Submitted to: Sunflower International Conference Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 7/30/2004
Publication Date: 8/29/2004
Citation: Jan, C.C., Feng, J. 2004. Helianthus californicus x HA 89 hybrids and the discovery of genes affecting meiotic division. International Sunflower Conference Proceedings. 16th International Sunflower Conference, August 29 - September 2, 2004, Fargo, ND. p. 713-719. Interpretive Summary: Wild Helianthus species have provided genetic diversity for the continuing success of the sunflower crop. The hexaploid Helianthus species have large genomes and are expected to possess more genetic variability than that of the diploid and tetraploid species, and therefore increase selection opportunities for breeding purposes. One hexaploid collection H. californicus CA47 was crossed with cultivated line HA89 and the hybrid progenies studied. Typical F1 hybrids had poor seed production by themselves, but had good seeds when pollinated with HA89, sufficient for further crosses for gene transfer in breeding programs. A single plant was unique, with 92.2% large pollen grains, suggesting genetically controlled chromosome doubling. This plant had a normal first stage of meiosis, but the second meiotic division was rarely observed, suggesting the production of unreduced gametes is under genetic control and is expressed uniformly in all heads of a plant. These genes controlling meiotic division may provide efficient means of chromosome doubling and amphiploid production and has the potential to revolutionize utilization of the perennial diploid and tetraploid Helianthus species for the improvement of cultivated sunflower.
Technical Abstract: Helianthus californicus, CA47, was crossed with cultivated line HA 89 in 2003. The F1 plants were evaluated for pollen stainability, microsporogenesis, and seed set from self-pollination, backcrossing with HA 89, and sib-pollination. The 14 F1 plants were placed in three groups, based on percent of large pollen grains, an indication of chromosome doubling and unreduced gametes. Group 1 represented normal CA47 x HA 89 F1 hybrids, having 2.5% large pollen grains, while the other two groups had 19.6 and 92.2% large pollen grains. All the F1s did not produce seed from self-pollination, but the and had an average seed set from sib-pollination was 0.92 seed per head indicating high degree of self-incompatibility. The F1s backcrossed with HA 89 averaged 11.94 seed per head for group 1, which is adequate for further crosses. Plants of the other two F1 groups had abnormal meiotic division, resulting in more dyads and triads instead of the normal tetrads, which continued to develop into large pollen grains containing an unreduced chromosome number of n=68. The majority of the pollen mother cells in one extreme plant ended meiotic division at dyads prior to the second division. Those plants with high frequency of dyads and large pollen grains suggested genetic control of the production of unreduced gametes. These genes have potential to revolutionize amphiploid production and enhance the utilization of perennial diploid and tetraploid Helianthus species for sunflower improvement.