Stress Messengers Jasmonic Acid and Abscisic Acid Negatively Regulate Plant Cell Cycle

Environmental stress affects plant growth and development. Several plant hormones, such as salicylic acid, abscisic acid, jasmonic acid and ethylene play a crucial role in altering plant morphology in response to stress. Developmental regulation often has the cell cycle machinery among its targets. We analyzed the effect of jasmonic acid (JA) and abscisic acid (ABA) on cell cycle progression in synchronized tobacco BY-2 cells. Both compounds were found to prevent DNA replication, keeping the cells in the G1 stage, when applied just before the G1/S transition. However, ABA did not have any effect on subsequent phases of the cell cycle when applied at a later stage, whereas JA effectively prevented mitosis on application during DNA synthesis. This demonstrates that JA treatment can freeze synchronized BY-2 cells in both the G1 and G2 stages of the cell cycle. Jasmonate administered after the S-phase was less effective in decreasing the mitotic index, suggesting that cell sensitivity towards JA is dependent on the cell cycle phase. In parallel, we employed a more complex system: Arabidopsis thaliana roots, where JA induced root growth inhibition was well documented. We used detailed image analysis of the root in order to describe the effects of jasmonic acid on the function of the root apical meristem.