137. Natural variants of the kalilo senescence plasmid.
Cynthia He, Natasja de Groot and Tony Griffiths. Botany, UBC, Vancouver, Canada.
The prototypic death plasmid 'kalilo' was originally found in Hawaiian strains of Neurospora intermedia. Each isolate bearing the plasmid shows a strain-specific lifespan. Death is by integration of the plasmid into mtDNA. Although kalilo-homologous plasmids are not common, several examples have been reported (Arganoza et al. 1994). We have characterized several of these, and they fall into four types. 1) the protoypic kalilo; this has now been found in N. intermedia (Hawaii), and N. tetrasperma (Moorea-Tahiti). 2) LA-kalilo, a form with a modified 60 bp region in the TIRs; this has been found in N. tetrasperma (Louisiana) and N. crassa (Haiti). 2) Short-kalilo, a form with a 700 bp deletion in the TIRs; found in N. discreta (Thailand and Ivory Coast). 4) Gel-kalilo, a form with complex differences in the TIRs; found in Gelasinospora only (Louisiana). The coding regions of all types contain two open reading frames showing little variation. The poster will describe the detailed structure of these plasmids and discuss the significance of their curious distribution.