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The role of auxin‐binding protein 1 in the expansion of tobacco leaf cells
Author(s) -
Chen JinGui,
Shimomura Shoji,
Sitbon Folke,
Sandberg Göran,
Jones Alan M
Publication year - 2001
Publication title -
the plant journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.058
H-Index - 269
eISSN - 1365-313X
pISSN - 0960-7412
DOI - 10.1046/j.1365-313x.2001.01152.x
Subject(s) - auxin , arabidopsis , cell division , microbiology and biotechnology , cell , biology , plant cell , cell growth , chemistry , biophysics , biochemistry , botany , mutant , gene
Summary Tobacco leaf was used to investigate the mechanism of action of auxin‐binding protein 1 (ABP1). The distributions of free auxin, ABP1, percentage of leaf nuclei in G2 and the amount of auxin‐inducible growth were each determined in control tobacco leaves and leaves over‐expressing Arabidopsis ABP1 . These parameters were compared with growth of tobacco leaves, measured both spatially and temporally throughout the entire expansion phase. Within a defined window of leaf development, juvenile leaf cells that inducibly expressed Arabidopsis ABP1 prematurely advanced nuclei to the G2 phase. The ABP1‐induced increase in cell expansion occured before the advance to the G2 phase, indicating that the ABP1‐induced G2 phase advance is an indirect effect of cell expansion. The level of ABP1 was highest at the position of maximum cell expansion, maximum auxin‐inducible growth and where the free auxin level was the lowest. In contrast, the position of maximum cell division correlated with higher auxin levels and lower ABP1 levels. Consistent with the correlations observed in leaves, tobacco cells (BY‐2) in culture displayed two dose‐dependent responses to auxin. At a low auxin concentration, cells expanded, while at a relatively higher concentration, cells divided and incorporated [ 3 H]‐thymidine. Antisense suppression of ABP1 in these cells dramatically reduced cell expansion with negligible effect on cell division. Taken together, the data suggest that ABP1 acts at a relatively low level of auxin to mediate cell expansion, whereas high auxin levels stimulate cell division via an unidentified receptor.