Impact of biocontrol microbes on soil microbial diversity in ginger (Zingiber officinale Roscoe).

BACKGROUND: Bacteria are the most diverse and abundant group of soil organisms that influence plant growth and health. Bacillus and Trichoderma are commonly used as biological control agents (BCA) that directly or indirectly act on soil bacteria. Therefore, it is essential to understand how the applied microbes impact the indigenous microbial community before exploring their activity in the control of soilborne diseases. RESULTS: MiSeq sequencing of the 16S rRNA gene was used to decipher the shift of rhizosphere bacterial community in ginger (Zingiber officinale Roscoe) treated with Bacillus subtilus and Trichoderma harzianum at different concentrations. The dominant phyla in treated and nontreated samples were Proteobacteria, Actinobacteria, Acidobacteria and comprised up to 54.7% of the total sequences. There were significant differences between BCA treated and nontreated samples in the bacteria community. BCA treated plants presented higher bacterial diversity than nontreated and higher dosage of BCA had a larger impact on rhizosphere microbiota, but the 'dose-response relationship' varied in different bacterial groups. Potential biomarkers at genus level were found, such as RB41, Pseudomonas, Nitrospira, Candidatus_Udaeobacter. CONCLUSION: The combined use of Bacillus subtilus and Trichoderma harzianum could alter bacterial community structure and diversity in rhizosphere soil. BCA-microbes interactions as well as soil microbial ecology should be noticed in plant disease management. © 2021 Society of Chemical Industry.

Studies on the control effect of Bacillus subtilis on wheat powdery mildew.

BACKGROUND: Wheat powdery mildew is a worldwide fungal disease and one of the main diseases harming wheat production. Bacillus subtilis is a vital biocontrol bacteria with broad-spectrum antimicrobial activity. In this study, we systematically studied the control effect of B. subtilis on wheat powdery mildew. RESULTS: The control efficiency of 4 × 105 CFU ml-1 B. subtilis on wheat leaves was 71.75% in vitro and 70.31% in a pot experiment. Application of 4 × 105 CFU ml-1 B. subtilis significantly inhibited spore germination (spore germination rate of 22.23%) and increased appressorium deformity (appressorium deformity rate of 69.33%). This was significantly different from the results in the sterile water treatment. Through transcriptome sequencing analysis, we found that differentially expressed genes were mainly enriched in the biosynthesis and metabolism of amino acids (including phenylalanine), carbon metabolism, the pentose phosphate pathway and other pathways. In particular, the plant hormone signal pathway gene nonexpressor of pathogenesis-related genes 1 (NPR1) was significantly upregulated. CONCLUSION: B. subtilis at concentrations of 4 × 105 CFU ml-1 had a significant control effect on wheat powdery mildew and can inhibit germination of the conidial germ tubes and the normal development of appressorium. B. subtilis may induce disease resistance in wheat to control wheat powdery mildew, and this effect is related to the salicylic acid-dependent signal pathway. © 2021 Society of Chemical Industry.

Mechanisms and Active Compounds Polysaccharides and Bibenzyls of Medicinal Dendrobiums for Diabetes Management.

BACKGROUND: Medicinal dendrobiums are used popularly in traditional Chinese medicine for the treatment of diabetes, while their active compounds and mechanism remain unclear. This review aimed to evaluate the mechanism and active compounds of medicinal dendrobiums in diabetes management through a systematic approach. METHODS: A systematic approach was conducted to search for the mechanism and active phytochemicals in Dendrobium responsible for anti-diabetic actions using databases PubMed, Embase, and SciFinder. RESULTS: Current literature indicates polysaccharides, bibenzyls, phenanthrene, and alkaloids are commonly isolated in Dendrobium genusin which polysaccharides and bibenzyls are most aboundant. Many animal studies have shown that polysaccharides from the species of Dendrobium provide with antidiabetic effects by lowering glucose level and reversing chronic inflammation of T2DM taken orally at 200 mg/kg. Dendrobium polysaccharides protect pancreatic ß-cell dysfunction and insulin resistance in liver. Dendrobium polysaccharides up-regulate the abundance of short-chain fatty acid to stimulate GLP-1 secretion through gut microbiota. Bibenzyls also have great potency to inhibit the progression of the chronic inflammation in cellular studies. CONCLUSION: Polysaccharides and bibenzyls are the major active compounds in medicinal dendrobiums for diabetic management through the mechanisms of lowering glucose level and reversing chronic inflammation of T2DM by modulating pancreatic ß-cell dysfunction and insulin resistance in liver as a result from gut microbita regulation.

The Damaging Effects of Pedunsaponin A on Pomacea canaliculata Hemocytes.

Pomacea canaliculata hemocytes are the main functional cells in the immune defense system, and hemocyte destruction disrupts the immune response mechanism of P. canaliculata, resulting in abnormal growth, development, reproduction, and even death. Our previous study found that Pedunsaponin A significantly affects P. canaliculata hemocyte structure. This study further investigated the damaging effects of Pedunsaponin A on P. canaliculata hemocytes. The cell mortality rate results showed that the hemocyte mortality was significantly increased after treatment with Pedunsaponin A, and the mortality rate exhibited a significant positive correlation with treatment time and dose. The membrane potential results showed that the cell membranes of P. canaliculata hemocytes exhibited time-dependent membrane depolarization after 40 mg/L Pedunsaponin A treatment. At 36 h, the cell depolarization rate in the Pedunsaponin A treatment group was 41.43%, which was significantly greater than the control group (6.24%). The cytoskeleton results showed that Pedunsaponin A led to disordered and dispersed arrangement of microfilaments and changes in the cytoskeletal structure. The apoptosis and cell cycle results showed that Pedunsaponin A induced apoptosis and influenced the cell cycle to some extent. These results showed that the cell membrane and cytoskeleton of P. canaliculata hemocytes were damaged after treatment with Pedunsaponin A, which led to an increase in cell mortality, dysfunction, cell cycle abnormalities and apoptosis. This study provides a foundation for further identification of the site of Pedunsaponin A activity on hemocytes.

Compounds from the root of Pueraria peduncularis (Grah. ex Benth.) Benth. and their antimicrobial effects.

BACKGROUND: Pueraria peduncularis belongs to the genus Pueraria DC, and has a wide range of medical and agricultural activities. Previous studies have shown that P. peduncularis extracts have broad bioactivities against phytopathogens. In this paper, we systematically studied the fungicidal activity of root methanol extracts and further isolated the active compounds. RESULTS: The root methanol extract inhibited the mycelial growth of the five tested phytopathogens to different degrees. Among these phytopathogens, the inhibitory effect was greatest against R. solani, with an EC50 value of 324.72 mg L-1 . Eight compounds were subsequently isolated and identified from P. peduncularis. Among them, puercarpan A and medicarpin showed strong fungicidal activity, with MIC values against Rhizoctonia solani of 1.6 and 6.25 mg L-1 , respectively. Puercarpan A is a new compound, and its structure was established as (6aR,6bS,11aR)-6b-hydroxy-3-methoxypterocarpan-10-ene-7-one. CONCLUSION: The P. peduncularis extracts exhibit high antimicrobial activity against R. solani and have great potential value of P. peduncularis as a fungicide. © 2019 Society of Chemical Industry.