2 Physical Chemistry Identification
Through physical and chemical methods, seeds are used to produce specific reactions in certain special chemical agents, and physiological and biochemical indicators of the seeds are determined to identify the purity of the varieties. Such as fluorescence scanning analysis, phenol staining, guaiacol method. The physical identification method can be used to identify the differences between different species of seeds and seedlings containing fluorescent substances. Such as the use of ultraviolet light treatment of oat seeds can produce fluorescence, according to the presence or absence of fluorescence can distinguish between different varieties. The chemical identification method can identify varieties based on the differences in the composition and chemical substances of different varieties of husks and the differences in the coloration of different chemical reagents. The method is fast and simple, but the seeds that are required to be identified must have physical and chemical specific reactions, and their application range is also greatly limited, and they are currently used less frequently.
3 protein electrophoresis identification technology
The genotypes of different crop varieties are different, and the direct expression products of genes—proteins are also different in species, quantity, and structure. The electrophoresis method reveals gene differences based on differences in protein quantity, size, and structure, that is, a biochemical marker method that reflects the genotype by biochemical phenotypes, and has the advantages of rapidity, high accuracy, and good repeatability. The electrophoresis technique was used to isolate and stain the proteins of the seeds or seedlings of the prepared varieties, and the differences in protein electrophoresis bands were compared with the standard bands of the varieties to identify the authenticity and seed purity of the varieties. The electrophoresis identification method has been widely used in isozyme electrophoresis and seed protein electrophoresis methods in species identification and seed purity analysis.
3.1 Isozyme electrophoresis
Isoenzymes refer to the types of enzyme molecules that have the same origin, catalyze the same reaction, and have different structures. The difference in isozyme patterns is mainly caused by the differences in the alleles and nonallelic genes that determine the enzyme protein itself. The isoenzyme pattern is the molecular level phenotype after gene expression, and the analysis of the bands can be quickly and easily performed. The gene loci and alleles encoding these bands were identified. Isozyme electrophoresis is an isoenzyme that separates various enzymes from the crude protein extract of plant tissue by electrophoresis and histochemical staining, and converts various forms of the enzyme into visibly identifiable enzyme bands. By comparing the isozyme patterns, the purity of the crop seeds was determined. At present, isoenzyme electrophoresis has been widely used to establish genetic maps, population analysis and other related research. Compared with the morphological identification method, isozyme electrophoresis has two advantages: First, it is neutral in performance, and there is generally no major adverse effect on plant economic traits; second, it directly reflects the differences in gene products and is less affected by the environment. At present, in the identification of crop seed purity, the most commonly used and highly polymorphic are the esterase isozyme, peroxidase isoenzyme, and phosphatase isoenzyme, etc. The electrophoresis methods used are mostly polyacrylamide gels. Electrophoresis.
3.2 seed protein electrophoresis
Due to the different genetic composition of different varieties, their seed protein types, quantity, size and structure are not the same, and different protein bands are formed through electrophoresis to identify the authenticity and purity of the varieties. The proteins contained in seeds can be divided into albumin, globulin, gliadin, gluten, and so on. The identification of varieties is based on the diversity of gliadins (carrots) and globulin (legumes). Technologies include polyacrylamide gel electrophoresis, starch gel electrophoresis, and isoelectric focusing electrophoresis. However, seed protein electrophoresis is not easy to find specific proteins for some species with very close genetic composition, and it is difficult to find the characteristic bands for distinguishing using protein electrophoresis. In addition, the protein electrophoresis pattern is easily affected by the seed (or seedling) development stage and the expression organs, and sometimes is not stable enough, affecting the map analysis, thus affecting the accuracy of the identification results.