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COMPARATIVE BIOLOGY OF THE PHENYLPROPANOID PATHWAY IN PRIMITIVE TRACHEOPHYTES.  A.M. Patten, L.B. Davin, and N.G. Lewis.   Institute of Biological Chemistry, Washington State University, Pullman.

    Plants evolved onto land more than 400 million years ago and initiated a terrestial environment which allowed for the continued evolution of flora as well as for the later evolution of fauna onto land.  It is hypothesized that this crucial transition of plants to land was largely dependent on the evolution of supportive and conductive vascular systems via the phenylpropanoid pathway.  Continued evolution of this pathway allowed plants to adapt to extreme environments and achieve structures of enormous height, as well as providing myriad means of defense. This study is the first comprehensive examination to elaborate the phenylpropanoid pathway in the most primitive extant taxa of the tracheophytes, i.e. in the cryptogams (orders: Lycopodiales, Psilotales, Equisetales, Isoetales, and Selaginellales) and the ferns (orders: Ophioglossales and Polypodiales).  This was investigated as follows: via comparative examination of gene expression and anatomy of developing and mature tissues in the various taxonomic orders; cDNA library construction and screening for expression of genes encoding proteins central to phenylpropanoid synthesis; localization of said proteins and their encoding mRNAs by immunohistochemistry and mRNA in situ hybridization, respectively; examination of patterns of lignin deposition, an important product of both the early and extant phenylpropanoid pathway, as determined by light, epifluorescent, and electron microscopy techniques.  The results so obtained are providing new insights into how the pathway has evolved during adaptation to land.

Bolwell, G. P., Patten, A., Lewis, N. G., 2001. The Holy Grail of Wood Evolution. From Wood Anatomy to Tissue-specific Gene Expression: 

To What Extent do Molecular Studies of Biosynthesis of Cell Wall Biopolymers help the Understanding of the Evolution of Woody Species. Phytochemistry 57, 805-810.

(Supported by NASA:  NAG2-1513.)

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