基于太赫兹时域光谱的转基因与非转基因棉花种子鉴别

太赫兹光谱是介于红外与微波间的电磁波谱,很多生物大分子在该波段具有指纹特性。为探索棉花种子的转基因机理和性状表达的太赫兹光谱特性,该文利用太赫兹时域光谱技术对3种转基因棉花种子和1种常规育种棉花种子进行了鉴别试验探索研究。试验首先研究了棉花种子压片制备方法,然后借助太赫兹时域光谱设备,采集了4种棉花种子在有效频率范围内的太赫兹光谱信息,进而对太赫兹光谱包含的特征信息进行了定性分析,并初步探讨了4种样品的太赫兹吸收特性。试验结果表明:4种棉花种子在太赫兹波段呈现不同的光谱响应特性,尤其是在其吸光系数光谱图中,3种转基因棉种在1.21、1.23和1.41 THz处,对太赫兹呈现明显的吸收,而非转基因棉种却呈现微弱的吸收或不吸收;这些明显的差异表明太赫兹光谱可以作为鉴别转基因/非转基因棉花种子有效工具,该研究可为进一步揭示太赫兹光谱检测机理,发展转/非转基因物质快速检测方法提供参考。

Identification of transgenic and non-transgenic cotton seed based on terahertz range spectroscopy

Abstract: Terahertz radiation is the electromagnetic wave, which occupies a large portion between the infrared and microwave bands. Most biological macromolecules have fingerprint characteristics in this band. Firstly, the device for experiment i.e. the terahertz time-domain spectroscopy system (THz-TDS) was introduced. Then, in order to seek the terahertz spectrum characteristics of transgenic mechanism and the trait expression, 3 kinds of transgenic cotton seeds (Zhongmian No.838, Lumianyan No.28, and Guoshen No.7886) and a non-transgenic cotton seed (Xinluzao No.51) were studied in identifying experiments by terahertz time-domain spectroscopy. Because of the grease-like substance in the cotton seed, tablet mold was occlusive when compressing cotton seed. It made the tablet shaping difficult and the surface of the tablets rough and resulted in unperfect data. To solve the problem, when compressing tablet, a small amount of polyethylene powder was taken to spread in the bottom of the compression mould, then samples powder was spread on polyethylene powder, and then on the surface of samples powder a small amount of the powdered polyethylene was put again, and at last the tablet was compressed. During the experiment, the samples were placed in the THz-TDS to scan and reduce the accidental error. Each tablet was scanned in triplicate for different parts and the obtained spectral information is averaged. To avoid the interference such as the strong absorption of the water vapor and other polar molecules in the air, terahertz wave generation and detection device were sealed and filled with dry nitrogen. And the relative humidity of testing environment was less than 4%. The experimental temperature was kept at 298 K. By using terahertz time-domain spectroscopy equipment, we collected the terahertz spectral information of 4 species of cotton seeds in the effective time-domain range. After processed with the fast Fourier transform algorithm, THz spectroscopy time-domain information was transformed into the frequency-domain spectral information. Then a series of transformations were used to get their refractive index and absorption spectra. Qualitative analysis of the terahertz spectrum feature information was made. Terahertz absorption characteristics of 4 kinds of samples especially in 0.9-1.5 THz band and the reasons for this result were discussed in detail. The results showed that 4 kinds of cotton seeds presented different spectral response characteristics in 0.9-1.5 THz band. The 3 transgenic cotton varieties showed obvious absorption at 1.21, 1.23 and 1.41 THz, while non-transgenic cotton variety showed weak absorption or no absorption.