Abstract
Many steps of lateral root development were positively regulated by auxin, including initiation step. However, it was not clear how to control the lateral root initiation, spatially and temporary. We analyzed auxin accumulation spots in primary root continuously. About a half of them disappeared without cell division in wild type. Although the primary root elongated constantly, lateral root primodia were synthesized periodically from the auxin accumulation spots presented about 2 mm away from root tip. These suggested that the lateral root initiation was regulated by a periodic signal. The number of lateral root was slightly increased in puchi mutant and some of them were close. It took a long time when auxin accumulation spots were disappeared without cell division in puchi. Additionally, auxin accumulation spots could be observed adjacent to the newly synthesized lateral root primodia, which never detected in wild type. The expression of PUCHI was induced by auxin. About 85% of G2/M marker expressed sites were developed to LRP in both wild type and puchi. These suggested that PUCHI negatively regulated the lateral root initiation before cell division.
