| Rice is not only one of the main food crops in the world and one of the major cereal crops for human intake of trace elements.Zinc is one of the indispensable important elements in organisms and a component of a variety of enzymes,which participates in a variety of growth and metabolism activities such as photosynthesis,hormone synthesis and plant growth,and plays an irreplaceable role in the human body.Zinc deficiency can lead to decreased in the body’s immunity,loss of appetite,poor memory,slow growth and other trace element deficiency syndrome.The study shows that it is scientifically feasible to screen and cultivate Zinc-rich grain varieties to improve human zinc nutrition through plant breeding.In this study,genetic analysis and QTL mapping of zinc content in grains of local rice varieties Yang he bai pi dao in Ningxia,were carried out in order to provide theoretical basis for breeding new zinc-rich rice varieties by means of molecular breeding.The F2 population of the hybrid progeny of Ningxia zinc-rich local variety"Yang he Bai pi dao"and low zinc japonica variety"Ninggeng 24" was used as experimental materials,and 104 pairs of SSR markers were used to locate and analyze the QTL of controlling zinc content in rice;The RIL population constructed by crossing of" Yang he Bai pi dao " and "Ninggeng 35" was used to repeatedly detect QTL loci of zinc content in rice grains.The main results are as follows:1.The Genetic analysis of grain zinc content in F2 population of hybrid combination"Ninggeng-24/Yang he bai pi dao" shows that there were significant differences in zinc content in grains of parents "Ninggeng-24" and "Yang he bai pi dao",which were 19.05 mg/kg and 34.95 mg/kg,there was a significant difference in grain zinc content between the two parents.The average zinc content of F2 generation grains was 19.49 mg/kg,which was between the two parents and favored the low-value parent"Ninggeng-24",the variation range was 10.69～34.14 mg/kg,and the coefficient of variation was 17.35%.The grain zinc content of the population showed a single peak continuous distribution close to normal,this indicated that the zinc content of rice grains was inherited by quantitative traits controlled by polygenes.2.Polymorphism was screened for 1558 pairs of SSR primers,among which 104 pairs of SSR primers showed polymorphism between the parents of"Ninggeng-24" and "Yang he bai pi rice".Using the F2 population of the hybrid offspring of"Ninggeng-24/Yang he bai pi dao"as the mapping population,a genetic linkage map containing 104 SSR markers was constructed to cover the whole rice genome at 2856.7 cM,the average distance between the markers was 27.47 cM.3.Through the QTL detection of grain zinc content in the F2 population of the hybrid progeny of"Ninggeng-24/Yang he bai pi dao",four QTL loci were obtained,which were distributed on rice chromosomes 4,5,11 and 12,the distribution range of contribution rate is 0.24%-39.73%.Among them,the highest contribution rate of qZn-5-1 on chromosome 5 was 39.73%,and the synergistic alleles were from Ninggeng-24.4.The Genetic analysis of grain zinc content in F5 generation RIL population of hybrid combination "Ninggeng-35/Yang he bai pi dao" shows that there were significant differences in zinc content in grains of parents "Ninggeng-35" and "Yang he bai pi dao",which were 11.88 mg/kg and 34.95 mg/kg,there was a significant difference in grain zinc content between the two parents.The average zinc content of F5 generation grains was 15.94 mg/kg,which was between the two parents and favored the low-value parent "Ninggeng-35" The variation range was 11.65～25.65 mg/kg,and the coefficient of variation was 13.90%.The grain zinc content of the population showed a single peak continuous distribution close to normal,this indicated that the zinc content of rice grains was inherited by quantitative traits controlled by polygenes.5.Based on previous research,fourteen pairs of polymorphic SSR primers were screened by using"Ninggeng 35/Yang he bai pi dao",A total of 2 QTLs,qZn7-1 and qZn7-2，which control zinc content in rice grains were detected,the contribution rates are 28.48%and 28.51%,and the synergistic alleles were all from Yang he bai pi dao.The results laid a foundation for the construction of near-isogenic line population and the fine mapping of this locus. |
PDF Full Text Request