Taken together, these results indicate that tofM is a positive regulator for toxoflavin production. When B. glumae is grown in liquid media or on solid media after inoculation with the spreading method, TofM may supplement the regulatory function of the TofI/TofR QS in the production of toxoflavin. When B. glumae is grown on solid media after inoculation with the streaking method, however, TofM may cause the TofI/TofR QS-independent production of toxoflavin. Even though TofM is likely a key regulatory component of the tofI- and tofR-independent pathway(s) for toxoflavin production, additional regulatory components required for the production of toxoflavin in the absence of tofI or tofR have been identified and are currently being analyzed (Chen and Ham, unpublished).