| In this study, CML166 (tropical inbred line) and Zheng 58 (temperate inbred line) were used as parents to produce F2 and F2:3 populations (252 lines) in maize. Based on present or absent of PCR products, the point mutation of the photoperiod candidate genes were developed as molecular markers. These makers combined with SSR and IP molecular markers, genetic linkage map was constructed.13 photoperiod characteristics including silking stage, tasseling stage, powder phase etc, were used for QTL mapping analysis. Meanwhile, the new developed molecular markers were evaluated the effectiveness by comparing the location on the linkage map.The main results were as follows:(1) Polymorphism and codominant molecular markers were developed from the photoperiod candidate genesincluding CRY2,HY1,SE5,GHD7 and ZCN19, based on the development principle of IP molecular marker. Based on present or absent of PCR products, point mutations of he photoperiod candidate genes PIF3, PRR7, ZCN8 genes of t were also developed into dominant molecular markers which could be applied to establish genetic linkage map.(2) 111 SSR molecular markers,52 IP molecular markers (5 photoperiod candidate gene IP molecular markers) and 3 point mutations molecular markers were used for genetic analysis.143 molecular markers that were suitable for genetic laws of Mendel were used for genetic linkage map construction by QTL IciMapping V3.0 (LOD=3.0) software. As a result, we got a genetic map with 126 molecular markers. However, another 17 markers could not linked to the map.. The map covered all the 10 chromosomes of maize and span 1859.08cM.with an average distance 14.75 cM. The result showed that this map is suitable for further QTL analysis.(3) Using QTL IciMapping V3.0 (LOD>2.5) software (composite interval mapping method),13 photoperiod characteristics such as silking stage, tasseling stage, Powder phase etc. were applied to QTL analysis.76 QTLs loci were detected in Xishuangbanna and Chengdu photoperiod environments, and these QTLs loci were mainly distributed in 1,2,3, 4,5,8,9,10 chromosome. Among them,30 QTLs were in Xishuangbanna photoperiod environment, while otherwere 46 QTLs in Chengdu photoperiod environment. The phenomenon of different traits located to the same site or the same characters located to different sites were already found previously, probably due to pleiotropy of genes or other reasons. Totally 12 main QTLs were detected in the two environments, but the QTL were not consistent in each environment These may be caused byQTL X environment, environmental regulation and gene expression regulation.(4) 5 consistency QTLs loci were detected in two photoperiod environments. On chromosome 8, powder phase QTL was located between markers ZMZCN8-primer49, leaf numberwas between markers zsz75-umc1457, the QTL of lower ear leaf number was between markers zsz75-umc1457, while on chromosome 1, QTL of ear leaf length was between markers umc1245-umcl843, consistency andon chromosome 3, male branch number was between markers zsz40-umc1052. These QTLs provided a theoretical basis for the interaction of maize germplasm resources. And they were of vital significance to improve maize genetic breeding.(5) The QTL of powder phase,whichwas detected in both photoperiod conditions and located on chromosome 8 between markers ZMZCN8-primer49 (Bin8.07-8.08), could explain phenotypic variation 6.05% and 4.14% respectively in two different phtoperiod conditions of day length, consistent with the results of previous studies.The results of this study show,the molecular markers of development that it according to photoperiod candidate gene point mutation loci and intron insert or missing the variation can be used for corn QTL mapping analysis of photoperiod sensitivity traits, and QTL cloning research. |
PDF Full Text Request