2.10. TEM imaging of bacteria and nodule tissue
Nodule sections at 7 and 14 dpi were preserved with 4% formaldehyde
and 1% glutaraldehyde (EMS, Hartfield, PA) in 100mMPIPES buffer
(Sigma, St. Louis,MO) at pH 7.2 and post-fixedwith 1% OsO4 for 2 h at
room temperature. The sections were dehydrated, infiltrated, and embedded
as described previously (Brown et al., 2011).