Studies Of The Effect Of Nitric Oxide (NO) On The Growth And Cell Cycle Of The Primary Root In Oryza Sativa L.

Up until now, there are few reports of the relation between nitric oxide (NO) and cell cycle in plant. In this paper, sodium nitroprusside(SNP) was used as the donor of NO and was treated to the seeds of Oryza sativa LfZhong Zuo 9052) to primary investigate the relationship between NO and cell cycle of rice. The experiments were on the following three levels: l).the seeds were treated with different concentrations of SNP for different times. It was observed that SNP had inhibition on the growth of the primary roots and the inhibition was dose- and time-dependent, i.e, when SNP≥50μmol/L, the inhibition was very obvious, SNP=100μmol/L, the growth was fully inhibited; On the other hand, it was the most inhibited in the third day when the roots were treated in the same concentration of SNP and then weakened after three days.2).It was demonstrated that the cell cycle indexes were decreased as long as the concentrations of SNP were increased after collecting the cell division phase of the primary root-tip cells;it was indicated that the inhibition of NO on the cell cycle was in the transition of G1→S by flow cytometry analysis, so that the ratio of the cells in S/G2/M decreased.3).it was indicated, through the comparison of the expression level by realtime quantitative-PCR of the markers of cdc2Os-2,Histone H3,CDKB2;1 and CycB2;2 that were specialized in the cell cycle of Oryza sativa L,that NO had the inhibition to the marker of cdc2Os-2 that expresses from G1→ S.This result was consist with that in cytology. Since the ratio of the cellsin S/G2/M decreased after NO treatment,the expression of the other three markers--HistoneH3(S phase) CDKB2;1(S→G2 phase) and CycB2;2(M phase) were also decreased.Our results demonstrated that NO had the inhibition to cell cycle in Oryza sativa L,and the inhibition was in the transition of G1→S.