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Title: A KATANIN-LIKE PROTEIN REGULATES NORMAL CELL WALL BIOSYNTHESIS AND CELL ELONGATION

Author
item BURK, DAVID - UNIV OF GA DEPT OF BOT
item ZHONG, RUIQIN - UNIV OF GA DEPT OF BOT
item Morrison Iii, Wiley
item LIU, BO - UNIV OF CA PLANT BIO
item YE, ZHENG-HUA - UNIV OF GA DEPT OF BOT

Submitted to: The Plant Cell
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/4/2001
Publication Date: N/A
Citation: N/A

Interpretive Summary: Plants are a make up of fibers which are in turn a make up of cells. These fibers are one of the tissues that provide mechanical strength to the plant. Understanding the way in which fiber strength is regulated provides information on how plants can be altered to better adapt to agronomic practices. This work describes the characterization of the fragile fiber plant and the cloning of the gene which causes this weak fiber. It is shown that the reduction of the strength of the fiber results in a change in plant structure. In addition, the cloned gene produces a protein that breaks small fibers, prevents these fibers from growing longer, and produces a reduction in cell wall thickness thus preventing the plant from becoming larger. This study provides another piece of information in our understanding of the biochemistry of plant cell development that may be used in the development of more productive plant species.

Technical Abstract: Fibers are one of the mechanical tissues providing structural support to the plant body. To understand how the normal mechanical strength of fibers is regulated, we isolated an Arabidopsis fragile fiber (fra2) mutant defective in the mechanical strength of interfascicular fibers in the inflorescence stems. Anatomical and chemical analyses showed that fra2 mutation caused a reduction in fiber cell length and wall thickness, a decrease in cellulose and hemicellulose contents and an increase in lignin condensation, indicating that the fragile fiber phenotype of fra2 is a result of alternations in fiber cell elongation and cell wall biosynthesis. In addition to the effects on fibers, fra2 mutation resulted in a remarkable reduction in cell length in all organs, which led to a global alternation in plant morphology. The fra2 gene was shown to encode a protein with high similarity to katanin, a protein shown to be involved in regulating microtube disassembly by severing microtubules. Taken together these results suggest that fra2, a katanin-like protein, is essential not only for normal cell wall biosynthesis and cell elongation in fiber cells, but also for cell expansion in all organs.