Abstract
In plants, cortical microtubule (cMT) arrays generally determine the polarity of cell elongation. Many microtubule associate proteins are thought to be involved in formation and maintenance of the array organization. A dominant phs1-1 mutant allele of an Arabidopsis MAP kinase phosphatase-like protein showed compromised cMT organization and stability. Transgenic plants which expressed the genomic PHS1 gene fused to GUS reporter showed strong GUS activity in the elongating region of roots. A MAP kinase cascade involving PHS1 may be important for regulation of cMT arrays in the elongation zone of root. To isolate components in the PHS1 phosphorylation pathway, we mutagenized phs1-1 by EMS and isolated mutants that suppressed or enhanced the phs1-1 phenotype. More than 20 enhancer and suppressor mutants have been isolated and are being characterized.
