Cycloheximide in the nanomolar range inhibits seed germination of .

From the 992 samples of culture extracts of microorganisms isolated from soil in Japan, we found that the extract of sp. no. 226 inhibited seed germination without significantly affecting the seed germination of and the growth of and . Using ESI-MS, H-NMR, and C-NMR, we identified the active compound as cycloheximide. Cycloheximide had half-maximum inhibitory concentrations of 2.6 ng/mL for the inhibition of seed germination of and 2.5 µg/mL for that of the conidial germination of . . Since cycloheximide is known to inhibit translation by interacting with ribosomal protein L28 (RPL28) in yeast, we investigated whether RPL protein of plays a critical role in the inhibition of seed germination. Our data suggested that RPL27A was not sensitive to cycloheximide by comparing it to the strain expressing RPL28. These findings suggest the presence of an unidentified mechanism by which cycloheximide hinders seed germination.