Identification Of Fertility Restoration And Molecular Mapping Of Restore Gene For Two Maize Restore Lines Of CMS-C

In former studies,we found that inbred lines Z16,7250-14-1 can restore the fertility of C huangzaosi and C478.In this study,Z16 and 7250-14-1 were crossed with both isonuclear alloplasmic and isoplasmic allonuclear male sterile lines,respectively.Self-cross and back-cross were conducted for some of the fertility restored F₁ for genetic analysis and molecular mapping of fertility-restoring gene.Male fertility was investigated for all the F₁,F₂ and backcross populations.The results are as following:1.Z16 and 7250-14-1 were crossed with isoplasmic allonuclear male sterile lines CMo17,C698-3,C huangzaosi,C478 and C48-2 to identify the fertility of F₁.The results illustrate that Z16 and 7250-14-1 can restore the fertility of C huangzaosi,C478,C698-3 and CMo17 completely,and partly restore the fertility of C48-2.Z16cannot restore the fertility of RB48-2?CII?,ES48-2?CIII?,G48-2,EC48-2 and Lei48-2,while 7250-14-1 can partly restore the fertility of G48-2,EC48-2 and ES48-2?CIII?,but maintained the sterility of RB48-2?CII?and Lei48-2.Both Z16and 7250-14-1 can partly restore the fertility of SMo17,but cannot restore the fertility of T698-3 and TMo17.7250-14-1 can partly restore the fertility of S698-3,while Z16cannot restore the fertility of S698-3.Z16 and 7250-14-1 can restore the fertility of SauS1,SauS2,SauS3,SauW1,SauW2,SauA1,and SauA2,but cannot restore the fertility of SauS4 and SauS5.2.F₂ and BC1 populations were derived from crosses between two CMS-C lines?C huangzaosi and C478?and two restorer lines?Z16 and 7250-14-1?.The segregation ratio of fertile and sterile plants in the F₂ and BC1 populations derived from C huangzaosi×Z16 or C478×Z16 both fit to 3:1 and 1:1 via chi-square test,respectively.The results illustrate that the fertility restoration was controlled by a dominant gene for Z16 when crossed with C huangzaosi or C478.For 7250-14-1,the segregation ratio of fertile and sterile plants in the F₂ and BC1 populations derived from C huangzaosi×7250-14-1 fit to 3:1 and 1:1 via chi-square test,respectively.The results illustrate that the fertility restoration was also controlled by a dominant gene for 7250-14-1 when crossed with C huangzaosi.While the segregation ratio of fertile and sterile plants in the F₂ and BC1 populations derived from C478×7250-14-1 fit to9:7 and 1:3 via chi-square test,respectively,indicating that the fertility restoration of C478 by 7250-14-1 was controlled by two complementary dominant genes.3.Preliminary mapping results from an F₂ population,which derived from the cross of C huangzaosi×Z16 and contained 156 recessive individuals,revealed that the fertility-restoring gene was located at short arm of chromosome 8,and the InDel marker TIDP5557 was closely linked to the fertility-restoring gene with a genetic distance of 1.28 cM.Based on preliminary mapping results,we developed a set of new markers closely linked to the target gene.Another F₂ population containing 798recessive individuals were used to fine-map the fertility-restoring gene of Z16 to a494 kb interval between the marker B-1and the end of chromosome 8.4.Preliminary mapping results from an F₂ population,which derived from the cross of C huangzaosi×7250-14-1 and contained 143 recessive individuals,revealed that the fertility-restoring gene was located at short arm of chromosome 8,and the InDel marker IDP8319 was closely linked to the fertility-restoring gene with a genetic distance of 0.35 cM.Based on preliminary mapping results,we developed a set of new markers closely linked to the target gene.Another F₂ population containing 432recessive individuals were used to fine-map the fertility-restoring gene of 7250-14-1to a 249 kb interval between the marker B-1and Chr8-86080.5.In order to verify whether the fertility-restoring gene in Z16 and 7250-14-1 is allelic to Rf4 for CMS-C,allelic analysis was performed.The results showed that there were no segregation of fertility in the progenies of C huangzaosi×?Z16×CR?,C huangzaosi×?7250-14-1×CR?and C huangzaosi×?Z16×7250-14-1?and suggested that the fertility restoration was controlled by a dominant gene for C huangzaosi in Z16and 7250-14-1,which is allelic to Rf4 in CR.