G2 spirit bio

IPEC-J2 cells were collected in precooled fixation buffer (2.5% glutaraldehyde and 0.1 M phosphate buffer containing Na₂HPO₄ 12H₂O and NaH₂PO₄ 2H₂O) at 4 °C for 5 h. The cells were incubated for 2 h in osmic acid buffer (1% osmium tetroxide and 0.1 M phosphate buffer at pH 7.2–7.4) and dehydrated through a graded series of ethanol solutions. Next, the cells were embedded in a graded series of London Resin (LR) White resins and were finally embedded in fresh 100% LR White resin at 55 °C for 48 h. Then, samples were cut on a Leica UC7 ultramicrotome and collected on formvar-coated grids. Finally, the sections were poststained for 15 min with uranyl acetate and observed under a transmission electron microscope (TECNAI G2 SPIRIT BIO, FEI).

Sections (1 × 2 × 3 mm³) were obtained from the fruit infection sites and then soaked in 2 ml of 4% (v/v) glutaraldehyde solution (pH 6.8) for 12 h. The samples were carried out as follows: washed with phosphate buffer (0.1 M, pH 6.8) for four times, subjected to an ethanol gradient elution (30, 50, 70, 80, and 90%, v/v), embedded in SPI812 resin, ultrasonically sliced with an ultrathin slicer (Leica, EM UC7, Germany), and then stained with uranyl acetate and lead citrate. The cell wall was observed using a transmission electron microscopy (TEM; TECNAI G2 SPIRIT BIO, FEI, America) using 80 KV of accelerating voltage (Ding et al., 2019 (link)).