A functional complementation of a cotton MIZU-KUSSEI1 homolog in the hydrotropism response of Arabidopsis thaliana roots

Abstract

OBJECTIVE: Plants control the direction of root growth toward moisture due to their sessile nature, a phenomenon known as hydrotropism. In Arabidopsis thaliana, the MIZU-KUSSEI1 (MIZ1) protein is essential for the hydrotropic response. To investigate the molecular mechanism of hydrotropism in cotton, we examined the function of GhMIZ1, the closest homolog of Arabidopsis thaliana MIZ1. RESULTS: The GhMIZ1 gene, amplified from Gossypium hirsutum genomic DNA, was introduced into the Arabidopsis thaliana miz1 null mutant genome. Hydrotropism response in the transgenic mutant roots overexpressing GhMIZ1 was tested by using split-agarose plates containing 20% sorbitol. The expression of GhMIZ1 partially restored the hydrotropic response in miz1 mutant roots. This finding suggests that GhMIZ1 is capable of mediating hydrotropism in Arabidopsis thaliana, indicating that it serves as a functional homolog of MIZU-KUSSEI1.