Submitted to: Meeting Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 3/8/2008
Publication Date: 6/1/2008
Citation: Vick, B.A., Jan, C.C. 2008. Abscisic acid content of a nondormant sunflower (Helianthus annuus L.) mutant. Proceedings of 17th International Sunflower Conference, June 8-12, 2008, Cordoba, Spain. p. 405-409. Interpretive Summary: Occasionally during a breeding program, an unusual plant appears as the result of an unexpected mutation. This was the case when we noticed a sunflower plant in which the head was drying down for seed collection. But rather than dry down, the seeds on the head started to germinate and grow. We called this mutant "ndg" (nondormant green). This was a plant that had been derived from several sources through multiple crosses. One of the parents in the background of this plant was HA 89, a common cultivated line used as a standard reference sunflower line. Seeds of the mutant sunflower line frequently germinate on the head about 40 days after pollination. In contrast to other nondormant sunflower mutants reported previously, the cotyledons of this mutant remain green, whereas other nondormant mutants exhibit loss of pigmentation. The objective of our investigation was to compare levels of abscisic acid (ABA), a plant hormone that induces dormancy in developing embryos, in the "ndg" mutant with abscisic acid levels in normal type HA 89 from which "ndg" was derived. Measurements by immunoassay showed that abscisic acid content in the mutant and normal type were the same, indicating that reduced abscisic acid was not the cause of nondormancy.
Technical Abstract: A sunflower (Helianthus annuus L.) mutant was observed in the progeny of a cross between the sunflower cultivar HA 89 and an amphiploid of a H. divaricatus L. x P21 cross that exhibited loss of dormancy induction in the developing embryo. Seeds of this mutant frequently germinate on the head about 40 d after pollination (DAP). In contrast to other nondormant sunflower mutants reported previously, the cotyledons of this mutant remain green, whereas other nondormant mutants exhibit loss of pigmentation. The objective of this investigation was to compare the level of abscisic acid, a plant hormone that induces dormancy in developing embryos, in the nondormant green mutant (ndg) and HA 89 from which ndg was derived. Immunoassays showed that abscisic acid was present in ndg and the levels decreased from a maximum at 5 to 20 DAP to basal levels at 25 DAP. The levels of abscisic acid were not significantly different from those in the control plant HA 89. We conclude that the nondormancy trait is due to a mutation that renders ndg insensitive to abscisic acid.