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. Using reporter genes, it was shown that PHS1 functions in the elongation zone of roots. A MAP kinase cascade involving PHS1 may be important for regulation of cMT arrays in the region. To isolate components of the PHS1 phosphorylation pathway, we mutagenized phs1-1 by EMS and isolated many mutants that suppressed the phs1-1 phenotype. Many intragenic suppressors of and some missense alleles of alpha-tubulins were identified. Moreover new spr1 missense allele was also identified, suggesting that the PHS1 pathway was strongly related with the SPR1 microtubule functions.
