| Rice and wheat are the most important food crops in Jiangsu Province, and therefore, development and application of elite rice and wheat varieties are of great significance for the food security of Jiangsu Province. However, due to lack of high efficient method on identifying crop varieties, the illegal issues are frequently happened during the processes of new variety regional-trail and the seed marketing of elite varieties, which severely affect both application and innovation of elite variety. In the present study, two sets of SSR (simple sequence repeat) markers were employed to evaluate the authenticity of varieties from Jiangsu regional trails in 2014 and 2015, and from rice seed market of Jiangsu province in 2015. The first set marker includes 48 SSR markers from the national standard ’NY/T-1433-2014’, and the other consists of 52 SSR markers previously developed in our lab. Effects of the two sets markers on distinguishing these varieties were tested. In addition, a total of 103 wheat SSR markers was employed to identify the authenticity of wheat varieties selected from wheat seed market of Jiangsu province in 2015. The results we obtained are as follows:1) Total of 36 candidate rice varieties from Jiangsu new variety regional-trails in 2014 and 2015 were identified by using 93 SSR markers (7 markers were included in both marker sets). Each candidate variety had two independent samples from two years, respectively. Through comparison, we found two candidate varieties that were illegally changed during the two-years regional-trail, since the two independent seed samples of each of two varieties showed different genotypes on 15 and 26 SSR loci, respectively. For 355 varieties selected from rice seed market, we found a total of 112 varieties that showed at least 2 differential loci compared with the control variety, and half of these varieties did display different morphological traits compared with the control variety in field. In total, the varieties from ecotype ’Zhongshu Zhongjing’ had most counterfeits. The varieties with more than 3 differential loci as the control variety all displayed different morphological phenotype compared to the control in field, while, only one-third of the varieties with 2 differential loci showed morphological difference as the control variety in field.2) We found either of two sets of SSR markers could not distinguish all varieties that displayed morphological difference in field, while, combining the two sets SSR markers together could easily identify these varieties. We constructed the DNA fingerprints of 48 candidate varieties from 2015 regional-trail using both sets of SSR markers, and found the polymorphism of 48 markers from national standard ’NY/T-1433-2014’ are lower than that of 52 markers developed in our lab. Based on these data, we propose to use 93 SSR markers integrated from two marker sets to develop a local standard for identifying the authenticity and DNA fingerprint of rice varieties planted in Jiangsu province.3) By using 93 SSR markers, the genetic diversity of 48 varieties from Jiangsu regional-trail in 2015 were evaluated. The genetic similarity coefficient among 48 varieties ranged from 0.638～0.973 with an average of 0.778, demonstrating the varieties had narrow genetic bases. Among three different rice ecotypes, Zhongshu Zhongjing exhibited lowest genetic similar coefficient.4) The authenticity of wheat varieties selected from seed market of Jiangsu province in 2014 and 2015 were identified by using 103 SSR wheat markers. For 156 varieties tested in 2014, we found 18 and 45 varieties that showed 2 differential loci and more than 3 differential loci compared to the corresponding control variety, respectively; while, these number decreased to 15 and 8 for the varieties tested in 2015. This indicates the seed-market inspection using SSR markers has gained positive effect.5) The polymorphism of 95 SSR markers (8 markers without amplification band were removed) was analyzed using 63 wheat varieties. Eighteen of them were found have multiple unspecific amplification, disturbing the identification of specific amplification. The remaining 77 markers all had clearly specific amplification, which totally detected 178 alleles with an average of 2.31 alleles per marker detected. The average PIC (polymorphic information content) value for these markers was 0.317, and 22 markers had PIC values exceeding 0.5. These results indicate the 77 SSR markers have good polymorphism and could be used to identify DNA fingerprint of wheat varieties in future. |
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