Figure 3.

Effects of Dominant Repression of SND1 on Secondary Wall Thickening in Fibers.

The full-length SND1 cDNA was fused in-frame with the dominant EAR repression sequence and transformed into Arabidopsis plants. The phenotypes of the transgenic plants were examined. co, cortex; if, interfascicular fiber; ve, vessel; xf, xylary fiber. Bars = 75 μm in (C) and (D), 35 μm in (E), (F), (I), and (J), and 2.4 μm in (G) for (G), (H), (K), and (L).

(A) RT-PCR analysis showing expression of the SND1 repressor (SND1-SRDX) in the stems of three representative transgenic Arabidopsis lines. The expression of the endogenous SND1 gene (SND1) is shown for comparison.

(B) Wild type plant (left) and a transgenic Arabidopsis plant expressing the SND1 repressor (right).

(C) and (D) Longitudinal sections of the interfascicular region of stems showing the similar length of fiber cells in the wild type (C) and the SND1 repressors (D).

(E) and (F) Cross sections of the interfascicular region showing that the interfascicular fibers of SND1 repressors (F) had thin walls compared with those of the wild type (E).

(G) and (H) Transmission electron micrographs of interfascicular fiber walls of the wild type (G) and the SND1 repressors (H).

(I) and (J) Cross sections of the vascular bundle region of the wild type (I) and the SND1 repressors (J).

(K) and (L) Transmission electron micrographs of xylem cells showing that although the wall thickness of vessels was not changed, that of the xylary fibers was reduced severely in the SND1 repressors (L) compared with the wild type (K).