The importance of plant proteins from ABCB subfamily in auxin transport

Abstract

Polar auxin transport provides essential directional and positional information for many developmental processes in plants. At the cellular level, it is realized by both the passive diffusion and the active transport through the membrane proteins - AUX1/LAXes, PINs and ABCBs. The aim of this thesis was to characterize the role of ABCB1, ABCB4 and ABCB19 proteins in polar auxin transport using transformed tobacco BY-2 cell lines. It was shown that localization of the ABCB1, 4 and 19 is not polar on the plasma membrane (PM). The ABCB4 was also more stable on PM after the treatment with auxin influx inhibitors 1-NOA, 2-NOA and CHPAA; making use of ABCB4-cell line helped to uncover new characteristics of markers of endocytosis - the FM-dyes. The induction of ABCB19 has led to the decrease in 3H-NAA accumulation with characteristic cell phenotype (cells ceased to divide, started to elongate and there was formed an increased amount of starch granules), similar to the PIN7 overexpressing cell line. Thus, also the ABCB-based enhanced auxin efflux resulted in depletion of auxin from cells, and concomitantly changed their developmental program. The auxin starvation phenotype in the cell line with induced overexpression of PIN7 could be rescued by application of the auxin efflux inhibitor NPA; however, the...

Polar auxin transport provides essential directional and positional information for many developmental processes in plants. At the cellular level, it is realized by both the passive diffusion and the active transport through the membrane proteins - AUX1/LAXes, PINs and ABCBs. The aim of this thesis was to characterize the role of ABCB1, ABCB4 and ABCB19 proteins in polar auxin transport using transformed tobacco BY-2 cell lines. It was shown that localization of the ABCB1, 4 and 19 is not polar on the plasma membrane (PM). The ABCB4 was also more stable on PM after the treatment with auxin influx inhibitors 1-NOA, 2-NOA and CHPAA; making use of ABCB4-cell line helped to uncover new characteristics of markers of endocytosis - the FM-dyes. The induction of ABCB19 has led to the decrease in 3H-NAA accumulation with characteristic cell phenotype (cells ceased to divide, started to elongate and there was formed an increased amount of starch granules), similar to the PIN7 overexpressing cell line. Thus, also the ABCB-based enhanced auxin efflux resulted in depletion of auxin from cells, and concomitantly changed their developmental program. The auxin starvation phenotype in the cell line with induced overexpression of PIN7 could be rescued by application of the auxin efflux inhibitor NPA; however, the...