Fig. 2

The ccd7 mutants showed impaired SL biosynthesis and decreased SL-dependent biological activity: a GR24 treatment rescued the tillering phenotype of all T₁-mutant lines. One-week-old seedlings were grown in 50-ml tubes and GR24, a synthetic SL analog, was applied twice a week at 2.5 μM for 3 weeks. Cas9ox (Cont.), the SL-deficient mutant d17, and the SL-perception mutant d3 were used as controls. Tillering inhibition by GR24 feeding indicated that the high-tillering phenotype appeared because of lack of SLs biosynthesis. b-c Tillers per plant were recorded with or without GR24 treatment after 3 weeks of application. No. of tillers per plant were significantly reduced after GR24 treatment. Bars represent means ±SE (n = 6). Means not sharing a letter in common differ significantly at P_0.05. d Striga germination bioassay was conducted to measure SL bioactivity in T₁ mutant lines. The rice plants were grown under normal conditions for 3 weeks. Then in 4th week each line was grown under phosphate-deficient conditions for another week. The SLs were extracted from root exudates of each line and applied to pre-conditioned Striga seeds. Very low Striga seed germination was observed in mutants compared to control, indicating SL deficiency in these lines. Graph shows percent Striga germination in response to root exudates collected from each line. Cas9ox (Cont.) and d17 were used as control plant lines; in addition, the SL analog GR24 and H₂O were applied to Striga seeds with no root extracts for controls to show maximum and minimum germination. e LC–MS/MS analysis using multiple reaction monitoring (MRM) of rice root exudates. The MRM transitions for various SLs from root exudates of control, d17 and ccd7 T₁-mutant lines were observed. All of the mutants and d17 did not show any detectable signals for SLs. The chromatogram showed peaks for 4-deoxystrigol in the internal standard and control. One of the mutants (dl1) chromatogram is shown as an example