Purity and Authenticity Identification of 'Yuexiu No.3' Cucumber Hybrid Seeds Based on SSR Molecular Markers

Abstract

【Objective】'Yuexiu No.3' cucumber is a variety that is widely promoted in the South China region due to its strong growth, high yield, disease resistance, and stress tolerance. This study aims to establishing a rapid, accurate and effective method for seed purity identification.【Method】200 pairs of primers were used to select SSR markers with specificity based on the principle of complementary band pattern between the parents and 'Yuexiu No.3'. The seed purity identification results obtained using these primers were compared with the field biological identification results to verify their accuracy. The seeds of five cucumber varieties 'Zhongnong 108', 'Yuanfeng No.6', 'Jinlv No.5', 'Zhongnong No.8' and 'Jinyan No.4' and other 49 cucumber germplasm materials were selected and detected simultaneously with ' Yuexiu 3 ' cucumber varieties to identify the specificity of the selected SSR primers.【Result】Two pairs of SSR primers (3B-10 and 2B-41) were screened out from 200 pairs of primers that met the requirement of forming complementary bands between parental bands, PCR amplification using the 3B-10 primer produced a 160 bp maternal-specific band (P1-A) and a 190 bp paternal-specific band (P2-B). By comparing the sequencing results of the specific bands (P1-A, P2-B), it was found that the P2-B had an additional 6-base simple repeat sequence compared to the P1-A at positions 49-79 bp. PCR amplification using the 2B-41 primer produced a 218 bp maternal-specific band (P1-C) and a 206 bp paternal-specific band (P2-D). By comparing the sequencing results of the specific bands(P1-C, P2-D), it was found that the P1-C had a deletion of 12 bases compared to the P2-D at positions 120-131 bp. The results showed that these two pairs of SSR primers were able to effectively distinguish 'Yuexiu No.3' hybrid seeds from their parents and accurately identify the seed purity of 'Yuexiu No.3' cucumbers. In addition, the seed purity identification results of the two pairs of SSR primers were consistent with the field biological identification results. Both pairs of primers were capable of effectively distinguishing the 'Yuexiu No.3' cucumber seeds from the seeds of five other cucumber varieties, namely 'Zhongnong 108', 'Yuanfeng No.6', 'Jinlv No.5', 'Zhongnong No.8'and 'Jinyan No.4', as well as 49 other germplasm resources. However, among these 49 germplasm resources, 3B-10 displayed a higher level of polymorphism. Therefore, SSR marker 2B-41 was more suitable for confirming the authenticity of the 'Yuexiu No.3' cucumber variety.【Conclusion】The 3B-10 and 2B-41 pairs of SSR primers can rapidly, accurately and efficiently identify the purity of 'Yuexiu No.3' hybrid cucumber seeds. The identification is simple and low cost, which can replace the traditional method of hybrid seed purity identification, and has high commercial application value