QTL Analysis Of Grain Filling Rate And Associated Traits In Maize

In this investigation, a set of IF2 population which derived from an elite maize hybrid Nongda108, and using the RILs as the control whose individals crossing made up the IF2 population, were used to dissect the genetic basis of grain filling rate and associated traits in maize. In 2009and 2010, IF2 population and RILs were evaluated at two locations including Anyang and Zhengzhou in Henan province.The results were as follows.(1) In two years and four locations,a total of 69 QTLs associated with grain filling rate were detected using composite interval mapping method (CIM) at six grain filling stages in IF2 population and RILs. There were 23 QTLs identified in different environments,population or grain filling stages.And there were 45 QTLs detected amomg diffect environments,population or grain filling stages that whose R~2 over 10%.The R~2 of qGFR10a was the highest in all 69 QTLs,which detected at grain filling stageⅠin RILs , Anyang,2009.A total of 35 QTLs were detected in RILs,and 34 QTLs in IF2 population..(2) A total of 75 QTLs were detected associated with test weight at six grain development satages in different environments and populations.There were 19 QTLs identified in different grain development stages,environments or populations. R~2 of all QTLs was in range of 5.170%～29.726%. qTW5e, which had the highest R~2 was detected at grain development stage 5 in RILs,in Zhengzhou,2009. There were 30 QTLs were detected in RILs, and 45 QTLs in IF2 population.(3) A total of 113 QTLs were detected associated with ear traits. There were 25 QTLs associated with ear length, in which 12 QTLs were identified in different environments or populations. A total of 22 QTLs were located on 7 chrosomes associated with ear axis diameter,9 QTLs were identified.21 QTLs associated with ear diameter were detected,but none was identified among all environments and populations. A total of 30 QTLs were detected associated with rows in each ear, in which 13 QTLs were indntified. There were 15 QTLs associated with kernels in each row, in which only two QTLs were identified in IF2 population different years.(4) There 115 QTLs were detected for grain traits in total in the whole genome. There were 19, 34, 21, 18 and 23 QTLs for grain length , grain width, grain thickness , grain volume and grain weight, respectively. There were 19 QTLs associated with grain length , but none was identified in different environments and populations. 34 QTLs were detected for grain width,in which 16 QTLs were identified in IF2 population among all environments. Their R~2 in the range of 5.507%～18.448%. And there 11 QTLs were detected ,whose R~2 above on 10%.A total of 6 QTLs detected in RILs, 28 QTLs in IF2. There are 21 QTLs were detected for grain thickness, only two QTLs were identified. R~2 of 21 QTLs in the range of 4.920%～14.970%,in which R~2 of 7 QTLs overcome 10%. A total of 6 QTLs detected in RILs, 15 QTLs in IF2. A total of 18 QTLs were detected associated with grain volume, 7 QTLs were identified among different environments or populations. R~2 of single QTL in the range of 6.420%～16.993%.There were 5 QTLs detected in RILs, and 13 QTLs in IF2. In 23 grain weight associated QTLs, there were 5 QTLs identified in different environments or populations. R~2 of single QTL in the range of 4.511%～21.311%. 5 QTLs were detected in in RILs, and 18 QTLs in IF2.(5) There were 20 locis distributed on 9 chrosomes(except chrosome 4) that detected QTLs for grain filling rate and test weight at same time. Which showed that to dissect the dynamic of grain test weight at different grain development stages was another way for studying grain filling.(6) QTLs for all traits detected were clustered on the chrosomes.(7) 69 QTLs were detected for grain filling rate at 6 stages, most of which expressed at specific stage, the others expressed at serval stages. Here we defined QTLs of expression in serval stages and QTLs of expression at specific stage in high R~2 as major effection QTL. There were 9 QTLs were screened , who expressed at serval stage. And 10 QTLs expressed at specific stage in high R~2. All major effection QTLs for grain filling distributed on all chrosomes except chrosome 4. In 75 QTLs for grain test weight, 8 QTLs were screened that expressed at serval stages. And there were 13 QTLs screened that they expressed at specific stage in high R~2. Major effection QTLs for grain test weight distributed on chrosome 1, 2, 3, 5, 6, 7, 8 and 9. In which 4 major effection QTLs distributed on chrosome 5 and 7 respectively. In 113 QTLs for ear traits,14 QTLs were screened that who expressed at serval stages. And there were 13 QTLs screened that they expressed at specific stage in high R~2. Major effection QTLs for grain ear traits distributed on chrosome 1, 2, 3, 5, 6, 7, 8 and 9. In which 4 major effection QTLs distributed on all chrosomes except chrosome 4. In the 115 QTLs of Grain traits detected,we screen 11 QTLs which are stably expressed during different environments, accounting for 23.480% of the total. Also,we screen 4 environmental, specifically expressed QTLs in high R~2. All the major QTLs of grain traits distribute on 1, 2, 6, 7, 8 and 9 chromosomes.