Allopolyploid evolution in plants: patterns and processes within the genus Viola

This project aims at disentangling ?diploid? lineages in ancient polyploid groups using the genus Viola (Violaceae) as study object. Chromosome numbers, isozymes and our preliminary data on two low-copy nuclear RNA polymerase genes all suggest that the ma jority of temperate groups of Viola have allopolyploid origins, most likely independent of each other. Different group relationships have been suggested based on various and mostly classical approaches, and our preliminary results show potentials for eval uating these hypotheses. The goals outlined above will be reached by accessing and interpreting DNA variation in low- or single-copy nuclear genes. Introns of the RNA polymerase genes RPA2, RPB2, RPC2, RPD2a and RPD2b, and GpiC and AatC whose allozymic v ariation is often studied, have proved useful in other studies and will be used here as well. In addition, two independent sequence data sets from cpDNA (trnS-trnG) and nuclear ribosomal Internal Transcribed Spacer (ITS), both in practice uniparentally i nherited in Viola, will be generated. For most infrageneric groups material is readily accessible from plants in culture or from contacts abroad. By disentangling the ?diploid? lineages involved in polyploids, the project is expected to yield valuable ne w knowledge of the evolutionary processes at work in polyploids and to reveal interesting biogeographic patterns. Also, the data will be most valuable for constructing a suitable infrageneric taxonomy of the genus Viola, within the frames of the planned w orld-wide Violaceae monograph for the Species Plantarum Initiative.