Figure 1.

Rhizobia treatment could induce the protein level of DMI2 in a Nod factor receptor-independent manner. A, DMI2-HAST protein accumulated in the nodules compared with uninoculated roots. Protein samples were taken from 14-d-old nodules and 4-week-old uninoculated roots. B, DMI2-HAST protein was induced to a much higher level 24 h after rhizobia treatment. Four-week-old Medicago roots were treated with S. meliloti strain ABS7 hemA:LacZ at the concentration of OD₆₀₀ = 0.05 for 24 h. C and D, DMI2-HAST protein was induced to a similar level by rhizobia treatment in wild-type and Nod factor receptor mutant backgrounds. The gDMI2-HAST construct was transiently expressed in dmi2-1, hcl-1, and hcl-4, and transformed roots were treated with or without S. meliloti strain ABS7 hemA:LacZ. E, DMI2-HAST protein could be induced to a similar level by rhizobia in dmi2-1 and sunn-1 plants stably transformed with gDMI2-HAST. α-HA was used to detect the DMI2-HAST protein level, and tubulin was used as the loading control. The experiments were repeated five times with similar results.