Mapping Of Rf-I An Inhibitor Of The Rf5 Restorer Gene And Isotation And Charaction Of The Rf4 Restorer Gene Mutants Using Mu-inserted Method For Cms-C In Maize (Zea Mays L.)

The inbred line 6233 with C-type male cytoplasm was selected from restorer individuals of a F2 population derived from a cross between Cms-C Mo17 and Fengkel,and self-pollinated to F7,which the restorer line,Fengkel,had two dominant duplicate restorer genes,Rf4 and Rf5.The inbred line 6233 was tested for the restorer gene Rf5 using tightly linked molecular markers bnlg1711 and bnlg1346.The fertility of some F1 progeny derived from crosses between the sterile lines Cms-CMo17,Cms-C77,Cms-Es87-1,Cms-Es478,Cms-C237,and Cms-CZong3 and the restorer lines 6233,A619,Guang10-2,Dan958,and Fengkel,as well as from a bAckcross(Cms-C77×6233)×6233 were evaluated in Zhengzhou and Sayan, China.we foundrestorer gene Rf4 which has restorer Activity over all types of C-Cms, but the F1 progeny between Cms-C77 and 6233 presented sterility.Samples from the bAckcross population of(Cms-C77×6233)×6233 were also evaluated,finding 59 sterile plants and 56 fertile plants out of 123 individuals,a ratio of restored to sterile plants following the theoretical ratio 1:1 by the chi-squared test.These results demonstrate that the sterile line,Cms-C77,has a dominant inhibitor gene,which is named Rf-I that can inhibit expression of the restorer gene Rf5,using SSR markers we located the Rf-I gene on the chromosomal linked with primers umc2327,umc2326 reside on the chromosomal bin 7.02.the genetic distances between the Rf-I and the SSR primers were 3.4 cM,4.7 cM respectively,further research indicated that the inhibitor gene Rf-I,has no effect on the Rf4 restorer gene,in contrast to the effect on Rf5.we used a transposon-tagging strategy to isolate Rf4 Mutant(Rf4-m)alleles,two Rf4-m alleles were isolated through a screen of about 20000 F1 progeny plants named S3 and S5.The two Mutagenesis were derived from Mutator transposon stocks and may therefore have arisen by the insertion of Mu7 transposons,to identify such a transposon inserted within the Rf4 gene,we carred on amplified polymorphisms analysis to two parents and Rf4-m with a improvement approAch named Mu-AFLP, by selective amplification using a nested Mu7-specific primer bglⅡ-2 and a selective primer M1,we isolate a AFLP band about 750bp result from Rf4-m.These result provide material and technology for cloning the Rf4 restorer gene of C-Cms in maize.