| Rice is one of the most important food crops in the world,and at least half of the world's population feeds on rice.Most agronomic traits of rice are quantitative traits controlled by multiple genes.The identification and isolation of related genes are the premise and fo foundation rice molecular design breeding.Each chromosome fragment substitution line contains only one or a few fragments from the donor parent,which can eliminate background interference,so it is considered as an ideal material for QTL(Quantitative Trait Locus)analysis.The long-grain chromosome fragment substitution line Z1347 is a restorer of Xihui 18,which is a self-selected breeding line of indica rice,and is independently selected by the Rice Research Institute of Southwest University.It is cultivated through high-generation backcrossing and molecular marker-assisted selection.In this paper,the molecular identification,morphological analysis and evaluation of important agronomic traits of Z1347 were carried out,and the F2 segregating population constructed by the receptor Nipponbare as the female parent and the long-length chromosome fragment substitution line Z1347 as the male parent was used to locate QTL for important agronomic traits such as grain length.The main research results are as follows:1.Identification of Z1347 substitution segmentsOn the basis of previous studies,the 90 SSR markers on the Z1347 substitution fragment and 42 SSR markers outside the substitution fragment were used to further identify the substitution fragment and detect the genetic background of 10 strains of Z1347.It was found that the substitution fragments of 10 individual strains were consistent,and no background fragments were detected,indicating that Z1347 was homozygous.Z1347 contains 16 substitution fragments from Xihui 18,located on 12 chromosomes of rice.The shortest substitution length was 0.95 Mb,and the longest substitution length was 9.1Mb.The total substitution length was 52.3Mb,and the average substitution length was 4.36 Mb.2.Analysis of agronomic traits of Z1347Compared with the receptor Nipponbare,the grain length,aspect ratio,secondary branch number,total grain number and 1000-grain weight of Z1347 increased significantly;the plant height,effective panicle number,grain width and seed setting rate of Z1347 decreased significantly;There were no significant differences in ear length,primary branch number,grain number per ear and yield per plant between Z1347 and Nipponbare.It was suggested that Z1347 carried QTL of several different characters from xihui 183.Distribution and genetic analysis of grain length and other agronomic traits in secondary F2 populationThe F1 grain with the recipient Nipponbare as the female parent and the long-length chromosome fragment substitution line Z1347 was a long-grain type,indicating that the long grain of Z1347 may be dominantly inherited.However,the asymptotically significant(bilateral)test showed continuous distribution of these traits.The approximate P value of the grain length trait was 0.340,the approximate P value of the grain width trait was 0.291,and the approximate P value of the plant height traits(bilateral)was 0.696,the ear length P value was 0.068,the primary branch number P value was 0.153,the P value of the actual grain number per spike was 0.445,and the P value of 1000 grain weight was 0.505,which were greater than 0.05,which were consistent with the normal distribution.The P values of effective panicle number,secondary branch number,length-width ratio,total grain number and yield per plant were all less than 0.05,which did not conform to the normal distribution,indicating that these traits are still controlled by multiple genes and need further decomposition.4.Correlation analysis of secondary F2 population traitsGrain length was positively correlated with plant height,panicle length,primary branch number,secondary branch number,length-width ratio,grain number per panicle,total grain number,1000-grain weight and yield per plant,and positively correlated with effective panicle number,grain width and seed setting rate;Grain width was positively correlated with 1000-grain weight,and was negatively correlated with panicle length,primary branch number,secondary branch number,length-width ratio and total grain number,positively correlated with grain length and seed setting rate,and negatively correlated with effective panicle number,plant height,grain number per panicle and yield per plant.The length-width ratio was positively correlated with effective panicle number,plant height,panicle length,primary branch number,secondary branch number,grain length,grain number per panicle,total grain number,1000-grain weight and yield per plant,significantly negatively correlated with grain width,and negatively correlated with seed setting rate.The correlation coefficient was the total number of total grains and the number of secondary branches,and the correlation coefficient was 0.845,indicating that the total number of grains depends on the number of secondary branches.5.QTL mapping of Z1347 grain length and other agronomic traitsQTL mapping of 8 important agronomic traits in the secondary F2 population produced by the crossover of the Japanese Nipponbare and the long-length chromosome fragment substitution line Z1347 was carried out by using the SSR(Simple Sequence Repeats)markers with good effect in the substitution fragment.a total of 17 QTLs were identified and distributed on chromosomes other than 4th,5th,8th,10 th and 12 th.There were two QTLs with grain length,q GL3 was linked to RM5626 on chromosome 3,q GL7 was linked to RM6063 on chromosome 7;Length-width ratio has three QTLs,q RLW3 linked to RM5626 on chromosome 3,q RLW7 is linked to RM6063 on chromosome 7,and q RLW9 is linked to RM5389 on chromosome 9;plant height QTL(q PH1 and q PH3),effective panicle number QTL(q PN3),secondary branch number QTL(q NSB7),spike length QTL(q PL1,q PL6,q PL7 and q PL11),total particle number QTL(q SPP1,q SPP2 and q SPP7),1000-grain weight QTL(qGWT3). |
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