Abstract
In dark-grown rice (Oryza sativa L.) seedlings, coleoptiles and primary roots both show circumnutation. To investigate whether there is any relationship between the two organs in their circumnutation, we carried out three-dimensional and simultaneous recording of coleoptiles and roots. The following results were obtained: 1) The period of root circumnutation is shorter than that of coleoptiles. 2) Both clockwise and counterclockwise movements are observed in the two organs, and the directionality is not related between the two organs. 3) Root circumnutation occurs under red light, which completely prevents coleoptile circumnutation. 4) The agravitropic rice mutant lazy shows root circumnutation, although its coleoptile does not show any circumnutation. These results together indicate that the circumnutation of roots and that of coleoptiles are independently regulated. The observation that both clockwise and counterclockwise movements occur in the two organs indicate that the directionality of circumnutation is not genetically determined in rice.
