Author
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Seiler, Gerald |
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Submitted to: Proceedings Sunflower Research Workshop
Publication Type: Proceedings Publication Acceptance Date: 2/29/2000 Publication Date: N/A Citation: N/A Interpretive Summary: Cytoplasmic male sterility (CMS) and genetic fertility restoration have been used in the commercial production of hybrid seed of cultivated sunflower since 1972. The system has allowed sunflower to expand to new production areas due to the uniform maturity of the hybrids and their increased yield potential. The problem is that the female parent (PET1) has been the only one used worldwide for almost 30 years. The use of a single CMS makes the crop extremely vulnerable to pending changes of the pest complexes. Since the original PET1 was discovered in the wild ancestors of the cultivated crop, the objective of this study was to search for a new CMS source from the wild sunflower species. Cytoplasmic male sterile plants were discovered in a population of the closely related species, H. annuus, from Texas. Fertile plants from the original populations did not contain fertility restoration genes for the new cytoplasm. The new CMS was crossed with 12 standard fertility restoration testers. Seven of the 12 testers had fertility restoration genes for the new cytoplasm. Three of the testers were evaluated further for their pattern of fertility inheritance which appeared to be controlled by a single dominant gene. The new cytoplasm appears to be different than the commonly used PET1 cytoplasm. The discovery of a new cytoplasm will offer the sunflower industry a cytoplasm from the closest wild relative of the cultivated sunflower. Technical Abstract: Cytoplasmic male sterility (CMS) is a maternally inherited trait prevent- ing plants from producing normal pollen. This characteristic revolution- ized the sunflower industry by producing high-quality hybrid sunflowers. Worldwide production of cultivated sunflower presently utilizes only the French cytoplasm, PET1, discovered almost 30 yrs ago in the wild annual species, H.petiolaris. Use of a single cytoplasm creates a high degree of genetic vulnerability. Since the PET1 cytoplasm was discovered in the wild species, this study was initiated to discover a new cytoplasm from wild H.annuus. Cytoplasmic male sterile plants were discovered in a population closely related to species from Texas. Fertile plants from the original populations did not contain fertility restoration genes for the new cytoplasm. The new CMS source was crossed with a line containing genes from a wild H.annuus population from California. Fertile plants were obtained and inheritance of the fertility restoration genes appeared to be 2 complementary genes. The CMS was also crossed with 12 standard fertility restoration testers. Seven of the 12 testers had fertility restoration genes for the new cytoplasm. Three of the testers were evaluated further for their pattern of fertility inheritance which appears to be controlled by a single dominant gene. Use of a single dominant fertility restoration gene will facilitate the use of the new cytoplasm. The new cytoplasm has a different fertility restoration pattern than the commonly used PET1 cytoplasm indicating that they are different. Additional research is needed to find additional single dominant fertility restoration genes. Discovery of a new cytoplasm will offer the sunflower industry a cytoplasm from the closest wild relative of the cultivated sunflower. |
