Preliminary Study On The Heterotic Groups Of Local Maize(Zea Mays L.) Germplasm In Sichuan With RAPD And SSR Markers

Genetic diversity of local maize germplasm and the heterotic relationship between local lines and popularized lines were studied with the methods of RAPD(Random Amplified Polymorphic DNA) and SSR(Simple Sequence Repeat). The materials consisted of 14 representative local maize inbred lines in Sichuan and 14 popularized inbred lines at home. The yield heterosis of 110 combinations crossed based on some of these lines according to NC 11(10 X 11) mating design was used to verify the cluster analysis results of DNA molecular markers. The relationships between molecular genetic distance and yield heterosis were detected and the heterotic patterns based on high heterosis combinations were established. Besides, the difference between RAPD and SSR markers was also discussed. The main results were summarized as follows: 1. 28 inbred lines were analysed with RAPD markers, 25 random primers generated a total of 141 polymorphic bands, with an average of 6.18 per primer. The genetic similarity coefficient based on RAPD data was estimated with Nei抯 method. Cluster analysis using the program of UPGMA divided 28 inbred lines into 6 groups. 14 local lines, separated groups of Lancaster, Improvement Reid, Luda Red Cob and Tangsipingtou, were all clustered into the 5th group including some popularized lines. It was detected by RAPD markers that the local maize germplasm in Sichuan had a narrow genetic basis and a little different from that of popularized lines. 2. SSR markers were also used to detect genetic variation among the 28 inbred lines. 62 pairs of primers produced 298 polymorphic amplified fragements, the average number of alleles per SSR locus was 4.8 with a range from 2 to 10. The genetic similarity coefficient based on SSR data was calculated with Nei抯 method. Cluster analysis using the program of UPGMA divided 28 inbred lines into 7 groups. 9 of 14 local inbred lines were classified into the 4th group, while ES4O and Guang62-10 were formed the 5th group separately because of far genetic distance 3 from popularized lines. The genetic basis of local maize germplasm in Sichuan revealed by SSR markers was a little abroad. 3. The genetic similarity coefficient of 14 popularized lines were selected respectively from RAPD and SSR similarity coefficient matrix of 28 inbred lines to cluster by UPGMA. Cluster analysis results of RAPD agreed with known pedigree information to a certain extent while that of SSR were well reasonable and highly corresponded to parentage, field data and breeding practice. So SSR was more reliable than RAPD in the study on genetic diversities among local inbred lines. 4. Simple correlation analysis showed that molecular genetic distance was non- significantly correlated with F1 yield heterosis. The yield heterosis couldn抰 be deduced easily by the genetic distance of RAPD and SSR. Besides, the analysis of high heterosis combinations indicated that there were high heterosis among local maize gerinplasm in Sichuan and lines of popularized groups such as Suwan, Tangsipingtou and so on, that might establish heterotic patterns with some potential. Especially there were high heterosis among ES4O and Guang62-lO in the isolate group and popularized lines such as 48-2, 7922, Mo17 et aL, this separately group and corresponding groups of popularized lines above-mentioned might form heterotic patterns with more potential.