A Streptomyces species from the ginseng rhizosphere exhibits biocontrol potential.

Plants and their associated microbes live in complicated, changeable, and unpredictable environments. They usually interact with each other in many ways through multidimensional, multiscale, and multilevel coupling manners, leading to challenges in the coexistence of randomness and determinism or continuity and discreteness. Gaining a deeper understanding of these diverse interaction mechanisms can facilitate the development of data-mining theories and methods for complex systems, coupled modeling for systems with different spatiotemporal scales and functional properties, or even a universal theory of information and information interactions. In this study, we use a "closed-loop" model to present a plant-microbe interaction system and describe the probable functions of microbial natural products. Specifically, we report a rhizosphere species, Streptomyces ginsengnesis G7, which produces polyketide lydicamycins and other active metabolites. Interestingly, these distinct molecules have the potential to function both as antibiotics and as herbicides for crop protection. Detailed laboratory experiments conducted in Arabidopsis (Arabidopsis thaliana), combined with a comprehensive bioinformatics analysis, allow us to rationalize a model for this specific plant-microbe interaction process. Our work reveals the benefits of exploring otherwise neglected resources for the identification of potential functional molecules and provides a reference to better understand the system biology of complex ecosystems.

Integrated Transcriptome and Metabolome Analysis Reveals Phenylpropanoid Biosynthesis and Phytohormone Signaling Contribute to "Candidatus Liberibacter asiaticus" Accumulation in Citrus Fruit Piths (Fluffy Albedo).

"Candidatus Liberibacter asiaticus" (CLas) is a phloem-restricted α-proteobacterium that is associated with citrus huanglongbing (HLB), which is the most destructive disease that affects all varieties of citrus. Although midrib is usually used as a material for CLas detection, we recently found that the bacterium was enriched in fruits, especially in the fruit pith. However, no study has revealed the molecular basis of these two parts in responding to CLas infection. Therefore, we performed transcriptome and UHPLC-MS-based targeted and untargeted metabolomics analyses in order to organize the essential genes and metabolites that are involved. Transcriptome and metabolome characterized 4834 differentially expressed genes (DEGs) and 383 differentially accumulated metabolites (DAMs) between the two materials, wherein 179 DEGs and 44 DAMs were affected by HLB in both of the tissues, involving the pathways of phenylpropanoid biosynthesis, phytohormone signaling transduction, starch and sucrose metabolism, and photosynthesis. Notably, we discovered that the gene expression that is related to beta-glucosidase and endoglucanase was up-regulated in fruits. In addition, defense-related gene expression and metabolite accumulation were significantly down-regulated in infected fruits. Taken together, the decreased amount of jasmonic acid, coupled with the reduced accumulation of phenylpropanoid and the increased proliferation of indole-3-acetic acid, salicylic acid, and abscisic acid, compared to leaf midribs, may contribute largely to the enrichment of CLas in fruit piths, resulting in disorders of photosynthesis and starch and sucrose metabolism.

Enzymatic characteristics of a recombinant protease (rPepD) from Aspergillus niger expressed in Pichia pastoris.

The Aspergillus niger AS3.350 protease gene (pepD) was successfully cloned and expressed in Pichia pastoris KM71. The rPepD activity was 331.5 U/ml, and the optimum temperature and pH were 45 °C and 8-9 respectively. In addition, enzyme activity was significantly inhibited by PMSF, EDTA, Mg2+, Fe2+ and Zn2+ ions, and stimulated by Ca2+ which selectively bound to the T302 and D323 residues. Mutation in either or both of the residues inhibited rPepD expression, indicating that binding to Ca2+ is necessary for PepD expression and activity. The rPepD showed a wide substrate range, and was particularly selective to those with hydrophobic amino acids. The degree of rPepD-mediated hydrolysis of soy protein isolate, corn flour and gluten meal were 8.7%, 38.1% and 33.6% respectively, which was higher than that by Alcalase, indicating that rPepD has potential applications in the food processing industry.

Current Epidemic Situation and Control Status of Citrus Huanglongbing in Guangdong China: The Space-Time Pattern Analysis of Specific Orchards.

Huanglongbing (HLB) is the most harmful bacterial disease in citrus production in the world, and has been seriously ravaging the citrus groves of South China since the 1930s. The surveillance of the epidemiological characteristics of HLB is of utmost priority for citrus production in this region. In order to explore the effects of disease control measures, analyses on the space-time statistical features of the HLB epidemic, from 2019 to 2021, within six orchards in the Guangdong province are presented. Overall, the number of citrus plants in the orchards usually slightly decreased year by year. The reduction was mainly related to the level of plant susceptibility, which is correlated with citrus varieties. The maximum disease severity (incidence and race increment) was correlated with the awareness of this disease and the management intensity applied by the manager. A higher disease index was found in the conventional management orchards than in the comprehensive prevention and control orchards. Proper insect-protective screen houses can effectively prevent the epidemic of HLB, without affecting the fruit quality, and can also aid with higher yields. A high correlation was found between the geometry and topography of orchards and the HLB epidemic due to the wind direction from May to September and the Asia citrus psyllid activity characteristics. For flat orchards, the incidence of HLB in the north and entrance areas was higher than that in the southwest. In the mountain area, the incidence of the windward side in the south was higher than that of the leeward side in the north. Diseased trees tended to have an edge effect in the grove, whereas the trees of the same disease scale were found clustered in their distribution. These results allow a better understanding of HLB epidemiology and provide guidance for the early warning of HLB in new groves in areas that are severely affected by this disease. Furthermore, they also provide a scientific basis for the comprehensive prevention and control of HLB in old groves.