In situ localization of PNZIP mRNA
in different P. nil organs and following various light
treatments. Seedlings were grown in continuous light for 6 d and
then were exposed to 12 h of darkness or were interrupted at the
8th h by a 10-min NB with red light. Afterward, longitudinal and
transverse sections (7 μm thick) through the shoot meristem,
hypocotyl, cotyledon, and leaf tissues were collected and
hybridized with a PNZIP antisense RNA probe (A–C, E, G,
I, and J) or a PNZIP sense RNA probe as a control (D, F,
and H). Probes were labeled with digoxigenin-UTP. The
transcript-specific hybridization signal is shown in purple. A,
Vegetative shoot meristem of a 7-d-old seedling. B, Young expanding
leaf taken from the fourth or fifth position below the shoot meristem.
C, Hypocotyl. D, Hypocotyl hybridized with a PNZIP sense
RNA probe as a control. E, Cotyledon. F, Cotyledon hybridized with a
PNZIP sense RNA probe as a control. G, Leaf. H, Leaf
hybridized with a PNZIP sense RNA probe as a control. I,
Higher magnification of a young leaf. J, Young leaf after an NB
treatment. ep, Epidermis; lb, leaf blade; le, leaf; me, mesophyll; mv,
main vein; su, subepidermis; tr, trichome; vm, vegetative meristem; and
vt, vascular tissue. Bar = 25 μm.