While this model was developed from
microarray data comparing transgenic plants expressing ACC
deaminase under the control of a root-specific promoter, based
on physiological data, it is expected that non-transformed
plants treated with an ACC deaminase-producing plant growthpromoting
bacterium will behave similarly. Here, in the
absence of ACC deaminase, root-produced ethylene inhibits
transcription of auxin response factors thereby limiting auxinstimulated
plant growth as well as auxin promotion of ACC
synthase transcription. In the presence of ACC deaminase,
ethylene levels are decreased and the blockage of auxin
response factor transcription is relieved thereby facilitating
plant growth