Figure 4.

In Situ Localization of Lox1 Class Transcripts in Developing Tubers.

Thin sections (8 μm) through a new tuber were hybridized with digoxigenin-labeled RNA probes that were synthesized from a full-size POTLX-1 cDNA in either the sense or the antisense orientation. Accumulation of Lox1 class mRNA bound to the antisense digoxigenin-labeled probe was visualized by alkaline phosphatase activity and is seen as an orange-brown stain on the dark-field micrographs. ct, cortex; l, newly formed leaf; p, pith; vt, vascular tissue.

(A) to (D) Transverse sections through a new tuber were hybridized with POTLX-1 antisense riboprobe. The approximate locations of the transverse sections correspond to the labeled arrows in (E). Hybridization signals were detected in (B) and (C) but not in (A) and (D). The arrows in (B) indicate endodermis. (A) (D).

(E) A longitudinal section through a new tuber was hybridized with POTLX-1 antisense probe. .

(F) Close-up micrograph of the longitudinal section hybridized to the antisense probe shown in (E). The photographed area covers the junction of the stolon and the proximal portion of the new tuber. Note that the hybridization signal is not detected in this portion of the new tuber.

(G) Close-up micrograph of the longitudinal section hybridized to the antisense probe shown in (E). The photographed area covers the subapical portion of the new tuber.

(H) Close-up micrograph of the longitudinal section hybridized to the antisense probe shown in (E). The photographed area covers the apical region of the new tuber. The arrow indicates the apical dome in which Lox1 class transcripts accumulate to high levels. (H) (F) (H).

(I) In situ hybridization negative control. A longitudinal section through a new tuber was hybridized with POTLX-1 sense probe. No hybridization signal was detected. .