Advances in research on allelopathic autotoxicity effects of medicinal plants / 中草药

Allelopathic autotoxicity is one of the important factors for the continuous cropping obstacle of medicinal plants, which will reduce the yield and quality. With the development of medicinal plants industry, the problem of continuous cropping obstacle is becoming more and more serious. How to alleviate the continuous cropping obstacle of medicinal plants needs to be solved urgently. This paper combines the research status of allelopathic autotoxicity in medicinal plants. On the one hand, expounds the mechanism that the allelochemicals of medicinal plants inhibit the growth and development of medicinal plants by damaging the cell structures, interfering with the metabolism of reactive oxygen species and phytohormones, affecting photosynthesis and so on. On the other hand, based on the analysis of the relationship between allelochemicals and continuous cropping obstacle of medicinal plants, this paper elucidated some methods to alleviate the continuous cropping obstacle of medicinal plants, such as breeding antiallelopathic autotoxicity medicinal plants varieties, rational fertilizing, selecting proper cropping system and using microbial agents, in order to provide reference for the production of medicinal plants.

Identification and analysis of the calcium signaling system genes responding to continuous cropping injury in Rehmannia glutinosa L / 药学学报

Calcium signaling plays a critical role in response to various abiotic and biotic stresses in plants. Preliminarily evidence showed that calcium signaling perceived and transduced the harmful signaling generated from continuous cropping stress in R. glutinosa. To investigate the roles of calcium signaling in continuous cropping injury formation, the key genes involved in calcium signaling transduction were identified in R. glutinosa transcriptome through bioinformatic methods. Furthermore, the calcium ion concentration in both normal and continuous cropping R. glutinosa root cells were measured by potassium pyroantimonate precipitation and calcium fluorescence method. As a result, a set of 84 calcium signaling-related genes, including 5 CaMs, 12 CBLs, 21 CDPKs, 21 CIPKs, 16 CMLs, and 9 CRKs were captured in R. glutinosa transcriptome. The analysis of expression profile in continuous cropping compared to normal growth R. glutinosa indicated that continuous cropping stress significantly increased the expression of calcium signaling-related genes in continuous cropping R. glutinosa. At the same time, the abundance levels of 12 calcium signaling-related genes quantified by qPCR further validated the high expression of calcium signaling-related genes presented in continous cropping R. glutinosa. In addition, the continuous cropping condition significantly promoted the accumulation of intracellular calcium ions in R. glutinosa based on two methods of potassium pyroantimonate precipitation and calcium fluorescence. This study verified the possible roles of calcium signaling in the formation of continuous cropping injury on molecular and cellular level, which lays a solid foundation for illuminating formation mechanism of continuous cropping injury on molecular level.

Gene cloning and expression analysis of benzoic acid stress responsive transcription factor WRKY7 in Panax ginseng / 中国中药杂志

WRKY transcription factor is one of the most important transcription factor families widely existing in higher plants, which playing critical role in plant morphogenesis, development, biotic (including phytopathogens, pests etc.) and abiotic (drought, salt, chilling, high temperature, etc.) stress. In the present work, primers used to amplify full-length gene encoding WRKY transcription factor were designed based on the transcriptome data of P. ginseng that induced by benzoic acid, one of the most important autotoxins identified from root exudates and rhizosphere soil of P. ginseng. Then, a WRKY gene, temporarily named as WRKY7, was confirmed by RT-RCR. Furthermore, sequencing and sequence analysis of WRKY7 was conducted. Results indicated that, the full length cDNA of WRKY7 was 1 216 bp, the open reading frame (ORF) of which was 1 014 bp, encodes 337 amino acids. Homologous analysis and phylogenetic tree showed that, WRKY7 belonged to the Ⅲ category of WRKY families, which showing 87% similarity to WRKY6 in P. quinquefolius. Real-time PCR results showed that the expression of WRKY7 in P. ginseng induced by benzoic acid was up-regulated markedly than the control, so we speculated that WRKY7 was involved in the response to benzoic acid stress, which will be helpful for further research on the molecular mechanism of ginseng plant response to benzoic acid stress.

Autotoxicity in Pogostemon cablin and their allelochemicals

Abstract The effects of allelochemicals and aqueous extracts from different Pogostemon cablin (Blanco) Benth., Lamiaceae, parts and rhizosphere soil on growth parameters, leaf membrane peroxidation and leaf antioxidant enzymes were investigated in patchouli. P. cablin seedlings were incubated in solutions containing allelochemicals and aqueous extracts from different patchouli parts and its rhizosphere soil at several concentrations. Firstly, the growth parameters were significantly reduced by the highest concentration of leaves, roots and stems extracts (p < 0.05). As compared to the control, plant height was reduced by 99.8% in the treatment with leaves extracts (1:10). The malondialdehyde content increased greatly when patchouli seedlings were subject to different concentrations of leaves, roots and stems extracts; meanwhile, the superoxide dismutase and peroxidase activities showed an increase trend at the low concentration, followed by a decline phase at the high concentration of roots and leaves extracts (1:10). What's more, leaves and roots extracts had a more negative effect on patchouli growth than stems extracts at the same concentrations. Secondly, the total fresh mass, root length and plant height were greatly reduced by the highest strength of soil extracts. Their decrements were 22.7, 74.9, and 33.1%, respectively. Thirdly, growth parameters and enzymatic activities varied considerably with the kinds of allelochemicals and with the different concentrations. Plant height, root length and total fresh weight of patchouli were greatly reduced by p-hydroxybenzoic acid (200 μM), and their decrements were 77.0, 42.0 and 70.0%, respectively. Finally, three useful measures on reducing the autotoxicity during the sustainable patchouli production were proposed.

