cDNA Sequences of Three Kinds of β-tubulins from Rice

Complete nucleotide sequences of three kinds of rice /3-tubulin cDNA clones (pTUB22, R1623 and R2242) were determined. Southern hybridization indicated that these /3-tubulins consist of one gene family. Using RFLP mapping, these three /3-tubulin cDNAs were mapped to different chromosomes indicating at least three loci for the /3-tubulin gene. The deduced amino acid sequences of these cDNAs showed a high similarity to other plant /3-tubulins. The asparagine residue located at the 100th amino acid from the Nterminus of plant /3-tubulins was also conserved with these three /3-tubulins. This asparagine is thought to be responsible for the sensitivity against rhizoxin, the toxin of the pathogen of rice seedling blight, Rhizopus sp. a soil-borne microorganism. Expression of the three /3-tubulin genes was analyzed by Northern blotting and all three clones were expressed in root, the possible target tissue of rhizoxin. These results suggest that these clones are candidates of /3-tubulins targeted by rhizoxin.