The Constructions Of Three Near-isogenic Restorer Lines With Different Restorer Genes And The Genetic Analysis Of Their Restoring Effects On Their Isonuclear Cytoplasmic Sterile Line L-orfH79 In Rice

HL-CMS rice contains two steril genes,orfH79 and orf216,and its restorer line,9311,contains two restoring genes,Rf5 and Rf6.To analyse the interaction mode between the sterile genes and restoring genes,the three near-isogenic restorer lines with different restoring gene were constructed,and the genetic analyses of their restoring effects on their isonuclear cytoplasmic sterile line L-orfH79 were carried out.The following results were obtained:1.The HL-CMS line YTA was crossed with the restorer line 9311 and the F₁hybrid was backcrossed repeatedly with the corresponding maintainer line YTB.The plants containing Rf5,Rf6 and Rf5+Rf6 were selected with the specific molecular markers of Rf5 and Rf6 in both the successive backcross and selfing generations,and the homogenous isocytoplasmic near-isogenic restorer lines L-Rf5,L-Rf6 and L-Rf5+6 were finally constructed.It was fourther detected that the expression level of orf H79 in all those restorer lines has obviously decreased compared with YTA.2.The testcrosses between L-orfH79,a isonuclear allocytoplasmic sterile line of YTA,carring the sterile gene orfH79 without orf216,and L-Rf5,L-Rf6 as well as L-Rf5+6 were made respectivly,the relationship between the expression level of orf H79 and the degree of fertility restoration in their F₁ popullations was analysed.The statistical data showed that both the percentage of pollen fertility and the rates of bagged or natural seed-setting have negative correlation with the expression level of orf H79.3.With the new sterile gene orf216 as molecular marker,13 cultivated rice varieties,carring only a sterile gene orf216 without orfH79,were selected from among 824 cultivated varieties.And to identify the new resource of CMS,the cosses between those 13 cultivated rice varieties as females and YTB were made respectively.The obvious declines of pollen fertility and natural seed-setting rate in F₁ populations suggested that a novel cytoplasmic male sterile line L-orf216 could be created via successive backcross of the selected orf216-containg lines with YTB.