Abstract
Apical dominance is released by excision of apical buds or by auxin transport inhibitors to apical buds or internodes of seedlings. Recently, we demonstrated that application of natural auxin-inhibiting substances, raphanusanin B and 6-methoxy-2-benzoxazolinone (MBOA) not only to apical buds or internodes but also directly to lateral buds of pea (Pisum sativumL.) seedlings released apical dominance, suggesting that lateral bud growth inhibitor(s) were concerned with apical dominance. Therefore, search for the inhibitor(s) led to the isolation of indole-3-aldehyde from the pea seedlings. Endogenous indole-3-aldehyde content was higher in diffusates from explants with apical bud and IAA-treated decapitated explants than in those from decapitated ones. When this compound was applied to the cut surface of etiolated, decapitated plants or directly to the lateral buds, it inhibited outgrowth in both assays. These results suggest that indole-3-aldehyde plays an important role in apical dominance of Pisum sativum.
