Feature, expression, and subcellular localization analyses ofMdNup62
We initially performed a simple bioinformatics analysis ofMdNup62 . A phylogenetic tree of Nup62 from six Rosaceae
plants (Rosa chinensis , Pyrus communis ,Prunus persica , M. domestica , Rubus occidentalis ,
and Fragaria vesca ) was constructed using MEGA-X. MdNup62was most closely related to the Nup62 of pear (Figure 2a). The
aligned protein sequences revealed a conserved Nsp1_C domain (Figure
2b). The subcellular localization of MdNup62 was determined by
introducing 35S::MdNup62 -GFP into tobacco leaves (Figure 2c).
Tobacco leaves transformed with the empty vector 35S::GFP were used as
controls. In the tobacco leaves expressing 35S::MdNup62 -GFP, the
GFP signal was observed only in the nuclear pore, while the GFP signal
was detected throughout the control tobacco leaf cells, indicating thatMdNup62 localized to the nuclear pore.
The transcript levels of MdNup62 in different tissues were
determined using qRT-PCR (Figure 2d). The highest expression level was
in flower buds. An MdNup62 expression analysis during the flower
bud developmental stages revealed that the expression level was stable
at 30 to 60 days after flowering and reached its highest level at 70
days after flowering (Figure 2e).
Thus, MdNup62 maintained a
high expression level during flower bud induction, indicating that it
may be related to bud differentiation in apple.
We exposed apple tissue-cultured seedlings to a heat treatment. The
reactive oxygen species (ROS) accumulation in leaves increased from 0 to
6 h under heat-treatment conditions (Figure 2f). Moreover, the
expression level of MdNup62 was determined at different times
during the high-temperature treatment (Figure 2g). MdNup62 was
significantly induced by high temperature, and its expression level was
highest at 1 h after exposure to the high temperature. Thus,MdNup62 may be involved in the heat-resistance pathway of apple.