Abstract：InDel(insertion deletion length polymorphism) is the third generation of molecular markers which is based on genome sequencing. It has already applied to the genetic studies. In this research, we use F1 of Chinese cabbage (Brassica rapa L. ssp. pekinensis) (Yuxin No.4), its parents and eight half-blooded hybrid combinations as to be experimental material.Using the third generation of molecular markers - InDel and primer combination method to identify Chinese cabbage hybrid's purity rapidly. The results showed that there were three pairs primers (BrID10667, BrID90107 and BrID90147) presented stable codominance among 104 pairs of screened InDel primers in Yuxin No.4. The purity of first batch of materials for three primers was 98.00%. The purity of second batch of materials for three primers was 100.00%, 98.30%, 99.10%, respectively. The results tested in field is 100%,which was highly consistent with the results tested in indoor. The match index of two results were up to 99.13%. The results showed that the InDel markers, as an accurate and cost- efficient means, could be suitable for rapid purity identification of Chinese cabbage hybrid seeds. Using three pairs of specificity InDel primers which were screened out from 104 pairs of InDel primers to analyse Yuxin No.4 and eight other half-blood cross combinations, respectively. None of this three pairs of primers could distinguish Yuxin No.4 and eight other half-blood cross combinations at the same time. However, in this three primers, the annealing temperature of primer BrID90107 and primer BrID10667 was the same, but their position of amplification production was different. So we used multiplex primers BrID90107 and BrID10667 to identify Yuxin No.4 from their parental lines and eight other half-blood cross combinations. The results showed that multiplex primers methods could be used for rapid indoor identification of Chinese cabbage hybrid purity. Using the method of multiplex primers to test different hybrid lines could identify the contamination which caused by F1- hybrid seeds effectively, which indicated that InDel markers an have a wide range of application in rapid laboratory test of seed purities of Chinese cabbage hybrid.
