Chlorsulfuron inhibition of cell cycle progression and the recovery of G1 arrested cells by Ile and Val

Abstract

Cultured pea root tips were treated with 14 nM chlorsulfuron (CS) for up to 60 h. The progression of cells from G1 into S was monitored by measuring3H-thymidine (3H-Thy) incorporation into DNA. Chlorsulfuron treatment decreased the amount of3H-Thy incorporated; however, this amount never reached zero. Short-term labeling experiments indicate that the cells are arrested in a narrow band within G1. Cell progression recovered from the CS treatment when roots were transferred to either White's medium or White's supplemented with isoleucine (Ile) and valine (Val). Lag time before recovery began in the White's or White's plus Ile and Val medium was 12 and 4 h, respectively. The initial slope of the recovery curves was similar irrespective of the type of recovery media. Increasing the duration of CS treatment did not change the length of the lag or initial slopes of the recovery curves. The level of3H-Thy incorporation decreased with increasing duration of CS treatment for root segments transferred to Ile and Val recovery medium.