Inheritance and Characterization of Gynoecious "Pistillate" Panicle in American Wildrice.

Cultivated American wildrice (Zizania palustris) typically has monoecious panicles, the lower two-thirds of each panicle consisting of staminate florets and the upper one-third, pistillate. A variant phenotype--"pistillate"--has been known for some time, in which all florets of the panicle are gynoecious. This pistillate trait had been observed to be recessive and simply inherited. Pistillate panicles could be useful because they have the potential to bear two to three times the number of seeds that normal (monoecious) panicles do. They can also facilitate controlled crosses, where they are used as female plants for which emasculation (or otherwise excluding staminate florets) is unnecessary. Normal plants were selfed from lines that were either true-breeding normal or segregating for pistillate. Normal plants (either putatively heterozygous for pistillate or homozygous) were also crossed to pistillate plants. Progeny were phenotyped, confirming that pistillate panicle is recessive and controlled by a single gene. In the process of phenotyping progeny, individuals that were expected to be heterozygous were observed to have male florets with awns longer than 2 mm. Conversely, in homozygous recessive plants, male awns were smaller than 2 mm or absent. This "long-male-awn" phenotype should enable identification of heterozygotes for selfing to efficiently produce inbred lines with the pistillate allele. SSR markers associated with the trait are also being tested to identify pistillate genotypes prior to flowering, to confirm the association of long-male-awn with heterozygosity, and to map the pistillate gene.