Rapid and Efficient Detection of 16SrI Group Areca Palm Yellow Leaf Phytoplasma in China by Loop-Mediated Isothermal Amplification.

Areca palm yellow leaf (AYL) disease caused by the 16SrI group phytoplasma is a serious threat to the development of the Areca palm industry in China. The 16S rRNA gene sequence was utilized to establish a rapid and efficient detection system efficient for the 16SrI-B subgroup AYL phytoplasma in China by loop-mediated isothermal amplification (LAMP). The results showed that two sets of LAMP detection primers, 16SrDNA-2 and 16SrDNA-3, were efficient for 16SrIB subgroup AYL phytoplasma in China, with positive results appearing under reaction conditions of 64oC for 40 min. The lowest detection limit for the two LAMP detection assays was the same at 200 ag/µl, namely approximately 53 copies/µl of the target fragments. Phytoplasma was detected in all AYL disease samples from Baoting, Tunchang, and Wanning counties in Hainan province using the two sets of LAMP primers 16SrDNA-2 and 16SrDNA-3, whereas no phytoplasma was detected in the negative control. The LAMP method established in this study with comparatively high sensitivity and stability, provides reliable results that could be visually detected, making it suitable for application and research in rapid diagnosis of AYL disease, detection of seedlings with the pathogen and breeding of disease-resistant Areca palm varieties.

Dendrobium viroid, a new monocot-infecting apscaviroid.

Viroids are small circular RNA molecules which have been found to infect many dicot species. Only coconut cadang-cadang viroid and coconut tinangaja viroid have been reported so far to infect a monocot (coconut). Data mining in silico has proven an efficient approach to identify new viruses/viroids, and a systematic screen of public transcriptomic data revealed a 648 nucleotides (nt) sequence potentially representing a novel viroid-like RNA in a transcriptome shotgun assembly from Dendrobium officinale. This sequence contained two central conserved regions (CCRs) characteristic of members of the genus Apscaviroid, indicating that the viroid-like RNA is 324 nt in length. The infectivity of dimeric RNA transcripts generated by in vitro transcription of a synthetic cDNA, was demonstrated by directly injecting into the stems of young Dendrobium officinale plants. The presence of this novel viroid, tentatively designated as Dendrobium viroid (DVd), in the inoculated plants was confirmed by 2D-PAGE together with northern hybridization. DVd is predicted to have a rod-like secondary structure containing a CCR and a terminal conserved region (TCR), and phylogenetic analysis shows that it groups with the known members of the genus Apscaviroid. It is most closely related to citrus viroid V (56% nt identity). A field survey revealed a low DVd incidence (0.96%) in Dendrobium species in China. To our best knowledge, DVd is the only viroid known to infect orchids and the third one from monocotyledonous plants.

[Research on Glycyrrhizeae Radix standard decoction].

Fifteen batches of Glycyrrhizeae Radix standard decoction were prepared for determination of the content of the glycyrrhizic acid and liquiritin, then the transfer rate and the extract rate were calculated and a method was established to analyze the fingerprint by HPLC. According to the measurement of 15 batches of samples,the transfer rate of the glycyrrhizic acid and liquiritin were 59.4%-87.4% and 49.8%-78.9% with extract rate of 29.9%-38.9%. Moreover,10 common chromatographic peaks were determined based on their fingerprint by using similarity evaluation system for chromatographic fingerprint of traditional Chinese medicine (TCM)(2012A) .The similarity results of 15 batches of samples were analyzed and compared,and the results showed that the similarity was all higher than 0.9. Fifteen batches of samples,prepared by a standard method,have stable quality and the high similarity.The method displayed good precision,stability and repeatability in fingerprint analysis. Therefore,this study can provide a reference for the quality control of Glycyrrhizae Radix dispensing granules.