Figure 3.

Subcellular Localization of Storage Proteins in Seeds Requires NHX5 and NHX6.

Transmission electron micrographs of dry wild-type seeds ([A] to [D]) indicate the accumulation of electron-dense material in the extracellular space of nhx5 nhx6 ([E] to [H]). Immunogold labeling (10-nm gold particle) localized 12S globulin ([A], [B], [E], and [F]) and 2S albumin ([C], [D], [G], and [H]) in the apoplast of nhx5 nhx6 mature seeds. Immunolocalization of the pro form of 2S albumin in dry seeds using anti-N-terminal 2S antibody followed by immunogold labeling (10-nm gold particle) recognized the precursors of 2S albumin (immature/unprocessed) ([I] to [L]). Wild-type seed sections of storage vacuole (I) and middle lamella (J) and nhx5 nhx6 seed sections of storage vacuole (K) and middle lamella (L) are shown. CW, cell wall; LB, lipid body. Quantification of the number of immunogold particles in the apoplast and storage vacuole is presented in Results. White arrowheads point to gold particles. Bars in (A) and (B) = 0.2 μm; bars in (C) to (I) = 0.5 μm; bars in (J) to (L) = 200 nm.