Chromosomal location of fertility restoring genes for ‘wild abortive’ cytoplasmic male sterility using primary trisomics in rice uri icon

abstract

  • Identification and location of fertility restoring genes facilitates their deployment in a hybrid breeding program involving cytoplasmic male sterility (CMS) system. The study aimed to locate fertility restorer genes of CMS-WA system on specific chromosomes of rice using primary trisomics of IR36 (restorer), CMS (IR58025A) and maintainer (IR58025B) lines. Primary trisomic series (Triple 1 to 12) was crossed as maternal parent with the maintainer line IR58025B. The selected trisomic and disomic F-1 plants were testcrossed as male parents with the CMS line IR58025A. Plants in testcross families derived from disomic F-1 plants (Group I crosses) were all diploid; however, in the testcross families derived from trisomic F-1 plants (Group II crosses), some trisomic plants were observed. Diploid plants in all testcross families were analyzed for pollen fertility using 1% IKI stain. All testcross families from Group I crosses segregated in the ratio of 2 fertile: 1 partially fertile + partially sterile : 1 sterile plants indicating that fertility restoration was controlled by two independent dominant genes; one of the genes was stronger than the other. Testcross families from Group II crosses segregated in 2 fertile : 1 partially fertile + partially sterile : 1 sterile plants in crosses involving Triple 1, 4, 5, 6, 8, 9, 11 and 12, but families involving triple 7 and triple 10 showed significantly higher X(2) values, indicating that the two fertility restorer genes were located on chromosome 7 and 10. Stronger restorer gene (Rf-WA-1) was located on chromosome 7 and weaker restorer gene (Rf-WA-2) was located on chromosome 10. These findings should facilitate tagging of these genes with molecular markers with the ultimate aim to practice marker-aided selection for fertility restoration ability.

publication date

  • 1995
  • 1995
  • 1995