| As the material foundation of maize breeding,germplasm resources have been paid much attention by the breeders.Reasonable plant type is the reproductive foundation and important morphological characteristics of the high-yield crop varieties.The dwarf traits are an important aspect of ideal plant type.The dwarf maize has the characteristics of anti-lump,dense,suitable mechanized production and high utilization of light energy,so the exploration and genetic research of dwarfing genes in maize breeding has attracted more and more attention.But due to breeding and utilization of maize dwarf resources is single,restricting the further development of maize breeding of dwarf.Therefore,it's necessary to create,identify and utilize the new maize dwarf resources,the study regarded the maize inbred line R08,dwarf mutant R08d and homologous mutant R08h obtained by EMS mutagenesis as test materials,we contrast and research the difference of agronomic traits and molecular genetic among the three materials,using dwarf mutant R08d and five inbred lines for genetic mating design to analyses the inheritance law of the dwarf trait of the mutant,and the dwarf gene was mapped by BSA-SSR marker method.The main findings are as follows;1.The result of agronomic traits and molecular genetic differences among the mutants R08h,R08d and inbred lines R08:the plant height of the dwarf mutant R08d was dramatically decreased by 47.27%compared with the inbred line R08.The height of homologous mutant R08h was 2.3%higher significantly than that of R08.Plant height of the two mutant strains differs greatly by 94%.Mutant R08d shows dwarf plant,severely shortened internode,low spike height,small ear,low seed setting,tassel of that is slightly atavism.Homologous mutant R08h has characteristics with increased leaf number,smaller the leaf angle,less and shorter tassel branches,smaller tassel branch angle.According to NY/T1432-2014 "Protocol for the identification of maize varieties-SSR marker method",we detected R08h,R08d and R08 utilizing forty pairs of SSR core primers,and found genetic different locations 6,5,respectively.Between R08h and R08d exist six genetic different locations,it improves that the mutant R08h,R08d are different from inbred lines R08,based on genetic different locations greater than or equal to two.2.Inheritance of dwarf characters in mutant R08d:the dwarf mutant R08d was combined with five maize inbred lines of different genetic backgrounds to constitute six generations(P1,P2,F1,B1,B2,F2),and separation of plant height in Ya'an in identical populations were consistent with the that of Shuangliu.Plant height of reciprocal F1 populations showed normal,while There was no significant difference in plant height between the positive and negative F1 populations,and the effect of cytoplasmic heredity was not manifested;and the separation ratio of plant height in five backcross populations(B1)combined with R08d accords with 1:1;plant height of the B2 populations backcrossed with inbred lines(R08,K305,21-ES)is not isolated and shows the high stem;height segregation in the B2 populations backcrossed with dwarf inbred lines(K123d,K125d)fit a tall:a dwarf;and the separation ratio of plant height in F2 population crossed with common inbred lines is 3 tall:1 dwarf.The separation ratio of F2 in hybridization with dwarf inbred lines was in accordance with the that of two recessive single genes 9:7.In sum,the dwarf character of the R08d mutant,not nuclear cytoplasmic inheritance,was controlled by a pair of single recessive gene,which was named as dr08.Moreover,it's not allelic of dwarf genes controlled of two dwarf inbred lines K123d,K125d.3.Gene mapping results of dwarf traits in mutant R08d:F2 constructed with mutant R08d and maize inbred lines k305 was used as the primary mapping population,totally 2142 strains,of which 522 plants were dwarf.458 pairs of SSR primers with an average distribution of 10 chromosomes in maize were selected,and the 191 pairs polymorphic SSR primer were obtained between the parents R08d and K305.Three pairs of SSR primers,bnlg1523,umc1087,umc2261,were selected from the extremely tall and dwarf gene pool of F2.Subsequently,addition of forty pairs of SSR public primer on 3.0-3.03 interval of chromosome 3,we screened two pairs of SSR primer umc2376,bnlg1144 from that.Using five pairs of SSR primer amplifies and verifies dwarf individual plant in F2,the dwarf gene dr08 was mapped on the short arm of chromosome 3,located between the SSR markers bnlg1144 and bnlg1523,and the genetic distance was separately 2.0 cM and 1.5 cM. |
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