GB/T 34331-2017 in English

In-depth interpretation of GB/T 34331-2017 National Standard of the People's Republic of China "Transmission Electron Microscope Detection Method for Cucumber Green Mottle Mosaic Virus"

Background and Significance of Standard Formulation

Cucumber green mottle mosaic virus (CGMMV) is a quarantine pathogen that seriously affects cucurbit crops. It is spread through seeds and agricultural operations, resulting in serious yield reductions in crops such as watermelon and cucumber. The formulation of this standard aims to standardize the morphological detection method of the virus and provide a scientific basis for plant quarantine.

Comparison of standard frameworks

Technical background and method analysis

Virus particle morphology: CGMMV is a rigid rod-shaped structure with a typical diameter of $18~\mathrm{nm}$ and a length of $300~\mathrm{nm}$.

Detection steps:

• Sample preparation: Including three types of tissue crude juice, purified virus samples and ultrathin section samples
• Negative staining technique: Use phosphotungstic acid or uranyl acetate for negative staining to enhance the visibility of virus particles
• Ultrathin sectioning technique: Obtain ultrathin sections for electron microscopy observation through epoxy resin embedding and diamond knife cutting
• Immunoelectron microscopy: Use polyantisera to specifically bind to the virus to assist in morphological diagnosis

Implementation recommendations

Laboratory conditions: Equipped with a transmission electron microscope and an ultrathin slicer, ensure that the environmental humidity is controlled below 60%, and the temperature is stable at $(20\pm5)^{\circ}\mathrm{C}$.

Staff training: Detectors need to master the basics of virus morphology and electron microscope operation skills

Result verification: Double confirmation can be performed in combination with molecular biology detection (such as PCR) when necessary

Analysis of standard technology evolution

Based on the original SN/T 2964-2011 plant virus detection specification, this standard proposes more specific operating procedures and quality control requirements for the particularity of CGMMV. At the same time, advanced ultrathin sectioning technology and immunoelectron microscopy are introduced to make the test results more reliable.