Figure 7.

Effects of auxin and ethylene on cell wall formation of fibers on in vitro cultured ovules of GhMYBL1 RNAi cotton. A) Ultrathin cross-sections of fibers. The ovules with fibers (at 1 DPA) collected from the GhMYBL1 RNAi transgenic plants (MRiL4 and MRiL5) and WT were in vitro cultured in BT medium with 2.5 or 10 µm IAA and 0.1 µm ACC or 5 µm AVG for 25 d, and then fibers were sectioned and photographed by TEM. Scale bars = 2.0 µm. The ovules cultured in BT medium with 5 µm IAA were used as control (CK). The rectangle marked at a comparable and magnified position in each fiber cell. Scale bars = 1.0 µm. B) Measurement and statistical analysis of cell wall thickness of fibers on the cultured ovules in A (n ≥ 50, and at least 30 ovules from 20 bolls per group). C) RT-qPCR analysis of GhMYBL1 expression in fibers on the GhMYBL1 RNAi ovules cultured in vitro in A). D to I) RT-qPCR analysis of GhCesAs expressions in fibers on ovules of the GhMYBL1 RNAi lines cultured in vitro in A). The mean value and Sd were calculated from 3 biological replicates. Values marked with different letters indicate statistically significant differences (P < 0.05) between each group according to the Tukey HSD multiple range test. MRiL, GhMYBL1 RNAi transgenic cotton lines.