| Photoperiod is a major environment factor affecting plant development. Maize is short day plant and flowering time is affected by photoperiod. Sensitivity to photoperiod limits the potential for successful exchange of germplasm across different latitudes. Therefore, it is vital for maize breeders to understand the genetic basis of photoperiod sensitivity in their efforts to integrate tropical germplasm into temperate zone maize breeding.For resolving the genetic basis of photoperiod sensitivity in maize, in this research , a population of 207 recombinant inbred lines (F7) derived from a temperate and tropical inbred line cross were developed . In zhengzhou location of 2006, we detected the plant height and leaf numbers the two photoperiod relevant senstivity traits in different development periods, combining with the genetic linkage map, we detected the conditional QTLs and unconditional QTLs. In the base of F7 recombinant inbred lines ,we constrcted a F10 recombinant inbred lines, and an immortalized F2 population of 278 F1 cross which was constrcted by intercrossing of RIL population. The immortalized F2 population and the RIL population were evaluated in three location of two different photoperiod environment in 2007. Total aerial root numbers and effective aerial root numbers, the performinance data of the two photoperiod sensitivity relevant traits in RIL population and immortalized F2 popultion were used for QTL mapping and digenic interaction analysis. The main results obtained in this study were concluded as follow:1. Two genetic linkage maps, both containing 237 SSR polymorphic markers was constructed using F7 and F10 RIL populations, spanned a total length of 1753.6 and 1974.3 cM with an average space between two makers of 7.40 and 8.33 cM, respectively.2,In zhengzhou location, using the F7 RIL popution, 20 plant heigth QTLs were detected, distributing in the 9 chromosomes except the No. 2 chromosome, including 11 unconditional QTLs and 16 conditional QTLs ;11 leaf number QTLs were detected, distributing in the 1,2,4,7,8,9 and the 10 chromosomes ,including 8 unconditional QTLs and 6 conditional QTLs. In different stages, the expression of the plant numbers and the leaf numbers were different, some of them can be detected in several continuous times, while some others could be detected only in specific stages. None QTL can be detected in all the stages, it showed that none QTL can express in all the stages.3,In the three locations of two different photoperiod , the Total aerial root numbers and Effective aerial root numbers in the RIL (F10) and IF2 poputions both have significant differences, the frequency of all traits show continuous changes and normally distribution,so the two population can be used in QTL mapping and analysis. The conclusion also showed that the total aerial root numbers and the effective aerial root numbers were synergy effected by the additive effect and the dominant effect. The Total aerial root numbers and effective aerial root numbers was registered as phenotypic correlation and genotype correlation, the broad-sense heritability of the total aerial root numbers was higher than the effective aerial root numbers.4,6 QTLs that controlling total aerial root and 4 QTLs that controlling effective aerial root were detected in the F10 RIL, they were located in the 1,5,6,7,9,10 chromosomes and 3,5,9,10 chromosomes, respectively. The additive effect absolute value and the contribute value of all the QTLs that contriolling the effective aerial roots were low. 8 QTL that controlling total aerial root and 7 QTL that controlling effective aerial root were detected in the IF2 popution, they were located in the 1,2,5,7,8,10 chromosomes with 3 dominant effect and 5,6,8,9,10 chromosomes, respectively.5,Two similar total aerial root numbers QTLs and one sililar effective aerial root numbers were detected in the RIL(F10) and IF2 poputions in three different locations. The QTLs that controlling the total aerial root numbers were qTAR7-1 and qTAR10-1, located in umc1426-umc1159 segment of chr.7 and umc1873-umc1077 of chr.10, respectively. qTAR10-1 was the main effect QTL, can explained phenotypic variation 17.88%. qEAR10-1, the main effect QTL that controlling the effective aerial root numbers, also located in umc1873-umc1077 of chr.10, can explained phenotypic variation 6.37%. Using QTLNetwork2.0 software, epistasis was detected in the F10 RIL and IF2 poputions, they can explain some of the phenotype variations. It shows that the epistasis was abound exist in the heredity of the aerial roots, much more in the IF2 poputions, especially. Most of the QTLs and epistasis, detected in the RIL(F10) and IF2 poputions, have no significient interactions with the environment. There are only 3 interactions between QTLs and environment in the IF2 popution, all of them have low effect.6,We conclude that a main effect photoperiod sensitive QTL that located in the umc1873 region of chromosome 10 were detected in all the triats in the 3 poputions,it shows pleiotropic or closely linked each other, it is the base for the fine mapping and breeding. |
PDF Full Text Request