Abstract
The cell cytoskletal component actins, which regulate diverse biological functions during plant growth and development, are classified into vegetative and reproductive classes. Among the vegetative actins in Arabidopsis, ACT7 and ACT8 have been shown to regulate the root and root hair morphology respectively. However, the distinct role of ACT7 and ACT8 on root meristem development remains elusive. By analyzing the single mutant of ACT7 and ACT8, here we show that ACT7 but not ACT8 predominantly regulates the root meristem formation as judged by the root growth, cell length and cell production rate. On the other hand, ACT8 plays a major role in lateral root meirstem formation. A two-fold induction in lateral root number was observed in act8 mutant, suggesting that ACT8 is a negative regulator of lateral root development. ACT7, which is active in primary root meristem, affected the lateral root meristem development mildly. Further, act8 mutant but not act7 showed a reduced response to IAA or IBA mediated lateral root induction. Taken together, these results suggest that these two isovariants of actin play distinct role in root meristem formation.
