Premium
THE ONSET OF MITOSIS AND DNA SYNTHESIS IN ROOTS OF GERMINATING BEANS
Author(s) -
Davidson D.
Publication year - 1966
Publication title -
american journal of botany
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.218
H-Index - 151
eISSN - 1537-2197
pISSN - 0002-9122
DOI - 10.1002/j.1537-2197.1966.tb07362.x
Subject(s) - mitosis , biology , dna synthesis , vicia faba , vicia , chromatid , germination , cell cycle , dna , cell division , chromosome , microbiology and biotechnology , thymidine , botany , cell , genetics , gene
The time of onset of mitosis and DNA synthesis has been determined in roots of germinating seeds of Vicia faba . Mitosis is not initiated in all roots simultaneously. Dividing cells are seen 36 hr from the beginning of germination, but they are present in low frequency (0.02%). Dividing cells do not become frequent, i.e., occurring as 5% or more of all cells, until 56 hr, and it is not until 66–68 hr that all roots in a sample of 10 are mitotically active. DNA synthesis shows a similar sporadic beginning. It occurs in a few cells by 28 hr, and by 40 hr all roots exposed to 3 H–thymidine show active incorporation. For most cells in these germinating roots DNA synthesis precedes mitosis. In one root in 10, however, some cells are unlabeled when they enter mitosis, indicating that they had spent the dormant period in the G 2 phase of the mitotic cycle. The presence of these cells determines whether or not roots show chromatid and chromosome aberrations following irradiation during germination.