Results
Apple NPC structure and composition, and its expression patterns
Compared with vertebrate, apple NPC consists of 38 NUP proteins, but missing some Nups, such as Nup153, Nup358, Pom121, etc. Refer to the structure of vertebrate NPC (Tamura et al. , 2010), we devided apple NPC into five parts: Cytoplasmic filaments (Nup214 and Nup88), Cytoplasmic and Nuclear ring (Nup98, RAE1, and Nup107-160 Subcompex), Scaffold and central channal (GP210, NDC1, Nup62 Subcompex, and Nup93 Subcompex), Nuclear basket (Nup50 and Nup136), and Distal ring (Tpr/NUA), as well as GLE1, ALADIN, CG1, and HOS1 also participate in NPC constitution (Figure 1a). Additionally, MdNup62 interacts with MdNup54, forming the central apple NPC channel involving in nucleocytoplasmic transport (Figure S1) (Zhang et al. , 2020).
We examined the expression patterns of NPC components in different tissues of several apple varieties (Figure 1b; Table S1). The expression levels of MdNup62 as central channel component showed significantly higher in buds, stem, roots than in fruit of apples, but other channel component MdNup54 showed significantly low expression levels in all tissues compared with MdNup62 , indicating that MdNup62 play a key role in regulation of growth and stress response by controlling nucleocytoplasmic transport in apple.