Fig. 4: Proline alleviates the fungal non-self recognition reaction by inhibiting vic-related gene expression and ROS accumulation.

A Evans blue staining of two incompatible strains 1980m and Ep-1PNA367G co-cultured on PDA and PDA + P, for the detection of the necrotic zone and PCD response at their interface. The interface region indicated by the white frame in the upper panel was enlarged in the lower panel. Scale bar, 3 mm. B TEM visualization of cell fusion between Ep-1PNA367G and 1980m on PDA and PDA + P. The fusion pore is indicated by white arrows. The vacuole formation and organelle degradation are indicated by asterisks, and cell wall thickening is indicated by black arrows. Scale bar, 1 µm. C PI staining and visualization using confocal microscopy for detection of the cell death at the interface between 1980m and Ep-1PNA367G on PDA and PDA + P. The white box indicates regions where apoptosis occurs in the two incompatible strains stained by PI, while the addition of proline significantly reduces the extent of apoptosis in these regions. Scale bar, 50 µm. D Ep-1PNA367G and 1980m interface on PDA and PDA + P visualized under confocal microscopy; the orientation of the arrows indicates that the hyphae originally labeled with one fluorescent group showed a signal of another fluorescent group, suggesting the fusion of hyphae carrying different fluorescent labels. Scale bar, 50 µm. E Volcano plot showing the number of DEGs in co-cultured VIC strains on PDA and PDA + P. F GO enrichment analysis of down-regulated DEGs from (E). The pathways marked by magenta are closely related to PCD or ROS. G Heatmap showing the expression levels of vic-related genes when two VIC strains interface on PDA, PDA + P, and oilseed rape plants. H Expression levels of genes related to G proteins and ROS in strain 1980 alone, and co-cultured with Ep-1PNA367 on PDA and PDA + P, as shown by RT-qPCR. Data are mean ± SD of n = 3 independent experiments. I NBT staining of 1980m treated with supernatant from Ep-1PNA367G. Scale bar, 0.5 cm. J Transmission efficiency of SsDRV and SsRVL from Ep-1PN to 1980m or deletion transformants (n = 24 for co-cultures). Source data are provided as a Source Data file.