Guenter Theissen, Jena University, Germany
Sara von Arnold, VBSG, SLU
Lecture hall A281, Uppsala BioCentre, Ultuna
14:00 - 15:00
Evolutionary developmental genetics of Norway spruce variety ‘Acrocona’

The rapid origin of the angiosperm flower during evolution is still a scientific mystery. To help to solve it we investigate the genetic basis of reproductive organ formation in the putative sister group of the angiosperms, extant gymnosperms. Unfortunately, all extant gymnosperms are woody plants that require many years to enter the reproductive stage and hence are not easy to investigate genetically. Accordingly, there are almost no mutants available to study the genetic basis of gymnosperm reproduction. An remarkable exception is the natural Norway spruce (Picea abies) variety ‘Acrocona’, which is characterised by the precocious development of female cones at wrong, i.e. terminal positions of shoots. Acrocona plants occasionally develop hermaphroditic cones which may mimic intermdiate structures during the evolutionary origin of the angiosperm flower. We are studying two almost 20 years old F1 generations obtained from the selfing of an Acrocona plant and the cross between the same plant and a wild-type parent. Both populations provide a unique opportunity for long-term investigations on the segregation and expression of the Acrocona phenotyp in plants that grow under almost natural conditions. Our results corroborate the view that Acrocona is a monogenic, co-dominant, homeotic and heterochronic reproductive mutant that affects the reproductive phase transition, cone formation and plant habit of Norway spruce. We have located close relatives of Arabidopsis thaliana flower developmental control genes such as LEAFY, FT and a number of MADS-box genes on a Norway spruce chromosomal linkage map generated with one of the Acrocona populations. Their chromosomal map position excludes already several candidates genes as being at the Acrocona locus.