Construction Of Genetic Linkage MAP Based On A Ril Population Derived From The Hybrid Rice TD70/Kasalath And Mapping Of Qtls For The Important Agronomic Traits

Traits of plant type and panicle were important agronomic traits which were closely related to production in rice. The improvement of these traits was an important way to increase rice production. Because of quantitatively-genetic nature of traits related to plant type and panicle, it was fundamental to map corresponding position by molecular markers for cloning of corresponding genes and breeding of rice by MAS(Molecular marker-assisted selection). In this study,240F7and Fg lines were randomly selected among RIL (Recombination Inbreeding Lines) by single seed descent method (SSD) from a cross between Kasalath (Indica) with small grain and TD70(Japanica) with large grain as parents, which had significant differences between plant type traits and panicle traits, and was used to construct a molecular linkage map. Correlation and QTLs of10traits related to plant type and panicle were analyzed, the main results were described as follows:1Construction of genetic linkage map of riceTotal838SSR (Simple Sequence Repeat) markers were used to screen the polymorphism between two parents (Kasalath and TD70). Among302SSR markers with polymorphism,141were finally used to construct a genetic linkage map in population of240lines. It spanned1832.47cM length covering all12chromosomes (Chr.) with an average density of13cM, ranging from0.43cM and36.11cM. Frequency of male and female genotype in this RIL population was53%and47%, respectively, indicating the good balance in population structure.51.8percentage segregation distortion markers were detected in the RILs, which deviated to Kasalath. Except few markers on chromosome1and chromosome8, markers had the similar order and position with published Nipponbare sequences.2Correlation analysis on traits of plant type, panicle and yieldCorrelation of the plant type and yield traits had similar results between2010and2011in RIL. Plant height was significantly negatively correlated with panicles number per plant, but there was a significant positive correlation between plant height, flag leaf length and grain weight; Flag leaf length was significantly negatively correlated with flag leaf width and panicles number per plant; Plant yield was significantly positively related with flag leaf width and panicles number per plant. To some extent, increasing the width of flag leaf and number of panicles number per plant will help to improve the yield.Panicle length (PL) had a significantly positive correlation with the number of primary branches (PPB), total grains of per panicle (TSP) and grain weight (GW), but it was significantly negatively related with the grain density (GD). In addition, panicle length was significantly positively correlated with the number of primary branches per panicle, grain density, seed setting (SS) and grains yield per plant (GY). In all words, Panicle traits affected each other and their improvement could increase grain yield of per plant.3Mapping QTL of plant type traitsThe linkage map and QTL IciMapping3.1software were used to detect QTLs loci related to traits of plant type in RIL population in2010and2011.24QTLs controlling plant type were detected in two years. The number of QTLs controlling plant height, flag leaf length, flag leaf width, and panicles number per plant was respectively3,3,10and5. In2011,3QTLs controlling tiller angle were detected, located in another11chromosomes except chromosome10. Phenotypic variations of every trait in all QTLs ranged from34.5%to73.4%.9QTLs were detected in both2010and2011, including qPHl, qPH6and qPH12controlling plant height, qFLL3-1and qFLL3-2controlling flag leaf length, qFLW3, qFLW4-land qFLW8controlling flag leaf width, and qPN2controlling panicles number per plant. QTLs related to flag leaf length were mainly affected by female parents, while QTLs related to panicles number per plant was controlled by both parents. Additive effects of QTLs related to the plant height, flag leaf width and tiller angle were mainly affected by male parent.QTL clusters controlling traits of plant height, panicles number per plant, flag leaf length and flag leaf width were located between RM5389and RM165on chr.l, RM1278-RM3766and RM6080-RM6832on chr.3, close flank of RM3643on chr.4. All these QTL clusters may be the hotspot of plant type genetic for the ideal plant improvement.4. Mapping QTL of panicle traits32QTLs were identified for five panicle traits,5,5,8,10and3QTLs were detected for PL, PPB, TSP, GD, SS respectively, which were located on Chr.2, Chr.3, Chr.4, Chr.6, Chr.7, Chr.8and Chr.10. Total phenotypic variance of each trait that could explain ranged from39.0%to83.4%.8QTLs were detected in both2010and2011, which were qPL3, qPPB2, qTSP4, qTSP6-2, qGD3-2, qGD7and qSS3. The contribution of single QTL ranged from5.6%to30.1%. Except additional QTLs of PPB were coming from both parents, genetic effect from Kasalath was significantly larger than that of TD70in other panicle traits. QTLs from the male parent Kasalath can significantly improve panicle traits effect.QTLs were simultaneously detected affecting the traits of PPB, GD and SS. among these intervals of RM5699-RM424on Chr.2, RM489-RM3766on Chr.3, RM3367-RM1018on Chr.4, and RM3343-RM412on Chr.6. It revealed these traits maybe genetic linkage in a certain degree and consistent with the significant correlation among them.