| Yield improvement in maize is the result of multiple factors. As an important trait in the ear of maize, ear diameter (ED) is closely related to the improvement of yield in maize, which is often an important index in high yield per plant. Ear diameter in maize showed typical quantitative traits, use of quantitative genetic methods to study the ear diameter in maize, which is an imporant way in maize breeding to improve yield. In this study, the following three aspects:①Application of "major genes+polygenes mixed genetic model of plant quantitative traits" to analysis the genetic effect of ear diameter in 6 generations (P1,F1,P2,B1,B2,F2) in maize.②Analysis and locate the QTL of ear diameter in maize.③Analysis consensus map (Meta-analysis) based on previous studies and ours, were studied in order to further reveal the inheritance of ear diameter in maize. The main content of this study and the results are as follows:1. Application of "major genes+polygenes mixed genetic model of plant quantitative traits" to analysis the inheritance of ear diameter in maize in 6 generations from 4 reciprocal corss combinations 18white×1212, RP125×1212 at two years and two places and in 6 generations from combination B73×1212. The results showed that:①F1,B1,B2 generation showed as mid-inheritance in ear diameter in maize.②Ear diameter in maize is controled by major genes+polygenes in the aspect of genetic model. Among them, Combinations of ear diameter at YunNan (B73×1212,18white×1212,1212×18white,RP125×1212,1212xRP125) fitted the inheritance model of additive-dominance-epistasis polygenes model(C model), the total trend is no major genes; Combinations of ear diameter at SiChuan (18white×1212,1212xl8white,RP125×1212,1212×RP125) fitted the inheritance model of D-3 model (a pair of completely dominant major genes+additive-dominance polygenes model), E-1 model (two major genes with additive-dominance-epistasis effects+polygene with additive-dominance effects model) E-1 model,E model (two major genes with additive-dominance-epistasis+polygene with additive-dominance-epistasis effects model) respectively, the total trend is existng major genes.③In the aspect of gene effect, the main gene effect is additive effect of the ear diameter in maize and existing epistasis effect; the interaction effect in which interaction effect can be detected is not obviously; the estimated effect of first-order genetic parameters and the heritability of major gene+ploygenes in each combination are not high, which showed that ear diameter is highly effected by environment.2. In this study, ear diameter in maize was investigated by using F2 population, which derived from combination B73×1212. The F2 population were evaluated at Yunnan and Sichuan in 2008 and 2009, and the genetic linkage maps were constructed including 115 SSR markers, map covering 10 chromosomes of maize, the total length of the map is 1420cM, and the average distance is 12.35 cM. The results showed that:10 QTL of ear diameter in maize were identified at Yunnan and Sichuan, single QTL varied from 5.02% to 48.09%. Among of the 10 QTL,4 QTL were detected at Yunnan,which primary mode of action is additive effect,7 QTL were detected at Sichuan, which primary mode of action is over-dominant effect,1 QTL (yED-4) was detected both at Yunnan and Sichuan, which is a primary effect QTL, and located at 8 chromosome, the linkage marker is from umc1913 to umc1236, the average contribution rate is 18.48%, the mode of action was showed as additive effect and part-dominant effect at Yunnan and Sichuan respectively. Additive effect and over-dominant effect were the primary mode of action in the inheritance of ear diameter in maize.3. A total of 52 QTL conferring ear diameter was collected and analyzed by using bioinformatics tool, and the integration map including 33 QTL, which derived from the resultes of ours'and others'research, was constructed by BioMercator2.1 software, using Genetic Map IBM2 2008 Neighbors as reference. The results showed that:15 consensus QTL were found totally, which were located at 1,2,3,4,8,9 and 10 chromosome respectively. |
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