Figure 4: Ethylene production and its regulatory mechanisms in three cotton species (G. raimondii, G. arboreum and G. hirsutum).
(a) Comparisons of ethylene production from cultured ovules collected at 1 DPA and cultured for 14 d, with air samples collected at the different time points as shown. Data reported are the mean ± s.e.m. from three independent ovule culture experiments, with triplicate measurements for each sample. (b,c) Electrophoretic mobility shift assays (EMSA) showing the specific binding complex on the P6 fragment of ACO1 (b) and ACO3 (c) promoters. 32P-labeled probes were incubated with nuclear protein samples prepared from 10-DPA G. hirsutum ovules. Dotted lines shown on the top of each panel show the lost sequences in the corresponding genome with the red boxes representing MYB binding sites. In each panel, one representative EMSA obtained using probes originating from the Dt or the At subgenomes of G. hirsutum is shown in the middle, and data obtained using probes produced from G. arboreum (Ga) or G. raimondii (Gr) in the bottom. (d) Comparisons of the binding activity on P6 from ACO1 and ACO3 promoter regions of the three different cottons. Shown are data obtained from nucleoproteins prepared from 0-, 3-, 5-, 10-, 15- and 20-DPA ovules and incubated with P6 originating from G. raimondii, from the Dt copy of G. hirsutum and from G. arboreum. Error bars, mean ± s.e.m. from three independent EMSA experiments. (e) Phylogenetic and evolutionary analysis of ACO1 and ACO3 promoter regions from G. raimondii, G. arboreum and T. cacao. Scale bars, 100 bp. Statistical significance was determined using one-way analysis of variance software. *P < 0.05, **P < 0.01, ***P < 0.001.
