Abstract
In growing plant cell, cortical microtubules play an important role in regulating the direction of cell expansion. The phs2 is recessive mutant, which shows slightly left-skewing of root growth under a usual MS condition. But in the presence of 3uM propyzamide, the root growth shows right-skewing. The phs2 mutant had a frame-shift mutation in a novel gene. The genomic fragments including the loci rescued the phs2 drug responses, resulting that the loci was identified as the PHS2 gene. The PHS2 is encoded a TPR motif protein. The four homologous genes exist in Arabidopsis. We constructed GFP-PHS2 transgenic plants using genomic PHS2 clone. Their plants rescued the phs2 phenotype, showing that the GFP-PHS2 protein is functional. The fluorescent were detected on cortical microtubule fibers in the root, hypocotyl and leaf epidermal cells. These results were suggested that PHS2 is a novel microtubule associate protein, which regulates cortical microtubule array in plant.