Submitted to: Proceedings Sunflower Research Workshop
Publication Type: Proceedings
Publication Acceptance Date: January 29, 1999
Publication Date: N/A
Interpretive Summary: Because the world's sunflower production is based upon hybrids with a single male-sterile Helianthus petiolaris subsp. petiolaris Nutt. (PET1) cytoplasm and a few fertility restoration genes, new cytoplasmic male sterility (cms) is needed to diversify the crop's cytoplasmic background and to reduce its genetic vulnerability. A total of 22 cytoplasmic male- sterile mutants were produced from the maintainer line HA89 and cms from a Native American line, PI 432513, were completely restored by USDA restorers RHA 266, RHA 274, RHA 280, and RHA 296. Additional fertility restoration genes for cms PI 432513 were derived from Armavir, VNIIMK, and P21, and their restoration ability to the cmsPET1 has not been determined. The uniform and complete fertility restoration of the 22 mutant cmsHA89 and cms PI 432513 with the RHA lines suggested Rf1 or Rf2 genes played a role in their restoration. Since these restoration genes are already in commercial restoration lines, hybrid breeding programs could be focused exclusively on cms line development. The objectives of this study were (I) to determine the inheritance of fertility restoration of RHA lines for mutant cmsHA89 and cms PI 432513, (ii) to characterize the cms PI 432513, and to evaluate the inheritance of new fertility restoration genes, (iii) to determine the relationships among the three new genes and the Rf1 gene in RHA 274, and (iv) to evaluate the role of the Rf1 or Rf2 gene in fertility restoration for the cms mutants, cms PI 432513, and the classical cms PET1, and its implications for future hybrid development.
Technical Abstract: Four new restoration genes for cms PI432513 were identified from Armavir, VNIIMK, P21 & male-fertile plants of PI432513. F2 fertility restoration of cms PI432513 crossed by these restoration sources indicated control by a single dominant gene. Progenies of cms PI432513 testcrossed by F1s of half-diallel crosses among the respective 4 homozygous restoration lines and RHA274 suggested that restoration genes of RHA274, VNIIMK, P21 & PI432513 were at the same locus. Restoration genes from VNIIMK, P21 & PI432513 restored pollen stainability satisfactorily at 78 to 96% in heterozygous condition. Similar fertility restoration of these genes for the 6 mutant cmsHA89 and cmsHA89 (in PET1 cytoplasm) was also observed. The 6 mutant cmsHA89 lines were restored completely by RHA266, RHA274, RHA280 & RHA296, and their F2s again indicated single dominant gene control, which further suggested the cytoplasmic similarity among the cms lines in this study. F1s of half-diallel crosses among RHA266, RHA273, RHA274, RHA280 & RHA296 were then testcrossed onto cms lines, and their all male-fertile progenies among lines, except RHA280, confirmed the single Rf1 gene locus for fertility restoration. Confection line RHA280 was shown to have a restoration gene at a different locus than the Rf1 and was equally capable of restoring all lines in this study. These mutant cmsHA89 and the cms PI432513 sources are in H. annuus cytoplasm and are less likely to have adverse interaction with the nuclear genes of cultivated sunflower than cmsPET1 and, with widely used restoration genes currently in commercial breeding programs, will provide immediate alternatives for reducing genetic vulnerability associated with a single cms in sunflower commercial production.