ABP1 Mediates Auxin Accelerating of Vesicular Exocytosis in Plant

Abstract: In order to investigate the auxin regulation of vesicular transport in plant cell， we cloned the tobacco auxin binding protein 1 gene (ABP1) cDNA and recombined it into an inducible Ti vector pER16 in either sense or antisense direction. The vesicles labeled BY-2 were prepared by fusion secretory carrier membrane protein 2 (SCAMP2) with green fluorescent protein (GFP) and the cell line was further transformed by the two recombinants. The two membrane labeled transgenic BY-2 cell line were screened out and subjected to analysis of the ABP1 mediated auxin regulation of the vesicular transport. The expressions of transgene ABP1 and antiABP1 were first induced by estradiol and then treated with auxin. The vesicles transporting were observed under laser scan confocal microscope. The results showed that the fluorescence signal was significantly enhanced in the nucleus membrane， cytoplasmic membrane， and other endomembrane system when ABP1 was overexpressed. It indicates more active vesicular transportation in intracellular membranes after indole-3-acetic acid (IAA) treatment. The fluorescence signal was only maintained stronger around the nucleus but weak in the cytoplasmic membrane and other endomembrane systems if the ABP1 expression was antisense inhibited， because the vesicular transport was significantly reduced. The phenomena demonstrated that suppression of ABP1 significantly inhibited vesicular exocytosis. After the full estradiol induction of the ABP1 overexpression cell， we carried out a 0~6 min IAA treatment interval observation. The fluorescence signal was enhanced significantly around the nucleus membrane and then into endomembrane systems but with no obvious change in cytoplasmic membrane and two cells intervals. The Results indicated that within 6 min of IAA treatment exocytose vesicular transport was activated firstly between the nucleus and the endomembrane system， and then the exocytose transport between the endomembrane system to the plasma membrane. Thus we conclude that ABP1 is involved in auxin signal responded vesicular exocytosis in plant cell.

CSTR: 32200.14.cjcb.2014.09.0006