Rice, which serves as a staple food for more than half of the world’s population, is very susceptible to the pathogenic fungus, Magnaporthe oryzae. However, common wild rice (Oryza rufipogon), which is the ancestor of Asian cultivated rice (O. sativa), has significant potential as a genetic source of resistance to M. oryzae. Recent studies have shown that the domestication of rice has altered its relationship to symbiotic arbuscular mycorrhizae. A comparative response of wild and domestic rice inhabited by mycorrhizae to infection by M. oryzae has not been documented. In the current study, roots of wild and cultivated rice colonized with the arbuscular mycorrhizal (AM) fungus (AMF) Rhizoglomus intraradices were used to compare the transcriptomic responses of the two species to infection by M. oryzae. Phenotypic analysis indicated that the colonization of wild and cultivated rice with R. intraradices improved the resistance of both genotypes to M. oryzae. Wild AM rice, however, was more resistant to M. oryzae than the cultivated AM rice, as well as nonmycorrhizal roots of wild rice. Transcriptome analysis indicated that the mechanisms regulating the responses of wild and cultivated AM rice to M. oryzae invasion were significantly different. The expression of a greater number of genes was changed in wild AM rice than in cultivated AM rice in response to the pathogen. Both wild and cultivated AM rice exhibited a shared response to M. oryzae which included genes related to the auxin and salicylic acid pathways; all of these play important roles in pathogenesis-related protein synthesis. In wild AM rice, secondary metabolic and biotic stress-related analyses indicated that the jasmonic acid synthesis-related α-linolenic acid pathway, the phenolic and terpenoid pathways, as well as the phenolic and terpenoid syntheses-related mevalonate (MVA) pathway were more affected by the pathogen. Genes related to these pathways were more significantly enriched in wild AM rice than in cultivated AM rice in response to M. oryzae. On the other hand, genes associated with the ‘brassinosteroid biosynthesis’ were more enriched in cultivated AM rice. The AMF R. intraradices-colonized rice plants exhibited greater resistance to M. oryzae than non-AMF-colonized plants. The findings of the current study demonstrate the potential effects of crop domestication on the benefits received by the host via root colonization with AMF(s), and provide new information on the underlying molecular mechanisms. In addition, results of this study can also help develop guidelines for the applications of AMF(s) when planting rice.

We propose an asymmetrical interferometer to compensate the pattern effect in semiconductor optical amplifier (SOA) as an inline amplifier in dense wavelength-division-multiplexing (DWDM) system. Experiments are demonstrated with a commercial integrated Mach-Zehnder interferometer (MZI)-SOA. The experiments showed that in a 16/spl times/10-Gb/s DWDM system, the power penalty induced by the SOA decreased from 6.8 to 0.9 dB by the interference at 1 mW input power, and the input power dynamic range of the SOA was efficiently extended.

Fusarium root rot (FRR) seriously affects the growth and productivity of A. chinensis. Therefore, protecting A. chinensis from FRR has become an important task, especially for increasing A. chinensis production. The purpose of this study was to screen FRR control strains from the A. chinensis rhizosphere soil. Eighty-four bacterial strains and seven fungal strains were isolated, and five strains were identified with high inhibitory effects against Fusarium oxysporum (FO): Trichoderma harzianum (MH), Bacillus amyloliquefaciens (CJ5, CJ7, and CJ8), and Bacillus subtilis (CJ9). All five strains had high antagonistic effects in vitro. Results showed that MH and CJ5, as biological control agents, had high control potential, with antagonistic rates of 86.01% and 82.78%, respectively. In the pot experiment, the growth levels of roots and stems of A. chinensis seedlings treated with MH+CJ were significantly higher than those of control plants. The total nitrogen, total phosphorus, total potassium, indoleacetic acid, and chlorophyll contents in A. chinensis leaves were also significantly increased. In the biocontrol test, the combined MH + CJ application significantly decreased the malondialdehyde content in A. chinensis roots and significantly increased the polyphenol oxidase, phenylalanine ammonolyase, and peroxidase ability, indicating a high biocontrol effect. In addition, the application of Bacillus spp. and T. harzianum increased the abundance and diversity of the soil fungal population, improved the soil microbial community structure, and significantly increased the abundance of beneficial strains, such as Holtermanniella and Metarhizium. The abundance of Fusarium, Volutella, and other pathogenic strains was significantly reduced, and the biocontrol potential of A. chinensis root rot was increased. Thus, Bacillus spp. and T. harzianum complex bacteria can be considered potential future biocontrol agents for FRR.

The barriers caused by continuous tillage have had a negative impact on the crop and soil environment. Black soils are economically important as a valuable natural resource in Northeast China, but limited soil resources have led to continuous planting of major food crops and medicinal plants. At present, the extent to which two different types of plants—grains and medicinal plants that are successively grown on the same soil—have an impact on soil quality and microbiology is not known. In this study, we investigated the effects of different types of long-term continuous cropping on soil and soil microbial communities by determining the physicochemical properties, the soil community composition and function of grain crops and medicinal-plant soils with more than five years of continuous cropping, as well as fallow soils. The results showed that long-term continuous cropping reduced the pH of different types of soils, but there was no significant difference in the content of AK. The relative abundance of beneficial dominant phyla, such as Actinomycetes, Acidobacteria, and Green Campylobacter decreased and the relative abundance of pathogenic genera such as Alternaria and Didymellaceae, increased after the long-term continuous cropping of DM (grain crops) and DG (medicinal plants). Specifically, continuous cropping increased the relative abundance of fungi with pathogenic potential, such as Sordariomycetes, Dothideomycetes, Saccharomycetes, and Mucoromycetes in grain soils and Agaricostilbomycetes in herb soils. Among the soil physicochemical properties, NH₄⁺-N and pH were the most important factors contributing to changes in the composition of bacterial and fungal communities, respectively. Continuous cropping of different types of plants altered the diversity of the microbial communities, with the most significant effect from the continuous cropping of food crops. Our findings provide a scientific and theoretical basis for future agricultural research to improve soil microbial activity, mitigate continuous-cropping barriers, and increase productivity.