Genetic Analysis And QTL Mapping Of The Flag Leaf Traits In Rice (Oryza Sativa L.)

As a photosynthetic organ, leaf provides grain with filling substance, whereas its morphology significantly influences crop development and physiological function like photosynthesis, transpiration, stress resistance and so on. Thus, from practical point of view, leaf morphology study may play an important part in promoting rice production.In order to unveil genetic control of rolled flag leaf, super-long flag leaf and super-wide flag leaf, genetic analysises were carried out using F2 populations derived from Nipponbare and a rolled leaf mutant, TN1 and a super-long flag leaf mutant, three parents (Nipponbare, TN1 andâ…¡-32B) and a super-wide flag leaf mutant. respectively. The main results are as follows:1.Rolled leaf trait was controlled by one incomplete dominant gene.2.Super-long flag leaf trait could be controlled by one incomplete dominant gene.3.Super-wide flag leaf trait showed continuous distribution in F2 population, and thus was controlled by multiple genes.4.In addition, QTL mapping for flag leaf characters (Length, Width, Angle) and correlation analysis were carried out in two environments (Hangzhou, Hainan) by using two DH populations derived from ZYQ8/JX17 and CJ06/TN1, respectively. The main results are as follows:(1)In Hangzhou and Hainan, a total of 13 QTLs responsible for flag leaf length were identified in the DH populations. Among them, 7 QTLs distributed on chromosome 1, 2, 3, 4, 10 and 12 were detected in the population from the cross ZYQ8/JX17,and the other 6 QTLs located on chromosome 1, 4 , 6 and 8 were identitified in the population from the cross CJ06/TN1. qFLL-1 and qFLL-8 were detected in both sites by using DH populations from the cross ZYQ8/JX17and CJ06/TN1. A major QTL qFLL-4 (LOD 3.56) identified in the cross CJ06/TN1 explained 26.30% of the total variation, which may lay a foundation for gene fine mapping and molecular marker assisted breeding in rice.(2)In Hangzhou and Hainan, a total of 8 QTLs controlling flag leaf width were identified in the two DH populations. Among them, 5 QTLs were detected on chromosome 3, 4, 6, 11, 12 in ZYQ8/JX17 population. and 3 QTLs were detected on chromosome 1, 2, 4 in CJ06/TN1 population. qFLL-12 (LOD 6.72) controlling flag leaf width was identified in Hangzhou from the cross ZYQ8/JX17 and explained 20.85% of the total variation.(3)In Hangzhou and Hainan, a total of 9 QTLs controlling flag leaf angle were identified only in the DH population from the cross ZYQ8/JX17. Among them, six QTLs on chromosome 1, 2, 7, 9, 12 were detected in Hainan and the other three QTLs were detected on Chromosome 6, 8, 12 in Hangzhou, respectively. qFLA-1 (LOD 4.6)and qFLA-2 (LOD 5.65) identified in Hainan explained 12.5% and 13.8% of the variation, respectively.(4)With the prolong of days from sowing to heading, plant height, flag leaf length, flag leaf width and flag leaf area increased. This is the main reason that different QTLs identified in different environments.