MYB transcription factors are differentially expressed and regulated during secondary vascular tissue development in hybrid aspen

• More than 120,000 poplar ESTs have been sequenced from 20 different cDNA libraries by the Swedish Centre for Tree Functional Genomics. We screened this EST collection for MYB transcription factors involved in secondary vascular tissue formation, and genes assigned as PttMYB3Ra, PttMYB4a and PttMYB21a were selected for further characterisation. Three MYB genes showed different expression patterns in various organs, tissues and stem sub-sections representing different developmental stages of vascular tissue formation. Furthermore, the analysis showed that PttMYB21a expression was much higher in secondary cell wall formation zone of xylem and phloem fibers than in other developmental zones. Transgenic hybrid aspen plants, expressing the 3'-part of the PttMYB21a gene in antisense orientation were generated to assess the function of PttMYB21a gene in vascular tissue formation and lignification. All transgenic lines showed reduced growth and had fewer internodes compared to the wild-type. The analysis of selected lines showed that acid soluble lignin present in the bark was higher in transgenic lines as compared to wild-type plants. Moreover a higher transcript level of caffeoyl-CoA 3-O-methyltransferase [CCoAOMT];EC2.1.1.104) was found in the phloem of the transgenic plants, suggesting that PttMYB21a might function as a transcriptional repressor.

Ämnesord

TEKNIK OCH TEKNOLOGIER  -- Industriell bioteknik (hsv//swe)

ENGINEERING AND TECHNOLOGY  -- Industrial Biotechnology (hsv//eng)

Nyckelord

gene regulation

gravity

hormones

hybrid aspen

MYB transcription factors

sucrose

wood

r2r3-myb gene family

arabidopsis-thaliana

lignin biosynthesis

transgenic tobacco

plants

growth

promoter

pattern

auxin

woody

Publikations- och innehållstyp

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art (ämneskategori)