| Rice lodging is a major factor that affects the yield. Rice culm and associated traits are closely related to lodging resistance. Identification and application of lodging resistance QTLs in rice germplasm to develop lodging resistance varieties that can increase harvest index and improve the biomass in conditions of certain economic factors. Therefore, breeding aim to ideotype and high yield has been increasingly important in the current rice breeding. In this study, some new QTLs associated with lodging resistance were identified and effects of these QTLs were evaluated and dissected by stem diameter, length of elongating internodes, wall thickness of internode and resistance to lodging. The main results are as follows :1. Construction of genetic linkage map: Polymorphic markers were screened between Vary lava1312 and Huahui1462. A total of 154 SSR markers were finally available to construct a linkage map. The whole length of the map was1963.7 c M, and the average was 12.75 c M between adjacent markers.2. QTL mapping for stem diameter: Based on the phenotypes of stem diameter in F2:3 population in both 2013 and 2014, a total of 9 quantitative trait loci(QTLs) affecting stem diameter were detected on chromosomes 1, 2, 4, 5, 9 and 10, respectively. QTLs affecting the basal stem diameter(BCM) were detected on chromosomes 1, 2, 5, 9 and 10 with the LOD values of 2.9- 5.2 and explained 2.69%-12.01% of phenotypic variance. QTLs controling the stem diameter of the basalⅠelongating internode(FCM) were detected on chromosomes 1, 4, 5, 9 and 10 with LOD values of 2.60- 3.90 and explained 8.41%-16.14% of phenotypic variance. QTLs associated with the stem diameter of the basal Ⅱ elongating internode(SCM) were detected on chromosomes 1, 2, 4, 5, 9 and 10 with LOD values of 2.50- 3.70 and explained 2.61%-13.15% of phenotypic variance.3. QTL mapping for plant height(PH) : A total of 4 QTLs affecting PH were identified on chromosomes 1, 7 and 9, respectively, explained 2.61%-12.66% of phenotypic variance. 2 QTLs q PH1.1 and q PH9 were repeatedly detected between markers RM472 and YP4011 on chromosome 1, and between an interval of RM434 and RM296 on chromosome 9 in the two years, respectively. The LOD values of q PH1.1 and q PH9 were 4.90-5.60 and 8.50-8.90, which explained 2.61%-12.66% and 14.56%- 12.66% of phenotypic variance, respectively.4. QTL mapping for length of the basal elongating internodes : A total of 5 QTLs were detected on chromosomes 1, 6 and 9, respectively. Among of them, 2 QTLs affecting the length of the basalⅠelongating internode(FIL) were both detected on chromosomes 9 with LOD values of 3.20 and 3.60 and explained 14.21%-14.72% of phenotypic variance, respectively. The other3 QTLs controling the length of the basal Ⅱelongating internode(SIL) were detected on chromosomes 1 and 6 with LOD values of 2.80, 7.60, 2.70 and explained 5.80%-28.40% of phenotypic variance, respectively.5. QTL mapping for wall thickness of each internode: A total of 7 QTLs were detected on chromosomes 1, 3, 5 and 9, respectively. Among them, 2 QTLs affecting the wall thickness of the basal internode(BT) were both detected on chromosomes 9 with LOD values of 3.60 and 3.50 and explained17.00%- 15.96% of phenotypic variance, respectively. Only 1 QTL controling the wall thickness of the basal Ⅰelongating internode(FT) were detected on chromosomes 1 with LOD value of 3.10 and explained 7.56% of phenotypic variance. 4 QTLs associated with the wall thickness of the basalⅡinternode(ST) were both detected on chromosomes 9 with LOD values of 2.60-3.90 and explained 3.30%-14.97% of phenotypic variance, respectively.6. The ralationship between PH and stem diameter : the correlation coefficient in two years of PH and stem diameter were both significantly different(P>0.01). Furthermore, interestingly, a total of 5 QTLs(q BCM1、q BCM9、q FCM1、q FCM9.1 and q SCM1) affecting stem diameter were detected on chromosomes 1 and 9, and 2 QTLs(q PH1.1and q PH9) controling PH were located on the similar regions on chromosomes 1 and 9. A lot of QTLs located on the hot spot(an interval of RM4011 and YP41231) on chromosome 1, indicating that this segments were very important for lodging resistance. These results provided the relationship between PH and stem diameter of each internode on certain genetic level. |
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