Seed germination is sensitive to glucose (Gic), nitric oxide (NO) and polyamine (PA). To elucidate whether cross-talk among Gic, NO and PAs occurs in mediation of seed germination, effects of Gic, NO and spermine on seed germination of Lotus japonicus were studied. Gic retarded seed germination in a concentration-dependent manner. NO donor sodium nitroprusside (SNP) alleviated Gic-induced inhibition of seed germination, whereas the NO scavenger 2-(4-carboxyphenyt)-4,4,5,5-tetramethyl-imidazoline-1-oxyl-3-oxide (cPTIO) diminished the SNP-dependent alleviation of seed germination. These observations indicate that Glc may inhibit seed germination by interacting with NO signaling pathways. Exogenous spermine enhanced and the inhibitor of the spermine synthase, methyigtyoxal-bis-guanyl hydrazone (MGBG), inhibited seed germination, respectively. Like SNP, spermine alleviated the Glc-induced inhibition of seed germination, whereas MGBG exaggerated the Glc-induced inhibition of seed germination. These results suggest that Glc may inhibit the spermine synthesis, leading to reductions in seed germination. NO scavenger and spermine synthase inhibitor diminished the SNP-induced alleviation of Glc-induced inhibition of seed germination. These findings reveal that both NO and spermine participate in the Gic-induced inhibition of seed germination in L. japonicus. (C) 2008 Elsevier GmbH. All rights reserved.