QTL Mapping And Analysis For The Relevant Traits Of Plant Type In Maize

Studied the heredity rule and analysis the QTL of plant-type in maize,which were great significance for compact breeding and molectular marker assisted breeding in maize. F2:3 families were constructed deriving from the typical compact plant type inbreed line Yu82 and the typical spreading plant type inbreed line Shen137. Genetic studies of characters related to plant type were analyzed under the environments of Sanya and Zhengzhou. One hundred ninty-seven pairs SSR markers were selected to consturct a genetic linkage map, and QTL mapping and analysis about 6 traits related with plant type was carried out with complex interval mapping.The main results in this study were as follows:1. Under the environments of Sanya and Zhengzhou, the traits such as leaf angle, leaf orientation value, leaf length, leaf width, plant height and ear height in the F2:3 families have significant differences, the frequency of all traits show continuous changes and normally distribution,so the F2:3 population can be used in QTL mapping and analysis.2. Under the environments of Sanya and Zhengzhou, the leaf angle and leaf orientation value was showed mid-parent heterosis, there genetic ability were higher, attaining 0.89 and 0.84 respectively. The other traits were showed excess-parent heterosis, there genetic ability were lower, attaining 0.62,0.55,0.70,0.62 respectively. The mean value of most traits were near to the mean value of the parents in the F2:3 families except plant height. There were unidirectional transgressive segregation in the F2:3 population, such as leaf angle and leaf orientation value. The tremendous doubleaction transgressive segregation for most traits were also observed in the F2:3 population, such as leaf length, leaf width, plant height and ear height.3. One hundred and ninty-seven pairs SSR markers were selected to construct a genetic linkage map of F2:3 with the genetic distance of 2730.6cM (centimorgan) and on an average of 13.86cM using Mapmaker 3.0. And the shortest genetic distance is 0.1cM.4. 40 QTL were detected of 6 traits under the environments of Zhengzhou and Sanya, 4QTL were detected in the two environments, so there were 36 different QTL being detected. 20 QTL controlling the traits such as leaf angle, leaf orientation value, leaf width, plant height and ear height were detected in sanya, these QTL were on 1, 2, 3, 4, 5 and 7 chromosome respectively, and 7 of which on the chromosome 1. 20 QTL controlling the related traits of plant type were detected in zhengzhou , these QTL were on 1, 2, 3, 4, 5, 7, 8, 9 and 10 chromosome respectively, and 6 of which on chromosome 1. Under the two environments, leaf angle was detected 7 QTL, leaf orientation value was detected 10 QTL, leaf length was detected 3 QTL, leaf width was detected 6 QTL, plant height was detected 8 QTL, ear height was detected 6 QTL.5. The major QTL was detected,such as leaf angle, leaf orientation value,leaf length, leaf width, plant height and ear height. Furthermore, the distance was close to the marker what were at two sides of the markers. Leaf angle was detected one major QTL in bin 1.02, between markers umc1166and umc2226. The QTL can be explained phenotypic variation 14.73%. Leaf orientation value was detected one major QTL in bin 1.02, between markers bnlg1803 and umc2171. The QTL can be explained phenotypic variation 20.35%. Leaf length was detected one major QTL in bin 10.03, between markers bnlg1655 and umc1863. The QTL can be explained phenotypic variation 13.09%. Leaf width was detected one major QTL in bin 3.01/3.02, between markers umc2377 and umc1057. The QTL can be explained phenotypic variation 24.15%. Plant height was detected one major QTL in bin 7.01, between markers umc2160 and umc1270. The QTL can be explained phenotypic variation 14.45%.Ear height was detected one major QTL in bin 4.08, between markers umc2287 and umc1371. The QTL can be explained phenotypic variation 17.64%.6. Two QTL of leaf angle were detected both in Sanya and Zhengzhou. qLA1a was between markers umc1166 and umc2226, explained phenotypic variation 11.57% in Sanya and 14.73% in Zhengzhou. qLA1b was between markers bnlg1803 and umc2171, explained phenotypic variation 10.57% in Sanya and 13.23% in Zhengzhou. Two QTL of leaf orientation value were detected both in Sanya and Zhengzhou. qLOV1a was between markers umc2226 and bnlg1803, explained phenotypic variation 18.84% in Sanya and 15.22% in Zhengzhou. qLOV1b was between markers bnlg1803 and umc2171, explained phenotypic variation 20.35% in Sanya and 20.12% in Zhengzhou. Furthermore, The diatance was 7.5cM between the marker umc2226 and bnlg1803. So we can be used umc2226 and bnlg1803 to assist selection for shaped better plant type in maize.7. The QTL on chromosome 1 were much more than that on the others, and these QTL were nearly between markers umc1166and umc2226,umc2226 and bnlg1803,bnlg1803 and umc2171. The most QTL of the leaf angle and leaf orientation value were between these markers, what are key traits of plant type under the environments of Sanya and Zhengzhou. The value of LOD and the contribution of these QTL were major, so the gene controlling the leaf angle and leaf orientation value maybe near these markers.