Mapping Of The QTLs For Grain Shape And Grain Weight Using Single Segment Substitution Lines In Rice

Rice grain shape(grain length,GL;grain breadth,GB)is a main index of rice appearance quality,and also is the main factor affecting grain weight(GW),which will greatly influence the high-yield.It will be very greatly theoretically and practically meaningful to study the inheritance of grain shape and grain weight for breeding of rice variety with high-yield and good quality.In this paper,we developed a population consisting 54 single segment substitution lines(SSSLs)by using Nipponbare as recipient parent and 93-11 as donor parent to map QTLs controlling grain shape and grain weight,which lay a foundation for the following research of gene localization and molecular marker-assisted breeding work.The main results are as follows:1.A linkage map comprising 172 intron length polymorphisms(ILP)markers and 13 SSR markers was constructed based on the BC₁F₁ population consisting of 102 plants derived from Nipponbare/93-11//Nipponbare.The map covers 1905.70cM in total length with an average distance of 10.30cM between adjacent markers.Among these ILP and SSR markers,30 markers(16.22%)performed genetically distorted segregation(P＜0.05). Among them,there are 28(93.33%)distorted markers deviated toward donor parent 93-11, only 2 markers toward recipient parent Nipponbare.2.Based on F-statistic to test grain length,grain breadth and grain weight,the result shows there is no significant difference among these triple characters.Thus,we conclude that the difference(p≤0.001)between SSSL and recipient parent is not affected by environment factor,but is the real reflection of genotypic difference.Results from t test showed that the differences in GL,GB and GW between the two parents,93-11 and Nipponbare are significant at the level of 1%(p≤0.01).3.On 21 substituted segments,a total of 26 QTLs for GL,GB and GW were detected on chromosome 1,2,3,5,6,7,8,10 and 11 when receipted a significant level of 0.1%(p≤0.001).Among them,8 QTLs are for GL with their additive effects ranging from 0.12 to 0.56 mm,and their additive effect percentages ranged from 2.29%～10.98%;7 QTLs control GB with their additive effects ranging from -0.32 to -0.13mm,and their additive effect percentages varied from -10.32%～-4.19%;11 QTLs are for GW with their additive effects ranging from 0.09 to 0.27g,and their additive effect percentages varied from 4.26%～12.56%.4.Comparison of their positions of detected QTLs controlling GL,GB and GW show that,9 QTLs for GW share the same or similar positions of QTLs controlling GL or GB,suggesting that GL and GB may make some contributions to GW.Furthermore,GW shares more common QTLs with GL than GB,suggesting that GL can make more contributions to GW than GB makes.In addition,the positions of QTLs qGW-6 and qGW-10-3 for GW are different from these for GL and GB,indicating that there truly exists in some independent QTLs for grain weight.