| ice(Oryza sativa L.)is one of the world’s three major food crops,and more than half of the world’s population feeds on rice.High yield breeding is one of the main objectives of rice breeding.1000-grain weight is an important factor in rice yield.Chromosome single segment substitution lines are excellent materials for QTL identification,gene fine mapping,cloning and gene polymerization in rice.In our previous work,KT0041,a single segment chromosome substitution line with Huazhan as the recipient parent and 8001 as the donor parent,was obtained.Compared with Huazhan,1000-grain weight increased significantly.In this study,molecular marker-assisted selection technique was used to identify the material,and F2 population was constructed to locate QTLs related to 1000-grain weight and analyze their genetic effects.The main research results are as follows:1.Identification of chromosome single segment substitution line KT0041.After investigating the agronomic traits of the 112 substitution lines constructed in our laboratory,the single-segment substitution line KT0041 with significantly increased grain weight was selected.Subsequently,58 pairs of molecular markers on 12 chromosomes were used to identify the substitution fragments.It was found that the substitution fragments of 6 KT0041 plants were consistent,and the detection results were consistent with those of previous identifications.The longest substitution length of substitution fragment on chromosome 7 was 4.23 Mb.2.Analysis of agronomic traits of KT0041.Statistical analysis of agronomic traits of KT0041 from 2018 to 2021 showed that its phenotype was stable.Compared with Huazhan,the grain length,grain width,grain weight,panicle length,grain number per panicle,plant height,flag leaf length and flag leaf width increased significantly.Effective tillering and aspect ratio decreased significantly.It indicated that KT0041 and Huazhan had significant differences in agronomic traits.3.Frequency distribution of main agronomic traits in F2 population.The secondary F2 population was obtained by self-cross of Huazhan and KT0041,and the traits of all individuals in this population were measured and analyzed,and it was found that the skewness was-0.86～1.13,and the kurtosis was-0.5～5.37.The skewness and kurtosis of standard normal distribution should be 0 and 3,respectively,indicating that these traits are not standard normal distribution.Asymptotic significance(bilateral)test showed that these traits were continuous distribution.The approximate P values of grain length,grain width,plant height,ear length,grain number per panicle and 1000-grain weight were greater than 0.05,which were in line with normal distribution.The approximate P values of effective tillering,flag leaf width and flag leaf length were less than 0.05,which did not conform to normal distribution.4.Correlation analysis of secondary F2 population traits.In order to study the correlation between agronomic traits,the correlation analysis of F2 population was carried out,and it was found that most traits had significant positive correlation or negative correlation.1000-grain weight was significantly correlated with grain length,grain width,grain number per panicle and length-width.Grain length was positively correlated with plant height and flag leaf width.The main spike length was positively correlated with plant height,flag leaf length,flag leaf width and effective tillering.5.QTL qTGW-7 mapping for 1000-grain weight in KT0041.Using F2 secondary segregation population as QTL mapping population.After 8 pairs of molecular markers were used to detect the genotypes,12 different types were screened between markers S7-36 and RM1306.Combined with 1000-grain weight phenotype,it was speculated that qTGW-7 might be located in 270 Kb between markers S7-11 and S7-1,which could explain 5.29%(LOD＝4.63)of the grain weight variation.The above results provide a preliminary basis for further cloning qTG W-7 and material resources for high-yield molecular breeding of rice. |
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