA). Colonies on PDA at 25°C for 7 days were grayish brown and cottony. Mycelia were hyaline to grey, septate, branched, and 2 to 7 µm wide. Acervuli were dark brown to black and 198 to 486 µm in diameter, averaging 278.5 µm. Setae were pale brown to dark brown, 2 to 4 septa, 70.0 to 120.3 × 2.5 to 5.1 µm, base cylindrical, and narrower towards the apex. Conidiophores were unicellular, hyaline, phialidic, and 5.0 to 13.5 × 1.5 to 2.8 µm. Conidia were hyaline, aseptate, falcate, apices acute, oil globules, and 16.0 to 25.2 × 2.6 to 5.0 µm. Appressoria were spherical, ovate or obclavate, pale to dark brown, edge usually entire, and 9.5 to 15.5 × 6.5 to 11.5 µm. Morphological characteristics of the fungus were similar to those of Colletotrichum capsici (Syd.) Butler & Bisby (2). To validate Koch's postulates, pathogenicity tests were performed by spraying leaves of 20 healthy potted H. plantaginea (60-day-old plants) with a 106 conidia/ml aqueous suspension. Control plants were inoculated with sterile water. Plants were put into a glass cabinet for 48 h after inoculation and maintained at 25°C, relative humidity 98%. Then the plants were moved out and incubated in greenhouse at 10 to 25°C. After 10 days, all inoculated plants showed typical symptoms, whereas water sprayed controls remained healthy. C. capsici was consistently re-isolated from these lesions. The re-isolated fungus showed the same morphological characteristics as described above. Genomic DNA was extracted from the original isolate and the re-isolate from the pathogenicity test. PCR amplification of the internal transcribed spacer (ITS) regions from ribosomal DNA was performed with primers ITS1 (5'-TCCGTAGGTGAACCTGCGG-3') and ITS4 (5'-TCCTCCGCTTATTGATATGC-3'). PCR products of 513 bp were sequenced. There was 100% nucleotide identity for sequences of the original isolate and the re-isolate. The sequence was submitted to GenBank (Accession No. HM063417.1). BLAST analysis of the fungal sequence resulted in 100% identity to the sequence of C. capsici (Accession No. JX867217.1). Isolates have been deposited at the Institute of Vegetables and Flowers, Chinese Academy of Agricultural Sciences. To our knowledge, this is the first report of anthracnose caused by C. capsici on H. plantaginea in China (1). Its confirmation is a significant step toward management recommendations for growers. References: (1) D. F. Farr and A. Y. Rossman, Fungal Databases. Syst. Mycol. Microbiol. Lab. ARS, USDA. Retrieved from http://nt.ars-grin.gov/fungaldatabases/ , August 2013. (2) J. E. M. Mordue. CMI Description of Pathogenic Fungi and Bacteria. Commonwealth Mycol. Inst., Kew, UK, 1971.

Congenital dislocation of hip in children: a review of patients treated in the Institute of Orthopaedics and Traumatology, General Hospital, Kuala Lumpur, 1975-1988.

A retrospective review of patients with congenital dislocation of the hip (CDH) seen in the Institute of Orthopaedics, Kuala Lumpur General Hospital from 1975 to 1988 is presented. There was a female predominance of 17 to five. The average follow-up was 43 months and the average age at final assessment was 63 months. The results were assessed clinically and radiographically using Severin criteria. Eighty eight percent of the hips had excellent or good clinical results at final review compared with 40% of the hips which had excellent or good radiological grading (Severin I and II). Initial acetabular angle before treatment and types of treatment appeared to have a correlation with the final result. The incidence of avascular necrosis was 16%.