Effect of Autotoxicity and Soil Microbes in Continuous Cropping Soil on Angelica sinensis Seedling Growth and Rhizosphere Soil Microbial Population / 中草药·英文版

Objective: To study the effect of autotoxicity and the co-effect of autotoxicity and soil microbes from continuous cropping soil on Angelica sinensis growth, root yield and content of essential oils, and soil microbal population. Methods: The pot experiments were conducted upon A. sinensis seedlings in continuous cropping soil. At the different growth stages, we determined the seedlings in growth parameters, root yield, content of essential oils, ethanol extract, and cultivable microbial populations in rhizosphere soil. Results: A. sinensis seedlings were significantly inhibited in growth, root yield and quality. Compared with the control, the composition and structure of soil microbes were changed and the diversity indexes of bacteria functional groups were reduced in rhizosphere soil of A. sinensis. A. sinensis cropping problems were more seriously after the treatment with combination of autotoxicity and soil microbes than with autotoxicity alone. Conclusions: The autotoxicity and soil microbes from continuous cropping soil of A. sinensis could cause the continuous cropping obstacle together.

Protective Effect of Hexane and Ethanol Extract of Piper Longum L. on Gentamicin-Induced Hair Cell Loss in Neonatal Cultures

OBJECTIVES: Gentamicin (GM) is a commonly used aminoglycoside antibiotic that generates free oxygen radicals within the inner ear, which can cause vestibulo-cochlear toxicity and permanent damage to the sensory hair cells and neurons. Piper longum L. (PL) is a well-known spice and traditional medicine in Asia and Pacific islands, which has been reported to exhibit a wide spectrum of activity, including antioxidant activity. In this study, we evaluated the effect of hexane:ethanol (2:8) PL extract (subfraction of PL [SPL] extract) on GM-induced hair cell loss in basal, middle and apical regions in a neonatal cochlea cultures. METHODS: The protective effects of SPL extract were measured by phalloidin staining of cultures from postnatal day 2-3 mice with GM-induced hair cell loss. The anti-apoptosis activity of SPL extract was measured using double labeling by terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) and myosin-7a staining. The radical-scavenging activity of SPL extract was assessed using the 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay. RESULTS: SPL extract at a concentration of 1 microg/mL significantly inhibited GM-induced hair cell loss at basal and middle region of cochlea, while 5 microg/mL was effective against apical region hair cell loss. The protective effect of SPL extract was concentration dependent and hair cells retained their stereocilia in explants treated with SPL extract prior to treatment with 0.3 mM GM. SPL extract decreased GM-induced apoptosis of hair cells as assessed by TUNEL staining. The outer hair and inner hair counts were not decreased in SPL extract treated groups in compare to GM treated explants. Additionally, SPL extract showed concentration dependent radical scavenging activity in a DPPH assay. CONCLUSION: An anti-apoptosis effect and potent radical scavenger activity of SPL extract protects from GM-induced hair cell loss at basal, middle and apical regions in neonatal cochlea cultures.

Autotoxicity of water extracts from rhizosphere soil of cultivated Angelica sinensis and identification of their allelopathic compounds / 中草药

Objective: To explore the relationship between continuous cropping obstacle and autotoxicity of Angelica sinensis, autotoxic effect and organic compounds of rhizosphere soil water extract were determined. Methods: Distilled water (CK), water extract of rhizosphere soil (100, 125, 250, and 500 mg/ mL) were applied to testing their effect on early development of A. sinensis. Seed germination rate, germination index, elongation of radicle and embryo were recorded, and GC-MS was conducted for the compound identification in the extract. Results: The water extract at concentraion as low as 125 mg/mL significantly inhibited the germination and seedling growth of A. sinensis, and this inhibitory effect generally increased with the increase of the concentration of water extracts. Seventeen compounds in rhizosphere soil water extract were identified, including organic acids, ketones, aldehydes, esters, and hydrocarbons, most of them are allelophathic substance. Conclusion: Water extracts from A. sinensis rhizosphere soil have inhibitory effects on A. sinensis germination and seedling growth, and this inhibitory effect generally increased with the increases of the water extract concentration at a certain ranges. In conclusion, there is autotoxicity in continuous cropping of A. sinensis, which is one of the causes of problems associated with the continuous cropping obstacle of a single plant species.