| Maize plants have a very rich genetic diversity under the influence of long-term evolution,isolation,reproduction and artificial selection.Plant-type traits determine many aspects of maize plants,especially in plant yield.The genetic mechanism of plant type related traits has very important significance for maize yield and breeding.In this study,the RIL population(80007 × 80044)created by our lab was used as experimental material.And a genetic linkage map was successfully constructed.The RIL population and their parents were planted in 2014(E1),2015(E2)and 2016(E3),respectively.The plant height,ear height,length and number of tassel branches were measured in different years to find valuable QTL locus and provide important reference for the study of maize molecular marker-assisted selection breeding and QTL cloning.Meanwhile,we would find higher LOD values and explaining for phenotypic variation contribution rate QTLs,in order to further study the related genes by constructing subgroups,fine mapping and encryption linkage maps.The results showed that:1.There was significant correlations between plant height and ear height,plant height and tassel length,ear height and number of tassel branches.There was significant negative correlation between ear height and tassel length,tassel length and number of tassel branches.While there was no significant correlation between plant height and number of tassel branches.2.We successfully constructed a genetic linkage map containing 52 SSR molecular markers and 707 SNP molecular markers.The total length of the map is 1515.477 c M,and the average distance between markers is 2 c M.The total markers in chromosomes 1 to 10 of maize were 121,57,91,103,72,87,65,62,48 and 53.The average distance between the markers on each chromosome was 2.22 c M,2.15 c M,2.70 c M,1.50 c M,1.63 c M,1.38 c M,1.85 c M,2.80 c M,2.57 c M and 1.27 c M,respectively.3.QTL mapping results of the four important plant-type traits were as follows:Mapping of QTLs for plant height: in the three environments of E1,E2 and E3,there were 2、3 and 2 QTLs detected,respectively.The stable QTL q PH1-1 was detected in both E2 and E3;the other five QTLs were detected only in a single environment.We mapped 6QTLs for plant height,which could explain the phenotypic variation between 4.26% and19.24%(Table 9).Among them,1 QTL came from 80007 allele,playing a synergistic effect;5 QTLs came from 80044 allele,playing a synergistic effect.Moreover,q PH1-4 located on maize chromosome 1 was the main site for controlling plant height,which could explain19.24% phenotypic variation.Mapping of QTLs for ear height: in the three environments of E1,E2 and E3,there were1、7 and 4 QTLs detected,respectively.The stable QTLs q EH1-2 and q EH3-3 were detected in both E2 and E3;the other nine QTLs were detected only in a single environment.We mapped 11 QTLs for ear height,which could explain the phenotypic variation between 3.98%and 13.94%(Table 9).Among them,6 QTLs came from 80007 allele,playing a synergistic effect;5 QTLs came from 80044 allele,playing a synergistic effect.Moreover,q PH3-2located on maize chromosome 3 was the main site for controlling ear height,which could explain 13.94% phenotypic variation.Mapping of QTLs for tassel length: in the three environments of E1,E2 and E3,there were 2、6 and 2 QTLs detected,respectively.The stable QTL q TTL2 was detected in both E2 and E3;the other 8 QTLs were detected only in a single environment.We mapped 9 QTLs for tassel length,which could explain the phenotypic variation between 3.70% and 11.75%(Table 9).Among them,2 QTLs came from 80007 allele,playing a synergistic effect;the other 7 QTLs came from 80044 allele,playing a synergistic effect.Moreover,q TTL3-1located on maize chromosome 3 was the main site for controlling tassel length,which could explain 11.75% phenotypic variation.Mapping of QTLs for number of tassel branches: QTL was not detected in environment E1.In E2 and E3,there were 8 and 7 QTLs detected,respectively.The stable QTLs q TBN3-3、q TBN4-2 and q TBN9 were detected in both E2 and E3;the other 9 QTLs were detected only in a single environment.We mapped 12 QTLs for number of tassel branches,which could explain the phenotypic variation between 3.74% and 15.92%(Table 9).Among them,7QTLs came from 80007 allele,playing a synergistic effect;the other 2 QTLs came from80044 allele,playing a synergistic effect.Moreover,q TBN3-3 located on maize chromosome3 was the main site for controlling number of tassel branches,which could explain 15.92%phenotypic variation.Among QTLs of the four important plant-type traits,three QTL clusters were formed in three or more loci involving two environments,including 17 QTL loci,and located on chromosome 1,3 and 9,respectively. |
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