Figure 4

Co-silencing of Na α-dox1 and Na α-dox2 reduced plant growth of Nicotiana attenuata. (A) Relative transcript abundance of Naα-dox genes (mean ± SE of 5 biological replicates) in plants subjected to virus-induced gene silencing (VIGS). Wild-type plants (WT) and plants stably silenced for Naα-dox1 using an inverted repeat (IR) construct were inoculated with VIGS constructs when 22 days old. Gene expression levels relative to empty vector controls (ev) confirm the gene specific silencing of Naα-dox1 and Naα-dox2 and was analyzed in rosette leaves by SYBR Green-based real time PCR (B) Rosette diameter of 39-days old and (C) stalk length of 60-days old plants (mean ± SE of 11 biological replicates) silenced for Naα-dox1 and Naα-dox2 by VIGS. Stable and transient silencing of only Naα-dox1 as well as transient silencing of only Naα-dox2 did not affect plant growth, but the silencing of Naα-dox2 in a stable line silenced for Naα-dox1 resulted in stunted growth. Different letters signify significant differences in growth parameters or transcript abundance of Naα-dox1 (in black) and Naα-dox2 (in gray and brackets) respectively (ANOVAs with factor transformant: for rosette diameters F_4,50 = 12.81, P < 0.0001 for stem length F_4,50 = 197.87, P < 0.0001; Fischer's PLSD comparisons between VIGSα-dox2 in IR _α-dox M vs. all other transformants P < 0.0001, whereas for comparisons between all other transformants P > 0.21).