BACKGROUND Plant systemic resistance induced by botanical compounds is a promising alternative method of disease management. The natural product berberine, usually used as an antimicrobial in medicine, has been proven to have antifungal activity in agriculture. To investigate the induced resistance imparted by berberine, the effect of berberine against tobacco mosaic virus (TMV) and the mechanism governing this effect were determined. RESULT Berberine exhibited considerable in vivo anti‐TMV activity of up to 68.3% but had no in vitro direct effect on TMV. Moreover, berberine could induce immune responses against TMV in tobacco, including the hypersensitive reaction (HR), accumulation of H2O2, increases in defense enzymes and overexpression of pathogenesis‐related (PR) proteins. In addition, upregulation of salicylic acid (SA) biosynthesis genes PAL, CM1, ICS, PBS3 and the enzyme benzoic acid 2‐hydroxylase (BA2H) confirmed that SA was involved in the defensive signals. Berberine can induce crop resistance against TMV, Phytophthora nicotianae, Botrytis cinerea and Blumeria graminis in the greenhouse. CONCLUSION This paper highlights the use of berberine in manipulating tobacco to generate defense responses against TMV, which can be attributed to SA‐mediated induced resistance. The paper provides a theoretical basis for the application of berberine as a resistance activator and for further research on induced resistance by botanical natural product. © 2019 Society of Chemical Industry

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The relative aperture size and the field-of-view (FOV) are two significant parameters for optical imaging systems. However, it is difficult to improve relative aperture size and FOV simultaneously. In this paper, a freeform design method is proposed that is particularly effective for high performance systems. In this step-by-step method, the FOV is enlarged from a small initial value in equal-length steps until it reaches the full FOV; in each step, part of the area of one system surface is constructed. A freeform off-axis three-mirror imaging system with large relative aperture size and a wide FOV is designed as an example. The system operates at F/2.5 with 150 mm effective focal length and a 60° × 1° FOV. The average root-mean-square wavefront error of the system is 0.089λ (working wavelength λ = 530.5 nm).

In the development of anti-radiation excavator, the structure-design of lead glass windows is a key problem needs to solve. By conducting the irradiation and sun exposure experiment of ZF6 and ZF506 lead glass, we finally decided to use ZF6 lead glass to make the window of anti-radiation excavator. After reading books and conducting experimental research, we decide to increase the thickness of K509 glass at 5 mm on the outer edge of the lead glass's window.