Analysis On Hybrid Derivative Lines In Indica-Japonica Rice By SSR

To provide a scientific basis for breeding the practical and strong heterosis indica-japonica hybrid, genetic basis was analyzed, using derived lines of indica-japonica hybrid. The derived lines were developed by a series of material, including nine parents and fourteen derivative cultivars, in 21 years spanning 4 selection phases in Sanming Agricultural Science Research Institute. In this study, genetic diversity and relationship of this pedigree were discussed, using 130 SSR markers located in rice genome and pedigree allele variation method. The results were showed as follow.1. Out of 219 pairs of SSR primers, 130 pairs of SSR primers were proved with the significant polymorphism and stable band types. A total of 390 alleles were detected with 130 pairs of primers and each pairs exhibited 2 to 8 alleles with an average of 3. Among them, the effective number of alleles had 292.38, accounting of 74.97% of the total polymorphic loci; the average polymorphism information content (PIC) amounted to 0.504. The results showed that the 130 SSR markers could accurately detect the genetic difference between the materials used in the analysis.2. Genetic contribution rate of progenitor parent cultivators to offspring derived lines was analyzed, the results showed that Minghui72, 02428, Jiananjing and Ketan Nangka offered 18.97%, 12.03%, 6.28% and 5.58% of the average genetic contribution rate, respectively. Genetic contribution rate by progenitor parent cultivators was gradually decreased with increasing generations of offspring lines. The average of genetic contribution rate progenitor parent to multi-generation offspring lines were ranked in turn of Minghui72>02428>Jiananjing>Ketan Nangka. The genetic contribution rate to first generation of 92gk729 was 34.04%, 24.17%, 20.83%, 14.04%, respectively. The total genetic contribution rate to the late fourth generation of derived lines ranged from 30.77% to 46.15%. The total genetic contribution rate by direct parents 97gk1037 and 20gk719 to the fourth generation of derived lines varied from 56.92% to 84.62%, while 97gk1037 provided 32.15% and 20gk719 38.62%. With respect to the number of genetic loci, 97gk1037 contributed 63.7 to the fourth generation of derived lines and 20gk719 70.1. The total genetic contribution rate for five intermediate parents to offsprings varied from 36.87% to 64.49% and the average genetic contribution rate was ranked as in turn of WJ413>Huaming921>Duoxi1> Chaoyin1 and 47Jing.3. Cluster analysis by SSR showed that 23 materials were divided into four types, such as japonica, partial japonica, partial indica, indica. Japonica type rice included Jiananjing, 02428, Ketan Nangka and Chaoyin1; partial japonica consisted of 92gk729, 20gk719 and 47Jing; partial indica included 97gk419, 97gk1037, Minghui502, Minghui509, Minghui503, Minghui507, Minghui511, Minghui512, Minghui504, Minghui506, WJ413 and Huaming921; indica were formed by Minghui72, Duoxi1, Minghui 513 and Minghui514.Clustering result revealed the genetic background of materials used in the analysis and their indica or japonica properties.4. The genetic structure of hybrid derivative lines in indica-japonica rice was analyaed, using Neighbour-joining and Model-base method. The results showed that 23 materials were divided into 3 groups. Group I included four parents, the first offsprings, group II from the indica-japonica derived lines from the same hybrid, and group III included Minghui63-derived parents and their offsprings. The genetic differentiation between ancestors and offsprings was gradually significant with accompanied with increasing generations of offsprings. The genetic compositions of hybrid derivative lines in indica-japonica rice were gradually closed to indica rice during the process of genetic improvement.5. Analysis for the genetic diversity of hybrid derivative lines in indica-japonica rice showed that the genetic diversity level of parents was higher than that of offspring, with respect to seven indexes of polymorphic loci, percentage of polymorphic loci (PPB), observed number of alleles (Na), effective number of alleles (Ne), rare number of alleles (Nr), special number of alleles (Ns) and Nei genetic diversity index (H). The genetic diversity level of four indica-japonica differentiation types rice was ranked in turn of indica>japonica>partial japonica>indica. Both genetic differentiation coefficient and genetic distance between japonica and indica type rice were the greatest and those between partial indica and indica was the least, compared with those between other type rices. The genetic differentiation between partial japonica and indica, japonica and partial japonica, japonica and partial indica were moderate, while genetic differentiation between partial japonica and indica was relatively little..