科研之友
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摘要
The genome of Populus (poplar) has been shaped by a whole genome duplication event specific to the salicoid lineage. The MONOPTEROS (MP)/AUXIN RESPONSE FACTORS (ARF5) transcription factor plays a key role in auxinmediated morphogenesis and vascular development in Arabidopsis, and may play a similar role in secondary xylem development in Populus. We used EST and genome sequence information to identify and characterize two duplicated Populus MP genes, PoptrMP1 and PoptrMP2. PoptrMP1 and PoptrMP2 DNA binding and other domains are highly conserved relative to Arabidopsis MP, while the glutamine-rich middle domains are divergent. The two PoptrMP genes are located on duplicated regions of linkage groups II and V. Comparative analysis of the surrounding genes in both the Populus and Arabidopsis genomes revealed a high degree of conservation of gene content and order extending over 11 genes in the immediate vicinity, but also specific changes to genomic regions surrounding each MP locus, providing insights into genome evolution. Expression studies showed that PoptrMP1 and PoptrMP2 have overlapping but distinct expression patterns, suggesting that subfunctionalization of the duplicated genes has occurred, with PoptrMPI specialized for expression in developing secondary xylem. Transgenic Populus lines overexpressing PoptrMPI exhibited a 2-4 fold increase in expression of a Populus AtHB8 homolog, a proposed MP target gene, confirming conservation of this regulatory module.
- 出版日期2007-11
