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Structure and expression of phenylalanine ammonia-lyase-encoding genes in hybrid poplar

University of British Columbia

Genomic PAL sequences were isolated from a hybrid poplar genomic library. Three PAL genes were identified, two similar to each other {PALI and PAL2) and one diverged (PALS). PAL1 and PAL2were placed onto a poplar linkage map. The 3' and 5' regions of these two genes were sequenced, compared, and examined for functional motifs. An interesting motif was a promoter sequence conserved between PAL1 and PAL2, which is similar to AC boxes found in the promoters of other phenylpropanoid genes. The single intron was identified in both PAL1 and PAL2 and surrounding sequences compared for the two genes. The intron's position is conserved when PAL1 and PAL2are compared to each other and to other plant PAL genes. However, PALT and PAL2 possess introns of the same size, which has not been observed for any other plant PAL gene family. Expression of these genes was also examined. The promoters of PAL1 and PAL2 were fused to the reporter gene GUS and transformed into tobacco, where they directed essentially identical patterns of expression in vascular tissues and in ovules. No evidence of differential expression of PAL1, PAL2, or PAL3 was found in these transgenic tobacco or in comparative Northern blot analyses of RNA extracted from various poplar tissues. Seasonal variation in levels of PAL protein and PAL mRNA in bud/leaf and secondary xylem of poplar was investigated using Western and Northern blot analysis. PAL mRNA ievels were highest in leaves in March, and PAL protein levels were highest in leaves in April. In secondary xylem, PAL protein levels were highest in May.

Thesis/Dissertation

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2009-02-19

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http://hdl.handle.net/2429/4802

Botany

University of British Columbia

UBCV

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