Inheritance of Fertility Restoration for Two Cytoplasmic Male Sterility Sources of Helianthus pauciflorus (rigidus) Nutt.

Abstract

ABSTRACTNew sources of cytoplasmic male sterility (cms) and fertility restoration genes would reduce the genetic vulnerability of commercial sunflower (Helianthus annuus L.) hybrids because of the current use of a single male sterile H. petiolaris Nutt. cytoplasm and a few fertility restoration genes. The objectives of this study were to evaluate the inheritance of fertility restoration, to compare the cytoplasmic similarity between the two cms sources, and to confirm the vigor reducing effect of combining perennial species cytoplasms with cultivated nuclei. Cms‐RMX plants, maintained by backcrossing with inbred line HA89, were crossed with 21 prospective restoration lines. Male‐fertile F1 progeny were observed in crosses with ‘Luch’ and ‘RCMG1’. Segregation of male sterility in F2 and testcrosses with HA89 indicated fertility restoration was controlled by two complementary dominant genes. Identical segregation ratios of male fertile to male sterile in both F2 and testcross F1 were obtained with cms‐RIG1 using the fertility restoration genes identified for cms‐RIGX. These results suggest a single origin of the two cms sources. In a field test, cms‐RIGX plants produced no seeds after self‐pollination, and 99% seed set from open‐pollination, indicating complete male sterility and female fertility. The new cms‐RIG sources and corresponding fertility restoration genes will provide cytoplasmic diversity for sunflower hybrid production.