Figure 1.

DELLA protein complex is required for the mycorrhizal symbiosis. (A) Confocal images of R. irregularis colonization stained with wheat germ agglutinin (WGA)-conjugated Alexa Fluor 488 at 6 weeks post inoculation. Left, middle and right panels show normal arbuscule development in wild-type, no colonization in slr1 and occasional colonization events in slr1 mutant. Scale bars, 150 μm. (B) Internal root length colonization of slr1 mutants at 6 weeks post inoculation with R. irregularis. The experiment was repeated three times and representative data is shown. Error bars show standard errors. (C) Interactions between SLR1 and DIP1 in a Y2H assay. (D) Protein-protein interactions in N. benthamiana leaves revealed by BiFC. YFP fluorescence of leaves co-transformed with SLR1-YFPc (C-terminal half of YFP) or OsRAM1-YFPc and DIP1-YFPn (N-terminal half of YFP). No YFP fluorescence in OsRAM1-YFPn/YFPc, OsRAM1-YFPn/SLR1-YFPc, DIP-YFPn/YFPc and YFPn/SLR1-YFPc. (E) The MBP-DIP1 fusion protein interacts with His-SLR1 in pull-down assays using heterologously expressed proteins in E. coli. (F) A time course (10-40 DPI) of relative expression of DIP1 following R. irregularis inoculation. These experiments were replicated two times. Bars represent standard error. (G) Ink stained roots of rice reveal a greatly reduced level of infection in the DIP1 RNAi lines at 6 weeks post inoculation. Scale bars, 150 μm. (H) Quantification of R. irregularis colonization levels in 8 independent DIP1 rice RNAi lines at 6 weeks post inoculation (CK, empty vector control). (I) Interactions between DIP1, OsRAM1 and MtRAM1 are shown in a Y2H assay. (J) The MBP-DIP1 fusion protein can interact with His-OsRAM1 in pull-down assays with heterologously expressed proteins in E. coli. In (C, I): BD, binding domain; AD, activation domain. -LT, SD/-Leu-Trp; -LTHA, SD/-Leu-Trp-His-Ade. 30 mM 3-AT (3-aminotriazole) was used to suppress protein autoactivation.