Author
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Jan, Chao-Chien |
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Submitted to: European Conference on Sunflower Biotechnology
Publication Type: Abstract Only Publication Acceptance Date: 9/10/2003 Publication Date: 10/5/2003 Citation: Jan, C.C. 2003. Transfer of vigor restoration gene from Helianthus giganteus into cultivated background and its implication on gene transfer utilizing interspecific amphiploids [abstract]. Sixth European Conference on Sunflower Biotechnology, Sevilla, Spain, October 6-8, 2003. Interpretive Summary: Utilization of the perennial diploids, representing half of the 50 Helianthus species, is largely limited by poor crossability and F1 sterility in interspecific hybrids. Development of a 2-stage embryo rescue technique and a seedling colchicine treatment successfully solved these problems and led to the production of interspecific amphiploids. Seed set of six amphiploids of H. atrorubens, H. cusickii, H. grossesserratus, H. maximiliani, H. mollis, and H. pumilus crossed with P21 averaged 3.9%, and that of their backcrosses with cultivated HA89 was 2.7%. These results suggest an adequate supply of progeny for breeding selection. These amphiploids proved to be extremely valuable in our recent transfer of resistance to the new Orobanche race F that has appeared in Spain. Amphiploids (2n=68), their BC1F1 (2n=51) and BC2F1 (2n= 34-51) progenies, after crossing with cultivated line HA89 (2n=34), were evaluated for Orobanche resistance. Resistant germplasm lines with 2n=34 were selected and released within two years. Helianthus giganteus 1934 x HA89, F1 was colchicine-treated and backcrossed with HA89. A total of 77 seed were obtained from 10 heads of a single cms plant, and all the BC1F1 progeny were triploids with 2n=50-51, indicating the success of chromosome doubling and the backcrosses were equivalent to a cross with an amphiploid. The objectives of this study were to evaluate the effectiveness of identifying and transferring a new vigor restoration gene from H. giganteus into HA89, to study the inheritance of the vigor restoration gene, and to identify fertility restoration genes in both cultivated and wild sunflowers. Seed set of the triploid BC1F1 backcrossed with HA89 averaged 5.2%, and progeny segregated for chromosome numbers from 37 to 46. Seed set of BC2F1 increased to 29.5%, which continued to improve when advanced to BC4F1. Since HA89 does not contain vigor restoration gene for the vigor reducing perennial species cytoplasm, normal (N) plants with 2n=34 were selected as having the vigor restoration genes from H. giganteus, and their BC progeny segregation fit the 1 N to 1 RV (reduced vigor) ratio for the one dominant gene control of vigor restoration. Meanwhile, since our effort of identifying fertility restoration gene for this cms cytoplasm was not successful using cultivated lines, crosses using amphiploid pollen was initiated. Seed set was reduced when compared with their respective crosses when HA89 was used as the pollen source, with seed only from amphploids involving H. maximilian, H. cusickii, and H. pumilus. This reciprocal cross difference in seed set was primarily due to the early abortion of hybrid embryos and can be easily overcome with embryo culture. Our results further support the approach of transferring genes from perennial diploid species into cultivated background utilizing interspecific amphiploids, providing embryo culture is used in specific cross combinations. Technical Abstract: Utilization of the perennial diploids, representing half of the 50 Helianthus species, is largely limited by poor crossability and F1 sterility in interspecific hybrids. Development of a 2-stage embryo rescue technique and a seedling colchicine treatment successfully solved these problems and led to the production of interspecific amphiploids. Seed set of six amphiploids of H. atrorubens, H. cusickii, H. grossesserratus, H. maximiliani, H. mollis, and H. pumilus crossed with P21 averaged 3.9%, and that of their backcrosses with cultivated HA89 was 2.7%. These results suggest an adequate supply of progeny for breeding selection. These amphiploids proved to be extremely valuable in our recent transfer of resistance to the new Orobanche race F that has appeared in Spain. Amphiploids (2n=68), their BC1F1 (2n=51) and BC2F1 (2n= 34-51) progenies, after crossing with cultivated line HA89 (2n=34), were evaluated for Orobanche resistance. Resistant germplasm lines with 2n=34 were selected and released within two years. Helianthus giganteus 1934 x HA89, F1 was colchicine-treated and backcrossed with HA89. A total of 77 seed were obtained from 10 heads of a single cms plant, and all the BC1F1 progeny were triploids with 2n=50-51, indicating the success of chromosome doubling and the backcrosses were equivalent to a cross with an amphiploid. The objectives of this study were to evaluate the effectiveness of identifying and transferring a new vigor restoration gene from H. giganteus into HA89, to study the inheritance of the vigor restoration gene, and to identify fertility restoration genes in both cultivated and wild sunflowers. Seed set of the triploid BC1F1 backcrossed with HA89 averaged 5.2%, and progeny segregated for chromosome numbers from 37 to 46. Seed set of BC2F1 increased to 29.5%, which continued to improve when advanced to BC4F1. Since HA89 does not contain vigor restoration gene for the vigor reducing perennial species cytoplasm, normal (N) plants with 2n=34 were selected as having the vigor restoration genes from H. giganteus, and their BC progeny segregation fit the 1 N to 1 RV (reduced vigor) ratio for the one dominant gene control of vigor restoration. Meanwhile, since our effort of identifying fertility restoration gene for this cms cytoplasm was not successful using cultivated lines, crosses using amphiploid pollen was initiated. Seed set was reduced when compared with their respective crosses when HA89 was used as the pollen source, with seed only from amphploids involving H. maximilian, H. cusickii, and H. pumilus. This reciprocal cross difference in seed set was primarily due to the early abortion of hybrid embryos and can be easily overcome with embryo culture. Our results further support the approach of transferring genes from perennial diploid species into cultivated background utilizing interspecific amphiploids, providing embryo culture is used in specific cross combinations. |
