Isolation,screening and identification of endophytic fungi and detection of its antifungal effects against Alternaria panax / 中国中药杂志

To obtain biocontrol fungus for Alternaria panax,the antifungal effects of one strain of endophytic fungi isolated from leaves of healthy ginseng were screened and evaluated by using dual-culture method,and the taxonomic assignment of the screened strain was identified based on the morphological characters and ITS sequence analysis. The results of dual-culture showed that one of the endophytes marked as FS-01 had good antifungal effects and the inhibitory rates of FS-01 strain to A. panax was( 60. 21±0. 12) %.The hyphae junction of the both strains,A. panax dissolved,broke and winded,while the hyphae of FS-01 strain remained normal. The inhibitory rates of non-sterilized FS-01 strain fermentation liqud was( 13. 94±0. 21) %. Strain FS-01 identified as Chaetomium globosum.

Research on chemotaxis response of Alternaria panax to amino acid of ginseng root exudates / 中国中药杂志

Plate assay and spore germination method were used to study the chemotaxis response of Alternaria panax to arginine, glutamic acid, aspartic acid and threonine. The result showed that the optimum temperature of A. panax chemotaxis response to four amino acids were all 25 ℃. And chemotaxis responses of A. panax were different under conditions of different concentration and pH value. The chemotaxin reached to the highest under the condition of 2 mg•L⁻¹ and pH value was 7 for arginine, glutamic acid and threonine while 20 mg•L⁻¹ and pH value was 6 for aspartic acid . The data of chemotactic migration index (CMI) were 1.24, 1.38, 1.27, 1.31 and chemotactic growth rates(CGR) were 0.451 0, 0.353 0, 0.381 3, 0.228 8 and spores germination rates(SGR) were 57.33%，63%，56.67%，58% and the dry weight of mycelial (DWM) were 372.9, 348.5, 314.4, 390.2 mg•L⁻¹ respectively. It indicated that the low and middle concentration of amino acid had significant promoting effect on chemotaxis response of A. panax. As important substances generated in ginseng root, amino acids exhibited an efficient chemotactic effect on A. panax, and some even show inhibition effect under high concentration.

Cloning and expression analysis of polygalacturonase-inhibiting protein gene from Panax notoginseng / 中草药

Objective: To clone the full-length cDNA sequence of PnPGIP gene encoding polygalacturonase-inhibiting protein (PGIP) from Panax notoginseng and analyze the expression levels of PnPGIP. Methods: Based on P. notoginseng expressed sequence tag (EST) encoding PGIP, specific primers were designed and the full-length cDNA of EST was cloned with the method of rapid amplification of cDNA ends (RACE). The expression levels of PnPGIP were analyzed by qRT-PCR. Results: The full-length cDNA of PnPGIP was 1 171 bp and contained an intact open reading frame (ORF) of 981 bp, a 13 bp 5'-untranslated region (UTR), and a 177 bp 3'-UTR. The deduced amino acid sequence of PnPGIP has 326 amino acid residues which form a 36 770 polypeptide with a calculated pI of 5.83. qRT-PCR analysis indicated that the expression of PnPGIP was quickly induced after inoculation with Fusarium solani and Alternaria panax, and the highest transcription level was achieved at 4 h and 2 h post inoculation, respectively. Moreover, the expression of PnPGIP was induced in different degrees by methyl jasmonate (MeJA), ethylene (ETH), H2O2, and salicylic acid (SA). Conclusion: PnPGIP responds to F. solani and A. panax infection in the transcription level, and it is induced by several kinds of adversity stresses related signaling molecules. Therefore, PnPGIP may be involved in defense response of P. notoginseng against F. solani and A. panax.

Studies on Dynamics of Two Endophytic Bacterial Strains Inside Ginseng and Soil of Root Region / 世界科学技术-中医药现代化

This article was aimed to study the dynamics of biocontrol endobacteria in roots, stems and leaves of Panax ginseng and soils adjacent roots. Gradient screening and root irrigation methods were used to develop Rif-resistance bacteria and inoculation. Dilution plate method was used to count the number of them in roots, stems and leaves of P. ginseng and soils adjacent roots. The results showed that bacteria which can endure 120 μg·mL-1 Rif was developed, and no change was found on their antagonistic activity against A lternaria panax Whetz and Phytophthora cactorum. In roots and stems of P. ginseng, ge15 and ge25 showed the highest number in the initial.Then, populations of ge15 and ge25 in ginseng roots and stems decreased to a stable status gradually. In ginseng leaves, populations of ge15 and ge25 increased to the highest 3 days after inoculation, then, populations of them were decreased and kept at certain concentration. In ginseng rhizosphere soil, populations of ge15 showed reciprocating change, and which of ge25 showed increase initial, and then decrease to a stable status. It was concluded that endobacteria can keep a certain population in ginseng roots, stems, and leaves. Biocontrol agents based on them will be helpful for ginseng diseases controlling in the field.

First Report of Foliar Blight on Dendropanax morbifera Caused by Alternaria panax

Leaf spot and blight disease was observed on two-year-old seedlings of Dendropanax morbifera (Korean name: Hwangchil tree) during July of 2008 in Jindo Island, Korea. Symptoms included yellow-brown to dark brown irregularly enlarged spots frequently located along the veins of leaves. The lesions were often surrounded by chlorotic haloes. Severe leaf blight and subsequent defoliation occurred when conditions favored disease outbreak. The causal organism of the disease was identified as Alternaria panax based on morphological characteristics and sequence analysis of the internal transcribed spacer region of rDNA. A. panax isolates induced leaf spots and blight symptoms not only on D. morbifera but also on the other members of Araliaceae tested. This is the first report of foliar blight caused by A. panax on D. morbifera.