ISSR Analysis On Pedigree Of Hybrid Breeding Indica-Japonica Rice And Genetic Analysis On Yield And Stem Traits Of Bred Varieties

Indica and Japonica Subspecies contain huge heterosis,so the important contains for super hybrid rice breeding is to construct hybrid-breeding genealogy and research practical type and strong heterosis between Indica and Japonice subspecies in new period.This study used ISSR markers to analyze genetic diversity of rice breeding genealogy between Indica and Japonice subspecies which contained 25 parents and 36 cultivated lines with 18 years and 4-selected phases by the Agricultural Science Institution of San Ming.Based on the molecule clustering result,8 cultivated restorer lines,which matched with 8 rice male sterile lines applying in big area in production,were selected.According to imperfection double cross design(8×8),a suit of genetic materials including 2 generations of parents and F₁ was selected.With the Addictive-Dominant genetic model(AD model)and Statistical Analysis Methods,the genetic effects,heterosis and genetic correlations of the 15 yields and stem traits were analyzed systematically.The main research results are as follows:1.ISSR molecular marker analysis indicated that 10 primers showed clear and polymorphism in 54 supplied materials in 80 ISSR primers.10 primers had totally 76 strips whose scopes ranged from 200 to 2400 bps of the molecular weight,among which,58 strips showed polymorphism and accounted for 76.3%.The numbers of polymorphism strips in different primers ranged from 1 to 9,and the average numbers of each primer was 5-8.The ISSR markers can obviously classify 54 breeding-genealogy materials of Indica and Japonice subspecies.According to the ISSR markers' data,with genetic similarity coefficients 0.58 as valve value,we divided the 54 breeding genealogy materials of Indica and Japonice subspecies into 4 groups.2.Analysis of yield traits effects and heterosis of cultivated variety between Indica and Japonice subspecies indicated that the number of effective spikes per plant,the spikelets of main panicle and the number of grains main panicle were mainly controlled by addictive effects.Grain weight per plant,rate of seed setting main panicle and 1000-grain weight were mainly controlled by dominants effects. Except the rate of seed setting main panicle,the rate of the heredity in narrow sense of yield traits all showed prominence.The population mean heterosis of the grain weight per plant,the spikelets of main panicle,the number of grains main panicle,the rate of seed setting main panicle and the 1000-grain weight showed positive.Grain weight per plant,number of effective spikes per plant,spikelets of main panicle,number of grains main panicle,rate of seed setting main panicle and 1000-grain weight showed negative transgressive heterosis.The combination of the Guangzhan63S×Minghui512 had strong heterosis on improving rate of seed setting main panicle;ZhongjiuA×Minghui398 had strong heterosis on improving grain weight per plant and 1000-grain weight.3.Analysis of stem traits effects and heterosis of cultivated variety between Indica and Japonice subspecies indicated that the 10cm-root anti-fold power and the 10cm-root wall thick were mainly controlled by the additive effects.Traits of plant height,panicle length,first internode,second internode, third internode and 10cm-root stem thick were mainly controlled by the dominant effects.Except the lodging index of 10cm-root,the heredity in narrow sense of the rest traits all showed notable dominance and the 10cm-root anti-fold power was tiptop.The population mean heterosis of the stem traits all showed positive heterosis.The transgressive heterosis of plant height,panicle length,second intemode, third intemode and lodging index of the 10cm-root showed positive.The 10cm-root anti-fold power and the 10cm-root wall thick showed negative.Combination of the Guangkang13A×Minghui417 could obviously lower plant high,â…¡-32×Minghui398 could obviously strengthen 10cm-root anti-fold power, ZhongjiuA×Minghui509 could obviously increase the 10cm-root wall thick respectively.4.The genetic correlations analysis of yield and stem traits of cultivated variety between Indica and Japonice subspecies indicated that the genetic correlations of 1000-grain weight and grain weight per plant,number of effective spikes per plant showed mainly addictive positive correlation;number of effective spikes per plant,1000-grain weight and spikelets of main panicle,number of grains main panicle showed mainly addictive negative correlation.Grain weight per plant and spikelets of main panicle,number of grains main panicle showed distinctly dominance correlation.Except first intemode, second internode,third internode,second internode and 10cm-root wall thick,the addictive correlation of the rest traits were prominence level.Correlation degree of addictive was bigger than dominance; distinct-addictive negative correlations existed in number of effective spikes per plant and 1000-grain weight in stem traits.Distinct-addictive positive correlation existed in spikelets of main panicle and number of grains main panicle in stem traits.Results showed that addictive correlation was main function,and the related part of addictive effects could be accumulated in the process of choice.So we could make use of the addictive correlation indirectly to choose the yield traits and the effect of the choice was obvious in early generations.