Silver Birch - A Model for Tree Genetics?

Silver birch, Betula pendula (order Fagales), has many beneficial properties that make it an ideal model for tree genetics. In contrast to other trees, which have generation times from several years to decades, birch can be induced to flower within one year. Other advantages are easy inbreeding and hybridization with other related species. A large collection of genetic resources is already available through the Finnish Forestry Research Institute, including, for example, samples of natural variation from a wide geographic range throughout Finland and Russia, natural mutants such as trees with altered wood formation and growth, and trees with good or bad wood quality. Furthermore, birch behaves well in laboratory conditions – it grows well on agar plates and cloning and genetic transformation techniques have already been established.

We have recently sequenced de novo the genome of silver birch. The genome is diploid and relatively small, 440 Mbp, making it practical to assemble. The genome of one individual from a fourth generation inbred line was sequenced using a combination of 454, Illumina mate pair and paired end, SOLiD mate pair, and PacBio sequencing. We predicted 31,500 gene models for birch using data fusion of ab initio predictions, RNA sequencing data, EST libraries, and orthologous proteins from related species. Initial results from comparative genomics show that birch has not had recent genome duplication events.